Ipser et al.: Ground-Dwelling Ants in Georgia

A SURVEY OF GROUND-DWELLING ANTS
(HYMENOPTERA: FORMICIDAE) IN GEORGIA

REID M. IPSER, MARK A. BRINKMAN, WAYNE A. GARDNER AND HAROLD B. PEELER
Department of Entomology, University of Georgia, College of Agricultural and Environmental Sciences
Griffin Campus, 1109 Experiment Street, Griffin, GA 30223-1797, USA

ABSTRACT

Ground-dwelling ants (Hymenoptera: Formicidae) were sampled at 29 sites in 26 counties in
Georgia with pitfall traps, leaf litter extraction, visual searching, and bait stations. We found
96 ant taxa including nine species not previously reported from Georgia: Myrmica ameri-
cana Weber, M. pinetorum Wheeler, M. punctiventris Roger, M. spatulata Smith, Pyramica
wrayi (Brown), Stenamma brevicorne (Mayr), S. diecki Emery, S. impar Forel, and S.
schmitti Wheeler, as well as three apparently undescribed species (Myrmica sp. and two Ste-
namma spp.). Combined with previous published records and museum records, we increased
the total number of ground-dwelling ants known from Georgia to 144 taxa.

Key Words: ground-dwelling ants, Formicidae, survey, Georgia, species.

RESUME
Hormigas que habitan en el suelo (Hymenoptera: Formicidae) fueron recolectadas en 29 si-
tios en 26 condados del estado de Georgia con trampas de suelo, extraci6n de hojarasca, bus-
queda visual, y trampas de cebo. Nosotros encontramos 96 taxa de hormigas incluyendo
nueve species no informadas anteriormente en Georgia: Myrmica americana Weber, M.pin-
etorum Wheeler, M. punctiventris Roger, M. spatulata Smith, Pyramica wrayi (Brown), Ste-
namma brevicorne (Mayr), S. diecki Emery, S. impar Forel, y S. schmitti Wheeler, ademas de
tres species aparentemente no descritas (Myrmica sp. y dos Stenamma spp.). Al juntar es-
tos datos con las publicaciones y registros de museos, nosotros aumentamos el nmmero de
hormigas conocidas que habitan el suelo en Georgia a un total de 144 taxa.

The state of Georgia in the southeastern
United States is characterized by a relatively
wide range of soil, topographic and climatic condi-
tions. The eight Major Land Resource Areas (ML-
RAs) identified in the state are (1) Atlantic Coast
Flatwoods, (2) Southern Coastal Plains, (3) Caro-
lina and Georgia Sand Hills, (4) Black Lands, (5)
Southern Piedmont, (6) Southern Appalachian
Ridges and Valleys, (7) Sand Mountains, and (8)
Blue Ridge (USDA-SCS 1981). Each MLRA is
characterized by a unique combination or pattern
of soils, climate, water resources, and land use.
These factors, in turn, affect the biotic communi-
ties and habitats as well as the floral and faunal
characteristics of each.
The diversity and abundance of ants (Hy-
menoptera: Formicidae) in Georgia are relatively
unknown. Wheeler (1913) published a list of 72
ant species collected in Georgia by J. C. Bradley
and W. T. Davis; taxonomic revisions have since
decreased this list to 62 species. Since that publi-
cation, museum records and collections have been
the primary sources of occurrence and distribu-
tion of ant species in the state; these data are lim-
ited in scope. With the exception of Florida
(Johnson 1986; Deyrup 2003) and South Carolina
(Smith 1934), surveys for ant species are also lim-
ited from areas bordering Georgia.

The objective of the study reported herein was
to collect, identify, and catalog ground-dwelling
ant species from representative MLRAs in Geor-
gia. Undisturbed habitats were purposely sam-
pled to avoid high population levels of two
invasive ant species-Solenopsis invicta Buren
and Linepithema humile (Mayr)-that occur
throughout the state and reportedly compete with
and displace other ant species (Porter & Savig-
nano 1990; Holway 1999).

MATERIALS AND METHODS

Sample Methods and Sites

Twenty-nine sites were sampled 1 to 4 times be-
tween June 2000 and September 2002 for ground-
dwelling ants (Fig. 1). Most sites were located in
state parks; others were on state-owned proper-
ties. The sites represented six of the eight MLRAs
identified in Georgia. Information and characteris-
tics of each collection site are listed in Table 1.
Each site was 600 m2 and was located in
wooded areas and at least 60 m from any paths,
roads, or right-of-ways. Sampling methods em-
ployed were pitfall trapping, extraction from leaf
litter collections, visual searching, and baiting as
described by Agosti & Alonso (2000) and Bestle-

Florida Entomologist 87(3)

254

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@2

September 2004

.a;
Fran

EUB
is

20

a~

. "-, ON

S

EMJS.

o20

I in
021

A S
O 0 W

"-r

,
Mcmi .'

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:rrr

Fig. Georgia sites sampled for ground-dwelling ants, 2000-2002.

Fig. 1. Georgia sites sampled for ground-dwelling ants, 2000-2002.

meyer et al. (2000). For each sampling event, 20
pitfall traps were placed individually at 1-m in-
tervals along a transect. Traps were 40-ml plastic
vials filled to 60% of container volume with propy-
lene glycol. The vials were placed in the ground
with the upper opening level with the soil surface.
The traps remained in the ground for 7 d when
they were removed, capped, and transported to
the laboratory for processing. Leaf litter was
gathered by hand from several locations within
the 600 m2 site. These were combined and placed
in a 50-L plastic bag, stored on ice, and trans-
ported to the laboratory. In the laboratory, litter

samples were divided and placed in Berlese fun-
nels (Agosti & Alonso 2000) for 24 h to separate
ants. Bait stations used were those described by
Brinkman et al. (2001). Tuna packaged in oil, was
placed in a thin layer over the surface of a 2.5-cm
diam filter paper disk (Whatman no. 1) in a plas-
tic Petri dish (10 x 35 mm). Ten stations were
placed individually at 2-m intervals along a
transect. The stations remained uncovered on the
ground for 2 h. They were then covered, placed on
ice, and transported to the laboratory for process-
ing. The ground, tree trunks, fallen trees, and
other surfaces were visually searched for ants at

A!,

0
^ * '

-4MTO
\'^~aw-r

0
iSl

_ _:- _

TABLE 1. LOCATIONS AND CHARACTERISTICS OF SITES SAMPLED FOR GROUND-DWELLING ANTS IN GEORGIA, 2000-2002. ALL STUDY SITES WERE IN STATE-OWNED PROPERTY
(STATE PARKS OR UNIVERSITY OF GEORGIA).

Survey Site Sites County N;W Major Land Resource Areas Elevation

Cloudland Canyon
Sloppy Floyd
Fort Mountain
Red Top Mountain
Vogel
Amicalola Falls
Unicoi
Black Rock Mountain
Tallulah Gorge
John Tanner
Fort Yargo
UGA Whitehall Forest
Victoria Bryant
Tugaloo
Richard B. Russell
Bobby Brown
UGA Griffin Campus
Indian Springs
High Falls
Elijah Clark
Mistletoe
Providence Canyon
George L. Smith
Seminole
Reed Bingham
Laura S. Walker
Sapelo Island Dunes
North Sapelo Island
UGA Bamboo Farm

Dade
Chattooga
Murray
Bartow
Union
Dawson
White
Rabun
Rabun
Carroll
Barrow
Clarke
Franklin
Franklin
Elbert
Elbert
Spalding
Butts
Monroe
Lincoln
Columbia
Stewart
Emanuel
Seminole
Colquitt
Ware
McIntosh
McIntosh
Chatham

34 50.4; 085 28.9
34 26.4; 085 20.2
34 46.6; 084 42.5
34 08.6; 084 42.2
34 46.1; 083 54.9
34 34.2; 084 14.7
34 43.9; 083 43.6
34 54.4; 083 24.3
34 44.4; 083 23.3
33 36.1; 085 09.9
33 57.9; 083 43.4
3353.7; 08321.9
34 17.7; 083 09.7
24 29.5; 083 04.4
34 10.8; 082 45.9
33 58.1; 082 34.6
33 16.0; 084 17.2
33 14.9; 083 55.5
33 10.3; 084 00.7
33 51.3; 082 24.0
33 39.9; 082 22.9
32 04.0; 084 54.3
32 32.7; 082 07.5
30 48.2; 084 52.7
31 09.6; 083 32.3
31 08.5; 083 12.9
31 23.4; 081 15.9
31 23.4; 081 15.9
31 59.9; 08116.2

Sand Mountain
Sand Mountain/Southern Appalachian
Southern Appalachian/Blue Ridge
Southern Appalachian/Blue Ridge
Blue Ridge
Blue Ridge
Blue Ridge
Blue Ridge
Blue Ridge
Southern Piedmont
Southern Piedmont
Southern Piedmont
Southern Piedmont
Southern Piedmont
Southern Piedmont
Southern Piedmont
Southern Piedmont
Southern Piedmont
Southern Piedmont
Southern Piedmont
Southern Piedmont
Southern Coastal Plain
Southern Coastal Plain
Southern Coastal Plain
Southern Coastal Plain
Atlantic Coast Flatwoods
Atlantic Coast Flatwoods
Atlantic Coast Flatwoods
Atlantic Coast Flatwoods

602 m
303 m
906 m
325 m
236 m
900 m
887 m
1055 m
539 m
332 m
303 m
887m
236 m
374 m
214m
89 m
307 m
193 m
178 m
154 m
163 m
222 m
123 m
35 m
78 m
47m
Om
19 m
19 m

Florida Entomologist 87(3)

September 2004

TABLE 2. LIST OF GROUND-DWELLING ANTS COLLECTED IN GEORGIA 2000-2002 SURVEY WITH COLLECTION SITE (S)
NOTED.

Species

Acanthomyops interjectus (Mayr)
Amblyopone pallipes (Haldeman)
Aphaenogaster ashmeadi (Emery)
Aphaenogaster fulva Roger
Aphaenogaster lamellidens Mayr
Aphaenogaster miamiana Wheeler
Aphaenogaster picea/rudis/texana complex2
Aphaenogaster tennesseensis (Mayr)
Brachymyrmex depilis Emery
Brachymyrmex musculus Forel
Camponotus americanus Mayr
Camponotus castaneus (Latreille)
Camponotus floridanus (Buckley)
Camponotus nearcticus Emery
Camponotus pennsylvanicus (De Geer)
Camponotus subbarbatus Emery
Crematogaster ashmeadi Mayr
Crematogaster cerasi (Fitch)
Crematogaster lineolata (Say)
Crematogaster minutissima Mayr
Cyphomyrmex rimosus (Spinola)
Dorymyrmex bureni Trager
Dorymyrmex insanus (Buckley)
Forelius analis (Andre)
Forelius pruinosus (Roger)
Formica archboldi Smith
Formica exsectoides Forel
Formica pallidefulva Latreille
Formica rubicunda Emery
Formica schaufussi Mayr
Formica subintegra Wheeler
Formica subsericea Say
Hypoponera opaciceps (Mayr)
Hypoponera opacior (Forel)
Lasius alienus
Lasius neoniger Emery
Leptothorax curvispinosus Mayr
Leptothorax pergandei Emery
Leptothorax schaumii Roger
Leptothorax smith Baroni Urbani
Linepithema humile (Mayr)
Monomorium minimum (Buckley)
Monomorium viride Brown
Myrmecina americana Emery
Myrmica americana Weber
Myrmica pinetorum Wheeler
Myrmica punctiventris Roger
Myrmica spatulata Smith
Myrmica sp. (undescribed)3
Odontomachus brunneus (Patton)

Survey sites'

5
6,8,21,9
10,28
6,10,11,18,19
11,16,18,19
27
1,2,3,4,5,6,7,8,9,10,11,12,13,14,16,18,19,20,21,23,29
23
18,19,22,23,24,25,26,29
23,29
1,2,4,10,11,14,18,19
10,14,29
19,24,29
10,21,26
1,2,4,8,9,10,11,18,19,23
1,19
2,4,9,10,11,12,14,16,18,19,20,21,23,26,28,29
29
1,2,7,9,11,12,14,18,19,20
10,18,19
22,24,25,26
22,25,26,27,29,26
25,29
10,14,18,19,29
25
10
1
6,10,14,17,19,20,21,23,29
1
10,19
10
1,5,6,7,9,10,11,18,20
5,7,18,20,23,29
10,17,18,19,20,21,23,29
5,6,8,18,19,25,29
10
2,3,4,9,10,11,29
9,16,24,28,29
14,19

10,17,21,25
1,10,18,19,21
27
1,3,4,5,8,9,10,11,13,14,16,20,21
6,18,23
19
5,7,8,9,10,18,19
5,9
6
29

Sites and site information are provided in Table 1.
'Aphaenogasterpicea/rudis/texana complexincludes A. picea (Wheeler), A. picea rudis Enzmann, A. texana Wheeler, and A. tex-
ana carolinensis Wheeler species (S. Cover, personal communication).
'Previously undescribed species (S. Cover, personal communication).
'Solenopsis molesta complexincludes S. carolinensis Forel, S. molesta (Say), S. pergandei Forel, S. texana Emery, S. truncorum
Forel species (S. Cover, personal communication).
'Two previously undescribed species and first records from Georgia (S. Cover, personal communication).

Ipser et al.: Ground-Dwelling Ants in Georgia

TABLE 2. (CONTINUED) LIST OF GROUND-DWELLING ANTS COLLECTED IN GEORGIA 2000-2002 SURVEY WITH COLLEC-
TION SITE (S) NOTED.

Species

Survey sites'

Pachycondyla chinensis (Emery)
Paratrechina arenivaga Wheeler
Paratrechina faisonensis (Forel)
Paratrechina parvula (Mayr)
Paratrechina vividula (Nylander)
Pheidole adrianoi Naves
Pheidole bicarinata Mayr
Pheidole bicarinata vinelandica Forel
Pheidole crassicornis Emery
Pheidole dentata Mayr
Pheidole dentigula Smith
Pheidole littoralis Cole
Pheidole metallescens
Pheidole morrisii Forel
Pheidole tysoni Forel
Pogonomyrmex badius (Latreille)
Polyergus lucidus Mayr
Ponera pennsylvanica
Prenolepis imparis (Say)
Proceratium croceum (Roger)
Proceratium pergandei (Emery)
Pseudomyrmex ejectus (Smith)
Pyramica bunki (Brown)
Pyramica carolinensis (Brown)
Pyramica ornata (Mayr)
Pyramica rostrata (Emery)
Pyramica wrayi (Brown)
Solenopsis geminata (Fabricius)
Solenopsis invicta Buren
Solenopsis molesta complex4
Stenamma brevicorne (Mayr)
Stenamma diecki Emery
Stenamma impar Forel
Stenamma schmitti Wheeler
Stenamma spp. (2 undescribed species)5
Strumigenys louisianae Roger
Tapinoma sessile (Say)
Trachymyrmex septentrionalis (McCook)

11,14,15,16,18
6,10,12,19,22
1,7,10,11,14,17,19,21,28,29
19
2,4,7,9,10,11,19,20,28,29

10,21,26,29
10,14
18,19,22,23,25,26
1,10,14,16,19,21,23,24,29
10,18,19,23,24,28,29
23
23
29
10,18,19,21,23
27,29
29
1,2,5,6,7,8,9,10,11,14,18,19
1,2,3,5,6,7,8,9,10,11,12,14,16,18,19,20,23
7
19
21
11
3
10,18,19,21
18,19
29
27
10,18,19,21,22,24,25,26,28,29
2,4,7,9,10,11,12,14,17,18,19,21,22,23,24,26,29
18
1,4,5,6,7,8,9,23
18,19
5,6,8,18,19
6
18,19,21,23,29
3,6,8,9,18,19,21
13,14,19,22,23,25

Sites and site information are provided in Table 1.
2Aphaenogasterpicealrudis/texana complexincludes A. picea (Wheeler), A. picea rudis Enzmann, A. texana Wheeler, and A. tex-
ana carolinensis Wheeler species (S. Cover, personal communication).
'Previously undescribed species (S. Cover, personal communication).
'Solenopsis molesta complexincludes S. carolinensis Forel, S. molesta (Say), S. pergandei Forel, S. texana Emery, S. truncorum
Forel species (S. Cover, personal communication).
5Two previously undescribed species and first records from Georgia (S. Cover, personal communication).

each sampling time. The total amount of time
spent on visual searching was 1.5 h, but varied
based on the number of individuals involved in
the search. Ants discovered in the visual searches
were collected, placed in 70% ethyl alcohol, and
transported to the laboratory for processing.
In the laboratory, ant specimens were sepa-
rated and placed in 95% ethyl alcohol. Identifica-
tions were made with keys by Bolton (1994, 2000);
Buren (1968); Creighton (1950); Cuezzo (2000);

Deyrup et al. (1985); DuBois (1986); Gregg (1958);
Holldobler & Wilson (1990); Johnson (1988);
MacKay (2000); Smith (1957); Snelling (1973,
1988); Snelling & Longino (1992); Taylor (1967);
Trager (1984, 1988); Ward (1985, 1988); Wilson
(1955); and Wing (1968), and by comparison with
specimens housed in the University of Georgia
Natural History Museum (Athens, GA). Stefan
Cover (The Museum of Comparative Zoology, Har-
vard Univ., Cambridge, MA) and Mark Deyrup

Florida Entomologist 87(3)

September 2004

TABLE 3. SPECIES OF GROUND-DWELLING ANTS PREVIOUSLY REPORTED TO OCCUR IN GEORGIA BUT NOT COLLECTED IN
THE 2000-2002 STATE SURVEY.

Species

Acanthomyops claviger (Roger)
Acanthomyops murphy (Forel)
Aphaenogaster ashmeadi (Emery)
Aphaenogaster treatae Forel
Camponotus caryae (Fitch)
Camponotus decipiens Emery
Camponotus discolor (Buckley)
Camponotus impressus (Roger)
Camponotus socius Roger
Crematogaster missuriensis Emery
Crematogaster pilosa Emery
Crematogaster sp. (undescribed)
Cryptopone gilva (Roger)
Discothyrea testacea Roger
Dolichoderus mariae Forel
Dolichoderus pustulatus Mayr
Dorymyrmex grandulus (Forel)
Formica difficilis Emery
Formica integra Nylander
Formica nitidiventris Emery
Formica obscuriventris Mayr
Leptothorax bradleyi Wheeler
Leptothorax texanus Wheeler
Monomorium pharaonis (L.)
Myrmica latifrons Starcke
Nievamyrmex carolinensis (Emery)
Nievamyrmex nigrescens (Cresson)
Neivamyrmex opacithorax (Emery)
Paratrechina longicornis (Latreille)
Pheidole pilifera (Roger)
Ponera exotica Smith
Proceratium creek De Andrade
Proceratium crassicorne Emery
Pseudomyrmex pallidus (Smith)
Pyramica abdita (Wesson)
Pyramica angulata (Smith)
Pyramica clypeata (Roger)
Pyramica dietrichi (Smith)
Pyramica laevinasis (Smith)
Pyramica ohioensis (Kennedy & Schramm)
Pyramica pergandei (Emery)
Pyramica pilinasis (Forel)
Pyramica pulchella (Emery)
Pyramica reflexa (Wesson)
Solenopsis picta Emery
Solenopsis tennesseensis Smith
Solenopsis xyloni McCook
Tetramorium bicarinatum (Nylander)

Record

UGANHM'
UGANHM1
Wheeler 1913
Wheeler 1913
UGANHM'
Wheeler 1913
Wheeler 1913
ABS2
Wheeler 1913
ABS2
Wheeler 1913
ABS2
UGANHM1
ABS2
Wheeler 1913
Wheeler 1913
UGA NHM1
Wheeler 1913
Wheeler 1913
Wheeler 1913
Wheeler 1913
Wheeler 1913
ABS2
Wheeler 1913
Wheeler 1913
UGANHM'
UGANHM'
Wheeler 1913
Wheeler 1913
UGANHM'
ABS2
ABS2
ABS2
Wheeler 1913
ABS2
ABS2
UGANHM1
UGANHM1
ABS2
ABS2
ABS2
ABS2
ABS2
ABS2
UGANHM'
ABS2
Jouvenaz et al. 1977
UGA NHM1

University of Georgia Natural History Museum.
'Archbold Biological Station.

(Archbold Biological Station, Lake Placid, FL) con-
firmed species identifications. Voucher specimens
have been deposited in the University of Georgia
Natural History Museum and the Museum of
Comparative Zoology at Harvard University.

RESULTS AND DISCUSSION

Ninety-six species of ground-dwelling ants rep-
resenting 33 genera were collected and identified
in this 2-year survey (Table 2). Of those collected,

Ipser et al.: Ground-Dwelling Ants in Georgia

9 species have not been previously reported from
Georgia. These are Myrmica americana Weber, M.
pinetorum Wheeler, M. punctiventris Roger, M.
spatulata Smith, Pyramica wrayi (Brown), Ste-
namma brevicorne (Mayr), S. diecki Emery, S. im-
par Forel, and S. schmitti Wheeler.
Of those previously unreported species, M.
americana was collected from 3 sites, M. pine-
torum was collected from 1 site, M. punctiventris
was collected from 7 sites, and M. spatulata was
collected from 2 sites. Ants of this genus nest in
soil and in rotting wood and are primarily carniv-
orous, but they will feed on plant exudates such
as nectar (Creighton 1950). In addition, P. wrayi
and S. brevicorne were each collected from 1 site,
S. diecki was collected from 8 sites, S. schmitti
was collected from 5 sites, and S. impar was col-
lected from 2 sites. All Stenamma species are car-
nivorous, and Pyramica are specialized predators
of collembolans (Holldobler & Wilson 1990).
Eleven individuals of Myrmica and 3 individu-
als of Stenamma, possibly representing two spe-
cies, were collected from Amicalola State Park in
Dawson Co. (site 6) and represent as yet unde-
scribed species (S. Cover, pers. comm.). Those
specimens were collected on 2-V-2000, primarily
by pitfall trapping and leaf litter collection.
A review of ant specimens deposited in the
Archbold Biological Station (ABS), the University
of Georgia Natural History Museum (UGANHM),
the lists of ants published by Wheeler (1913), and
a survey conducted by Jouvenaz et al. (1977) re-
veal that 48 species of ground-dwelling ants rep-
resenting 21 genera have been reported from
Georgia but were not collected in the survey re-
ported herein (Table 3). To date, these two lists
(Tables 2 and 3) comprise the ground-dwelling
ant species reported from Georgia. Species col-
lected within the Aphaenogaster picea/rudis/tex-
ana complex and the Solenopsis molesta complex
are footnoted in Table 2.
In terms of occurrence and distribution, Pre-
nolepis imparis (Say) was collected from 17 of the
29 sites sampled, the Aphaenogaster picea/rudis/
texana complex from 21 sites; the Solenopsis mo-
lesta complex from 17 sites, and Crematogaster
ashmeadi Mayr from 16 sites in this survey. All
other species were collected from less than one-
half of the sites. Members of the genus Pheidole
were most numerous with 2,765 individuals rep-
resenting 10 species collected at 14 sites. Dory-
myrmex burnei (Trager), D. insanus (Buckley),
and Cyphomyrmex rimosus (Spinola) were col-
lected only at southern sites, while Amblyopone
pallipes (Haldeman), Ponera pennsylvanica Buck-
ley, and Tapinoma sessile (Say) were collected
from sites in northern Georgia. Pseudomyrmex
ejectus (Smith) was collected from pitfall traps at
one site. Pseudomyrmex spp. are characteristi-
cally arboreal in their habits. These specimens
most likely dropped to the forest floor, and thus

were collected as ground-dwellers. Three species -
the seed harvester Pogonomyrmex badius (La-
treille), the obligate slave raider Polyergus luci-
dus Mayr, and the generalist Aphaenogaster
miamiana Wheeler-were recovered only on
Sapelo Island, a barrier island on Georgia's coast.
The survey reported herein provides a basis for
various ecological studies and assessments. Ant as-
semblages, species composition, and community
structure are important in terms of community ecol-
ogy. For example, in Australia, ants are one of the
most functionally important faunal groups (Mat-
thews & Kitching 1984; Anderson 1992) and are
model organisms for studies in community ecology
(Anderson 1983, 1988, 1991; Greenslade & Halliday
1983). Ants also have been used as bio-indicators in
mine site rehabilitation (Majer 1983, 1985).
Schultz & McGlynn (2000) noted the many in-
teractions that occur between ants and other or-
ganisms within habitats. They further postulated
that if these interactions are understood, one
could predict ecological conditions within a given
habitat based upon the presence or absence of
specific ants. Furthermore, one could correlate
the presence of a specific ant species with specific
ecological conditions, and these correlations could
be used as predictors of ant biodiversity and in-
teractions among ant species (Alonso 2000).
This survey is the first published listing of
ground-dwelling ants in Georgia since Wheeler
(1913). This compilation will serve to support
biodiversity, systematics, and ecological studies
for Georgia and surrounding environs.

ACKNOWLEDGMENTS
Stan Diffie, Vanessa Hammons, and Jeremy David-
son provided technical support. Georgia Department of
Natural Resources provided permission to use state
parks for collection sites. Stefan Cover (The Museum of
Comparative Zoology, Harvard University) and Mark
Deyrup (Archbold Biological Station, Lake Placid, FL)
verified species identifications, and Cecil Smith of the
Georgia Natural History Museum supplied equipment
and allowed access to ant specimens.

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ALONSO, L. E. 2000. Ants as indicators of diversity, pp.
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Florida Entomologist 87(3)

Mao et al.: Sweetpotato Weevil and Drought Stress

INFLUENCE OF DROUGHT STRESS ON SWEETPOTATO
RESISTANCE TO SWEETPOTATO WEEVIL, CYLAS FORMICARIUS
(COLEOPTERA: APOINIDAE), AND STORAGE ROOT CHEMISTRY

LIXIN MAO1, LOUIS E. JETT2, RICHARD N. STORY1, ABNER M. HAMMOND1,
JOSEPH K. PETERSON3 AND DON R. LABONTE4
'Department of Entomology, Louisiana Agricultural Experiment Station
Louisiana State University Agricultural Center, Baton Rouge, LA 70803 USA

2Sweet Potato Research Station, Louisiana Agricultural Experiment Station
Louisiana State University Agricultural Center, Chase, LA 71324 USA
Current address: Department of Horticulture, University of Missouri, Columbia, MO 65211 USA

3USDA-ARS, US Vegetable Laboratory, 2700 Savannah Highway, Charleston, SC 29414 USA

4Department of Horticulture, Louisiana Agricultural Experiment Station
Louisiana State University Agricultural Center, Baton Rouge, LA 70803 USA

ABSTRACT

The effect of drought stress on the resistance of sweetpotato roots to sweetpotato weevil
(SPW), Cylas formicarius (Fab.), was studied in 1997 and 1998 in two genotypes ("Beaure-
gard" and "Excel") with different SPW susceptibility. Storage roots produced under drought
or normal conditions were tested for adult feeding, oviposition, larval survival and pupal
weight in the laboratory under no-choice and free-choice test conditions. The levels of sweet-
potato resin glycoside and caffeic acid in the periderm tissue of the roots were also deter-
mined. Drought-stressed roots received significantly more SPW eggs under no-choice and
free-choice conditions and more feeding punctures under free-choice conditions than non-
stressed roots in 1997. Larval survival rate was significantly lower on drought-stressed
roots. A significant drought effect on feeding, oviposition and larval survival was absent in
1998. Drought stress had no effect on sweetpotato resin glycosides content in both years, but
significantly reduced the content of caffeic acid in 1997. Genotype had a significant effect on
SPW feeding in 1997 and on feeding and oviposition in 1998 under free-choice test condi-
tions, where Beauregard was preferred for both feeding and oviposition. Beauregard also
supported a significantly higher larval survival rate compared with Excel. Resin glycosides
or caffeic acid contents were similar for the two genotypes in 1997, while higher level of resin
glycosides was detected in Excel than in Beauregard in 1998. The interaction between
drought stress and genotype was significant for adult feeding under free-choice conditions
and for larval survival, indicating a different response between the two genotypes.

Key Words: host plant resistance, feeding, oviposition, resin glycosides, caffeic acid.

RESUME

El efecto de estres causado por la sequoia sobre la resistencia de las raices del camote (= ba-
tata) al "gorgojo del camote" Cylas formicarius (Fab.), se studio durante 1997 y 1998 en dos
genotipos ("Beauregard" y "Excel") con susceptibilidad diferentes al insecto. Las raices alma-
cenadas producidas bajo condiciones de sequoia o condiciones normales fueron evaluadas
para la alimentaci6n de adults, la oviposici6n, la sobrevivencia de las larvas, y el peso de las
pupas en el laboratorio bajo condiciones de pruebas de no-alternativa y de selecci6n libre.
Los niveles del gluc6sido de la resina del camote y el acido cafeico en el tejido del peridermo
de las raices tambien fueron determinados. Las raices con el estr6s de la sequoia recibieron
significativamente mas huevos del gorgojo de camote bajo las condiciones de no alternative
y de selecci6n libre y mas picaduras de alimentaci6n bajo las condiciones de no-alternativa
que en las raices sin estr6s en 1997. Un efecto significativo de la sequoia sobre la alimenta-
ci6n, oviposici6n, y sobrevivencia de las larvas no se present en 1998. El estr6s de la sequia
no tenia efecto sobre el contenido de los gluc6sidos de la resina de camote en ambos aios,
pero reduj6 significativamente el contenido del acido cafeico en 1997. El genotipo tuvo un
efecto significativo sobre la alimentaci6n y la oviposici6n en 1998 bajo condiciones de prue-
bas de selecci6n libre, donde el Beauregard fue preferido para la alimentaci6n y la oviposi-
ci6n. El genotipo Beauregard tambien suporto una tasa de sobrevivencia de larvas
significativemente mas alta en comparaci6n con el Excel. El contenido de los gluc6sidos de
la resina o del acido cafeico fueron similares para los dos genotipos en 1997, mientras que
niveles mas altos de gluc6sidos fueron detectados en Excel que en Beauregard en 1998.

Florida Entomologist 87(3)

Sweetpotato weevil (SPW) Cylas formicarius
(Fab.) is a destructive insect pest of sweetpotato
Ipomoea batatas (L.) Lam. worldwide (Chalfant et
al. 1990). It attacks sweetpotato both in the field
and during storage. Adults make feeding and ovi-
position punctures on root surfaces, reducing root
quality and market value. Larvae feed internally
and induce terpenoid production in storage roots
that imparts a bitter taste and renders even
slightly damaged roots unfit for human or animal
consumption (Uritani et al. 1975). The search for
SPW-resistant sweetpotato cultivars has been con-
ducted for decades, but little success has been
achieved partly because of the inconsistent expres-
sion of the resistance (Collins et al. 1991). Sweetpo-
tato exhibits a wide variation in a number of traits
such as yield, dry matter, intercellular space, nutri-
ent content, flavor components, secondary metabo-
lites, and resistance to microorganisms and insects
(Ezell & Wilcox 1958; Hammett 1974; Collins et al.
1987; Woolfe 1991; Clark & LaBonte 1992; Thomp-
son et al. 1992; Marti et al. 1993). Identification of
environmental factors that affect the expression of
resistance and the knowledge of the magnitude of
these variations would assist in the development of
cultivars with stable SPW resistance. In addition,
secondary plant compounds are often associated
with host plant resistance. Sweetpotato resin gly-
cosides and caffeic acid are two such compounds
found in the sweetpotato storage roots that have
shown insecticidal activities (Peterson & Harrison
1992; Peterson et al. 1998; Jackson & Peterson
2000). Any effect of environmental factors on the
level of these two compounds may provide insights
on sweetpotato weevil resistance.
Drought stress is a common abiotic environ-
mental factor that induces physical and/or chem-
ical changes in plants and consequently
influences the associated herbivorous insects
(Holtzer et al. 1988). In this study, both field and
laboratory experiments were conducted to deter-
mine the impact of drought stress on SPW resis-
tance by measuring adult feeding, oviposition,
larval survival, and development (pupal weight)
on storage roots. Two genotypes with different
levels of SPW susceptibility were used. Sweetpo-
tato resin glycosides and caffeic acid contents also
were analyzed.

MATERIALS AND METHODS

Field Experiment

The experiments were conducted at the Sweet
Potato Research Station, Louisiana State Univer-
sity Agricultural Center, Chase, Louisiana, in
1997 and 1998. "Beauregard" and "Excel" were
used because Beauregard, a major cultivar in the
region, is susceptible to SPW and Excel has
shown a moderate level of resistance (Story et al.
1996). The treatments were 2 x 2 factorial combi-

nations of water treatment (drought stressed and
irrigated) by genotype arranged in a randomized
complete block design with 4 replications. Each
plot consisted of four 25-plant rows. Uniform
transplants were mechanically transplanted on
30 June, 1997, and 27 June, 1998 in a Gilbert silt
loam with a pH of 5.6 at 0.3-m spacing within
rows on 1.0-m centered beds. The fields were fu-
migated with TeloneTM C-17 (1,3-dicholropropene)
2 weeks before transplanting. Standard cultural
practices were followed throughout the growing
season (Boudreaux 1994).
The drought stress treatment was initiated 50
days after transplant (DAT) by constructing
moveable rain shelters over the plots to exclude
natural precipitation. The shelters were placed
over the plots wherever there was more than 30%
chance of precipitation in the local weather fore-
cast. Otherwise, the plots were left open. The irri-
gated plots were watered starting 3 weeks after
transplant with drip tubes (3.8 ml/min). Storage
roots were harvested at 120 DAT, cured (30C,
90% RH for 7 d), and stored at 15 2C for about
30 d before the bioassays and chemical analyses
were started.

Insect Rearing

A SPW colony was established in January of
1997 from a field-collected population (about 500
adult insects) and maintained on storage roots of
Beauregard in plastic containers (5.6 L) with
screen covers at 28 2C and 85 10% RH in the
laboratory located at Louisiana State University
Baton Rouge campus. In preparing experimental
insects, 5 fresh storage roots (US #1) were exposed
to about 1000 unsexed adults for 5 d and then re-
moved and kept under the conditions described
above. Emerging adults were collected weekly and
held with fresh storage roots. Female adults 3-4
wk old were used in the bioassays to ensure ade-
quate egg-laying capability (Wilson et al. 1988).

Adult Feeding and Oviposition Bioassay

The bioassay technique was an adaptation of
one previously described by Mullen et al. (1980)
that has been used in several SPW feeding and
oviposition studies (Wilson et al. 1988). The appa-
ratus consisted of a 24-well tissue culture plate
(12.5 x 8.5 x 2.0 cm, Falcon Model 3047, Becton
Dickenson & Co., Lincoln Park, NJ) placed in a
rectangular clear plastic container (17 x 12 x 6
cm, Tri-State Plastic, Dixon, KY). Cores were cut
from storage roots with a cork borer (1.6 cm diam-
eter) and were inserted into the wells so that only
the periderm was exposed. The diameters of the
cores and the wells were the same, providing a
close fit. Female adults were kept without food for
3 h before being introduced into the arena at a
density of 2 weevils per root core. A moist cotton

September 2004

Mao et al.: Sweetpotato Weevil and Drought Stress

ball was placed in the container to prevent desic-
cation of the cores. After 24 h the number of feed-
ing punctures on each root core was counted, and
after 48 h the number of eggs was counted. No-
choice tests were conducted by presenting a single
root core in the arena. Free-choice tests were con-
ducted by presenting 4 root cores in the arena
which were cut from one root (U.S. #1) randomly
selected from each treatment combination. Before
testing, the roots were gently washed with tap
water and allowed to dry. All tests were conducted
at 28 + 5C, 85 10% RH under total darkness to
eliminate light as a variable. For each treatment,
the tests were repeated 4 times with 4 roots (sam-
pling units). Roots from four field blocks were
tested in 4 consecutive weeks.

Larval Survival and Development Bioassay

SPW were reared individually in Petri dishes
by transferring a single egg into a root section
(about 1.5 x 1.5 x 1.5 cm) in a cavity (1-2 mm deep,
4.0 mm diameter) cut with a cork borer. Eggs
were obtained by exposing Beauregard storage
roots to a large number of females for 24 h. A pair
of needle-nosed forceps was used to transfer eggs.
At 12 d after the eggs were deposited, root sec-
tions were examined to determine if eggs had
hatched. Nonviable eggs or rotten root sections
were discarded. At about 25 d after oviposition,
root sections were dissected for pupae. Larval sur-
vival and pupal weight were recorded. Two repli-
cations of each treatment combination were
conducted with sample sizes ranging from 18 to
32 pupae each. The bioassays were conducted un-
der conditions of 28 5C and 85 10% RH in to-
tal darkness.

Chemical Analysis

The chemical analysis was conducted in the
USDA-ARS Vegetable Laboratory, Charleston,
South Carolina. Storage roots were carefully
washed under flowing water and allowed to dry.
Periderm tissue was gently scraped off with a scal-
pel, dried at 50C, and ground to a fine powder in
liquid nitrogen with a mortar and pestle. Subse-
quently the powder was re-dried at 40C and stored
in vials under nitrogen at -20C until analysis.
Powder samples were weighed (200 mg) into Te-
flon-lined, screw-capped test tubes, and 2.0 ml of
methanol were added containing 0.08 mg of chrysin
(recrystallized from amyl alcohol) as an internal
standard. Test tubes were ultrasonicated for 20
min while the surrounding water was ice-cooled.
The tubes were centrifuged and the supernatant
was filtered through Nylon-66 membrane filters
(0.20 pm, Pierce Chemical Company, Rockville, IL)
into auto injector vials. Resin glycosides and caffeic
acid concentrations were analyzed by reverse-
phase HPLC with 20 pl of the solution. For resin

glycosides, a H20/MeOH linear gradient from 60%
to 100% MeOH in 15 min was used and held at
100% MeOH for 25 min; flow rate was 1 ml min-1
and detection was at 230 nm. For caffeic acid, a sec-
ond injection of 20 pl was made, with the same sam-
ple as was used for the resin glycosides analysis. A
H20/MeOH linear gradient from 10% to 100%
MeOH in 35 min was used and held at 100% MeOH
for 25 min; flow rate was 1 ml min-1 and detection
was at 340 nm. Each solvent contained 0.1% HJPO4.
The column used was a Beckman Ultrasphere Cl., 5
pm (4.6 x 250 mm, Beckman and Coulter, Fuller-
ton, CA). Purified reference substances were used
as external standards to determine response factor
versus chrysin for quantification. Reference glyco-
side material was purified by Sephadex column
chromatography followed by semi-preparative
HPLC as described previously (Peterson et al.
1998). Reference caffeic acid was purchased from
Aldrich Chemical Company (Milwaukee, WI).

Data Analysis

The data were analyzed by year using two-way
analysis of variance (PROC GLM, SAS 1990). A
square-root transformation was used for larval
survival data. Year effect was evaluated by ana-
lyzing the data by one-way analysis of variance.
The significance level was a = 0.05.

RESULTS

Adult Feeding and Oviposition

Drought stress significantly increased adult
SPW feeding and oviposition in free-choice tests
and oviposition in no-choice tests in 1997 (Table
1). In 1998, drought stress had no significant ef-
fect on oviposition or on feeding (Table 1). Year ef-
fect was significant on feeding (no-choice test: F =
23.08, df = 1,24, P < 0.0001; free-choice test: F =
10.09, df = 1,24, P = 0.0041) and on oviposition
under both testing conditions (no-choice test: F =
50.51, df = 1,24, P <0.0001; free-choice test: F =
17.50, df= 1,24, P = 0.0003). Beauregard received
more feeding punctures than Excel in free-choice
tests, but not in no-choice tests in 1997. No signif-
icant cultivar effect was found on oviposition in
1997. In 1998, cultivar had a significant effect on
both feeding and oviposition in free-choice tests
where Beauregard was the preferred cultivar, but
there was no cultivar effect in no-choice tests (Ta-
ble 1). The interaction of drought stress and culti-
var was significant for feeding in free-choice tests
in 1997, but not in 1998 (Table 1).

Larval Survival and Development

Drought stress significantly reduced larval
survival rate in 1997, but not in 1998 (Table 2).
No significant drought effect was found on pupal

TABLE 1. THE EFFECT OF DROUGHT STRESS AND CULTIVAR ON SWEETPOTATO WEEVIL ADULT FEEDING AND OVIPOSITION UNDER NO-CHOICE AND CHOICE TEST CONDITIONS
IN 1997 AND 1998.

1997 1998

No-choice test Choice test No-choice test Choice test

Water Feeding Feeding Feeding Feeding
Cultivar treatment punctures' Eggs' punctures' Eggsd punctures' Eggs' punctures' Eggs'

Beauregard Drought 31.0 4.3 9.3+ 1.1 51.6 5.5 9.6 1.5 38.4 4.1 12.4 0.9 46.6 5.9 12.1 1.1
Beauregard Irrigated 27.9 2.3 7.1 0.4 30.8 1.4 8.3 0.7 43.7 5.7 13.2 1.3 50.3 1.6 11.9 0.6
Excel Drought 24.4 1.1 8.8 0.5 26.8 1.9 9.6 1.6 36.3 2.0 12.6 1.2 35.2 4.3 10.6 1.1
Excel Irrigated 25.3 2.7 6.3 0.5 23.1 1.1 6.1 0.6 32.3 5.2 9.31 0.7 36.4 4.9 8.4 0.9

Mean + SEM.
"Water treatment: F = 0.15; df = 1,9; P = 0.7055. Cultivar: F = 2.76; df = 1,9; P = 0.1311. Interaction: F = 0.49; df = 1,9; P = 0.5002.
'Water treatment: F = 13.32; df = 1,9; P = 0.0053. Cultivar: F = 1.04; df = 1,9; P = 0.3335. Interaction: F = 0.06; df = 1,9; P = 0.8132.
Water treatment: F = 25.83; df = 1,9; P = 0.0007. Cultivar: F = 45.86; df = 1,9; P < 0.0001. Interaction: F = 12.59; df = 1,9; P = 0.0062.
'Water treatment: F = 5.90; df = 1,9; P = 0.0380. Cultivar: F = 1.18; df= 1,9; P = 0.3052. Interaction: F = 1.18; df = 1,9; P = 0.3054.
'Water treatment: F = 0.03; df = 1,9; P = 0.8574. Cultivar: F = 3.99; df = 1,9; P = 0.0768. Interaction: F = 1.92; df = 1,9; P = 0.1987.
Water treatment: F = 2.90; df = 1,9; P = 0.1225. Cultivar: F = 2.71; df = 1,9; P = 0.1341. Interaction: F = 1.10; df = 1,9; P = 0.3168.
'Water treatment: F = 0.75; df = 1,9; P = 0.4084. Cultivar: F = 20.38; df= 1,9; P = 0.0015. Interaction: F = 0.20; df = 1,9; P = 0.6670.
hWater treatment: F = 2.72; df = 1,9; P = 0.1332. Cultivar: F = 11.18; df = 1,9; P = 0.0086. Interaction: F = 1.72; df = 1,9; P = 0.2220.

Mao et al.: Sweetpotato Weevil and Drought Stress

weight in both years. Higher larval survival rate
was found on Beauregard than on Excel in 1997
and in 1998 (Table 2). Weevils reared on Beaure-
gard had lower pupal weight than that of Excel in
1997, but not in 1998. Drought and cultivar inter-
action effect was significant for larval survival in
1997, but not in 1998. No significant interaction
effect was found with pupal weight (Table 2). The
test for year effect was not significant for larval
survival (F = 1.18; df= 1,16;P= 0.2936) and pupal
weight (F = 1.34; df = 1,16; P = 0.2642).

Resin Glycosides and Caffeic Acid Contents

Drought stress did not have a significant effect
on the level of resin glycosides in either year (Ta-
ble 3). Drought stress significantly reduced the
level of caffeic acid in 1997, but not in 1998. Excel
tended to have a higher level of resin glycosides
than Beauregard, but this difference was statisti-
cally significant only in 1998. Both genotypes con-
tained similar levels of caffeic acid (Table 3). No
significant interaction effect was found. Year ef-
fect was significant for caffeic acid (F = 88.45; df=
1,21; P < 0.0001), but not for resin glycosides (F =
0.01; df= 1,21;P = 0.9283).

DISCUSSION

The impact of drought stress on plants and its
consequences on herbivorous insects has drawn
much attention. Numerous studies have been re-
ported on the subject with often conflicting results
obtained in different insect-host plant systems
(Holtzer et al. 1988; Koricheva et al. 1998).
Drought is often associated with heavy insect
damage (Kelly 1917; White 1969). Several expla-
nations for this ecological consequence have been
proposed, including higher plant nutritional qual-
ity, more favorable micro-environment, and di-
minishment of plant defense systems (White
1974; Mattson & Haack 1987). More recent stud-

ies regarding the effect of drought stress on in-
sects have focused on evaluating host suitability,
and found that drought-stressed plants often
have reduced suitability. Many insect species,
such as Pseudoplusia includes (Lambert &
Heatherly 1991), Epilachna varivestis (McQuate
& Conner 1990), and Empoasca fabae (Hoffman
et al. 1990, 1991), exhibited a lower feeding and/
or oviposition level, longer development time,
higher mortalities, and lower fecundities when
fed on drought-stressed plants. Our study showed
that drought stress seemed to favor SPW feeding
and oviposition but reduced larval survival rate.
The magnitude of the response of the two geno-
types appeared to differ.
Drought stress may alter the production of sec-
ondary plant compounds (Gershenzon 1984; Holt-
zer et al. 1988). Sweetpotato contains numerous
secondary compounds, which are produced either
constitutively or upon induction by external
agents (Kays 1992). Boehmeryl acetate found in
the periderm tissue of storage roots was identified
as a SPW oviposition stimulant (Son 1989). The
results of this study suggest that drought stress
may increase the activity of this oviposition stim-
ulant because weevils deposited more eggs on
drought-stressed plants. Jackson and Peterson
(2000) reported sublethal effects of sweetpotato
resin glycosides on Plutella xylostella. Caffeic
acid showed adverse effects on a generalist herbi-
vore, Helicoverpa zea (Summers & Felton 1994)
and sweetpotato pathogenic fungi (Harrison et al.
2003a). Recent analyses showed that the levels of
resin glycosides and caffeic acid vary between
sweetpotato genotypes and within genotypes
among years or areas of production (Harrison et
al. 2003a, b). This may indicate a relationship be-
tween the quantity of these two compounds and
the antibiosis of sweetpotato. It also may indicate
that the production of these compounds is subject
to environmental influence. The results in this
study show that drought stress significantly re-

TABLE 2. THE EFFECT OF DROUGHT STRESS AND CULTIVAR ON SWEETPOTATO WEEVIL LARVAL SURVIVAL AND PUPAL
WEIGHT REARED ON STORAGE ROOTS IN 1997 AND 1998.

1997 1998

Water Larval Pupal weight Larval survival Pupal weight
Cultivar treatment survival (%) (mg), (%) (mg)d

Beauregard Drought 95.4 2.5 7.20 0.1 94.5 1.6 7.44 0.3
Beauregard Irrigated 97.4 0.8 7.22 0.1 100.0 0.0 7.68 0.2
Excel Drought 79.4 1.1 7.57 0.2 88.3 4.3 7.61 0.0
Excel Irrigated 91.4 0.1 7.84 0.6 88.9 4.2 8.06+ 0.1

Mean + SEM.
"Water treatment: F=12.02; df=1,9; P=0.0071. Cultivar: F=29.04; df =1,9; P=0.0004. Interaction: F=6.26; df=1,9; P=0.0338.
'Water treatment: F=1.03; df =1,9; P=0.3363. Cultivar: F=12.05; df=1,9; P=0.0070. Interaction: F=0.80; df =1,9; P=0.3956.
'Water treatment: F=1.90; df=1,9; P=0.2014. Cultivar: F=16.27; df=1,9; P=0.0030. Interaction: F=1.23; df =1,9; P=0.2962.
'Water treatment: F=1.73; df =1,9; P=0.2209. Cultivar: F=1.06; df=1,9; P=0.3301. Interaction: F=0.15; df=1,9; P=0.7075.

Florida Entomologist 87(3)

September 2004

TABLE 3. THE EFFECTS OF DROUGHT STRESS AND CULTIVAR ON RESIN GLYCOSIDE AND CAFFEIC ACID LEVELS IN PERI-
DERM TISSUE OF SWEETPOTATO STORAGE ROOTS IN 1997 AND 1998.

1997 1998

Water Resin glycoside Caffeic acid" Resin glycoside Caffeic acidd
Cultivar treatment (% DW) (% DW) (% DW) (% DW)

Beauregard Drought 0.84 0.150 (3) 0.17 0.071 (3) 0.86 0.100 (3) 0.44 0.021 (3)
Beauregard Irrigated 0.74 0.212 (4) 0.31 + 0.025 (4) 0.75 0.081 (4) 0.44 0.037 (4)
Excel Drought 2.16 1.052 (4) 0.18 0.001 (4) 1.54 + 0.151 (3) 0.46 0.009 (3)
Excel Irrigated 1.10 + 0.125 (4) 0.22 0.015 (4) 1.73 + 0.155 (4) 0.44 0.019 (4)

Mean + SEM (sample size); DW = dry weight.
"Water treatment: F = 2.56; df= 1,8; P = 0.1481. Cultivar: F = 1.55; df= 1,8; P = 0.2483. Interaction: F
'Water treatment: F = 8.24; df= 1,8; P = 0.0198. Cultivar: F = 1.62; df= 1,8; P = 0.2389. Interaction: F:
'Water treatment: F = 1.20; df= 1,7; P 0.3100. Cultivar: F= 62.37; df= 1,7; P< 0.0001. Interaction: F
dWater treatment: F = 1.86; df= 1,7; P= 0.2150. Cultivar: F = 0.69; df= 1,7; P = 0.4342. Interaction: F

duced the level of caffeic acid but had no effect on
the level of resin glycosides, suggesting that the
lower larval survival rate observed on drought
stressed plants was not due to higher caffeic acid
or resin glycoside content. It appears that there is
no relationship between the level of these two
compounds and sweetpotato weevil resistance.
This is possibly because of the feeding behavior of
the weevil, in which weevils chew through the
periderm and feed primarily on the tissue be-
neath it, thereby avoiding the periderm layer.
In addition, the effect of drought stress on
SPW resistance and on the storage root chemistry
was not consistent between years. Significant
drought effects in 1997 diminished in 1998. This
may be due to the unusual hot and dry conditions
in the area in 1998, in which all plots perhaps
were stressed.

ACKNOWLEDGMENTS

The authors thank Drs. Mike Stout, Richard Goyer,
and Thomas Riley for reviews, and Jeff Murray and
Aboubacar Diagne for assistance in conducting the
study. The authors also thank anonymous reviewers for
comments on the manuscript. Approved for publication
by the Director of the Louisiana Agricultural Experi-
ment Station as manuscript number 02-17-0245.

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Florida Entomologist 87(3)

September 2004

SURVEY OF PARASITOIDS OF WHITEFLIES (HOMOPTERA: ALEYRODIDAE)
IN CASSAVA GROWING REGIONS OF COLOMBIA AND ECUADOR

H. E. TRUJILLO1, B. ARIAS1, J. M. GUERRERO', P. HERNANDEZ1, A. BELLOTTI1 AND J. E. PENA2
'Centro Internacional de Agricultura Tropical, CIAT, A.A. 6713, Cali, Colombia

2University of Florida, Department of Entomology and Nematology
Tropical Research and Education Center, Homestead, FL USA

ABSTRACT

A survey for parasitoids of the whiteflies, Bemisia tuberculata Bondar, Trialeurodes variabi-
lis Quantaince, T vaporariorum (Westwood),Aleurotrachelus socialis Bondar, Tetraleurodes
sp., Aleuroglandulus malangae Russell and Aleurodicus sp., was conducted in 6 cassava
growing regions of Colombia and Ecuador. In Colombia, the degree of infestation was pre-
dominantly high (>29 whiteflies/cm2) for A. socialis, B. tuberculata and T variabilis in all
cassava growing regions. In Ecuador, levels of infestations were high for Aleurodicus sp.,A.
socialis, B. tuberculata, Tetraleurodes sp. in the coastal region, and for T vaporariorum in
the Highlands. The parasitoid fauna of the whiteflies appeared to be more diverse in Colom-
bia than in Ecuador. Eleven species of parasitoids representing 5 genera, 4 families and two
superfamilies, as well as 1 hyperparasitoid, were collected from the cassava growing regions
of Colombia and 4 species were collected from Ecuador. The parasitoids, Amitus macgowni
Evans and Castillo, Encarsia sp., E. hispida De Santis, E. pergandiella Howard, E. bellottii
Evans and Castillo, E. luteola group, E. sophia (Girault and Dodd), E. strenua group, Eret-
mocerus sp., Metaphycus sp. and Euderomphale sp., were collected. There were notable dif-
ferences in parasitism among the different geographic regions and whitefly species. In
general, Eretmocerus was the dominant genus in Colombia and Ecuador, followed by Encar-
sia sp. We found A. macgowni in regions characterized by high temperatures and bimodal
rainfall. Percent parasitism per region surveyed ranged from 3 to 25% in Colombia and from
12 to 21% in Ecuador.

Key Words: whiteflies, parasitoids, Colombia, Ecuador, cassava, Manihot.

RESUME

Se efectu6 un studio de reconocimiento de parasitoides de las moscas blancas Bemisia tu-
berculata Bondar, Trialeurodes variabilis Quantaince, T vaporariorum (Westwood), Aleu-
rotrachelus socialis Bondar, Tetraleurodes sp., Aleuroglandulus malangae Russell y
Aleurodicus sp. en regions productoras de yuca de Colombia y Ecuador. En Colombia, los
niveles de infestaci6n fueron altos (>29 moscas blancas/cm2), particularmente paraA. socia-
lis, B. tuberculata y T variabilis y en el Ecuador para Aleurodicus sp., A. socialis, B. tuber-
culata, Tetraleurodes sp., en la region de la costa y T vaporariorum en la region de la sierra.
Aparentemente, la fauna de parasitoides fu6 mas diverse en Colombia que en Ecuador. Se
colectaron 11 species de parasitoides, los cuales representan 5 g6neros, 4 families y dos su-
perfamilias en Colombia y 4 species de parasitoides en Ecuador. Los parasitoides fueron
Amitus macgowni Evans y Castillo, Encarsia sp., E. hispida De Santis, E. pergandiella
Howard, E. bellottii Evans y Castillo, grupo E. luteola, E. sophia (Girault and Dodd), grupo
E. strenua, Eretmocerus sp., Metaphycus sp. y Euderomphale sp. Hubo diferencias en para-
sitismo entire las diferentes regions geograficas y species de mosca blanca. En general, Eret-
mocerus fue el g6nero que predomin6 en Colombia y Ecuador, seguido por Encarsia. A.
macgowni fu6 encontrado en diferentes regions geograficas caracterizadas por temperatures
altas y dos epocas con alta precipitaci6n. El promedio de parasitismo por region fluctu6 entire
3 a 25% en Colombia y entire 12 al 21% en Ecuador.

Translation provided by the authors.

Whiteflies (Homoptera: Aleyrodidae) injure aleurodes variabilis Quantaince, Aleurotrachelus
valuable agricultural commodities through me- socialis Bondar, Tetraleurodes sp., and Aleuro-
chanical feeding and virus transmission. Cas- glandulus malangae Russell (Castillo 1996)) in
sava, Manihot esculenta Crantz, is no exception to Colombia and of Bemisia tabaci (Gennadius) in
this rule, acting as a host of several species of Africa and Asia (Bellotti & Vargas 1986) where it
whiteflies (i.e., Bemisia tuberculata Bondar, Tri- vectors African cassava mosaic virus (ACMD).

Trujillo et al.: Parasitoids of Whiteflies in Cassava

While this disease has not been reported yet in
the Americas (Brown & Bird 1992), in Colombia,
other diseases such as 'cassava frog skin disease'
(CFSD) and common cassava mosaic are trans-
mitted by B. tuberculata Bondar. Aleurotrachelus
socialis is known to be the most important white-
fly in the northern coast, eastern plains and west-
ern area of Colombia, but other species of
whiteflies (e.g., T variabilis, Tetraleurodes sp.) in-
festing cassava are poorly known (Castillo 1996).
Gold (1987) reported that cassava whiteflies in
the area of Nataima, Tolima, Colombia are at-
tacked by a complex group of natural enemies, in-
cluding parasitoids, predators, and fungi and
reported that among the natural enemies, parasi-
toids were more important mortality factors of cas-
sava whiteflies than predators. Castillo (1996) and
Evans and Castillo (1998) reported several cassava
whitefly parasitoids in the northern cassava grow-
ing areas of Colombia. The parasitoids belong to
the genera Encarsia, Eretmocerus (Hymenoptera:
Aphelinidae) and Amitus (Hymenoptera: Platyga-
stridae). Specifically, the species are Encarsia hisp-
ida De Santis, E. bellottii Evans and Castillo, and
three undescribed species of Eretmocerus andAm-
itus macgowni Evans and Castillo.
The objectives of the present study were to de-
termine the frequency of cassava whitefly parasi-
toid species in different geographical areas of
Colombia and Ecuador.

MATERIALS AND METHODS

This survey was conducted from April 1998
through June 2000 in the cassava growing re-
gions of Colombia and Ecuador. The surveyed ar-
eas of Colombia were the Caribbean coast,
Andean region, Valle Interandino del Cauca
(Cauca), and Valle Interandino del Magdalena
(Magdalena); the surveyed Ecuadorean regions
were the coastal area and the highlands (Sierra).
Geographic and climatic characteristics of each
region are addressed in Table 1. In each area, the
number of surveys ranged from 1 to 6 depending
on cassava crop availability through the years.
Each survey was conducted on 2-6-month-old cas-

sava crops during periods of low or no rainfall in
each surveyed area.
Sampling for whitefly species consisted of col-
lecting a single leaf from the middle plant canopy
from each of 100 randomly selected plants. A disc
of 2.54 cm2 was excised from the leaf lobe that had
the highest density of whitefly pupae and then
placed in a 5-ml glass vial with 70% alcohol and
transported to the laboratory. Whitefly density/
cm2 was grouped into three different categories:
high (>29 pupae/cm2), medium (12-28 pupae/cm2)
and low (<11 pupae/cm2). Whitefly pupae were
identified with the keys of Caballero (1992; 1994)
and Martin (1987). For further identification, pu-
pae were sent to A. Hamon (Florida Department
of Plant Industry and Consumer Services,
Gainesville, FL).
To determine parasitism, 40 additional leaves
were collected during each survey. Leaves were
inspected for whitefly pupae, and the dominant
whitefly species was identified. Once again, 2.54
cm2 of leaf were excised and those whitefly species
with the lowest density in the sample were re-
moved, leaving only the most abundant whitefly
species in the sample. Samples were placed indi-
vidually in 25-ml glass vials and held for 2-3 days
at 24.5 4C and 70 5% RH under laboratory
conditions until parasitoids emerged. Emerging
parasitoids were identified to genus with the tax-
onomic keys of Polaszek et al. (1992) for Amitus,
Eretmocerus, Encarsia, Metaphycus and
Signiphora; LaSalle & Schauff (1994) for Euder-
omphalini, and Rose & Zolnerowich (1997) for
Eretmocerus. Each specimen was individually
placed in a gel capsule vial and sent for further
identification by G. A. Evans (Florida Depart-
ment of Plant Industry and Consumer Services,
Gainesville, FL) and M. Rose (Montana State
University, Bozeman, MT).

RESULTS AND DISCUSSION

Whitefly Species

Aleurotrachelus socialis, B. tuberculata, T
variabilis, and Tetraleurodes sp. were collected

TABLE 1. CLIMATIC AND GEOGRAPHICAL RANGE OF CASSAVA GROWING REGIONS INCLUDED DURING THE 1998-2000
SURVEY IN COLOMBIA AND ECUADOR.

Elevation Rainfall No.
Country Region (m) (mm) T ( C) Latitude Longitude Surveys

Colombia Caribbean 12-154 861-1313 25-37 8.53N-10.46N 74.37W-75.48W 3
Andean 600-1800 1556-2696 18-26 1.48N-2.27N 76.30W-77.10W 4
Cauca 960-990 1155-1722 19-29 3.01N-3.32 76.16W-76.28W 6
Magdalena 330-550 1211-2965 26-27 4.01N-10.02N 74.38W-75.02W 3
Ecuador Coast 25-130 833-2229 22-26 0.54S-2.07S 79.29W-80.44W 1
Highland 1550 673 19-28 0.24N 77.58W 1
Geographic Information System, CIAT, 2000 (unpublished).

Florida Entomologist 87(3)

from the cassava growing regions of Colombia,
confirming the results of Gold (1987), Arias
(1995), and Castillo (1996). In Colombia, the de-
gree of infestation was predominantly high (>29
whiteflies/cm2) for A. socialis, B. tuberculata, and
T variabilis in all cassava growing regions, with
the exception of the Andean region, where T vari-
abilis was the dominant species (Table 2). The
lowest degree of infestation (<11 whiteflies/cm2)
was observed in the Caribbean coast for Aleurod-
icus sp. and A. malangae. We did not record T va-
porariorum from any of the surveyed cassava
regions of Colombia (Table 2).
Levels of infestations were high for Aleurodi-
cus sp., A. socialis, B. tuberculata, and Tetraleu-
rodes sp. for the coastal region of Ecuador. We
found T vaporariorum, which commonly infests
beans, Phaseolus vulgaris, for the first time at
high infestation levels in cassava in the coastal
and highlands regions of Ecuador (Table 2).
In general,A. socialis, B. tuberculata, Tetraleu-
rodes sp., and Aleurodicus sp. were distributed in
climatic regions characterized by high tempera-
tures and extensive periods of drought (e.g., Car-
ibbean, Magdalena). Trialeurodes sp. was found
in higher numbers in mountainous regions, char-
acterized by lower temperatures and high rainfall
(Andean) (Table 1).

Parasitoids

The parasitoid fauna of whiteflies appeared to
be more diverse in Colombia than in Ecuador.
Eleven species of parasitoids representing 5 gen-
era, 4 families and two superfamilies, as well as 1
hyperparasitoid, were collected from the cassava

growing regions of Colombia and 4 species were
collected from Ecuador. Two of the Eretmocerus
species are undescribed (Table 3) (M. Rose, pers.
comm.). All other parasitoid species collected dur-
ing this study were reported by Castillo (1996) and
Evans & Castillo (1998). There were notable dif-
ferences among the different geographic regions.
On the Caribbean coast, A. socialis was parasit-
ized by 8 species, with the genus Eretmocerus com-
prising 70% of the parasitoids (Table 4). In the
Andean region, Eretmocerus sp., parasitized all
whitefly species, but E. pergandiella was the pre-
dominant parasitoid of T variabilis. The hyperpar-
asitoid Signiphora aleyrodis Ashmead appeared in
high densities in almost all sampled regions, prob-
ably reducing the efficacy of the parasitoids of A.
socialis. In the Magdalena region, 73% ofA. socia-
lis were parasitized by A. macgowni, followed by
Encarsia sp (26%). In the Caribbean, Andean, and
Magdalena sampled regions of Colombia, B. tuber-
culata was parasitized by two undescribed species
of Eretmocerus in addition to several described
and undescribed Encarsia species. In the Cauca
region the number of parasitoid species on A. so-
cialis was almost the same as that collected on the
Caribbean coast. However, the dominant genus
was Encarsia (99%), represented by the species E.
hispida, E. sophia, E. luteola, and E. bellotti.
The proportion of each parasitoid species col-
lected from T variabilis varied among the sam-
pled geographical areas of Colombia. Encarsia
was dominant in the Caribbean coast and in An-
dean region while Eretmocerus was dominant in
Magdalena. In the Andean region, E. pergandi-
ella was more frequent, followed by Eretmocerus
sp., and E. hispida (Table 4).

TABLE 2. NUMBER OF WHITEFLIES RECORDED ON CASSAVA LEAVES IN 6 GEOGRAPHICAL AREAS OF COLOMBIA AND EC-
UADOR.

Colombia Ecuador

Caribbean Andean Cauca Magdalena Coastal Highlands
Whitefly species Total (%)a Total (%) Total (%) Total (%) Total (%) Total (%) Total (%)

Aleurodicus sp. 4 (0.29) 0 (0.00) 0 (0.00) 0 (0.00) 21(1.54) 0 (0.00) 25 (1.83)
Aleuroglandulus 1 (0.07) 0 (0.00) 0 (0.00) 0 (0.00) 0 (0.00) 0 (0.00) 1 (0.07)
malangae
Aleurotrachelus 141(10.37) 69 (5.07) 80(5.88) 215(15.81) 48 (3.53) 0 (0.00) 553 (40.66)
socialist
Bemisia tuberculata 112 (8.24) 50 (3.68) 0 (0.00) 37 (2.72) 5 (0.37) 0 (0.00) 204 (15.01)
Tetraleurodes sp. 16 (1.18) 0 (0.00) 0 (0.00) 0 (0.00) 68 (5.00) 0 (0.00) 84(6.18)
Trialeurodesvariabilis 74(5.44) 303 (22.28) 0 (0.00) 28 (2.06) 0 (0.00) 0 (0.00) 405 (29.78)
Trialeurodes 0 (0.00) 0 (0.00) 0 (0.00) 0 (0.00) 51(3.75) 37 (2.72) 88(6.47)
vaporariorum
Total 348 422 80 280 193 37 1360(100)

"Percent each whitefly species at localities.

September 2004

Trujillo et al.: Parasitoids of Whiteflies in Cassava

TABLE 3. PARASITOIDS EMERGING FROM CASSAVA WHITEFLIES COLLECTED IN COLOMBIA AND ECUADOR.

Order Superfamily Family Genus Species

Hymenoptera Platygastroidea Platygastridae Amitus macgowni Evans and Castillo
Chalcidoidea Aphelinidae Encarsia sp.
E. hispida De Santis
E. pergandiella Howard
E. bellotti Evans and Castillo
E. sophia (Girault and Dodd)
E. luteola group
E. strenua group
Eretmocerus sp.
Encyrtidae Metaphycus sp.
Eulophidae Euderomphale sp.
Signiphoridae Signiphora aleyrodisa Ashmead

aHyperparasitoid.

The complex of parasitoids collected from
whiteflies in cassava in Ecuador has only been
identified to the generic level (G. Evans, M. Rose,
pers. comm). In the coastal region,A. socialis was
parasitized by Encarsia, followed by Amitus and
Eretmocerus;Aleurodicus was parasitized by Eu-
deromphale sp. Tetraleurodes and Trialeurodes
were mostly parasitized by Eretmocerus sp., and
B. tuberculata was parasitized by Encarsia sp.,
and Euderomphale. In the highlands region, T.
vaporariorum was the only whitefly species col-
lected, with approximately 16 pupae/2.54 cm2.
The dominant parasitoids were Encarsia spp.
representing 98% of the sample (Table 4).
In general, Amitus macgowni showed a local-
ized distribution in those areas (e.g., Magdalena)
with high temperatures and bimodal rainfall.
With the exception of Ecuador, Eretmocerus was
found both in warm regions and cool regions. De-
scription and identification of the species within
this genus will determine if the undescribed spe-
cies are more frequent in some climatic areas
than in others. Euderomphale was found in
higher numbers in those areas (e.g., Coastal) with
a low whitefly density, high temperatures, and
minimal rainfall. E. pergandiella showed a gen-
eral distribution among the different climatic re-
gions (Magdalena, Andean), and particularly
associated with Trialeurodes sp. The species E.
hispida, E. sofia, E. bellottii, and Metaphycus sp.,
were found in the Magdalena region, character-
ized by high temperatures and a yearly average
precipitation of 1,000 mm.
These observations indicate that both Colom-
bia and Ecuador have a diverse parasitoid fauna
attacking whiteflies on cassava. At the same time,
these results indicate that the parasitism trend is
influenced by the characteristics of each geo-
graphical area. During this study, some parasi-
toid species were discovered for the first time in
some of the geographical areas of Colombia. In

the Caribbean coast and in the Cauca region, A.
socialis was parasitized by E. sophia; B. tubercu-
lata was parasitized by E. sophia and Metaphycus
sp. in the Caribbean coast, and by E. pergandiella
and Euderomphale sp. in the Andean region. For
the first time, E. pergandiella and E. sophia were
collected as parasitoids of T variabilis in the Car-
ibbean coast, while E. hispida was the dominant
parasitoid in the Andean region.
Because of the temporal and spatial limitation
of our collections, parasitism of whiteflies on cas-
sava will probably vary within the year, and data
presented here may underestimate parasitism.
For instance, high periods of parasitism may have
been interspersed with periods of 0% parasitism.
The highest frequency of parasitoids was ob-
tained in A. socialis, which in general had the
highest density in most of the surveyed regions
(Table 5). Low levels of parasitism were not un-
common and ranged from 3-5% in the Andean and
Cauca regions of Colombia, 10-12% for the Carib-
bean and Highlands regions of Colombia and Ec-
uador, respectively, to 21 and 25% in the coastal
region of Ecuador and Magdalena region of Co-
lombia, respectively (Table 5). These data suggest
that parasitoids are ineffective in reducing cas-
sava whitefly populations in the surveyed areas of
Colombia and Ecuador. However, it is necessary
to do a more thorough study on those parasitoids
that cause higher mortality. For instance,
A. macgowni was observed as the dominant para-
sitoid of A. socials in the Magdalena region.
Therefore, studies toward augmentation and con-
servation ofA. macgowni should be encouraged in
that region. Life cycle and behavioral studies of
Encarsia pergandiella as an important parasitoid
of Trialeurodes sp., should be conducted.
During this study, whitefly densities were low
in Ecuador. Therefore, further studies are neces-
sary to properly determine the potential of each
parasitoid species in that country.

-21

TABLE 4. FREQUENCY OF PARASITOIDS FROM WHITEFLY SPECIES IN 6 GEOGRAPHICAL REGIONS OF COLOMBIA AND ECUADOR

Parasitoid species

Whitefly Encarsia E. E. E. E. luteola E. E.Strenua Eretmoceru Amitus Metaphycus Euderomphale Signiphora
Country Region species sp. hispida pergandiella sophia group bellotti group s sp. macgowni sp. sp. aleyroidis

Colombia Caribbean Aleurodicus sp. 1 0 0 0 0 0 0 0 0 0 0 0
Aelurotrachelus 12 12 0 7 12 4 0 101 0 2 1 45
socialist
Aleuroglandulus 0 0 00 0 0 0 0 0 0 0 0 0
malangae
Trialeurodes 5 0 5 3 2 0 1 8 0 0 0 0
variabilis
Bemisia 2 0 1 2 0 0 0 0 0 0 0 0
tuberculata
Tetraleurodes sp. 0 2 0 0 0 0 0 0 0 0 0 0
Andean
Aleurotrachelus 0 0 0 0 0 5 0 2 0 0 0 11
socialis
Trialeurodes 0 5 36 0 0 0 0 12 0 0 0 0
variabilis
Bemisia 0 0 6 0 0 0 0 11 0 0 2 3
tuberculata
Cauca Aleurotrachelus 28 139 0 54 27 5 0 1 0 0 0 0
socialis
Magdalena Aleurotrachelus 338 0 0 0 0 0 0 0 936 0 0 29
socialist
Trialeurodes 0 0 0 0 0 0 0 9 0 0 0 0
variabilis
Bemisia 6 0 0 0 0 0 0 14 0 0 0 0
tuberculata
Ecuador Coastal Aleurodicus sp. 1 0 0 0 0 0 0 0 0 0 11 0
Aleurotrachelus 13 0 0 0 0 0 0 3 4 0 0 29
socialist
Tetraleurodes sp. 3 0 0 0 0 0 0 21 0 0 0 3
Trialeurodes 0 0 0 0 0 0 0 22 0 0 0 0
vaporariorum
Bermisia 6 0 0 0 0 0 0 0 0 0 1 0
tuberculata
Highlands Trialeurodes 92 0 0 0 0 0 0 2 0 0 0 0
vaporariorum

b0

Trujillo et al.: Parasitoids of Whiteflies in Cassava

TABLE 5. NUMBER OF EMERGING PARASITOIDS FROM CASSAVA WHITEFLIES IN 6 GEOGRAPHICAL AREAS OF COLOMBIA
AND ECUADOR.

Colombia Ecuador

Caribbean Andean Cauca Magdalena Coastal Highlands TotalWhitefly
Whitefly species Total (TW) Total (TW) Total (TW) Total (TW) Total (TW) Total (TW) (% Parasitism)

Aleurodicus sp. 1(15) 0 (0) 0 (0) 0 (0) 13 (33) 0 (0) 14 (29)
Aleuroglandulus 0(1) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
malangae
Aleurotrachelus 146 (1418) 19 (1241) 254 (7411) 2142 (8472) 21(161) 0 (0) 2582 (14)
socialist
Bemisia tuberculata 25 (320) 22(122) 0 (0) 21(52) 1(9) 0 (0) 69 (14)
Tetraleurodes sp. 2 (32) 0 (0) 0 (0) 0 (0) 28 (99) 0 (0) 30 (23)
Trialeurodes 26(146) 54 (694) 0 (0) 9 (46) 0 (0) 0 (0) 89 (10)
variabilis
Trialeurodes 0 (0) 0 (0) 0 (0) 0 (0) 19 (92) 96 (776) 115 (13)
vaporariorum

Totals 200(1932) 95(2057) 254(7411) 2172(8570) 82 (394) 96 (776)

Total = Total parasitoids emerging.
TW = Total whitefly pupae.

ACKNOWLEDGMENTS

We thank R. Cave for suggestions to improve the
manuscript. We thank G. Evans, M. Rose, and A. Hamon
for insect identification. This work was supported by a
grant from USAID to the International Center for Trop-
ical Agriculture (CIAT). Florida Agricultural Experi-
ment Station Journal Series No. R-09645.

REFERENCES CITED

ARIAS, B. 1995. Estudio sobre el comportamiento de la
mosca blanca Aleurotrachelus socialis Bondar (Ho-
moptera: Aleyrodidae) en diferentes genotipos de
yuca (Manihot esculenta Crantz). Tesis Universidad
Nacional de Colombia. Palmira, Colombia. 166p.
BELLOTTI, A. C., AND O. VARGAS. 1986. Mosca blanca del
cultivo de la yuca: Biologia y Control. Guia de estu-
dio. CIAT. Cali, Colombia. 34 pp.
BROWN, J.K., AND J. BIRD. 1992. Whitefly transmitted
geminiviruses and associated disorders in the Amer-
icas and the Caribbean Basin. Plant Disease 76: 220-
225.
CABALLERO, R. 1992. Whiteflies (Homoptera: Aleyrodi-
dae) from Central America and Colombia including
slide-mounted pupal and field keys for identification,
field characteristics, hosts, distribution, natural en-
emies and economic importance. MSc. thesis, Kan-
sas State University, Manhattan.
CABALLERO, R. 1994. Clave de campo para inmaduros
de moscas blancas de Centroam6rica (Homoptera:
Aleyrodidae). Escuela Agricola Panamericana,
Zamorano, Honduras. 4 pp.

CASTILLO L., J. A. 1996. Moscas blancas (Homoptera:
Aleyrodidae) y sus enemigos naturales sobre cultivos
de yuca (Manihot esculenta Crantz) en Colombia. BS
thesis, Universidad del Valle, Facultad de Ciencias,
Departamento de Biologia. Cali, Colombia. 174 pp.
EVANS, G. A., AND J. A. CASTILLO. 1998. Parasites of
Aleurotrachelus socialis (Homoptera: Aleyrodidae)
from Colombia including descriptions of two new
species (Hymenoptera: Aphelinidae: Platygasteri-
dae). Florida Entomol. 81: 171-178.
GOLD, C. S. 1987. Crop diversity and tropical herbi-
vores: Effects of intercropping and mixed varieties
on cassava whiteflies, Aleurotrachelus socialis
Bondar and Trialeurodes variabilis Quaintance in
Colombia. PhD dissertation, University of Califor-
nia, Berkeley. 362 pp.
MARTIN, J. H. 1987. An identification guide to common
whitefly pest species of the world (Homoptera, Aley-
rodidae). Tropical Pest Management 33: 298-322.
LA SALLE, J., AND M. E. SCHAUFF. 1994. Systematics of
the tribe Euderomphalini (Hymenoptera: Eulo-
phidae): parasitoids of whiteflies (Homoptera: Aley-
rodidae). Syst. Entomol. 19: 235-258.
POLASZEK, A., G. A. EVANS, AND F. D. BENNETT. 1992.
Encarsia parasitoids of Bemisia tabaci (Hymenop-
tera: Aphelinidae, Homoptera: Aleyrodidae): a pre-
liminary guide to identification. Bull. Entomol. Res.
82: 375-392.
ROSE, M., AND G. ZOLNEROWICH. 1997. Eretmocerus
Haldeman (Hymenoptera: Aphelinidae) in the
United States, with descriptions of new species at-
tacking Bemisia (tabaci complex) (Homoptera: Aley-
rodidae). Proc. Entomol. Soc. Washington 99: 1-27.

Florida Entomologist 87(3)

September 2004

LABORATORY PARASITISM BY PHYMASTICHUS COFFEE
(HYMENOPTERA: EULOPHIDAE) UPON NON-TARGET
BARK BEETLES ASSOCIATED WITH COFFEE PLANTATIONS

ALFREDO CASTILLO1, FRANCISCO INFANTE', GUILLERMO LOPEZ1, JAVIER TRUJILLO2,
LAWRENCE R. KIRKENDALL3 AND FERNANDO E. VEGA4
'El Colegio de la Frontera Sur (ECOSUR), Carretera Antiguo Aeropuerto km 2.5.
Tapachula 30700 Chiapas, Mexico

2Colegio de Posgraduados, Instituto de Fitosanidad, Montecillo, 56230 Edo. de M6xico, Mexico

'Institute of Zoology, University of Bergen, Allegaten 41, N-5007 Bergen, Norway

4Insect Biocontrol Laboratory, U. S. Department of Agriculture, Agricultural Research Service
Beltsville, Maryland, 20705-2350, USA

ABSTRACT

Phymastichus coffee (LaSalle) is an African parasitoid of adults of the coffee berry borer Hy-
pothenemus hampei (Ferrari) that has been introduced to Mexico and other Central and
South American countries for the biological control of this important pest. The present study
assessed the host specificity of this parasitoid in the laboratory. We tested the acceptance
and parasitism of P. coffee on five species of bark beetle adults commonly found in coffee
plantations of Mexico: Hypothenemus crudiae, H. plumeriae, H. eruditus, Scolytodes borealis
and Araptus fossifrons. As a control, we used adults of H. hampei, the natural host. P. coffee
parasitized and successfully completed its life cycle in H. crudiae and H. eruditus, as well as
in H. hampei. The degree to which bark beetles were attacked by P. coffee was estimated by
percent of parasitism, which was 64% for H. hampei, 14% for H. crudiae, and 6% for H. eru-
ditus. The risk of potential deleterious effects of the parasitoid on non-target organisms in
coffee agroecosystems is discussed.

Key Words: Host specificity, Phymastichus, Hypothenemus, Scolytodes, Araptus, Mexico.

RESUME

Phymastichus coffee (LaSalle) es un parasitoide africano de adults de la broca del caf6 Hy-
pothenemus hampei (Ferrari) que ha sido introducido a M6xico y otros paises de Centro y
Sudam6rica para el control biol6gico de esta important plaga. El present trabajo se llev6
a cabo con la finalidad de evaluar la especificidad de hu6spedes de este parasitoide en el lab-
oratorio. Se prob6 la aceptaci6n y parasitismo de P. coffee sobre adults de cinco species de
descortezadores comunmente encontrados en plantaciones de caf6 de M6xico: Hypothenemus
crudiae, H. plumeriae, H. eruditus, Scolytodes borealis yAraptus fossifrons. Como control se
usaron adults de H. hampei (hospedero natural). P. coffee parasite y complete exitosamente
su ciclo biol6gico en s6lo dos species de escolitidos, H. crudiae y H. eruditus, ademas de H.
hampei. El grado en el cual los descortezadores fueron atacados por P. coffee fue estimado
por el porcentaje de parasitismo el cual fue de 64% para H. hampei, 14% para H. crudiae, y
6% para H. eruditus. Es discutido el riesgo de los efectos negatives potenciales de este par-
asitoide sobre organismos no blanco en agroecosistemas de caf6.

Translation provided by the authors.

Phymastichus coffee LaSalle (Hymenoptera:
Eulophidae) is a primary parasitoid of the coffee
berry borer (CBB), Hypothenemus hampei (Fer-
rari) (Coleoptera: Scolytidae), the most devastat-
ing pest of coffee throughout the world (Baker
1999). This parasitoid, indigenous to Africa, was
first recorded in 1987 from Togo parasitizing the
CBB (Borbon-Martinez 1989), and subsequently
was described as a new species (LaSalle 1990).
Phymastichus coffee has a pan-African distribu-

tion, having been collected from east Africa
(Kenya) and west Africa (Togo, Benin, Cameroon,
Burundi, and Ivory Coast) (Infante et al. 1992).
So far, this parasitoid has been introduced to cof-
fee producing countries, such as Colombia, Guate-
mala, Honduras, Jamaica, El Salvador, Ecuador,
India, Brazil and Mexico for biological control
purposes (Castillo, unpublished data). This spe-
cies is the only known parasitoid of adults of CBB,
and is considered to be a potentially useful tool in

Castillo et al.: Parasitism by P. coffee upon Non-target Bark Beetles

integrated pest management programs against
H. hampei (L6pez-Vaamonde & Moore 1998;
Baker 1999).
Eulophidae is one of the largest families in Hy-
menoptera with nearly 4000 described species
(Noyes 1998; Gauthier et al. 2000). The subfamily
Tetrastichinae, to which P. coffee belongs, has an
extraordinarily wide host range and exhibits a
great variety of life styles. Members of this sub-
family attack over 100 families of insects, as well
as mites, spider eggs, and even nematodes (J. La-
Salle, pers. comm.). Despite the fact that P coffee
has already been imported and released in vari-
ous countries of the Americas, it is important to
determine whether this parasitoid can attack
non-target scolytids.
The objective of this study was to test the host
specificity of P coffee in the laboratory with six
bark beetles species commonly found in coffee
plantations of Mexico, with H. hampei serving as
the control. A previous study in Colombia reported
that P coffee was able to parasitize H. obscurus,
H. seriatus, and Araptus sp. in the laboratory (L6-
pez-Vaamonde & Moore 1998). We included differ-
ent species than those examined in Colombia;
thus, this study serves to further elucidate the po-
tential risk of P. coffee for non-target scolytids.

MATERIALS AND METHODS

Parasitoids

We used mated females of P coffee, which were
less than lh old from the time they emerged from
CBBs. The parasitoids were obtained from a col-
ony established in the laboratory in March of
2000. The colony was initiated with insects im-
ported from Guatemala with methodology de-
scribed by Infante et al. (1994). Adult CBB
females obtained from the field were used for par-
asitoid rearing. The insect colony is normally
maintained at 26 + 2C, 75 10% RH and 8:16
(L:D) photoperiod.

Hosts

We offered six species of bark beetles collected
as adults in coffee plantations near Tapachula,
Chiapas to adults of P coffee in the laboratory. The
parasitoid was never released in the plantations
where we collected the bark beetles. To minimize
the risk, the CBBs were obtained by dissecting
infested coffee fruits from the field, while we
collected Hypothenemus eruditus Westwood,
Hypothenemus crudiae (Panzer), Hypothenemus
plumeriae (Nordlinger), and Scolytodes borealis
Jordal from petioles of Cecropia sp. leaves. The
three Hypothenemus species we used are wide-
spread and co-occur with Coffea spp. where the
latter are native (Wood 1982; Wood & Bright
1992). They are extremely polyphagous, and have

been collected from dozens of host species. The Sc-
olytodes breeds only in fallen Cecropia leaves
(Jordal 1998). Araptus fossifrons Wood, a Me-
soamerican species previously collected from vari-
ous seed pods and lianas (Wood & Bright 1992),
was captured using CBB traps (Dufour 2002).

Experimental Procedure

The host specificity of P coffee was evaluated
in the laboratory in a non-choice test. Fifty speci-
mens of each species were placed individually in
40 x 10 mm glass vials and immediately after-
wards, a P. coffee female was introduced. The in-
sects were observed for five hours under a 20W
fluorescent lamp. We considered oviposition to
have occurred when the female parasitoid
adopted a characteristic ovipositing position on
the elytra of the scolytids (L6pez-Vaamonde &
Moore 1998). Hosts attacked by P coffee were
transferred individually into vials containing
CBB diet (Villacorta & Barrera 1996) and para-
sitization was assessed based on the emergence of
the progeny, or by dissecting the hosts that did
not yield parasitoids. We also recorded the time
required for the encounter (defined as the time
elapsed between the release of the parasitoid in
the arena until it assumed the characteristic ovi-
positing position on the beetle), and the handling
time (defined as the time elapsed between the en-
counter and the end of parasitization). Environ-
mental conditions of the laboratory during the
development of parasitoid's progeny were 26
2C and 70-80% RH.

Taxonomy

Samples of the species used were compared by
Kirkendall with type material, or with specimens
in his collection or in the S. L. Wood collection
which had been compared with type material.
Vouchers for all species are in Kirkendall's collec-
tion at University of Bergen, Norway.

RESULTS

Oviposition attempts by P coffee were ob-
served on all scolytid species tested, but parasiti-
zation and development of progeny was
completed on only two species of bark beetles, in
addition to H. hampei (Fig. 1). The percentage
parasitism for H. hampei, H. crudiae, and H. eru-
ditus was 64%, 14% and 6%, respectively (Table
1). We did not detect any oviposition by P coffee in
S. borealis, H. plumeriae, and A. fossifrons, nor
did we find adult or immature stages of the para-
sitoid after hosts were dissected. Sex ratio of
progeny produced by P coffee in the three species
was 1:1. The shortest encounter time was be-
tween P. coffee and H. hampei (mean = 23 min).
Encounter time was 5-6 times longer when para-

Florida Entomologist 87(3)

Fig. 1. Adults of three species of scolytids parasitized by Phymastichus coffee in the laboratory, showing the hole
made by the emerging wasp adult: (A) H. hampei (B) H. eruditus and (C) H. crudiae.

sitization was on H. crudiae or H. eruditus. How-
ever, the handling time was shorter (1.5 min) in
H. eruditus than in the other hosts. In most cases
P coffee allocated more than two eggs per host af-
ter a single attack. Development of immature
stages of the parasitoid ranged from 39 to 42.6
days (Table 1).

DISCUSSION

Phymastichus coffee parasitized two species of
Hypothenemus in addition to its natural host,
H. hampei. Our findings confirm the oligophagic
behavior of P coffee reported by L6pez-Vaamonde
& Moore (1998). Five species of beetles are now
known to serve as hosts for P coffee: H. obscurus,
H. seriatus, Araptus sp (Lopez-Vaamonde &
Moore 1998), H. crudiae and H. eruditus (this
study), thus indicating that this parasitoid is not
specific to the CBB. Host specificity tests under
laboratory conditions are the first step in assess-
ing the potential host range of a given species
(Orr et al. 2000; Babendreier et al. 2003a, 2003b).
Although laboratory tests can overestimate the
range of hosts under field conditions (Sands
1997), they are necessary to give an idea of the
number of hosts at risk of being attacked in the
field. Based on laboratory trials, specificity can be

demonstrated in the field later on (Barron et al.
2003; Babendreier et al. 2003b). Accordingly, par-
asitism by P coffee on H. crudiae and H. eruditus
in the laboratory does not necessarily mean that
these beetles will be attacked by this parasitoid in
the field. Careful observations under field condi-
tions should be carried out before concluding that
these beetles are alternative hosts of P coffee.
There are no reports of parasitism by P coffee
on other hosts under field conditions. However,
entomologist are not specifically collecting other
bark beetles in or around coffee plantations, so
parasitism of other hosts is unlikely to be re-
corded. Encounters between the parasitoid and
scolytids in the field are likely, since the five spe-
cies of polyphagous beetles parasitized by P cof-
fea in the laboratory are common in coffee agro-
ecosystems and the disturbed habitats which of-
ten surround them (Atkinson & Equihua-Mar-
tinez 1985).
Our results could have important implications
in the biological control of CBB in Latin America
if further studies demonstrate that P coffee at-
tacks these scolytids in the field. First, with sev-
eral host species available, there would be a risk
of dilution of the parasitism exerted on CBB in
the field. Second, one or more of these species
might be more easily reared in large numbers in

TABLE 1. PARASITISM BY PHYMASTICHUS COFFEE ON SEVERAL BARK BEETLES SPECIES UNDER LABORATORY CONDI-
TIONS. FIFTY SPECIMENS OF EACH SPECIES WERE EXPOSED TO FIFTY PARASITOID FEMALES INDIVIDUALLY.

Parasitism Time required for Handling Progeny Development
attempts the encounter with time Parasitism production of parasitoids
Scolytidae species (%) host (min SE)' (minm SE)2 (%) of P coffee (days)

Hypothenemus hampei 78 23.0 4.4 5.8 0.7 64 54 42.6
Hypothenemus crudiae 58 136.2 26.0 4.2 0.8 14 14 40.4
Hypothenemus eruditus 50 123.0 + 23.0 1.5 + 0.4 6 4 39
Hypothenemus plumeriae 36 0 -0 0 0
Scolytodes borealis 8 0 -0 0 0
Araptus fossifrons 46 0 -0 0 0

Defined as the time elapsed between the release of the parasitoid in the arena and when it assumed the characteristic oviposi-
tion position on the beetle.
'Defined as the time elapsed between the encounter and the end of the parasitization.

September 2004

Castillo et al.: Parasitism by P. coffee upon Non-target Bark Beetles

the laboratory than the CBB, which has more
stringent food requirements, for mass rearing of
P coffee for augmentative biological control pro-
grams against CBB. Third, these scolytids could
be important as alternative hosts in the field, in-
creasing survival of the parasitoid during the in-
tercropping season, when the CBB population is
at its lowest. Intercropping season in coffee inter-
feres severely with the establishment of natural
enemies of CBB (Barrera et al. 1990).
Finally, taking into consideration that parasit-
ism of non-target hosts is usually much higher in
the laboratory than in the field (Orr et al. 2000), it
is possible that the levels of laboratory parasitism
of H. crudiae and H. eruditus do not reflect a poten-
tial risk of this parasitoid for populations of non-
target bark beetles in the field. Only careful field
observations can answer this important question.

ACKNOWLEDGMENTS

This research was supported by "Consejo Nacional
de Ciencia y Tecnologia" (CONACYT), project 37335-B
and by USDA Cooperative Agreement No.58-1275-2-
F068. We are grateful to Roman Montes and Giber
Gonzalez for technical assistance, and Guadalupe Nieto
for photographic material.

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lini and Corthylini. Coleopterists Bull. 39: 355-363.
BABENDREIER, D., S. KUSKE, AND F. BIGLER 2003a.
Non-target host acceptance and parasitism of Tri-
chogramma brassicae Bezdenko (Hymenoptera: Tri-
chogrammatidae) in the laboratory. Biol. Control 26:
128-138.
BABENDREIER, D., S. KUSKE, AND F. BIGLER 2003b. Par-
asitism on non-target butterflies by Trichogramma
brassicae Bezdenko (Hymenoptera: Trichogramma-
tidae) under field cage and field conditions. Biol.
Control 26: 139-145.
BAKER, P. S. 1999. La broca del caf6 en Colombia. In-
forme final del proyecto MIP para el caf6. DFID-CE-
NICAFE-CABI Bioscience. 148 pp.
BARRERA, J. F., D. MOORE, Y. J. ABRAHAM, S. T. MUR-
PHY, AND C. PRIOR 1990. Biological control of the cof-
fee berry borer, Hypothenemus hampei, in Mexico
and possibilities for further action. Brighton Crop
Protection Conference-Pest and Diseases 4: 391-396.
BARRON, M. C., N. D. BARLOW, AND S. D. WRITTEN.
2003. Non-target parasitism of the endemic New
Zealand red admiral butterfly (Bassaris gonerilla)
by the introduced biological control agent Pteroma-
lus puparum. Biol. Control 27: 329-335.
BOURBON-MARTINEZ, 0. 1989. Bioecologie d'un rav-
ageur des babies de cafeier, Hypothenemus hampei

Ferr. (Coleoptera; Scolytidae) et de ses parasitoides
au Togo. Ph. D. Dissertation. University Paul Sa-
batier. Toulouse, France 185 pp.
DUFOUR, B. P. 2002. Validaci6n de la trampa BROCAP
para el control de la bro ca del caf. Boletn de Divul-
gaci6n. IICA-PROMECAFE 93: 14-20. Guatemala.
GAUTHIER, N., J. LASALLE, D. L. QUICKE, AND H. C. J.
GODFRAY. 2000. Phylogeny of Eulophidae (Hy-
menoptera: Chalcidoidea), with a reclassification of
Eulophinae and the recognition that Elasmidae are
derived eulophids. Systematic Entomol. 25: 521-539.
INFANTE, F., J. F. BARRERA, S. T. MURPHY, J. G6MEZ, AND
A. CASTILLO. 1992. Cria y cuarentena de Phymasti-
chus coffee LaSalle (Hymenoptera: Eulophidae) un
parasitoide de la broca del caf6 introducido a Mexico.
XV Simposio Latinoamericano de Cafeticultura, Xal-
apa, Veracruz, 80 pp.
INFANTE, F., S. T. MURPHY, J. F. BARRERA, J. GOMEZ, W.
DE LA ROSA, AND A. DAMON. 1994. Cria de Phymas-
tichus coffee parasitoide de la broca del caf6, y algu-
nas notas sobre su historic de vida. Southwestern
Entomol. 19: 313-315.
JORDAL, B. H. 1998. A review of Scolytodes Ferrari (Co-
leoptera: Scolytidae) associated with Cecropia (Ce-
cropiaceae) in the northern Neotropics. J. Natural
Hist. 32: 31-84.
LASALLE, J. 1990. A new genus and species of Tetras-
tichinae (Hymenoptera: Eulophidae) parasitic on the
coffee berry borer, Hypothenemus hampei (Ferrari)
(Coleoptera: Scolytidae). Bull. Entomol. Res. 80: 7-10.
LOPEZ-VAAMONDE, C., AND D. MOORE. 1998. Developing
methods for testing host specificity of Phymastichus
coffee LaSalle (Hym.: Tetrastichinae), a potential bi-
ological control agent of Hypothenemus hampei (Fer-
rari) (Col.: Scolytidae) in Colombia. Biocontrol
Sci.Tech. 8: 397-411.
NOYES, J. F. 1998. Catalogue of the Chalcidoidea of the
world. Electronic publication (CD-ROM). ETI, Am-
sterdam.
ORR, D. B., C. GARCIA-SALAZAR, AND D. A. LANDIS. 2000.
Trichogramma non-target impacts: a method for bi-
ological control risk assessment, pp. 111-125 In P. A.
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611-616.
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an artificial diet. Vedalia. 3: 45-48.
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North and Central America (Coleoptera: Scolytidae),
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lytidae and Platypodidae (Coleoptera), Part 2: Taxo-
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Memoirs 13: 833-1553.

Florida Entomologist 87(3)

DESCRIPTIONS OF THE FINAL INSTAR OF EURYTOMA NODULARIS
AND E. HERIADI (HYMENOPTERA: EURYTOMIDAE)

J. TORMOS, J. D. Asis, S. F. GAYUBO AND M. A. MARTIN
Unidad de Zoologia, Departamento de Biologia Animal, Facultad de Biologia,
Universidad de Salamanca, 37071-Salamanca (Spain)

ABSTRACT

The final instars of Eurytoma nodularis and E. heriadi are described and illustrated. Mor-
phological structures of diagnostic value are discussed. The most salient character shown by
the mature larvae of these two species lies in the mandibles, which are simple (unidentate),
a feature that, according to current knowledge, is only shared with E. verticillata.

Key Words: larva, Eurytoma, morphology.

RESUME
Se described, y dibujan, las larvas maduras de Eurytoma nodularis y E.heriadi. El caricter
mas relevant, s6lo compartido con E. verticillata, radica en la presencia, en ambas species,
de mandibulas unidentadas.

Translation provided by the author.

The family Eurytomidae includes some 1424
species in 88 genera (Noyes 2003). Included spe-
cies display diverse larval feeding habits and are
mainly parasitoids of Diptera, Coleoptera, Hy-
menoptera, and Lepidoptera (Gauld & Bolton
1988; Zerova & Fursov 1991), although phytoph-
agy (Crosby 1909; Bugbee 1941, 1971, 1967) and
entomophytophagy (Phillips 1917, 1927; Claridge
1961; Bugbee 1975) are known.
The genus Eurytoma Illiger, 1807, with 692
species, is the largest of the family Eurytomidae
(Noyes 2003). This study addresses the larval
morphology of two species of this cosmopolitan ge-
nus: Eurytoma nodularis Boheman, 1836, and E.
heriadi Zerova, 1984. These species are parasi-
toids of Hymenoptera Aculeata that nest in hol-
low stems. Within Eurytoma, the main studies of
mature larvae have been carried out by Roskam
(1982), Henneicke et al. (1992) and Dawah &
Rothfritz (1996).

MATERIALS AND METHODS

Material Examined

Eurytoma nodularis: SPAIN: Segovia: Iscar, 2
mature larvae from nest of Eumenidae December
1999, emerg. 1 female May 2000 (one mature
larva was fixed and preserved in 70% ETOH for
subsequent study and description); Caceres: Mes-
tas, 4 mature larvae from nest of Eumenidae De-
cember 1999, emerg. 2 females, 1 male May 2000
(one mature larva was stored in a vial with 70%
ethanol for later study). E. heriadi: SPAIN: Avila:
Barco de Avila, 2 mature larvae from nest of Try-

poxylon Latreille, 1796 (Hymenoptera, Apoidea:
Crabronidae) December 1999, emerg. 1 female
May 2000 (one mature larva was stored in a vial
with 70% ethanol for later study). Voucher speci-
mens are deposited at the: a) Fundaci6n Ento-
mol6gica "Torres-Sala" (Valencia, Spain) (larvae),
and b) Institute of Zoology of National Ukrainian
Academy of Sciences (Ukraine) (adults).
In both cases, the larvae were obtained from
nests established in stems of Phragmites austra-
lis (Cav.) (Poaceae), which had been placed in the
field between April-December 1999 when they
were collected and transported to the laboratory.
Nests were opened one week after collection to
allow the development of possible natural ene-
mies. The contents of each cell were transferred to
glass vials and kept at 6-8C over the winter. Dur-
ing the following spring (May 2000), the vials
were transferred to a culture chamber at 28C,
60-80% RH, to trigger emergence of the images,
thus making it possible to identify the occupants
of the nests and their parasitoids.
The methodology used in the preparation of ma-
ture larvae was similar to that employed by Evans
(1987). Terminology and organization used in the
ensuing descriptions fundamentally follow that of
Henneicke et al. (1992). The following abbrevia-
tions have been used in the descriptions: A1-9 =
abdominal segments; ADP = anterodorsal protu-
berances; AN = antennae; APP = anterior pleuros-
tomal process; ATR = atrium of spiracle; AS = anal
segment; BA = base of mandibles; BL = blade of
mandibles; C = ventral articular process of mandi-
ble; CA = closing apparatus of spiracle; CLP =
clypeus; CLPS = clypeal setae; D = dorsal setae; d

September 2004

Tormos et al.: Final Instar of Eurytoma

= diameter; DAP = dorsal articular process of man-
dible; DT = dorsal terminal seta; EPST = epistomal
arc; EPX = epipharynx; FI = inferior frontal setae;
FS = superior frontal setae; GE = setae on the ge-
nae; h = height; HY = hypostomal setae; 1 = length;
LM = labrum; LMS = labral setae; LS = prelabial
sensilla; LUM = labium; MD = mandibles; MS =
maxillary setae; MX = maxillae; n = number of
specimens; P = pleural setae; PLOS = lateral post-
labial setae; PLST = pleurostoma; POS = postla-
bial setae; PPA = maxillary papilla; PPP =
posterior pleurostomal process; PRLS = lateral
prelabial setae; PRMS = middle prelabial setae; SP
= spiracles; ST = spiracular trachea; TH1-3 = tho-
racic segments; V = ventral setae, and w = width.

DESCRIPTIONS OF MATURE LARVAE

Eurytoma nodularis Boheman
General aspect (Fig. 1)

Body 1 = 6.6-7.2 mm (x = 6.9), maximum w =
1.7-2.1 mm (x = 1.9) (n = 2), shape varying be-
tween barrel-shaped and cylindrical, slightly
broader in mid region, ADP present on TH3-A9,
with three thoracic and ten abdominal segments,
tapering anteriorly and more strongly curved pos-
teriorly. Color yellowish. Weakly sclerotized, ex-
cept for MD, SP and setae. Anus small, sub-
terminal, transverse. Pleural lobes very scarcely
developed. Tegument setose, with: a) D (1 = 180-
410 pm): three pairs on TH1-A2; two pairs on A3-
A7; a pair on the A8 and A9; b) DT (1 = 90 pm) two
pairs; c) P (1 = 170-425 pm): four pairs on TH1-
AS2; two pairs on A3-A9; d) V (1 = 150-420 pm): one
pair on TH1-A9. SP (Fig. 3) on TH2, TH3, and on
Al-A7;ATR (1 = 70 pm, d maximum = 30 pm) fun-
nel-shaped, with approximately fourteen cham-
bers; CA (1 = 20 pm; w = 9 pm) adjacent to ATR.

Cranium (Fig. 4)

Cranium 0.5x as high as broad (w = 657 pm, h
(from apex of cranium to base of MD) = 335 pm),
narrower than TH1, very weakly sclerotized, with
four pairs of long setae (1 = 11.5-13.5 pm): FI (1 =
11.5 pm), FS (1 = 13 pm), GE (1 = 12.5 pm), HY (1 =
13.5 pm). AN approximately 2.5x as long as broad,
located below middle of cranium, with three small
sensilla on apex. CLP and LM without setae or
sensilla; EPX with two pairs of small sensilla (a).
Tentorium (Fig. 5) with the PLST and its APP and
PPP sclerotized and differentiated. EPST almost
indistinct, and very weakly sclerotized.

Mouthparts

Mandibles (MD) (Figs. 4, 5) (1 = 10.25 pm, w =
6.25 pm) sclerotized, more heavily sclerotized at
their BL, unidentate, with a wide BA, with prom-
inent DAP and C; MX and LUM completely fused

(Fig. 6): MX with a pair of short MS (1 = 9.5 pm)
and a protuberant PPA (9 x 5.5 pm); LUM with a
pair of PRMS (1 = 20 pm), one pair of PRLS (1 = 9
pm), and three pairs of LS (d = 2 pm) on the prela-
bial membrane, postlabial membrane with one
pair of long POS (1 = 23.5 pm) at center and two
pairs of small PLOS (1 = 9 pm).

Diagnosis

The mature larva of E. nodularis can be char-
acterized and distinguished from the mature lar-
vae of other known Eurytoma spp. by the
combination of the following characters: a) anten-
nae located below middle of cranium; b) the pres-
ence of more than four rows of setae dorsally and
pleurally; c) segment Al with one pair of ventral
setae; d) more than two dorsal setae present on
abdominal segments A6-8; e) mandibles simple,
crescentic, with one acute tooth.

Eurytoma heriadi Zerova
General aspect (Fig. 2)

Body (1 = 5.2 mm, maximum w = 1.8 mm) shape
varying between barrel-shaped and cylindrical,
slightly broader in mid region, ADP present on
TH3-A8, with three thoracic and ten abdominal
segments, tapering anteriorly and more curved
posteriorly. Color yellowish. Weakly sclerotized,
except for MD, SP and setae. Anus small, subter-
minal, transverse. Pleural lobes very scarcely de-
veloped. Tegument setose, with: a) D (1 = 190-
415pm): two pairs on each of the TH1-3; a pair on
Al-A9; b) DT (1 = 85 pm) one pair; c) P (1 = 180-440
pm) three pairs on each of the TH1-3; two pairs on
Al-A5; a pair on A6-A9; d) V (1 = 160-435 pm) one
pair on TH1-A9. SP on TH2, TH3, and on Al-A7;
ATR (1 = 60 pm, d maximum = 22 pm) funnel-
shaped, with approximately ten chambers; CA (1 =
15 pm; w = 6 pm) adjacent to ATR.

Cranium (Fig. 7)

Wider than high (w = 448 pm, h (from apex of
cranium to base of MD) = 255 pm), narrower than
TH1, very weakly sclerotized, with three pairs of
long setae (1 = 10-12 pm): FS (1 = 11 pm), GE (1 = 10
pm), HY (1 = 12 pm). AN approximately 2.5x as long
as broad, located in the middle or above the middle
of cranium, with three small sensilla on apex. CLP
and LM with a pair of short CLPS and LMS, respec-
tively; EPX with two pairs of small sensilla (a) (Fig.
4). Tentorium with the PLST and its APP and PPP
sclerotized and differentiated. EPST almost indis-
tinct, and very weakly sclerotized.

Mouthparts

MD (1 = 8 pm, w = 4 pm) sclerotized, more
heavily sclerotized at their BL, unidentate, with a

Florida Entomologist 87(3)

rv

I~ -

-t
7-

K

I f.

2 2 mm
~--------II

1. 2mm

CA
ATR 7

'.> S T

.0,1 mm

3 0,1 mm

H I
H .,'

LF'A

PLOS p LUM
Xand
MX

4, 0,2mm

DAP APP

//APP

\ PLST

.1?

): ) I
...-.. -...?.-~

C

5 0,1mm

6 0,1 mm

Figs. 1-6. Mature larvae of Eurytoma nodularis Boheman and E. heriadi Zerova. E. nodularis: (1) General as-
pect. (3) Spiracle. (4) Cranium. (5) Tentorium and mandibles. (6) maxillae and labium. E. heriadi: (2) General as-
pect. (Abbreviations: A1-9 = abdominal segments; ADP = anterodorsal protuberances; AN = antennae; APP =
anterior pleurostomal process; ATR = atrium of spiracle; AS = anal segment; C = ventral articular process of man-
dible; CA = closing apparatus of spiracle; CLP = clypeus; D = dorsal setae; DAP = dorsal articular process of man-
dible; DT = dorsal terminal seta; EPST = epistomal arc; EPX = Epipharynx, (a) = sensilla; FI = inferior frontal setae;
FS = superior frontal setae; GE = setae on the genae; HY = hypostomal setae; LM = labrum; LS = prelabial sensilla;
LUM = labium; MX = maxillae; P = pleural setae; PLOS = lateral postlabial setae; PLST = pleurostoma; POS = post-
labial setae; SP = spiracles; ST = spiracular trachea; TH1-3 = thoracic segments; V = ventral setae, and w = width.)

September 2004

1.

1
r_
I

~----~~

j

Tormos et al.: Final Instar of Eurytoma

wide BA, with prominent DAP and C; MX and
LUM completely fused: MX with a pair of short MS
(1 = 8 pm) and a protuberant PPA (8.5 x 5 pm);
LUM (Fig. 8) without setae, with a pair of small LS.

Diagnosis

The mature larva of E. heriadi can be charac-
terized and distinguished from mature larvae of

other known Eurytoma spp. by the combination of
the following characters: a) cranium without FI
setae; b) the presence of more than four rows of
setae dorsally and pleurally; c) segment Al with
one pair of ventral setae; d) mandibles simple,
crescentic, with one acute tooth.
Taxonomic position. The mature larvae of
these two species can be inserted in the key of
Henneicke et al. (1992) as follows:

1. Hypostomal setae (Hy) shorter than half the width of labrum
..................................... .. Sycophila mellea (Curtis, 1831), Tetramesa Walker, 1848
-Hypostomal setae longer or about as long as half the width of labrum (Figs. 4, 7) ......................... 2
2. More than two dorsal setae (D) present on abdominal segments A6-8 (Fig. 1) ............................ 3
-At least one of abdominal segments A6-8 with only two dorsal setae (Fig. 2) .. .......................... 4
3. Mandibles bidentate ................ ............................... E. (Ahtola) atra (Walker, 1832)
- Mandibles unidentate (Figs. 4, 5) ............................................. E. nodularis Boheman
4. Mandibles bidentate ................ ............................... Eurytoma appendigaster group
- Mandibles unidentate (Fig. 7) ............................................... Eurytoma heriadi Zerova

DISCUSSION

The mature larvae ofE. nodularis and E. heri-
adi share the following characters with other Eu-
rytoma: a) body mainly barrel-shaped, broader in
mid-region; b) head hemispherical, without pro-
nounced clypeus, with hypostomal setae longer or
about as long as half the width oflabrum, and with
inconspicuous and unpigmented craneal sclerites;
c) integument with setae arranged in distinct rows
along all body segments, and with ventral setae

arranged in paired rows; d) atrium of spiracle long.
However, the following characters differentiate
these larvae from most other known larvae of the
genus: a) the presence of more than four rows of
setae dorsally and laterally; b) segment Al with
one pair of ventral setae; c) mandibles simple,
crescentic, with one sharp/acute tooth. Addition-
ally, E. nodularis has the antennae located below
middle of cranium, and more than two dorsal setae
present on abdominal segments A6-8, and in E. he-
riadi the cranium is without FI setae.

.CLPS

LS

MD
MD

8 0,1 mm
7
0,2 mm

Figs. 7-8. Mature larvae ofE. heriadi Zerova: (7) Cranium. (8) Maxillae and labium. (Abbreviations: CLPS = cly-
peal setae; LMS = labral setae; LS = prelabial sensilla; MD = mandibles; MS = maxillary setae; PPA = maxillary
papilla.)

r

The most salient character shown by the ma-
ture larvae of these two species lies in the mandi-
bles, which are simple, a feature that, according
to current knowledge, is only shared with E. ver-
ticillata (F., 1798) (Zerova 1983). In this respect,
it should be noted that Danks (1970) described a
mature larva of an indeterminate species ofEury-
toma, a parasitoid of rubicolous aculeates, indi-
cating that it was probably E. nodularis. This
larva had unidentate mandibles.

ACKNOWLEDGMENTS

We thank Michael W. Gates (National Museum of
Natural History, USA) for observations and critical
reading of the manuscript. M.D. Zerova (Institute of Zo-
ology of National Ukrainian Academy of Sciences,
Ukraine) corroborated the determinations of the parasi-
toids. For this study the laboratories of the Fundaci6n
Entomol6gica "Torres-Sala" were used. Financial sup-
port for this paper was provided from the Junta de
Castilla y Le6n, project SA 18/96.

REFERENCES CITED

BUGBEE, R. 1941. A new species of the Eurytoma rhois
complex from the seeds of Schmaltzia (Rhus) trilo-
bata. J. Kansas Entomol. Soc. 14: 97-102.
BUGBEE, R. 1967. Revision of chalcid wasps of the genus
Eurytoma in America north of Mexico. Proc. U.S.
Natl. Museum 118: 432-552.
BUGBEE, R. 1971. A new species of Arizona Eurytoma
phytophagous in Ceanothus. ~. ... seeds. J. Kansas
Entomol. Soc. 44: 111-112.
BUGBEE, R. 1975. Eurytoma species from Mexico and
Guatemala with synonyms and keys (Hymenoptera:
Eurytomidae). Ann. Entomol. Soc. Amer. 68: 251-256.
CLARIDGE, M. 1961. An advance towards a natural clas-
sification of eurytomid genera (Hym., Chalcidoidea)
with particular reference to British forms. Trans.
Soc. British Entomol. 14: 167-185.

September 2004

CROSBY, C. 1909. On certain seed-infesting chalcis flies.
Cornell University Agric. Exp. Sta.Bull. 265: 367-388.
DANKS, H. V. 1970. Biology of some stem-nesting ac-
uleate Hymenoptera. Trans. R. Entomol. Soc. Lond.
122 (11): 323-399.
DAWAH, H. A., AND H. ROTHFRITZ. 1996. Generic-level
identification of final instar larvae of Eurytomidae and
their parasitoids associated with grasses (Poaceae) in
N.W. Europe (Hymenoptera: Braconidae, Eulophidae,
Eupelmidae, Eurytomidae, Ichneumonidae, Pteromal-
idae). J. Natural History 30: 1517-1526.
EVANS, H. E. 1987. Order Hymenoptera. pp. 597-710 In
F. W. Stehr [ed.]. Immature Insects, Volume 2. (Ken-
dall/Hunt Publishing Company. Dubuque. Iowa).
GAULD, I., AND B. BOLTON. 1988. The Hymenoptera. Ox-
ford University Press. Oxford. 332 pp.
HENNEICKE, K., H. A. DAWAH, AND M. A. JERVIS. 1992.
Taxonomy and biology of final-instar larvae of some
Eurytomidae (Hymenoptera: Chalcidoidea) associ-
ated with grasses in the UK. J. Natural History 26:
1047-1087.
NOYES, J. S. 2003. Universal Chalcidoidea Database.
World Wide Web electronic publication. www.nhm.ac.
uk/entomology/chalcidoids/index.html [accessed 05-
Sep-2003]*
PHILLIPS, W. 1917. Report on Isosoma investigations. J.
Econ. Entomol. 10: 139-146.
PHILLIPS, W. 1927. Eurytoma parva (Girault) Phillips
and its biology as a parasite of the wheat jointworm,
Harmolita tritici (Fitch). J. Agric. Res. 34: 743-758.
ROSKAM, J. C. 1982. Larval characters of some euryto-
mid species (Hymenoptera, Chalcidoidea). Proc.
Koninklijke Nederlandse Akademie van Weten-
schappen 85: 293-305.
ZEROVA, M. D. 1983. Morphological developmental and
biological features of the preimaginal phases of two
species of the genus Eurytoma III (Hymenoptera, Eury-
tomidae), the secondary parasites of Lepidoptera.
DokladyAkademiiNauk Ukrainskoi SSR (B) 10:74-78.
ZEROVA, M. D., AND V. N. FURSOV. 1991. The Palaearctic
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developing in stone fruits (Rosaceae: Prunoidae).
Bull. Entomol. Res. 81: 209-219.

Florida Entomologist 87(3)

Zolnerowich & Rose: Eretmocerus rui n. sp.

ERETMOCERUSRUI N. SP (HYMENOPTERA: CHALCIDOIDEA:APHELINIDAE),
AN EXOTIC NATURAL ENEMY OF BEMISIA (TABACI GROUP)
(HOMOPTERA: ALEYRODIDAE) RELEASED IN FLORIDA

GREGORY ZOLNEROWICH1 AND MIKE ROSE2
'Department of Entomology, 123 Waters Hall, Kansas State University, Manhattan, KS 66506-4004

2Department of Entomology, Leon Johnson Hall, Montana State University, Bozeman, MT 59717

ABSTRACT

Eretmocerus rui n. sp. imported from Hong Kong and released against Bemisia (tabaci
group) in Florida is described. This thelytokous species was recovered after release, but it is
unknown if it is established in Florida.

Key Words: biological control, Eretmocerus, Aphelinidae, Bemisia, Aleyrodidae.

RESUME

Se describe a Eretmocerus rui n. sp., especie introducida de Hong Kong y liberada en la Flor-
ida para el control de Bemisia. Esta especie telit6quica fue recapturada despu6s de su lib-
eraci6n, pero se desconoce si esta establecido en la Florida.

Translation provided by the authors.

Numerous populations of exotic parasitic Hy-
menoptera, primarily in the genera Encarsia and
Eretmocerus (Hymenoptera: Chalcidoidea: Aphe-
linidae), were introduced during population ex-
plosions of Bemisia (tabaci group) (Homoptera:
Aleyrodidae: Aleyrodinae) in the southern United
States during the 1980s and 1990s. Introductions
ofEretmocerus Haldeman (Haldeman 1850) were
emphasized, as this genus is composed of primary
parasites that attack Aleyrodidae (Rose et al.
1996). Zolnerowich & Rose (1998) characterized
and described five of the introduced Eretmocerus
species that were released in the U.S., while Rose
& Zolnerowich (1997a, b) characterized and de-
scribed species of Eretmocerus indigenous to, or
naturally occurring in, the United States.
Most of the Eretmocerus populations released
in the United States were introduced through the
USDA-APHIS quarantine laboratory in Mission,
Texas (Goolsby 1996; Goolsby et al. 1998). How-
ever, biological control researchers in Florida also
introduced natural enemies of Bemisia (tabaci
group) through the quarantine laboratory in
Gainesville. One of these is an undescribed spe-
cies of Eretmocerus that F. D. Bennett (Nguyen &
Bennett 1995) discovered attacking a Bemisia
species in Hong Kong. This thelytokous species
(McAuslane & Nguyen 1996) was consigned from
quarantine, reared in culture, and released in
Florida. We describe that species here to aid in de-
termination of the Eretmocerus species complex
attacking Bemisia (tabaci group) in Florida, effi-
cacy evaluations of the same, and discovery of

possible utilization of non-target whitefly hosts by
exotic Eretmocerus species released in Florida.

MATERIALS AND METHODS

Terminology and measurements follow those
used by Rose & Zolnerowich (1997a). Measure-
ments of 61 morphological features were taken
from 10 females in the type series that were
mounted in balsam or Hoyer's. Measurements
were made with a customized data acquisition
program written for an Apple Macintosh com-
puter, and linked to a digitizing tablet and Zeiss
compound microscope equipped with Nomarski
contrast enhancement. In the description, stated
lengths are means.

Eretmocerus rui Zolnerowich and Rose, new species
(Figs. 1-3, 5)

Diagnosis

Females of Eretmocerus rui can be identified
by the presence of 3 setae on each parapsis, the
presence of 6 setae on the mesoscutum, a very
elongate, cylindrical antennal club that is 6.88-
8.06x as long as wide (Fig. 1), a long ovipositor ap-
proximately the same length as the club, and a
long, narrow forewing about 2.7x as long as wide
(Fig. 2).
Of the Eretmocerus species known from the
U.S. (Rose & Zolnerowich 1997a, b; Zolnerowich &
Rose 1998) only E. furuhashii Rose and Zolnero-

Florida Entomologist 87(3)

Fig. 1. Eretmocerus rui, female antenna.

which bears 3 setae on the parapsis. However, fe-
males of E. furuhashii bear 4 setae on the
mesoscutum and have much shorter (about 4.3-5x
as long as wide) antennal clubs that are clavate
with slightly deflected rostratee) apices.
All other nominal exotic Eretmocerus species
introduced and released against Bemisia (tabaci
group) in the United States bear 4 setae on the
mesoscutum and 2 setae on the parapsis. Those
species are E. emiratus Zolnerowich and Rose,
E. hayati Zolnerowich and Rose, E. melanoscutus
Zolnerowich and Rose, and E. mundus Mercet.

Female

Length of specimens in Hoyer's 0.575-0.75 mm
(n = 10). Holotype female 0.75 mm. Body light yel-
low. Head amber. Antennae pale amber. Legs pale
yellow. Wings hyaline.
Face and occiput with transverse substrigulate
sculpture, interscrobal area vertically substrigu-
late. Antenna (Figs. 1 and 3) with radicle 3.7x as
long as wide; scape 5.08x times as long as wide,
2.31x as long as radicle, 2.01x length of pedicel,
0.55x length of club; pedicel 2.6x as long as wide,
1.12x as long as radicle, 0.50x length of scape. Fu-
nicle I triangular, dorsum 0.21x length of venter.
Funicle II subquadrate, somewhat compressed,
dorsum 0.73x length of venter. Club cylindrical,
narrowed at apex, 7.4x as long as greatest width,
14.3x as long as narrowest width, 1.83x length of
scape, 3.69x length of pedicel.

,a '
----- -\

2
Fig. 2. Eretmocerus rui, female forewing.

Mesoscutum trapezoidal with 6 setae, anterior
14 with cellular reticulate sculpture, remainder
with faint elongate reticulations. Parapsis with 3
setae, anterior margins with elongate cellular re-
ticulations; axilla with 1 seta, faintly reticulate.
Scutellum with 4 setae, anterior pair shorter, 2
placoid sensilla lateral and closer to the posterior
pair of setae, and with faint, elongate reticula-
tions. Metanotum slightly more narrow in longi-
tudinum than propodeum; propodeum with faint
transverse reticulations, central lobe broad and
smooth, reaching V2 distance into gastral tergite
II. Endophragma extending into gastral tergite II.
Forewing (Fig. 2) 3.09x as long as wide be-
tween points on wing margin immediately above
apex of stigmal vein and at distal apex of frenal
fold; 2.73x as long as maximum width of disc (the
area distad of an imaginary line extending from
the distal apex of the frenal fold to the wing mar-
gin immediately above the distal apex of the stig-
mal vein). Longest anterior alary fringe 0.15x
width of disc, longest posterior alary fringe 0.32x
width of disc. Base of wing with 1 seta, distal por-
tion of costal cell with 3 setae. Marginal vein with
3 longer setae, 8-16 setae between marginal vein
and partial linea calva; setae often interspersed
above tubercles and extending about 23 distance
to proximal advent of frenal fold. Partial linea
calva closed posteriorly by setae, including those
just described, with 13-14 tubercles on ventral
surface near posterior end; a group of 19-29 setae,
depending on size of specimen, including those
closing the distal margin of the linea calva, gener-
ally point toward the anterior margin of the wing;
102-130 setae, depending on size of specimen, in
disc (excluding a row of setae around the interior
margin) generally point toward distal apex of
wing. Submarginal vein 2.78x as long as marginal
vein and 3.62x length of stigmal vein. Marginal
vein 1.31x length of stigmal vein.
Hind wing 7.31x as long as wide with 0-2 setae
in disc.
Gastral tergite I with reticulations on lateral
anterior margins, remaining tergites appear
smooth; gastral tergites I-IV with paired setae as
follows: 1, 1, 2, 2, 2, 2. Syntergum with 4 setae.
Ovipositor prominent, exserted, nearly equal
(1.01x) to length of club, 1.85x length of scape,
1.13x length of midtibia.

Male

There is only one male known, and this speci-
men is uniquely different from nominal exotic
biparental Eretmocerus species in the United
States in its overall paucity of pigment (see Zol-
nerowich & Rose 1998).
Specimen mounted in Hoyer's with head am-
ber; antennae pale fuscous overall, pedicel and
multiporous plate sensilla slightly darker. Prono-
tum pale fuscous, propodeum and anterolateral

September 2004

Zolnerowich & Rose: Eretmocerus rui n. sp.

portion of gastral tergite I pale fuscous, remain-
der of dorsal habitus pale. Forewing with submar-
ginal vein fuscous, remaining veins and proximal
1/3 of costal cell pale fuscous, becoming slightly
darker in a narrow band proximal to frenal fold;
frenal fold fuscous; all setae in forewing dark;
pale fuscous band around forewing margin. Hind
wing venation fuscous. Coxa and trochanter pale,
with femur, tibia, and tarsi pale brown on all legs.
Aedeagus pale fuscous.

Host

Bemisia (tabaci group) on Hibiscus sp. in labo-
ratory culture in Gainesville, FL.

Etymology

This species is named for our colleague, Ru
Nguyen, Research Entomologist for the Florida
Department of Agriculture and Consumer Ser-
vices, Division of Plant Industry, Gainesville.
Nguyen undertook the rearing and release pro-
gram for E. rui in Florida and conducted biological
studies on this species. He is currently undertak-
ing field recovery sampling for Eretmocerus spp.
attacking Bemisia (tabaci group) and other white-
fly genera in Florida. He was instrumental in suc-
cessful biological control programs directed
against the citrus whitefly, Dialeurodes citri (Ash-
mead) (Aleyrodidae: Aleyrodinae) in Florida, and
the citrus blackfly, Aleurocanthus woglumi
(Ashby) (Aleyrodidae: Aleyrodinae) in Florida and
elsewhere. Nguyen also facilitated the successful
introduction of Entedononecremnus krauteri Zol-
nerowich and Rose (Hymenoptera: Chalcidoidea:
Eulophidae) against the invading giant whitefly,
Aleurodicus dugesii Cockerell (Aleyrodidae: Aleu-
rodicinae) in Florida.

DISCUSSION

Eretmocerus rui was originally reared from Be-
misia sp. collected on Emilia sp. (Asteraceae) in
1992 by F. D. Bennett during searches for natural
enemies of Bemisia (tabaci group) in Hong Kong.
Nguyen & Bennett (1995) discussed the importa-
tion, release, and recovery of natural enemies of
Bemisia (tabaci group) in Florida. Eretmocerus
rui was released in 10 Florida counties, and spec-
imens were recovered a few weeks after release.
However, it is not known ifE. rui is permanently
established in Florida. Sampling of Bemisia
(tabaci group) and other whitefly genera in Flor-
ida to recover Eretmocerus species, and to eluci-
date species and species complexes associated
with whitefly species is underway.
McAuslane & Nguyen (1996) discussed the re-
productive biology and behavior of E. rui (their
Eretmocerus sp.), and noted the significance of
thelytoky to applied biological control. Although

we describe the single male specimen of E. rui,
males are not necessary for reproduction.
De Barro et al. (2000) compared sequences of
the D2 expansion segment of the 28S ribosomal
RNA gene between an unnamed species of Eret-
mocerus from Hong Kong and Eretmocerus queen-
slandensis Naumann and Schmidt (in De Barro et
al. 2000), which was described from Bemisia
tabaci in Queensland, Australia. Out of 590 posi-
tions, they found the sequence from the Hong
Kong Eretmocerus differed from E. queenslanden-
sis by a single mutation at position 206, and sug-
gested the two were conspecific. There is a
possibility that the species of Eretmocerus from
Hong Kong they used is the same as E. rui, but
unfortunately, preserved specimens or voucher
material from their analysis are not available.
However, there are a number of striking mor-
phological differences between E. rui and E. queen-
slandensis which lead us to believe that if the
Eretmocerus from Hong Kong used by De Barro et
al. was indeed E. rui, the two are not conspecific.
The most obvious difference lies in the amount of
pigmentation, with unmounted females of E.
queenslandensis being fuscous, with this dark pig-
mentation also very evident on cleared, slide-
mounted specimens (Fig. 6). Females ofE. rui have
the head and antennae amber, the legs and body
are light yellow, and there are no fuscous markings
(Fig. 5). Additional morphological differences in-
clude: the club ofE. queenslandensis is 4.8-6.4x as
long as wide (Fig. 4), the club ofE. rui is 6.88-8.06x
as long as wide (Figs. 1 and 3); the parapsis of
E. queenslandensis has 2-3 setae, that ofE. rui has
3 setae; the placoid sensilla on the scutellum are
very close to the posterior pair of scutellar setae in
E. queenslandensis (Fig. 6), while in E. rui they are
usually more anterior and lateral to the posterior
setae (Fig. 5). There are other morphological differ-
ences, but the ones given here are the most obvious
to the untrained eye.

Material Examined

Holotype female in balsam with 3 other fe-
males on a single slide with a single right-hand
label with the following data: Hong Kong, 14 VII
1992, FD Bennett 1312, Bemisia tabaci, lab cul-
ture Fl, Eretmocerus rui, Zol.& Rose 2003, HO-
LOTYPE (in red ink, author's note). The left side
of the slide is frosted glass upon which is written:
1312, Eret., 4 V. Written in black ink on the glass
below the coverslip is: balsam. The coverslip is
ringed with red Glypt. The holotype is the bottom
left specimen. The specimens are mounted with
the heads facing the bottom of the slide.
The paratype series consists of three females
mounted in balsam on a single slide with the ho-
lotype, 13 females and one male individually
mounted on slides in Hoyer's with two labels each
that bear the following data: Left label: Name:

Florida Entomologist 87(3)

September 2004

Fig. 3. Eretmocerus rui, female antenna.
Fig. 4. Eretmocerus queenslandensis, female antenna.
Fig. 5. Eretmocerus rui, female thorax and metasoma.
Fig. 6. Eretmocerus queenslandensis, female thorax and metasoma.

Eretmocerus rui, paratype (in red ink), Det. Rose
and Zol. 2002, Coll. R. Nguyen, No., Corr. R.
Nguyen II-18-93. Right label: Loc. (Hong Kong),
Univ. Fl. Gainesville, Date: II-18-1993, Host: Be-
misia (culture), Det., On: Hibiscus.
The holotype female and three paratype fe-
males on a single slide and single male paratype
specimen will be deposited in the USDA-ARS Sys-
tematic Entomology Laboratory at the U.S. Na-
tional Museum, Washington, D.C. The remaining
type slides and additional specimens will remain
with the authors while ongoing systematic stud-
ies on Eretmocerus species recovered from white-
fly in the U.S. are in progress.

Additional Material Examined

USA: Florida: Gainesville DPI, XII.2.1994, lab
culture on Hibiscus, R. Nguyen (25 females);
USA: Florida: Gainesville, II.15.1995, Bemisia
lab culture, cage 2, R. Nguyen (10 females).

ACKNOWLEDGMENTS

This study was supported by the USDA-CSREES-
National Research Initiative. The authors express their
appreciation to Ru Nguyen for providing specimens of

Eretmocerus used in this study. The authors express their
gratitude to Ben Shaw, Lucid Art, for the drawings, and
to Jack McShea, Cinnabar Macintosh, Livingston, Mon-
tana, for developing the digitizing software (Rosebud II)
used for data acquisition and analysis. This article is
Contribution No. 03-362- from the Kansas Agricultural
Experiment Station (KAES) and was supported in part
by KAES Hatch Project No. 583, Insect Systematics.

REFERENCES CITED

DE BARRO, P. J, F. DRIVER, I. D. NAUMANN, G. M.
CLARKE, S. SCHMIDT, AND J. CURRAN. 2000. Descrip-
tions of three species of Eretmocerus Haldeman (Hy-
menoptera: Aphelinidae) parasitising Bemisia tabaci
(Gennadius) (Hemiptera: Aleyrodidae) and Trialeu-
rodes vaporariorum (Westwood) (Hemiptera: Aley-
rodidae) in Australia based on morphological and
molecular data. Australian J. Entomol. 39: 259-269.
GOOLSBY, J. A. 1996. Biological control of sweetpotato
whitefly. pp. 37-57 In L. E. Wendel 1996, Annual Re-
port of USDA-APHIS, Mission Texas Plant Protec-
tion Center (Technical Report).
GOOLSBY, J. A., M. A. CIOMPERLIK, B. C. LEGASPI, JR., J.
C. LEGASPI, AND L. E. WENDEL. 1998. Laboratory
and field evaluation of parasitoids of exotic parasi-
toids of Bemisia tabaci (Gennadius) (Biotype "B")
(Homoptera: Aleyrodidae) in the Lower Rio Grande
Valley of Texas. Biol. Control 12: 127-135.

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HALDEMAN, S. S. 1850. On four new species of Hemi-
ptera of the genera Ploiaria, Chermes, Aleurodes,
and two new Hymenoptera, parasitic on the last
named genus. Amer. J. Sci. 9: 108-111.
MCAUSLANE, H. J., AND R. NGUYEN. 1996. Reproductive
biology and behavior of a thelytokous species of Eret-
mocerus (Hymenoptera; Aphelinidae) parasitizing
Bemisia argentifolli (Homoptera: Aleyrodidae). Ann.
Entomol. Soc. Amer. 89: 686-693.
NGUYEN, R., AND F. D. BENNETT. 1995. Importation and
field release of parasites against silverleaf whitefly,
Bemisia argentifolli (Bellows and Perring) in Florida
from 1990-1994. Proc. Florida State Hort. Soc. 108:
43-47.
ROSE, M., AND D. ROSEN. 1991-92. Eretmocerus debachi
n. sp. (Hymenoptera: Aphelinidae), an effective par-
asite of Parabemisia myricae (Homoptera: Aley-
rodidae). Israel Jour. Entomol. 25/26: 199-207.
ROSE, M., AND G. ZOLNEROWICH. 1997a. Eretmocerus
Haldeman (Hymenoptera: Aphelinidae) in the United

States with descriptions of new species attacking Be-
misia (tabaci complex) (Homoptera: Aleyrodidae).
Proc. Entomol. Soc. Washington 99: 1-27.
ROSE, M., AND G. ZOLNEROWICH. 1997b. The Genus
Eretmocerus (Hymenoptera: Aphelinidae): Parasites
of Whitefly (Homoptera: Aleyrodidae). Special Publi-
cation, California Department of Food and Agricul-
ture. 8 pp.
ROSE, M., G. ZOLNEROWICH, AND M. S. HUNTER 1996.
Systematics, Eretmocerus and Biological Control,
pp. 477-498 In D. Gerling and R. T. Mayer. Bemisia
1995: Taxonomy, Biology, Damage, Control and Man-
agement. Intercept Ltd. 702 pp.
ZOLNEROWICH, G., AND M. ROSE. 1998. Eretmocerus
Haldeman (Hymenoptera: Aphelinidae) imported
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Proc. Entomol. Soc. Washington 100: 310-323.

Florida Entomologist 87(3)

September 2004

FACTORS AFFECTING THE TRAPPING OF MALES
OF SPODOPTERA FRUGIPERDA (LEPIDOPTERA: NOCTUIDAE)
WITH PHEROMONES IN MEXICO

EDI A. MALO1, FERNANDO BAHENA2, MARIO A. MIRANDA3 AND J. VALLE-MORA'
'Departamento de Entomologia Tropical, El Colegio de la Frontera Sur
Apdo. Postal 36, Tapachula, 30700, Chiapas, M6xico

2Centro Nacional de Investigaciones para la Producci6n Sostenible, INIFAP
Apdo. Postal 58260, Morelia, Michoacan, M6xico

3Campo Experimental Valle de Apatzingan, INIFAP
Apartado Postal 262, Apatzingan, Michoacan

ABSTRACT

Four commercial sex pheromones and virgin females were tested as attractants for male fall
armyworm (FAW), Spodoptera frugiperda with Scentry Heliothis traps in sorghum fields in
Chiapas, Mexico. We observed significant differences among the lures tested. Pherotech, vir-
gin females, and Scentry lures elicited different responses from Chemtica and Trece lures.
In another experiment performed in Michoacan, Mexico, we found that Scentry Heliothis
traps baited with Chemtica lures placed at 1.5 m above ground caught significantly more
males than traps placed at a height of 2 m. In contrast, the capture of S. frugiperda males
with bucket traps placed at 1 m height was not significantly different from that of traps
placed at 1.5 and 2 m height. When baited with pheromone, Scentry Heliothis traps caught
more non-target insects than bucket traps. Apidae was the most prevalent family of non-tar-
get insects caught in both experiments.

Key Words: Spodoptera frugiperda, trapping, pheromones, Mexico, non-target insects.

RESUME

Se evaluaron cuatro feromonas comerciales y hembras virgenes como atrayentes contra el
gusano cogollero Spodoptera frugiperda usando trampas tipo Heliothis en un campo de sorgo
en Chiapas. Las captures de los machos con las feromonas comerciales Chemtica y Trece fu-
eron significativamente diferentes a las captures obtenidas con las feromonas Pherotech,
Scentry y hembras virgenes. En otro ensayo realizado en el Estado de Michoacan, M6xico,
encontramos que las captures obtenidas con las trampas tipo Heliothis cebadas con fero-
mona de Chemtica y colocadas a una altura de 1.5 m arriba del suelo, fueron significativa-
mente mejores que las captures de las trampas colocadas a 2 m. Por lo contrario, las captures
obtenidas con las trampas bucket colocadas a 1 m de altura fueron muy similares a las de las
trampas colocadas a 1.5 m y 2 m. Las captures de la entomofauna asociada fueron much
mayores en las trampas tipo Heliothis que las obtenidas con las trampas bucket, siendo Ap-
idae la familiar mas abundante.

Translation provided by authors.

The fall armyworm (FAW), Spodoptera fru-
giperda (J.E. Smith), is a major pest of corn, rice,
and forage grass (Pashley 1989), and is found in
almost all parts of Mexico with the greatest dam-
age occurring in the Southern and Eastern tropi-
cal States (Andrews 1980). Control of S.
frugiperda in maize is achieved by application of
methyl parathion, chlorpyrifos, methamidophos,
and phoxim, among others insecticides. There are
a number of problems related to the habitual use
of synthetic pesticides including detrimental ef-
fects on the health of farm workers in rural com-
munities in Latin America (McConnell & Hruska

1993; Tinoco & Halperin 1998). For this reason,
additional methods of control are desirable for de-
velopment of a safe system of integrated pest
management in the field, including the use of
pheromones. Lepidopteran pheromones have
been used for insect monitoring, mass trapping,
and mating disruption of a great diversity of in-
sect pests (Wyatt 1998). The female-produced sex
pheromone of S. frugiperda, which is commer-
cially available, has been shown to be a useful tool
for monitoring male populations (Adams et al.
1989; Mitchell et al. 1989; Lopez et al. 1990; Gross
& Carpenter 1991; Weber & Ferro 1991). How-

Malo et al.: S. frugiperda Caught with Sex Pheromone

ever, commercial sex pheromones lures made in
Great Britain and USA can give erratic capture
rates in Mexico and Central America (Andrade et
al. 2000; Malo et al. 2001).
The population of adult male S. frugiperda is
frequently monitored with plastic funnel traps
(Universal Moth Traps or "bucket" traps or Uni-
traps) baited with sex pheromones components as
lures (Mitchell et al. 1985; Tumlinson et al. 1986).
However, this type of trap gave poor results when
tested in the coastal plain of Chiapas, Mexico
(Malo et al. 2001). Many of the parameters for
monitoring FAW with sex pheromone traps have
already been described (Mitchell et al. 1985;
Mitchell et al. 1989; Pair et al. 1989). However,
there exists the possibility that these parameters
may differ from one region to another. It is there-
fore necessary to determine the trap and commer-
cial sex pheromone combination most appropriate
for use in southern Mexico. For example, two
FAW strains have been reported in Mexico, which
are believed to be due to reproductive isolation of
the populations arising from geographical isola-
tion (Lopez-Edwards et al. 1999). In this study, we
tested a selection of commercial lures. We also re-
port the evaluation of the height of traps placed in
the field and three designs of traps with Chemtica
lures. These experiments were made in the states
of Chiapas and Michoacan, two of the most impor-
tant maize growing states in Mexico.

MATERIALS AND METHODS

Chiapas Trial

The first trial was performed at El Manzano in
the municipality of Tapachula (1444'N, 9219'W,
altitude 20 m above sea level), Chiapas, Mexico, in
a field planted with sorghum at 20 days post-plant-
ing. This area has a humid tropical climate with
heavy rain in the summer, with an average annual
rainfall of 2,063 mm. The average annual temper-
ature is 26C, with April and May being the warm-
est months. Two crop cycles are grown annually in
El Manzano; sorghum or maize from January to
May, watered by sprinkler irrigation, and soybean
during the rainy season from July to October.
Four commercial sex pheromone lures and vir-
gin females as controls were evaluated in a fully
randomized plot design with three replicates of
each treatment. The replicate plots were ar-
ranged in parallel lines approximately 30 m apart
in a field planted with sorghum (10 ha). The traps
were placed at height of 1.5 m. Lures tested were
Scentry (Scentry, Inc., Buckeye, AZ), a gray rub-
ber septum dispenser; Trece (Trece, Inc., Salinas,
CA) a red rubber septum dispenser, obtained
through Gempler's, Inc. (Belleville, WI); Chemtica,
a bubble cup (Chemtica, Heredia, Costa Rica);
Pherotech, a red rubber septum dispenser (Phero-
tech, Delta, BC, Canada) and a virgin female

(from the laboratory colony) used as control. The
traps used were the Scentry Heliothis trap, which
is a white double cone collapsible plastic net (Ec-
ogen, Inc., Billings, MT). The traps were placed on
10 February 2001 and they remained in place for
one week. The trap captures were recorded daily
from 11 to 16 February, a total of 6 observation
dates. The virgin female was checked daily and
replaced when necessary. On each date, we emp-
tied the traps and recorded the number of S. fru-
giperda males. All non-target insects captured
were identified to order (Borror et al. 1989).
Voucher specimens were placed in the insect col-
lection held at El Colegio de la Frontera Sur,
Tapachula, Chiapas, Mexico.

Michoacan Trial

The second trial was performed in Apatzingan
(19002'N, 102002'W), Michoacan, Mexico, from 29
July to 26 September, 2001. Apatzingan is at an
altitude of 320 m above sea level with a tropical
dry climate. Two varieties of maize (V454 and
V455) were grown here, at the usual density of
50,000 plants/ha with 80 cm row spacing. A two-
factor design was used in the experiment. Two
types of traps were used, Scentry Heliothis trap
and a green reusable bucket trap (Gempler's).
The traps were placed at heights of 1, 1.5, and 2 m
above the ground. Traps were hung on wooden
stakes placed at 30-m intervals along planted
rows. We used a bubble cup, commercial sex pher-
omone from Chemtica. The treatments were ar-
ranged in a fully randomized plot design with
four replicates of each treatment. All lures were
changed monthly. Trap captures were recorded
every 3-4 d, and the treatments were rotated after
each observation date. On each date, we emptied
the traps and recorded the numbers of FAW
males and non-target insects captured. All non-
target insects captured were identified to family
(Borror et al. 1989). Voucher specimens were
placed in the insect collection held at Centro Na-
cional de Investigaciones para la Produccion Sos-
tenible (CENAPROS), Morelia, Mexico.
At the same time that the traps baited with
pheromone were being checked, evidence of feed-
ing damage produced by FAW larvae was evalu-
ated in 100 plants chosen at random within the
area of trapping. Typically, larvae stay in the
whorl, feeding on new leaves, so the damage to
the newly expanding leaves and the presence of
frass is easily detected by visual examination of
the whorls.

Statistical Analysis

The numbers of male FAW captured per trap
per sample period were converted to percentages
of the total number of moths captured by each
trap and lure within each plot (Mitchell et al.

1985). Percentage values were arcsine trans-
formed to increase the homogeneity of variance
and normality. Results of the experiment to test
lures were analyzed by one-way ANOVA and re-
sults of the traps placed at different heights were
analyzed by two-way ANOVA (trap x height).
Treatment means were compared with the Tukey
test (P = 0.05). The number of non-target insects
caught with the lures in the Chiapas State trial
was analyzed as a randomization test (Manly
1994). The effects of trap and height on the fami-
lies of non-target insects caught at prevalence
above 5% in Michoacan State were analyzed by a
contingency table involving 2 (traps) x 3 (heights)
x 7 (insect families) in the GLIM program (Gener-
alized Linear Interactive Modeling, Numerical
Algorithms Group, 1993) in a log-linear model.

RESULTS

Chiapas Trial

The total capture ofS. frugiperda males for all
traps pooled throughout the 6 days was 727.
There were significant differences among lures
tested (F = 12.5, df = 5,25, P < 0.01). Chemtica
and Trece lures elicited a greater capture than
virgin females, Scentry, or Pherotech lures (Fig.
1). A very low number of non-target insects (n =
64) were captured during the period of trapping,
mainly Apidae (bees), representing 64% of the
total non-target insects caught. Other orders
captured were Coleoptera, Lepidoptera, and Hy-
menoptera. No significant differences were de-
tected in non-target insects caught in relation to
the lures used in a randomization test (P > 0.05).
Chemtica and virgin females were the lures that

September 2004

attracted the greatest number of non-target in-
sects caught (32 and 31%, respectively). Trece,
Scentry, and Pherotech lures captured 20.3%,
14%, and 1.5%, respectively.

Michoacan Trial

The total capture of S. frugiperda males was
2397. Of the total number of males captured,
81.1% were caught with the Scentry Heliothis
trap and 18.9% with bucket traps. The efficiency
of Scentry Heliothis traps was affected by height,
whereas the catch of bucket traps was indepen-
dent of height, resulting in a significant interac-
tion effect (F = 4.3; df= 2,15; P = 0.03) (Fig. 2).
The number of insects caught with pheromone
traps (Scentry Heliothis and bucket traps placed
at different heights) as well as the feeding dam-
age produced by S. frugiperda larvae on the
plants was generally higher at the start of the
study, but at the end of the first month, the popu-
lation and the feeding damaged produced by FAW
larvae had decreased (Fig. 3). Great variation was
observed in the number of insects caught over
time and in the feeding damage resulting from
the FAW infestation. In this experiment, no
chemical insecticide was used to control FAW.
A total of 2352 non-target insects was caught
with both traps (Scentry and bucket) during the
trial period. Significant differences were observed
among the number of non-target insects at the
level of family (X2 = 488, df= 5, P < 0.01). The most
abundant non-target insects caught were Apidae,
followed by Cicadellidae and Tachinidae (Fig. 4).
Scentry Heliothis traps caught a total of 2000
non-target insects, whereas bucket traps caught
352. Apidae was the most prevalent group caught

I Scentry Trap O Bucket Trap

I 40
ab

30-

0 I

Chemtica Trece Scentry Pherotech Females
Lure

Fig. 1. Percent capture of male fall armyworm
(+SEM) with Scentry traps baited with commercial
lures in a sorghum field in Chiapas State, Mexico. Sig-
nificant differences within traps and height are shown
by different letters over the bars (Tukey test, P = 0.05).

25

20
15

10

10 15 20
Height
Fig. 2. Percent capture of male fall armyworm
(+SEM) with Scentry and bucket traps baited with
Chemtica lures and placed at different heights (mm) in
a maize field in Michoacan State, Mexico. Significant
differences within traps and height are shown by differ-
ent letters over the bars (Tukey test, P = 0.05).

Florida Entomologist 87(3)

Malo et al.: S. frugiperda Caught with Sex Pheromone

660

Date
E

Fig. 3. Seasonal mean number (+SEM) of male
Spodoptera frugiperda caught with sex pheromone
traps in a maize field in Michoacain, Mexico, is in line.
Percentage of feeding damage produced by S. frugiperda
at each observation date is in column.
at each observation date is in coliimn-

250

Scentry Trap

200

150

100

50 I

with Scentry Heliothis traps and Carabidae with
bucket traps. Carabidae, caught most with bucket
traps, was not included in the analysis of the ef-
fects of trap and height because few were caught
in Scentry Heliothis traps. Scentry Heliothis
traps placed at 1 m height caught a total of 910
non-target insects, whereas traps placed at 1.5 m
caught 649 non-target insects and traps placed at
2 m caught 441 non-target insects. Bucket traps
placed at 1 m caught a total of 105 non-target in-
sects, traps placed at 1.5 m caught a total of 139
non-target insects and traps placed at 2 m caught
a total of 108. Overdispersion was observed in the
distribution of data on the non-target insect fam-
ilies and different traps placed at different
heights. Overdispersion was corrected by the
methods described by Hinkley et al. (1990). No
significant interaction was detected among trap
type and height of traps (X2 = 9.98, df = 14, P =
0.76), indicating that the number of non-target
insects caught in the traps was independent of
the height at which the trap was placed. However,
a significant interaction was observed between

H Cicadellidae

M Flatidae

SSyrphidae

O Tachinidae

MVespidae

SApidae

SCantharidae

Bucket Trap

H1 H2 H3

H1 H2 H3

Fig. 4. Number of each non-target insect family caught with Scentry and bucket traps in a maize field in Micho-
acan State, Mexico. H1 = 1 m, H2 = 1.5 m, and H3 = 2 m height at which traps were placed.

Florida Entomologist 87(3)

family x type of trap x height of trap indicating
that each family of non-target insects responded
differently to trap type and height (Table 1).

DISCUSSION

From the results of the commercial lures
tested it is clear that the Chemtica and Trece
lures can be used for monitoring S. frugiperda
males in Mexico. Scentry Heliothis traps baited
with Chemtica lures placed at 1.5 m above ground
caught significantly more S. frugiperda males
than traps placed at a height of 2 m. In contrast,
capture with bucket traps was not affected by
trap height. The parameters for monitoring FAW
males with pheromone traps have been described
in studies performed in Florida, USA (Mitchell et
al. 1985; 1989; Pair et al. 1989). The results ob-
tained in Florida and the results in Mexico are
not markedly different. Trap height is one of the
most important aspects of trap deployment, along
with trap density and the position of the trap with
respect to vegetation (Wall 1989).
Hartstack screenwire cone traps and plastic
funnel traps were reported to capture more moths
than sticky and electric grid traps (Tingle &
Mitchell 1975; Mitchell et al. 1985). However,
when the population density of FAW was low, both
types of trap designs tested did equally well in
capturing S. frugiperda males (Mitchell et al.
1985; Adams et al. 1989; Pair et al. 1989). For
higher density populations, Hartstack traps gen-
erally performed better than unitraps (Mitchell et
al. 1985; Pair et al. 1989). Green traps were only
minimally attractive when baited with FAW pher-
omone and insecticide (Gross & Carpenter 1991).
Similar results were reported by Malo et al. (2001)
in the evaluation of commercial lures and traps;
green traps caught a low number of FAW males in
the coastal plain of Chiapas, Mexico. Trap color
has been reported to be influential to the capture
of several noctuids, including S. frugiperda. Plas-
tic bucket traps with green canopies, yellow fun-
nels, and white bucket traps collected more

Spodoptera spp. males than all-green traps in sev-
eral studies (Mitchell et al. 1989; Pair et al. 1989;
Lopez 1998). However, Meagher (2001a) reported
that more moths were captured in these standard
traps than all-white or all-green traps, as was also
reported with S. exigua (Lopez 1998). It was sug-
gested that a possible factor responsible for low
rates of capture of moths in green traps was the
low reflectance at wavelengths where moth vision
is most sensitive (Mitchell et al. 1989).
In this study, we caught very few non-target
insects in the trial conducted in Chiapas in traps
baited with pheromone. In contrast, in the Micho-
acan trail, the number of FAW males caught with
pheromone traps was similar to the number of
non-target insects. However, the presence of hon-
eybees, Apis mellifera L., was evident in both tri-
als. The fact that bees were caught in both traps
also elevated the apparent number of captures
(Fig. 4), although bee captures were more com-
mon in Scentry Heliothis traps. It is possible that
a few species of non-target moths may be at-
tracted by certain chemical components of the
pheromone of S. frugiperda. Weber and Ferro
(1991) reported that noctuids Leucania phragmit-
idicola Guenee, Sideridis rosea (Harvey) and Eu-
rois occulta (L.) were commonly caught in FAW
traps in Massachusetts, USA. Others have also
reported that baited traps attract non-target and
even beneficial insects (Adams et al. 1989; Mitch-
ell et al. 1989; Gauthier et al. 1991; Gross & Car-
penter 1991; Meagher & Mitchell 2001; Malo et
al. 2001; Meagher 2001a,b). Apparently trap color
may play a role in the attraction of the insects, for
example white or yellow traps can attract large
number of Bombus spp. (Hamilton et al. 1971;
Mitchell et al. 1989).
In conclusion, Scentry Heliothis traps with a
Chemtica and Trece lures gave good results for
monitoring FAW males in Chiapas, Mexico. Parts
of these results were reconfirmed in Michoacan,
Mexico and suggest that the traps are best placed
at a height of 1.5 m. However, these traps caught
a considerable number of non-target insects and

TABLE 1. TEST OF SIGNIFICANCE OF THE FACTORS INVOLVED IN A LOG-LINEAR MODEL OF TRAP DESIGN, TRAP HEIGHT,
AND FAMILY OF NON-TARGET INSECTS CAUGHT.

Source of variation X2 df P

Trap 591.5 19 <0.001
Height 188.4 20 <0.001
Family 301.0 24 <0.001
Trap-Height 9.98 14 0.76
Trap-Family 78.2 12 <0.001
Height-Family 97.8 28 <0.001

Trap used: Scentry type Heliothis and bucket.
Height at which traps were placed: 1, 1.5, and 2 m.
Family of non-target insects caught above 5%: Cicadellidae, Flatidae, Syrphidae, Tachinidae, Vespidae, Apidae, and Cantharidae.
Analysis performed in GLIM with Poisson error distribution corrected for overdispersion.

September 2004

Malo et al.: S. frugiperda Caught with Sex Pheromone

it is possible that one of the chemical compounds
from pheromones or the color of the trap may be
involved in the attraction of non-target insects.

ACKNOWLEDGMENTS

We thank Trevor Williams, Julio Rojas (ECOSUR)
and one anonymous reviewer who provided helpful re-
views of earlier versions of the manuscript. Armando
Virgen Sanchez for his technical assistance during the
field test performed in Chiapas. SIJMM-CONACYT
(project No. 19980301010) provided financial support to
Fernando Bahena and the Sistema de Investigaci6n Be-
nito Juarez (SIBEJ, project No. 980501024) to Edi Malo.

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Florida Entomologist 87(3)

September 2004

CABBAGE LOOPER MOTHS (LEPIDOPTERA: NOCTUIDAE)
TRAPPED WITH MALE PHEROMONE

PETER J. LANDOLT1, RICHARD S. ZACK2, D. GREEN' AND L. DECAMELO2
'USDA-ARS, Yakima Agricultural Research Laboratory, 5230 Konnowac Pass Road, Wapato, WA 98951 USA

2Department of Entomology, Washington State University, Pullman, WA 99164

ABSTRACT

Traps in field plots assessed attraction of the cabbage looper moth, Trichoplusia ni (Hibner),
to lures emitting synthetic chemicals identified as the pheromone of the male; linalool, p-
cresol and m-cresol. Male and female cabbage looper moths were captured in traps baited
with racemic linalool, but significantly greater numbers of both sexes were captured in traps
baited with the 3-component blend. Virgin and mated female cabbage looper moths were
captured, with up to 5 spermatophores per female in mated ones. Pheromone was dispensed
from polypropylene vials, and numbers of moths captured in traps increased with the size of
the hole in the vial lid, up to the maximum 25-mm diameter hole tested. Rates of release of
pheromone from vials with 25-mm diameter holes in the laboratory decreased from 4 to 3
milligrams per h over a four-week duration. This is the first evidence in the field of cabbage
looper response to the chemicals identified as pheromones of the male.

Key Words: pheromone, attraction, trap, behavior, cabbage looper, linalool, p-cresol, m-cresol.

RESUME

Mediante trampas de campo se estim6 la atracci6n de la palomilla del falso medidor, Tri-
choplusia ni (Hibner), a cebos que emiten linalool, p-cresol y m-cresol, quimicos sint6ticos
identificados como la feromona del macho. Se atraparon machos y hembras de la palomilla
del falso medidor en trampas cebadas con s6lo linalool rac6mico, pero se atraparon numeros
significativamente mayores de ambos sexos con la mezcla de los tres components. Se cap-
turaron palomillas virgenes y apareadas con hasta cinco espermat6foros por hembra. La fe-
romona se expuso en viales de polipropileno y el numero de palomillas capturadas por
trampa se increments con el tamano del orificio en la tapa del vial, hasta el maximo probado
de 25 mm de diametro. La tasa de liberaci6n de la feromona de los viales con orificio de 25
mm en laboratorio disminuy6 de 4 a 3 miligramos por hora en un period de cuatro semanas.
Esta es la primera evidencia de campo de la respuesta de la palomilla del falso medidor a los
quimicos identificados como la feromona del macho.

Translation provided by the authors.

The cabbage looper moth, Trichoplusia ni (Hib-
ner), uses two mate-finding strategies (Landolt &
Heath 1990; Lenczewski & Landolt 1991). One
strategy involves male attraction to the female-
produced sex pheromone which includes the major
component Z-7-dodecenyl acetate (Berger 1966),
and several other structurally related compounds
(Bjostad et al. 1984). The other strategy involves
female attraction to the male pheromone com-
posed of the major component S-(+)-linalool, as
well as p-cresol and m-cresol (Heath et al. 1992a;
Landolt & Heath 1989; Landolt 1995). S-(+)- or ra-
cemic linalool alone and the 3-component male
pheromone blend of linalool,p-cresol, and m-cresol
attracted females in a laboratory flight tunnel as-
say (Heath et al. 1992a). However, these chemicals
have not been tested in the field for their attrac-
tiveness to cabbage looper moths.
A synthetic lure for females could be developed
for use in monitoring the activities of females and

also for reducing reproduction of this pest in agri-
cultural crops. To date, however, there have been
no demonstrations in the field of female cabbage
looper moth attraction to synthetic male phero-
mone, although female and male attraction to
chemicals from flowers is well documented (Can-
telo & Jacobson 1979; Haynes et al. 1991; Heath
et al. 1992b). We report here the results of trap-
ping experiments that tested the hypothesis that
cabbage looper moths are attracted to the male
pheromone compounds. Because pure S-(+)-lina-
lool was not available in amounts sufficient for
these experiments, we used racemic linalool, both
alone and in combination withp- and m-cresol.

MATERIALS AND METHODS

Universal moth traps, (UniTraps, IPM Tech-
nologies, Portland, OR) were used in all tests.
These traps had white buckets, yellow cones, and

Landolt et al.: Cabbage Loopers Trapped with Male Pheromone

green tops, and included a 6.5-cm2 piece of Vapor-
tape (Hercon Environmental Inc., Emigsville, PA)
stapled to the inside of the bucket wall to kill cap-
tured insects. Traps were hung from fences or
stakes in or adjacent to irrigated fields of alfalfa,
Medicago sativum, or corn, Zea mays, at a height
of 0.5 m, and were 10 to 15 m apart. Pheromone
chemicals were dispensed from polypropylene
narrow mouth bottles (vials) (#2006 9125 for 4 ml
vials, #2118 9050 for 15 ml vials, Nalge Nunc
International, Rochester, NY). These pheromone
dispensers (vials) were suspended vertically with
wire inside the UniTrap buckets.
The first experiment tested attractiveness of
the 3-component blend of racemic linalool, p-
cresol and m-cresol (Aldrich Chemical Co., Mil-
waukee, WI) to cabbage looper moths. Two ml of a
90:5:5 mixture of linalool, p-cresol, and m-cresol
were added to a 2.5-cm diam cotton ball inside of
a 4-ml vial. Vials had a 3-mm diameter hole in the
lid for pheromone emission. Control traps had no
lures. Five pairs of treated and control traps were
maintained from 20 to 28 August 2001. Traps
were checked for moths three times (every 2 to 3
days), providing 15 samples. Treatment and con-
trol traps were alternated in position each time
that traps were checked.
The second experiment tested for a role of the
cresols in cabbage looper moth attraction to the 3-
component pheromone blend of linalool, p-cresol,
and m-cresol. The 3 treatments were (1) a trap
with no lure as a control, (2) a trap with a 4-ml
vial containing 2 ml of racemic linalool on a cotton
ball, and (3) a trap with a 4-ml vial containing 2
ml of a 90:5:5 mixture of racemic linalool, p-
cresol, and m-cresol on a cotton ball. Each vial
had a 3-mm diameter hole in the lid for phero-
mone emission. A randomized complete block ex-
perimental design was used, and the ten replicate
blocks were maintained from 17 July to 4 Septem-
ber 2003. Traps were checked and treatments
randomized each week for 7 weeks, providing 70
samples. Lures were replaced every two weeks.
The third experiment evaluated a range of re-
lease rates of the 3-component blend of racemic
linalool, p-cresol, and m-cresol. The objective was
to determine if attractiveness of the pheromone to
cabbage looper moths increased with increasing
amounts of pheromone released and to determine
an optimum lure for trapping cabbage looper
moths with male pheromone. Lure release rate
was altered by changing the diameter of the hole
in the vial lid. Treatments were 15-ml vials, each
with 2 ml of an 90:5:5 mixture of racemic linalool,
p-cresol, and m-cresol, and with holes 1.5, 3, 6,
12.5, and 25 mm in diameter. The larger vials
were used to accommodate holes of a greater di-
ameter in the vial lid. A randomized complete
block design was used, and the 5 blocks were
maintained from 4 to 25 September 2003. Traps
were checked and treatments randomized each

week, providing 15 samples. Lures were replaced
every week.
Female moths captured in traps baited with
the 3-component blend in experiments two and
three were stored in 70% ethanol and then dis-
sected under a binocular microscope for determi-
nation of their reproductive status. The presence
of fat in the abdomen was noted, the numbers of
mature eggs in the ovaries were counted, and the
number of spermatophores in the bursa copula-
trix was recorded. This information was used to
categorize the reproductive state of female moths
captured in the system of Hitchcox (2000). Moths
in category I were unmated and immature, with
no spermatophore, abundant fat, and fewer than
10 mature eggs present. Moths in category II
were mated and immature, with one or more
spermatophores, fat in the abdomen, and fewer
than 10 mature eggs present. Moths in category
III were mated and mature, with one or more
spermatophores, 10 or more mature eggs and
with some fat present. Moths in category IV were
senescent, with one or more spermatophores
present, no fat, and fewer than 10 mature eggs.
Release rates of male pheromone from vials
with 25-mm diameter holes were determined as
weight lost over time. Ten 15-ml polypropylene vi-
als were each loaded with 5 ml of male pheromone
(90:5:5 ratio of racemic linalool, p-cresol, and m-
cresol) on 3 cotton balls. Dispensers were then
weighed one day after loading, then daily until 28
days after loading. Daily weight loss was deter-
mined by subtracting the vial weight from the
weight of the vial the day before. Hourly weight
loss was calculated by dividing daily weight loss
by 24. The weight lost was then attributed to
emission of male pheromone from the dispensers.
Trap catch data for treatments in experiments
number 1 and 2 above were compared with a
paired t-test. Data for experiment 3 were subjected
to a quasilinear (with a square root transforma-
tion) regression analysis to determine if numbers
of moths captured varied with pheromone release
rate (vial hole size). Daily weight loss data were
subjected to a regression analysis to determine if
dispenser weight loss per day changed with time.
All statistical analyses were performed with the
Statmost software (DataMost 1995).

RESULTS

In the first experiment, cabbage looper moths
were captured in traps baited with the mixture of
racemic linalool, p-cresol, and m-cresol, while no
moths were captured in unbaited traps (Table 1).
Numbers of moths in baited traps were signifi-
cantly greater than in unbaited traps (t = 3.45, df
= 14, P = 0.002). These moths were not sorted by
sex, and were not dissected to determine repro-
ductive status. A total of 143 cabbage looper
moths were captured in traps in this experiment.

Florida Entomologist 87(3)

TABLE 1. MEAN ( SE) NUMBERS OF CABBAGE LOOPER MOTHS CAPTURED IN TRAPS BAITED WITH VIALS LOADED WITH
THE RACEMIC LINALOOL, P-CRESOL, AND M-CRESOL.

Test 1. Moths/trap

Control 0.0 0.00 a
Linalool, p-cresol, m-cresol 9.5 2.80 b
Test 2. Females/trap Males/trap

Control 0.0 0.00 a 0.0 0.00 a
Linalool 0.2 0.08 b 0.5 0.13 b
Linalool, p-cresol, m-cresol 0.5 0.14 c 0.9 0.15 c

Means followed by the same letter are not significantly different by paired t-test at P < 0.05.

In the second experiment (Table 1), numbers of
both sexes of the cabbage looper moth were
greater in traps baited with racemic linalool alone
(t = 3.65, df = 84, P < 0.001 for females, t = 4.75, df
= 84, P < 0.001 males) or with the combination of
linalool and cresols (t = 4.33, df= 84, p < 0.001 for
females; t = 5.53, df = 84, P < 0.001 for males)
compared to unbaited traps. Numbers of both
sexes captured in traps baited with racemic lina-
lool, p-cresol, and m-cresol were significantly
greater than the numbers of both sexes trapped
with racemic linalool alone (t = 2.18, df = 84, P =
0.016 for females; t = 1.62, df = 84, P = 0.05 for
males). Totals of 79 female and 141 male cabbage
looper moths were captured in this test.
In the third experiment, numbers of both sexes
of the cabbage looper moth increased with the in-
creases in diameter of hole in the vial lid (Fig. 1),
with greatest numbers of males and greatest
numbers of females in traps baited with phero-
mone in vials with a 25-mm hole in the lid. For fe-
males, there was a significant regression of
numbers of moths captured by vial hole diameter
(r2 = 0.80, P = 0.01, Y = -01.36 + 16.6 SQRT X,
where Y is vial hole diameter, and X is numbers of
moths per trap). For males there was also a signif-
icant regression of numbers of moths captured by
vial hole diameter (r2 = 0.97, P = 0.0004, Y = 1.35
+ 13.0 SQRT X). Totals of 48 females and 61
males were captured in this test.
Seventy-one female cabbage looper moths that
were captured in traps baited with linalool, p-
cresol and m-cresol were dissected in order to cat-
egorize their reproductive condition. The greatest
number of females were in category III, mated
and mature (n = 31). The smallest number of fe-
males dissected were in category II, mated and
immature (n = 3). Category I, unmated and im-
mature, and category IV, senescent, were repre-
sented by 19 and 18 moths respectively. Fifty-one
female moths were mated (71.8%), and those that
were mated, possessing from one to 5 spermato-
phores (mean = 2.5 + 0.15 spermatophores per fe-
male). Twenty female moths of the 71 dissected
(28.2%) were unmated.

There was a significant negative regression of
daily vial weight loss in relation to the age of vials
(r2 = 0.14, P = 0.03, Y = 3.87 0.0386X, where Y is
weight lost, and X is days in age). Daily weight
loss of vial dispensers loaded with cabbage looper
male pheromone was near 4 milligrams per h dur-
ing the first several days after loading of the vials
with pheromone, dropping to near 3 milligrams
per h near the end of the 4 week evaluation (Fig. 2)

DISCUSSION

Previous studies have demonstrated attrac-
tion of female and male cabbage looper moths to
male pheromone. Females were attracted to male
cabbage looper moths in a flight tunnel (Landolt
& Heath 1989) and a field cage (Lenczewski &
Landolt 1991), and both sexes were attracted to
males in cotton fields (Landolt 1995). Female cab-
bage looper moths in a flight tunnel were at-
tracted to the combination of S-(+)- or racemic
linalool and p-cresol and m-cresol, 3 compounds
isolated from hairpencils of male cabbage looper
moths (Heath et al. 1992a). The flight tunnel at-
traction response was significantly reduced with
the omission of the cresols from the blend or the
omission of S-(+)-linalool from the blend. These
studies did not address moth attraction to male
pheromone compounds under field conditions or
the possible use of male pheromone as a lure for
trapping female cabbage looper moths.
This is the first demonstration in the field of
male and female cabbage looper moth attraction
to the chemicals identified as the male phero-
mone of T ni by Heath et al. (1992a). We interpret
captures of the moths in traps as evidence of ori-
entation responses to the chemicals used as lures
in the trap. Males and females were attracted
then to racemic linalool and to the 3-component
blend of linalool and the two cresols. Numbers of
male or female cabbage looper moths in traps
were higher when the cresols were present in the
lure, indicating some importance of these com-
pounds in male attractiveness to females. Addi-
tional testing in the field will be necessary to

September 2004

Landolt et al.: Cabbage Loopers Trapped with Male Pheromone 29

Female

Male

12 25

Vial Hole Diameter (mm)

Fig. 1. Mean ( SE) numbers of female and male cabbage looper moths captured in traps baited with linalool, p-
cresol, and m-cresol in a polypropylene vial with a hole in the lid for pheromone release. Vials had different hole di-
ameters (1.5, 3, 6, 12, and 25 mm) to alter the rate of release of pheromone.

determine if attraction of moths to pheromone is
stronger when S-(+)-linalool is used instead of ra-
cemic linalool, and to determine if both p-cresol
and m-cresol increase attractiveness of the pher-
omone to cabbage looper moths.
Other species of moths were not captured in
traps in this study, and the cabbage looper male
pheromone chemicals are not reported as attrac-
tants for other species of insects. Linalool was
tested previously as a possible floral lure for al-
falfa looper moths, with no indication of attrac-
tiveness to either alfalfa looper or cabbage looper
moths (Landolt et al. 2001). At that time (summer
2000) there were many alfalfa looper moths but
few cabbage looper moths in the area; thus, the
lack of cabbage looper moths captured did not in-
dicate a lack of attractiveness of chemicals tested.
Specificity of this lure in attracting only or prima-
rily cabbage looper moths would be desirable for
monitoring applications, because responses of
other species of moths might be interpreted as
false positives for cabbage looper moths.

The attraction of cabbage looper moths to male
pheromone in the field may be a mate-finding or a
food-finding response, or both. In addition to its
presence in, and release by, male cabbage looper
moths (Heath et al. 1992a), linalool is present in
the odor of honeysuckle flowers which are visited
by cabbage looper and other moths in search of
nectar (Pair 1994; Schlotzhauer et al. 1996). Cab-
bage looper females that are deprived of sugar are
more strongly attracted to males, suggesting re-
sponses to male pheromone may be based in part
on food-finding needs (Landolt et al. 1996). Fe-
males attracted to males (Landolt 1995) and syn-
thetic male pheromone (herein) include both
mated and unmated individuals. Some possessed
5 spermatophores, indicating mating up to 5
times before responding to the male pheromone
in the study. Perhaps male cabbage looper moths
contribute nutritional material in the spermato-
phore and mimic flowers by releasing chemicals
characteristic of certain moth-visited flowers, as a
strategy of luring females.

I I r

Florida Entomologist 87(3)

September 2004

T
A T
ITT A
AT A A

T I

T 6A Nu..1 T
T A

A [A

I I I I I I I I I I I I I II I I I I I IA

1 3 5 7 9 11 13 15 17 19 21

23 25 27

Age in Days

Fig. 2. Mean ( SE) loss of weight per hour over time, for 15-ml polypropylene vials loaded with 5 ml of male cab-
bage looper pheromone, with a 25-mm diameter hole in each vial lid.

Males of other noctuid moths produce chemi-
cals in hairpencils that are also present in the
odors of flowers (Birch & Hefetz 1987), but are not
known to be attractive to conspecific moths. For
example, 2-phenylethanol is present in the vola-
tiles of the moth-visited flowersAbelia grandiflora
(Haynes et al. 1991) and Gaura drummondii
(Shaver et al. 1997). This compound is also found
in the hairpencils ofMamestra configurata (Walker)
(Clearwater 1975), Polia nebulosa (Hufnagel), and
Peridroma saucia (Hiibner) (Birch 1972; Birch et
al. 1976). Birch & Hefetz (1987) suggested that the
tendency for male scents to resemble plant odors is
because females likely already have receptors for
these chemicals and have behavioral responses to
those food plant odors.

ACKNOWLEDGMENTS
Technical assistance was provided by T. Adams, J. Al-
faro, and J. Brumley. This project was supported in part
by a grant from the Environmental Protection Agency
and a USDA, CSREES Western Regional IPM Grant.
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BIRCH, M. C. 1972. Male abdominal brush organs in
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BIRCH, M. C., G. G. GRANT, AND U. E. BRADY. 1976.
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BIRCH, M. C., AND A. HEFETZ. 1987. Extrusible organs
in male moths and their role in courtship behavior.
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BJOSTAD, L. B., C. E. LINN, JR., J. W. DU, AND W. L.
ROELOFS. 1984. Identification of new sex pheromone
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synthetic precursors. J. Chem. Ecol. 10: 1309-1323.
CANTELO, W. W., AND M. JACOBSON. 1979. Phenylace-
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CLEARWATER, J. R. 1975. Pheromone metabolism in
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rata (Walk.) (Lepidoptera: Noctuidae). Comp. Bio-
chem. Physiol. B. 50: 77-80.
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graphics. DataMost, Salt Lake, Utah.
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HEATH, R. R., P. J. LANDOLT, B. D. DUEBEN, R. E. MUR-
PHY, AND R. E. SCHNEIDER 1992a. Identification of
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males. J. Chem. Ecol. 18: 441-453.

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HEATH, R. R., P. J. LANDOLT, B. DUEBEN, AND B. LENC-
ZEWSKI. 1992b. Identification of floral compounds of
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in apple orchards of Washington state. M.Sc. Thesis,
Washington State University, Pullman. 75 pp.
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moths, Trichoplusia ni (Lepidoptera: Noctuidae) to
males in the field. Florida Entomol. 78: 96-100.
LANDOLT, P. J., AND R. R. HEATH. 1989. Attraction of fe-
male cabbage looper moths (Lepidoptera: Noctuidae)
to male-produced sex pheromone. Ann. Entomol.
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D. DUEBEN, AND J. G. MILLAR 1996. Starvation of
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LENCZEWSKI, B., AND P. J. LANDOLT. 1991. Temporal
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SCHLOTZHAUER, W. S., S. D. PAIR, AND R. J. HORVAT.
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Florida Entomologist 87(3)

September 2004

SURVIVAL AND INFECTIVITY OF STEINERNEMA SCAPTERISCI
(NEMATODA: STEINERNEMATIDAE) AFTER CONTACT
WITH SOIL DRENCH SOLUTIONS

KATHRYN A. BARBARA AND EILEEN A. BUss
University of Florida, Entomology and Nematology Department, Gainesville, FL 32611

ABSTRACT
After a nematode application, mole crickets (Orthoptera: Gryllotalpidae: Scapteriscus spp.)
are frequently assayed to confirm nematode establishment and infectivity. However, the stan-
dard soap flush was suspected of providing false negatives under field conditions. Thus, we ex-
amined the effect of several potential flushing solutions on the survival and infectivity of
Steinernema scapterisci Nguyen and Smart (Nematoda: Steinernematidae) as well as flush-
ing ability under field conditions. Seventy percent of S. scapterisci died in lemon dish deter-
gent solution, confirming that assays for nematode infection of soap-flushed mole crickets are
likely to be inaccurate. When sampling for mole crickets in areas where S. scapterisci has been
applied, a potential alternative to the standard soap drench is a dilute permethrin drench.

Key Words: Sampling, soap flush, soil drench, entomopathogenic nematode, biological con-
trol, integrated pest management.

RESUME
Despu6s de una aplicaci6n de nematodos, los grills topo (Orthoptera: Gryllotalpidae: Scap-
teriscus spp.) son evaluados frecuentemente para confirmar el establecimento y la capacidad
de infectar de los nematodos. Sin embargo, la lavada conjab6n que es el process usado usual-
mente, es sospechada de proveer datos negatives falsos bajo condiciones de campo. Por ello,
nosotros examinamos el efecto de diferentes soluciones para la lavada sobre la sobrevivencia
y la capacidad de infectar de los Steinernema scapterisci Nguyen y Smart (Nematoda: Stei-
nernematidae) asi como la habilidad para lavar bajo condiciones de campo. Setenta por
ciento de los S. scapterisci mueren en una soluci6n de detergente con limon para plates, con-
firmando que los ensayos para determinar la infecci6n de nematodos de grillo topos lavados
con jab6n son probablemente imprecisos. Cuando recolectan los grillos topo en areas donde
S. scapterisci ha sido aplicado, una alternative a la lavada basica conjab6n es una lavada con
una soluci6n diluida de permetrina.

Mole crickets (Orthoptera: Gryllotalpidae:
Scapteriscus spp.) are subterranean pests of turf-
grass in Florida and much of the southeastern
United States (Walker & Nickle 1981; Walker
1985). Mole cricket damage and cost of control in
Florida in 1986 was estimated at $45 million with
an additional $33 million in Alabama, Georgia,
and South Carolina combined (Frank & Parkman
1999). Estimates of annual expenditure in 1996
were over $18 million for insecticides in Florida
turf, and over $12 million in control costs (Hudson
et al. 1997). Mole crickets damage turf by their
tunneling in the soil, which exposes and dries out
roots and by direct root feeding. As a result, the
turfgrass thins and bare patches appear. The tun-
neling and mounds that mole crickets make also
disrupt the playing surface on golf courses, espe-
cially the roll of the golf ball on greens. Superin-
tendents and golf course members have little
tolerance for damage (Frank & Parkman 1999).
Insecticides are usually targeted against the most
destructive, nymphal stage. A more sustainable,
environmentally friendly management approach
for mole cricket control is needed.

Several biological control agents have been in-
vestigated for control of Scapteriscus spp. mole
crickets in Florida (Hudson et al. 1988). One of
these biological control agents is an entomopatho-
genic nematode, Steinernema scapterisci Nguyen
and Smart. Steinernema scapterisci was origi-
nally collected in Uruguay in pitfall-trapped
Scapteriscus mole crickets in the 1980s (Nguyen
& Smart 1990). The nematode was cultured and
released in several Florida counties in 1985,
where it established a population, and was spread
from the release site by infected Scapteriscus
mole crickets (Hudson et al. 1988; Parkman &
Frank 1992). The nematode kills the adult and
late instar nymphs of Scapteriscus borellii Giglio-
Tos and S. vicinus Scudder, and to a lesser extent
S. abbreviatus Scudder. Fewer small to medium-
sized nymphs of S. borellii and S. vicinus become
infected (Nguyen 1988).
Several techniques have been used to sample
mole crickets including counts of dead nymphs
and adults after insecticide applications (Short &
Koehler 1979), estimation of surface burrowing
(Walker et al. 1982; Cobb & Mack 1989), pitfall

Barbara & Buss: Soil Drench Solutions on Steinernema scapterisci

trapping (Lawrence 1982; Adjei et al. 2003), re-
moval with a tractor mounted soil corer (Williams
& Shaw 1982), sound trapping (Walker 1985) and
soil drenching (Short & Koehler 1979; Walker
1979; Hudson 1989). However, results from each
of these techniques are often inconsistent (Short
& Koehler 1979; Lawrence 1982, Hudson 1988).
Comparisons of different methods have indicated
that soil drenching with soap solutions is the
most practical and consistent at obtaining direct
counts of mole crickets (Short & Koehler 1979;
Hudson 1988).
Soil drenching with a solution of 15 ml of
lemon dishwashing detergent in 3.8 L of water is
inexpensive and commonly used by turfgrass
managers to sample soil pests. Soil drenches with
soap solutions irritate mole crickets and force
them out of the soil. Soap flushes are often used
for monitoring mole crickets to determine the
size, age, and species present, the relative popula-
tion density over time, and for control timing.
However, it was suspected that soap flushes,
when used to monitor mole crickets potentially
infected with S. scapterisci, might be lethal to the
nematodes because nematodes are rarely found
in soap-flushed mole crickets (our observations,
and K. B. Nguyen & G. C. Smart, Entomology and
Nematology Dept., University of Florida, pers.
comm.). Solutions such as pyrethroids, ammonia,
vinegar, Lysol, and other soap detergents have
previously been tested as potential soil drench so-
lutions (Short & Koehler 1979).
This study was conducted to determine if a
standard soap detergent solution affects S. scap-
terisci survival and infectivity in pest mole crick-
ets. Potential alternatives to the standard soap
drench solution were also evaluated.

MATERIALS AND METHODS

Nematodes and Mole Crickets

Steinernema scapterisci (Nematac S, Becker
Underwood, Ames, IA) were stored at 7C in a
cold room until used (<3 mo). Nematode viability
was tested before each application by dissolving a

pinch (~10 mg) of Nematac S into water and
observing nematode shape and mobility under a
light microscope. Healthy nematodes were
opaque in color and S-shaped with oscillating
movements. Dead or unhealthy nematodes were
translucent, straight, and lacked movement. The
product was used if viability was >50% and dis-
carded if <50% viable.
Scapteriscus vicinus were collected from pitfall
traps or sound traps in Alachua Co., FL, and re-
turned to the laboratory. Each mole cricket was
placed in a 120-ml plastic vial (Thorton Plastics
Salt Lake City, UT) with sterilized sand and held
for >14 d to ensure health. Surviving mole crick-
ets were used in this study. Mole crickets were
maintained at 23C with a photoperiod of 12:12
(L:D) and fed commercial cricket chow (Purina,
St. Louis, MO).

Bioassay

Nematode viability and infectivity were as-
sessed after exposure to various drenching materi-
als. Steinernema scapterisci were extracted from
Nematac S using a modified Baermann tech-
nique (K. B. Nguyen, pers. comm.). Steinernema
scapterisci were kept at a density of 10,000 infec-
tive juveniles in solutions of water (control), lemon
dishwashing detergent (Joy), insecticidal soap
(Safer Soap, Woodstream Corporation, Litiz, PA),
and permethrin (Spectracide Bug Stop, Spectrum
Brands, St. Louis, MO) for test 1. The mixtures
were kept at room temperature (24C) in a 125-ml
Erlenmeyer flask with 125-ml per flask on a shaker
at 65 rpm. There were five replicates for each treat-
ment. Concentrations (Table 1) were selected
based on recommendations for flush extraction of
mole crickets in the field (Short & Koehler 1979)
and label rates for mole cricket control. After 24h,
10-pl samples were taken from each treatment and
placed on a microscope slide. The number of living
and dead nematodes were counted with a dissect-
ing microscope (10x); three 10-pl counts were taken
and averaged to determine percent mortality for
each replicate. Immobile nematodes were touched
with a probe to determine survival.

TABLE 1. MEAN NEMATODE MORTALITY AND PERCENT OF MOLE CRICKETS INFECTED WITH STEINERNEMA SCAPTERISCI
AFTER EXPOSURE FOR 24 H TO VARIOUS DRENCHING SOLUTIONS.

Mean % nematode % Mole crickets infected
Treatment Rate mortality ( SEM)' with S. scapterisci2

Water n/a 6.2 3.95 16.7
Lemon Joy 15 ml/ 3.79 L 70.6 4.52* 8.3
Insecticidal Soap 15 ml/ 3.79 L 90.0 7.82* 0
Permethrin 18 ml/ 3.79 L 35.6 1.97* 16.7

*Statistically significant values using Dunnett's method comparing treatments to water.
n = 20, F = 54.68, df= 19, 3, P = < 0.0001.
n = 12, R = 0.2971, df= 11, 3, X = 4.843 (likelihood), P = 0.18.

Florida Entomologist 87(3)

A second test was initiated to further test po-
tential drench materials. Treatments for test 2
included water (control), azadirachtin (Safer@
Brand BioNeem, Woodstream Corporation, Litiz,
PA), citrus oil (Green Sense@, Garland, TX), garlic
extract (Garlic Barrier@, Garlic Research Labs,
Inc., Glendale, CA), lemon juice (Realemon, Rye
Brook, NY), permethrin (Spectracide Bug Stop@,
Spectrum Brands, St. Louis, MO) and cyfluthrin
(Bayer Advanced Lawn and Garden@, Bayer En-
vironmental Sciences, Montvale, NJ). Concentra-
tions (Table 2) were selected based on label and
half label rates for mole cricket control. Methods
from test 1 were repeated.
Nematode infectivity was assessed by filtering
nematodes from above solutions and adding 50 liv-
ing infective juveniles to 120-ml plastic cups (Fisher
Scientific, Pittsburgh, PA) containing 20 g sterilized
sand, 4% deionized water, and one S. vicinus adult.
Dead mole crickets were dissected and the presence
or absence of nematodes was recorded.
The above solutions were tested for their effec-
tiveness at flushing mole crickets at the Univer-
sity of Florida G. C. Horn Turfgrass Research Unit
in Gainesville, FL, on 20 and 28 May 2003. Each
treatment from tests 1 and 2 (3.8 L of each solu-
tion) was applied to areas of bermudagrass (Cyn-
odon dactylon [L.] Persoon) that had mole cricket
damage (75 cm2). The numbers of adult and first
instar mole crickets emerging from the soil within
3 min were counted. Five replicates for each solu-
tion were completed. Any turfgrass phytotoxicity
was noted at 1 h and 1 wk posttreatment.
The effect of nematode infected crickets ex-
posed to soap solutions was also tested. Scap-
teriscus abbreviatus adults were obtained from a
lab colony at the University of Florida Entomol-
ogy and Nematology Department, Gainesville, FL
and were inoculated with about 10,000 nema-
todes by applying predetermined amount (ap-
proximately 150 pl) of concentrated nematode
solution onto a piece of filter paper (Fisher #P8,

5.5 cm) inside a petri dish with one S. abbreviatus
adult. The mole cricket was allowed to incubate in
the petri dish for 1, 5, 8, 12, or 24 h (five mole
crickets per treatment). Scapteriscus abbreviatus
was used because S. vicinus adults were unavail-
able at the time of the test. All infected mole crick-
ets were then dipped into a 118-ml Solo souffle
cup (Gainesville Paper Co., Gainesville, FL) con-
taining the soapy water or soapy water followed
by a deionized water rinse for 5 sec. Untreated
controls were healthy, uninfected mole crickets
dipped in water. Mole crickets were placed into
20-dram plastic scintillation vials (Fisher Scien-
tific, Pittsburgh, PA) and observed every 24 h for
10 days. On day 10, mole crickets were dissected
and the presence of nematodes was noted.

Statistical Analysis

Nematode mortality and field test data were
subjected to an analysis of variance (SAS Insti-
tute 2001). Treatments were compared to the con-
trol (water) by Dunnett's means comparison
method (a = 0.05). Nematode infectivity data
were subjected to Chi-square analysis (SAS Insti-
tute 2001). Treatments were compared to the con-
trol (water) and the standard soap flush solution
(15 ml lemon dish detergent/3.8 L water) by Dun-
nett's means comparison method (a = 0.05). Nem-
atode mortality data were transformed by
arcsine-square root transformation before statis-
tical analysis; nontransformed data are pre-
sented. Effects of nematode infected crickets
exposed to soap solutions data were subjected to
PROC GLM (SAS Institute 2001) procedure.

RESULTS AND DISCUSSION

Insecticidal soap, lemon dishwashing soap,
and permethrin at the label rate for mole cricket
control caused significantly more nematode mor-
tality than water (Table 1). Nematodes exposed to

TABLE 2. MEAN NEMATODE MORTALITY AND INFECTIVITY AFTER EXPOSURE FOR 24 H TO VARIOUS DRENCHING SOLU-
TIONS.

Mean % nematode % Mole crickets infected
Treatment Rate mortality ( SEM)1 with S. scapterisci2

Water n/a 12.9 7.89 3.7
Citrus Oil 15 ml/ 3.79 L 32.1+ 9.47 3.7
Cyfluthrin 8 ml/ 3.79 L 6.4 6.44 3.7
Cyfluthrin 15 ml/ 3.79 L 4.1 + 4.12 3.7
Garlic Extract 111 ml/ 3.79 L 0 3.7
Lemon Juice 15 ml/ 3.79 L 6.8 6.76 0
BioNeem 60 ml/ 3.79 L 4.4 4.38 0
Permethrin 9 ml/ 3.79 L 10.8 6.73 3.7
Permethrin 18 ml/ 3.79 L 0 3.7

n = 45, F = 2.70, df= 44, 8, P = 0.193.
n = 27, R = 0.1349, df= 26, 8, X'= 4.170 (likelihood), P = 0.18.

September 2004

Barbara & Buss: Soil Drench Solutions on Steinernema scapterisci

all treatments showed similar infectivity in mole
crickets (R2 = 0.2971; df = 2,11; x2 = 4.843; P <
0.184) (Table 1). Nematode mortality was similar
among all treatments in test 2 (Table 2). Nema-
todes surviving all treatments except azadirach-
tin and lemon juice, demonstrated a low
percentage infectivity of mole crickets, no signifi-
cant treatment differences were observed (R2 =
0.1349; df= 2,26; X2 = 4.170;P < 0.842) (Table 2).
In the field, insecticidal soap and the higher
rate of permethrin flushed significantly more
mole crickets than water (Table 3). However,
when all treatments were compared to the stan-
dard lemon dish detergent, insecticidal soap and
permethrin brought a similar number of mole
crickets to the surface (n = 55;F = 2.88; df= 10,54;
P = 0.008). None of the mixtures tested produced
any noticeable phytotoxicity to the turf.
Soil drenches with a mixture of lemon dish de-
tergent and water are commonly used to monitor
turfgrass insects such as mole crickets, chinch
bugs (Blissus spp.), big-eyed bugs (Geocoris spp.),
and several species of caterpillars (Short & Koeh-
ler 1979; Hudson 1989). Soil drenches are inex-
pensive and are not labor intensive when
compared with other methods of monitoring mole
cricket populations. These other methods include
large pitfall traps (Lawrence 1982; Adjei et al.
2003), an emitter producing a synthetic song of
male mole crickets (Parkman & Frank 1993), and
a soil-coring device (Williams & Shaw 1982). Each
method requires more than one person, are labor
intensive or costly (Lawrence 1982; Williams &
Shaw 1982).
Seventy percent of S. scapterisci died in the
lemon dish detergent solution. Assays for nema-
tode infection of soap-flushed mole crickets, the
method currently used by many turfgrass manag-
ers, are likely to be inaccurate. Krishnayya &
Grewal (2002) reported a toxic effect of a common

soap surfactant (Ajax@) on S. feltiae Bovien nem-
atodes. They found 24% mortality of nematodes
when incubated at 4, 24, 72, and 120 h (Krish-
nayya & Grewal 2002). Kaya et al. (1995) re-
ported an insecticidal soap (M-Pede) adversely
affected S. carpocapse (Weiser) and Heterorhabdi-
tis bacteriophora Poinar survival and infectivity.
However, infectivity may not be affected if the
nematodes are combined with an insecticidal
soap and applied immediately (Kaya et al. 1995).
Nematodes cannot be stored in an insecticidal
soap solution because without aeration, nema-
tode survival can be adversely affected (Kaya et
al. 1995). The toxicity of metal ions present in
soap may be responsible for the high mortality in
soap solutions (Jaworska et al. 1994; Krishnayya
& Grewal 2002).
Tests of exposure of nematode infected mole
crickets to soap solutions show that soap flush so-
lution does not greatly affect nematode infection
at least 8 h post infection (Table 4). The soap flush
solutions may potentially kill nematodes in cer-
tain areas of the body (i.e., mouth) and further
testing should be done to determine this. Immedi-
ately rinsing flushed mole crickets with clean wa-
ter may potentially increase the accuracy of
determining nematode infection. The unavailabil-
ity of S. vicinus at the time of experimentation
may have also led to inconsistent, low levels of in-
fection. It is known that S. scapterisci does not in-
fect S. abbreviatus as successfully as S. vicinus or
S. borellii (Nguyen 1988).
Although permethrin solutions killed some
nematodes in our experiments, S. scapterisci infec-
tivity was not compromised and field flushes suc-
cessfully extracted mole crickets from the soil. The
field data concur with Short & Koehler (1979) who
reported that pyrethrins were the most effective
material, flushing a mean of 11.5 mole crickets/0.6
m2. Hudson (1988) compared three sampling tech-

TABLE 3. MEAN NUMBER OF MOLE CRICKETS EMERGING FROM BERMUDAGRASS WITH VARIOUS DRENCHING SOLUTIONS
IN MAY 2003.

Mean number of mole crickets
Treatment Rate flushed ( SEM)

Water n/a 0
Citrus oil 15 ml/ 3.79 L 2.6 1.6
Cyfluthrin 8 ml/ 3.79 L 0.2 0.2
Cyfluthrin 15 ml/ 3.79 L 4.0 2.1
Garlic extract 111 ml/ 3.79 L 0.4 0.2
Lemon juice 15 ml/ 3.79 L 0.6 0.4
BioNeem 60 ml/ 3.79 L 3.2 1.2
Permethrin 9 ml/ 3.79 L 2.6 1.1
Permethrin 18 ml/ 3.79 L 5.8 1.4*
Insecticidal soap 15 ml/ 3.79 L 5.4 1.3*
Lemon Joy 15 ml/ 3.79 L 4.6 2.1

*Means statistically significant values by Dunnett's method comparing treatments to water.
n = 54, F = 2.88, df= 59,10, P = 0.01.

Florida Entomologist 87(3)

September 2004

TABLE 4. PERCENT NEMATODE INFECTION FROM MOLE CRICKETS EXPOSED TO TREATMENT SOLUTIONS 1, 5, 8, 12, OR
24-H POST INFECTION.

Time Post Infection 1 H 5 H 8 H 12 H 24 H

Joy (15 ml/ 3.79 L) 0 40 60* 60* 100*
Joy (15 ml/ 3.79 L)+ H20 rinse 40 40 100* 80* 100*
Control' 0 0 0 0 0

n = 75, F = 6.77, df= 14, 2, P < 0.0001.
*Means within columns statistically significant values when compared to control.
'Control = uninfected, healthy mole crickets immersed in water.

niques, soil flushing with lemon dish detergent or
synergized pyrethrins, and a tractor mounted soil
corer. None of the methods were significantly dif-
ferent. Our results from the field test show drench-
ing solutions of permethrin are useful in
determining if mole crickets collected in the field
are infected with S. scapterisci nematodes. A soil
drench containing permethrin may be the best
monitoring tool to flush mole crickets to determine
the presence of S. scapterisci.
However, there are disadvantages to pyre-
throids as soil drenches for mole crickets. Pyre-
throid drenches at the half or full label rate may
cause more mole cricket mortality than a soap so-
lution. Subsurface mortality of mole crickets can
be as high as 65% with pyrethroids or similar in-
secticides (Ulagaraj 1974; Walker 1979; Hudson
1988). Applicator exposure to insecticides is in-
creased with a pyrethroid soil drench.
Soil drenches are effective, non labor-intensive
methods to sample soil insect populations. Soap
detergent solutions, although inexpensive, may
not accurately indicate mole crickets infected
with S. scapterisci. Permethrin solutions are less
cost effective (Short & Koehler 1979), but are ef-
fective at flushing mole crickets potentially in-
fected with nematodes.

ACKNOWLEDGMENTS
We are grateful to G. Diaz-Saavedra and T Hinks
(Becker Underwood) for providing nematodes and tech-
nical assistance, and to Y. Wang and B. Owens for assis-
tance in field tests. We thank N. Leppla and J. H. Frank
for advice and review of earlier versions of the manu-
script. Funding was provided by the Florida State Leg-
islature and the Department of Agriculture and
Consumer Services. This is the Florida Agricultural Ex-
periment Station Journal Series No. R-10104.

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FRANK, J. H., AND J. P. PARKMAN. 1999. Integrated pest
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rhabditis bacteriophora entomopathogenic nematodes
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NGUYEN, K. B. and G. C. Smart. 1990. Steinernema scap-
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and acoustical communication (Orthoptera: Gryllo-
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Florida. Agric. Exp. Sta. Bull. 846. (1984) 54 pp.
WALKER, T. J., AND D. A. NICKLE. 1981. Introduction
and spread of pest mole crickets: Scapteriscus vini-
cus and S. acletus reexamined. Ann. Entomol. Soc.
Am. 74:158-163.
WALKER, T. J., R. C. LITTELL, AND N. DONG. 1982.
Which mole crickets damage bahiagrass pastures?
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194.

Florida Entomologist 87(3)

A NEW SPECIES OF ANTRUSA AND THREE NEW SPECIES OF CHOREBUS
(HYMENOPTERA: BRACONIDAE) FROM THE IBERIAN PENINSULA

M. FISCHER', J. TORMOS2, I. DOCAVo3 AND X. PARDO4
'Naturhistorisches Museum Wien, Zweite Zoologische Abteilung (Insekten)
Burgring 7, A-1014 Wien, Postfach 417, Austria

2Unidad de Zoologia, Facultad de Biologia, Universidad de Salamanca, 37071-Salamanca, Spain

3Fundaci6n Entomol6gica "Torres-Sala", Paseo de la Pechina, 15, 46008-Valencia, Spain

4Universitat de Valencia, Institut Cavanilles de Biodiversitat i Biologia Evolutiva,
Apartat Oficial 2085, 46071 Valencia, Spain

ABSTRACT
Antrusa curtitempus, Chorebus liliputanus, C. propediremptum, and C. vicinus, four new
species of Dacnusini from the Iberian Peninsula, are described, illustrated, and compared
with allied species. Keys for their discrimination are provided. The taxonomic rehabilitation
of the genusAntrusa is proposed.
Key Words: new species, Antrusa, Chord .... ". -.I i... Dacnusini, Braconidae.

RESUME
Se described, e ilustran, cuatro nuevas species de Dacnusini de la Peninsula Ib6rica: An-
trusa curtitempus, Chorebus liliputanus, C. propediremptum, y C. vicinus. Se discuten sus
afinidades filogen6ticas, y se propone la rehabilitaci6n taxon6mica del g6nero Antrusa.

Translation provided by the authors.

In this work, four species of Dacnusini (Hymen-
optera: Braconidae: Alysiinae)-Antrusa curtitem-
pus, Chorebus liliputanus, C. propediremptum, and
C. vicinus-from the Iberian Peninsula, are de-
scribed as new, illustrated, and compared with al-
lied species. Keys for their discrimination are
provided. The genusAntrusa Nixon is rehabilitated
taxonomically.
The terms for body morphology and wing vena-
tion, together with the criteria for collecting bio-
metric data, follow Fischer (1973, 2002) with the
two following modifications: (a) mesosoma vs. tho-
rax, and (b) setae vs. hairs. All the material exam-
ined is deposited at the Museo del Medio
Ambiente (Valencia, Spain). The following abbre-
viations have been used in the descriptions: a2 =
lower vein of B (brachius); B = brachial cell; cql =
first cubital cross-vein; cu2 = 2nd abscissa of cu (=
cubital vein); cu2' = second abscissa of cubital
vein of hind wing; culb = lower cubital-anal cross
vein (3rd discoideal segment); d = discoidal vein;
F, Fl, F2, etc.= flagellomere (s), flagellomere 1, 2,
etc.; Fm, Fp = middle flagellomere (s), penulti-
mate flagellomere; M = medial cell of hind wings;
np = parallel vein nervouss parallelus); r' = radiel-
lus (radial vein of hind wing); nr = recurrent vein
nervouss recurrens); nr' = recurrent vein of hind
wing; nv = nervulus; R = radial cell; r, rl, r2 = ra-
dial vein, first, second abscissa of radius; st =

pterostigma; SM' = submedial cell of hind wings;
T, T1, T2, T3, T2+3 = tergite (s), first, second, third
tergite, second + third tergite.

Genus Antrusa Nixon

The genus was described by Nixon (1943). Later,
it was sunk into synonymy with Exotela Foerster
by Griffiths (1964) based on his interpretation of
characters in the light of phylogenetic systematics.
E. Haeselbarth (Zoologische Staatssammlung,
Munich) regarded Antrusa Nixon as justified (un-
published notes). The reason for the Exotela-di-
lemma was the fact that the decisive character of
Exotela, the postfurcal nr, does not apply to all spe-
cies. Another difficulty is the diagnostic separation
from Dacnusa Haliday, with which it shares most
characters. Antrusa can be characterized and de-
limited from Exotela, Dacnusa and Chorebus Hali-
day by a combination of the following characters:
(a) mandibles three-dentate; (b) nr antefurcal; (c)
T1 with medial longitudinal keel; (d) no sexual di-
morphism of the pterostigma. The latter character
is significant for separation from Dacnusa, but
cannot be easily applied without having both sexes
available. The longitudinal carina of T1 may be
helpful. The three-dentate mandibles separate
Antrusa from Chorebus, and the antefurcal nr sep-
arates it from Exotela in the restricted sense.

September 2004

Fischer et al.: New Species of Alysiinae

Antrusa curtitempus sp. nov. (Figs. 1-4)
Female-Body length: 1.5 mm.

Head (Fig. 1): Twice as wide as long, twice as
wide as face, 1.33 times as wide as mesoscutum,
eyes at least 1.8 times as long as temples, pro-
truding, eyes narrowed behind, eyes and temples
rounded in a common bow; toruli in normal posi-
tion, occiput bayed inwards; upper side with scat-
tered setae on the sides, occiput and in the ocellar
area, epicranial suture between ocelli; distance
between ocelli greater than ocelli width, distance
between an ocellus and eye as long as width of
ocellar area. Face 1.5 times as wide as high, only
slightly and evenly convex, middle elevation
nearly missing (only faintly visible in a certain
oblique position), with rather evenly distributed,
scattered setae, seta points discernable, edges of
eyes only slightly converging below, nearly paral-
lel sided. Clypeus slightly convex, 3 times as wide
as high, with few outstanding setae. Tentorial
pits round, their diameter as great as the dis-
tance from eyes. Labrum triangular, protruding,
with inconspicuous setae. Mandible (Fig. 2)
slightly longer than wide, lower edge straight, up-
per edge slightly directed upwards, tooth 1
rounded, tooth 2 pointed and only slightly pro-
truding, tooth 3 broadly rounded, an incision be-
tween tooth 2 and 3, outer surface shiny to
uneven and a few scattered setae. Antennae 23-
segmented, scarcely longer than body, the basal
flagellar segments about 2.5 times as long as
wide, the following slightly shorter, Fp about 1.5
times as long as wide; the setae as long as the seg-
ment width, in lateral view 3 sensillae visible.
Mesosoma: 1.4 times as long as high, upper
side convex. Mesoscutum about 1.25 times wider
than long, evenly rounded anteriorly, notauli de-
veloped on declivity and crenulate, merging into
the anteriorly crenulated lateral rim, central lobe
and declivity setose, dorsal slit reaching middle of
disc. Prescutellar furrow rectangular, with 3 longi-
tudinal ridges. Scutellum triangular. Postaxillae
and metascutum glabrous. Propodeum reticulate,
with pentagonal area, a longitudinal carina in-

side, with basal carina and costulae. Furrows of
sides of pronotum crenulate below. Prescutellar
furrow broad, irregularly striated, tapering ante-
riorly and reaching edge, not reaching middle
coxa, prepectal furrow narrow, passing into the
crenulate anterior mesopleural furrow, posterior
mesopleural furrow simple, epicoxal area of mid-
dle coxa with a few scattered setae only. Metapleu-
ron glabrous, uneven, with long scattered setae,
delimited from propodeum by an irregular
lamella. Hind femur 5 times as long as wide, hind
tarsus hardly shorter than hind tibia.
Wings (Fig. 3): st parallel-sided, reaching be-
yond middle of R, r arising from base of st by a
distance as long as rl, the latter slightly longer
than the width of st when infolded, distal half of
r2 almost straight, R not reaching tip of wing, cu2
developed by a distance greater than cql long, nr
clearly antefurcal, d slightly longer than nr, nv
postfurcal, B about twice as long as wide, closed
by vein culb, np arising from middle of B; r' and
cu2' indicated only as folds, nr' absent.
Metasoma: T1 (Fig. 4) 1.5 times as long as
wide, apically 1.5 times as wide as basally, evenly
narrowed towards base, dorsal keels converging
and uniting near middle to a longitudinal median
keel, the remainder smooth, laterally a lamella
which is medially slightly angulated (lateral
view), the spiracle outside the lamella. Ovipositor
sheath as long as hind basitarsus, reaching
slightly beyond tip of metasoma.
Color: Black. Yellow: anellus, labrum, mouth
parts, tegulae, wing venation, legs, and parts of
the lower side of the metasoma.
Male-Unknown.
Host-Unknown.
Material examined: Holotype: female, SPAIN:
Castell6n: Alcora, 7-VII-1990. Paratype: SPAIN:
Castell6n: Alcora, 7-VII-1990, 1 female.
Etymology: The specific name "curtitempus"
means "short temple" and refers to the narrowed
and shortened part of the head behind the eyes
(in dorsal view).
Taxonomic position: The west-Palearctic spe-
cies may be separated as follows:

1. Head (Fig. 1) behind eyes strongly narrowed; temples about half as long as eyes; eyes and temples rounded in a
common curve. Body length: 1.5 mm. Spain ........................ A. curtitempus sp. nov. (female)
-Head behind eyes as wide as at eyes or wider; eyes about as long as temples ............................ 2
2. Head behind eyes widened. T2+3 setose all over, T2 weakly sculptured. Scape and pedicel yellow. Antennae 29-
32 segmented. Body length: 2.5 mm. England, Germany, Central Russia ............... A. vaenia Nixon
-Head at temples not or only slightly wider than at eyes. Setae of T2+3 not distributed over the entire surface; a
broad, bare area between T2 and T3. Only T1 sometimes longitudinally striated ................... .3
3. r2 nearly evenly bent ....................................................................... 4
- r2 distally bisinuate; tegulae dark ............................................................... 5
4. T1 longitudinally striated, weak points between the striae, shiny. Hind femora 5.5 times as long as wide. Mesos-
cutum setose only anteriorly, the rest predominantly bare. T2 glabrous, bare. T1 brownish; T2+3 dark
brown. Antennae 31-segmented. Body length: 2.2 mm. Central Russia ......... A. chrysotegula (Tobias)

Florida Entomologist 87(3)

-Hind femora 4.5 times as long as wide. Mesoscutum nearly entirely covered with short, fine semi-appressed setae.
T2 weakly longitudinally rugose at base. Metasoma yellow, T2 dark brown, T1 black. Antennae 30-seg-
mented. Body length: 2.3 mm. Moldavia .................................. A. chrysogastra (Tobias)
5. Antennae 23-36-segmented, F up to 28-segmented. Head behind eyes clearly widened. T1 narrow, folds stron-
ger. T2 smooth. Body length: 2.2-2.3 mm. Western Europe; North-West and Central Russia; Azerbaijan
..... ....................................................... A. melanocera (Thomson)
-Antennae 28-34-segmented. Head behind eyes not widened. T1 somewhat wider, the folds rather weak. T1 some-
times weakly sculptured. 2.0-2.4 mm. Western Europe; North-, Central and South-West Russia; Azer-
baijan; Siberia (Irkutsk) .............................................. A. flavicoxa (Thomson)

Genus Chorebus Haliday
Chorebus liliputanus sp.nov. (Figs. 5-6)
Male-Body length: 1.2 mm.

Head: Twice as wide as long, 1.4 times as wide
as the mesoscutum, 1.9 times as wide as the face,
2.5 times as wide as T1, at eyes as wide as behind
them; eyes 1.2 times as long as the temples, toruli
not especially prominent, occiput slightly bayed
inwards, upper side with very few setae on sides
and occiput; ocelli small, distance between them
greater than their diameter, epicranial suture not
visible. Face 1.33 times as broad as high, setose
all over, seta points present, middle elevation
only feebly indicated and bare, edges of eyes
slightly rounded. Clypeus trapezoidal, 3 times as
wide as high. Tentorial pits small. Mandible (Fig.
5) as wide as long, lower edge straight, upper edge
only slightly directed upwards, distally only very
little broader than at base; tooth 2-pointed, not
very prominent, tooth 1 round on tip, an obtuse
angle between tooth 1 and tooth 2, tooth 3 and
tooth 4 pointed, positioned one behind the other,
from tooth 1 and tooth 4 arise keels, which unite
to a faint, round carina separating a distal
smooth area, from the lower part of the inner sur-
face arise long, bent setae which surpass teeth 3
and 4 and the lower edge; labrum triangular,
prominent, setose; maxillary palpi as long as
height of head. Antennae as long as body, 22-seg-
mented; F1-F3 about 3 times, Fm 2.5 times, Fp
twice as long as wide, the F closely lined up, the
numerous setae shorter than the F width, in lat-
eral view 2 sensillae visible.
Mesosoma: 1.3 times as long as high, consider-
ably higher than head, upper side strongly
arched. Mesoscutum 1.4 times as wide as long,
anteriorly round, notauli on declivity irregularly
lamellate, crenulate, reaching lateral edge in
right angle, absent on disc; setae on the declivity,
along the imaginary course of the notauli, near
lateral and posterior rim, seta points developed
on declivity. Prescutellar fovea deep, narrow,
densely crenulate. Axillae with long white setae.
Postaxillae crenulate behind. Metascutum with
short central lamella, lateral areas covered with
white setae. Propodeum densely covered with
dirty white tomentum. Sides of pronotum covered
with long, white setae, bare only above. Prepectal
furrow narrow, densely crenulate, passing into

the crenulate epicoxal furrow, precoxal furrow
densely crenulate, shortened behind. Metapleu-
ron densely covered with white setae, with a cen-
tral swelling. Hind femora 5 times as long as
wide, hind tarsi at most slightly shorter than
hind tibia.
Wings (Fig. 6): st mostly parallel-sided, nar-
rowed only towards the end, r arising behind base
of st by a distance equal to the length of rl, r2
evenly curved, R ending considerably before tip of
wing, nr antefurcal, cu2 scarcely developed, d 1.1
times as long as nr, nv postfurcal, B open distally
and below, culb absent, a2 mostly absent; r' and
cu2' practically absent, nr' absent, SM' half as
long as M'.
Metasoma: T1 1.5 times as long as wide, api-
cally straight-lined and narrowed, spiracles on
small tubercles, densely rugose, dorsal carina
only near base, with dense white tomentum,
fewer setae only along middle line. The rest of
metasoma oval, depressed, smooth and bare, ex-
cept for single rows of setae near the hind edges of
the T.
Color: Black. Antennae dark including base.
Yellow: anellus, mouthparts, the entire legs, tegu-
lae, wing venation and T2+3. Wing membrane hy-
aline.
Female-Unknown.
Host-Unknown.
Material examined: Holotype: male, SPAIN:
Castell6n: Burriana, 30-VI-1990. Paratype:
SPAIN: Castell6n: Burriana, 30-VI-1990, male.
Etymology: The name refers to the very small
size of the species.
Taxonomic position: The species is nearest to
Chorebus melanophytobiae Griffiths, 1968 from
which it can be distinguished as follows:
Chorebus melanophytobiae: (a) from tooth 1 of
the mandible arises a lamella which runs to the
base of the mandible; (b) r2 unevenly bent, dis-
tally rather straight; (c) distal part of st wedge-
shaped; (d) base of antennae brown. Body length:
1.4-1.6 mm.
Chorebus liliputanus: (a) from tooth 1 and
tooth 4 of the mandible (Fig. 5) arise keels, which
unite to a faint, round carina separating a distal
smooth area; (b) r2 (Fig. 6) evenly curved; (c) st
mostly parallel-sided, narrowed only towards the
end; (d) base of antennae dark like the remainder.
Body length: 1.2 mm.

September 2004

Fischer et al.: New Species of Alysiinae

Remarks: According to the original description
of Chorebus melanophytobiae (Griffiths 1968a),
there are also specimens with the base of the an-
tennae dark, like the remaining F. On the other
hand, a contrasting yellow color of the antennal
base is often taken as an important specific char-
acter. In spite of there being several, although
only small, differences between Chorebus mel-
anophytobiae and Chorebus liliputanus, we do not
believe that the two taxa are conspecific.

Chorebus propediremptum sp. nov. (Figs. 7-9)
Male-Body length: 1.4 mm.

Head: 1.8 times as wide as long, 1.7 times as
wide as face, 1.33 times as wide as mesoscutum;
between eyes as broad as between temples, eyes
as long as temples, distance of toruli from eyes
and between them as great as their diameter, up-
per side only with very few setae on vertex and oc-
ciput and in the ocellar area, ocelli small, the
distance between them greater than their diame-
ter; epicranial suture distinct on occiput, fading
away between ocelli. Face 1.4 times as broad as
high, moderately setose with distinct seta points,
edges of eyes very weakly rounded, median eleva-
tion very weak. Clypeus trapezoidal, 3 times as
wide as high, with some faint, long setae. Tento-
rial pits as wide as their distance from eyes. La-
brum projecting, apically round, with long setae.
Mandible (Fig. 7) 1.1 times as long as wide, tooth
2 protruding and pointed, tooth 1 as long as tooth
2 and apically rounded, a right angle between
tooth 1 and 2, tooth 3 resembling an intercalar
swelling on lower edge of tooth 2, tooth 4 re-
tracted, lower edge slightly bulged downwards,
short keels arising from teeth 1 and 4, distal area
slightly excavated. Maxillary palpi not longer
than the head high. Antennae at most slightly
longer than body, 30-segmented, most F equally
wide, only the F towards the apex slightly nar-
rower; Fl 3 times, F2 2.5 times, F10 2 times, Fp 2
times as long as broad, the F beyond the middle
clearly separated from each other, but not very
much, the numerous setae shorter than the F
width, in lateral view 3 sensillae visible.
Mesosoma: 1.33 times as long as high, upper
side very weakly rounded, nearly flat, strongly
bent downwards behind. Mesoscutum 1.4 times
as broad as long, round on lateral lobes, anteri-
orly nearly straight, notauli distinct on declivity,
crenulate here, passing in a bow into the mar-
ginal furrow which is anteriorly crenulate, faintly
indicated on disc near to the elongate dorsal
fovea, with many setose hollows on declivity, with
a row of setae along notauli. Prescutellar fovea
deep, crenulate. Axillae with white setae. Postax-
illae clearly smooth. Metascutum and propodeum
covered with dense, dirty white setae obscuring
the surface, spiracles of propodeum on small tu-
bercles. Sides of pronotum without any sculpture,

bare. Precoxal furrow narrow, bisinuate, crenu-
late, shortened behind, reaching the anterior
edge, presternal furrow crenulate, posterior me-
sopleural furrow simple. Metapleuron with cen-
tral swelling and radiating setae, covered with
dirty white pubescence obscuring the surface.
Hind femora 5 times as long as wide, hind tarsi as
long as hind tibiae.
Wings: st nearly parallel sided, wedge-shaped
in distal third, r arising from base of st by a dis-
tance equal to length of rl, r2 unevenly bent,
nearly straight distally, R ending considerably be-
fore tip of wing, nr antefurcal, d scarcely longer
than nr, nv postfurcal throughout its width, B
open on distal corner; a2 weak, culb absent, np
very weak, or indicated only as a fold.
Metasoma: T1 (Fig. 8) 1.5 times as long as
wide, parallel sided, narrowed near base, dorsal
carinae only near base, surface irregularly and
densely net-like rugose, the few white setae not
obscuring the surface, the setae longer and more
numerous on apical corners.
Color: Black. Yellow: base of antennae as far as
Fl, mouth parts, all legs, tegulae, wing venation
and T2+3. Clypeus brownish. Wing membrane
hyaline.
Female-Unknown.
Host-Unknown.
Material examined: Holotype: male, SPAIN:
Castell6n: Almenara, 5-VII-1990. Paratype:
SPAIN: Castell6n: Almenara, 25-VII-1990, 1
male.
Etymology: The name indicates that the spe-
cies stands near Chorebus diremtus (Nees von Es-
enbeck, 1834).
Taxonomic position: The species is, according
to Griffiths's key (1968b) and Tobias's key (1986),
nearest to Chorebus flavipes (Goureau, 1851) or
Chorebus diremtus. The species can be differenti-
ated from each other as follows:
Chorebus diremtus: Mesosoma about 1.45
times as long as high vs. Chorebus propediremp-
tum: Mesosoma 1.33 times as long as high.
Chorebus flavipes: (a) sides of pronotum bare
and smooth centrally, with a little fine pubescence
mainly below the oblique suture; (b) T1 caudally
broadened; (c) mesosoma 1.4 times as long as
high. Body length: 1.8 mm vs. Chorebus prope-
diremptum: (a) sides of pronotum predominantly
shiny, without setae; (b) T1 (Fig. 8) parallel sided;
(c) mesosoma 1.33 times as long as high.

Chorebus vicinus sp.nov. (Figs.9-11)
Female-Body length: 1.7 mm.

Head: 1.9 times as wide as long, 1.4 times as
wide as mesoscutum, 1.7 times as wide as face, 4
times as wide as T1; eyes as long as temples, be-
hind eyes scarcely wider than between eyes. Up-
per surface with scattered, very fine setae on the
sides, the occiput, and in the ocellar area, seta

Florida Entomologist 87(3)

points not recognizable. Ocelli small, the distance
between them greater than their diameter, epic-
ranial furrow very weak. Face 1.2 times as wide
as high, with short, white, not very dense setae,
only near eyes a few longer, erect setae, seta
points very fine, middle elevation scarcely devel-
oped, edges of eyes weakly rounded. Clypeus
three times as wide as high, glabrous, trapezoi-
dal, slightly standing out from face. Tentorial pits
small. Mandibles (Fig. 9) as long as wide, apically
only a little wider than at base, 3-dentate, the
teeth blunt and of about equal width, edges
rounded between teeth, keels arising from teeth 1
and 3, forming a round lamella, which separates a
smooth, inward sloping area distally. Labrum
broad, prominent. Palpi of the present example
damaged. Antennae slightly longer than body, 24-
segmented; Fl 4 times as long as wide, F2 as long
as Fl, the following very gradually shorter, Fm
about 2.5 times, Fp twice as long as wide; the F
clearly separated from each other, the setae
shorter than the F width, in lateral view 3 sensil-
lae recognizable.
Mesosoma: 1.33 times as long as high, upper
side arched. Mesoscutum wider than long, round

6, 1 nm M

Itsma

9U0.2mm_

anteriorly, notauli (Fig. 10) only on anterior de-
clivity, upper surface with moderately long, white
setae, only areas on side lobes and a small area on
the disc bare, seta points especially visible anteri-
orly, dorsal fovea oval. Prescutellar furrow crenu-
late at depth. Axillae dirty white, setose.
Postaxillae hardly sculptured. Sides of metas-
cutum hidden by white setae. Propodeum densely
covered with short white setae hiding the punc-
tate surface, spiracles small. Sides of pronotum
bare. Precoxal furrow densely crenulate, short-
ened behind, reaching the anterior edge of me-
sopleuron, prepectal furrow narrow, crenulate,
passing over to the broader crenulate epicoxal
furrow, posterior mesopleural furrow simple.
Metapleuron with a rosette of dirty white setae
around a central swelling. Hind femora 5 times as
long as wide, hind tarsi as long as hind tibiae.
Wings (Fig. 11): st parallel sided, metacarp
less than half as long as the distal part of st, r
arises from base of st by a distance as long as rl,
r2 unevenly curved, R ending long before tip of
wing, nr strongly antefurcal, d 1.2 times as long
as nr, nv postfurcal throughout its length, B later-
ally open, culb absent, a2 (lower vein of B) grad-

3. mm

70.wnin

1 02 mon

11| I mm |

Figures. 1-4.Antrusa curtitempus (female). Fig. 1. Head in dorsal view. Fig. 2. Mandible. Fig. 3. Anterior right
wing. Fig. 4. T1: First tergite of metasoma. Figures 5-6. Chorebus liliputanus (male). Fig. 5. Mandible. Fig. 6. An-
terior right wing. Figures 7-8. Chorebus propediremptum (male). Fig. 7. Mandible. Fig. 8. T1. Figures 9-11. Chore-
bus vicinus (female). Fig. 9. Mandible. Fig. 10. Notauli. Fig. 11. Anterior right wing.

September 2004

4 0.4 m

51 0.2 rmm

Fischer et al.: New Species of Alysiinae

ually extinct distally, np not developed; r' and cu2'
developed only as folds.
Metasoma: T1 twice as long as wide, sides
slightly converging anteriorly, rugose all over,
evenly covered with white setae, dorsal lamellae
short, spiracles on small tubercles. T2 with few
scattered setae on basal half. Ovipositor sheaths
hardly projecting beyond the apex of metasoma.
Color: Black. Yellow: anellus, mouth parts, all
legs, tegulae, and wing venation. Wing membrane
hyaline.
Male-Unknown.
Host-Unknown.
Material examined: Holotype: female, SPAIN:
Castell6n: Alcora, 17-VII-1990. Paratype: SPAIN:
Castell6n: Alcora, 19-VII-1990, 1 female.
Etymology: The epithet means "neighbor" to
indicate the morphological similarity between
Chorebus vicinus and Chorebus transuersus
(Nixon, 1954).
Taxonomic position: It runs in the key of Grif-
fiths (1968b) and also in the key of Tobias (1986)
to Chorebus transuersus. The latter also has 3-
dentate mandibles. The species are separated
from each other by several characters:
Chorebus transuersus (male, female): Anten-
nae of female 28-36-segmented, of male 34-36-
segmented, base of antennae to F2 yellow-brown,
the apical F 2.5 times as long as wide. Mandible
longer than wide. Sides of pronotum densely set-
ose below and sculptured. Notauli developed as
rugose furrows reaching as far as middle of me-
soscutum. Metacarp as long as distal part of st.
Chorebus vicinus (female): Antennae of female
24-segmented, dark including the base. The api-
cal F twice as long as wide. Mandibles (Fig. 9) as
long as wide. Sides of pronotum bare. Notauli
(Fig. 10) present only on anterior declivity, absent
on disc. Metacarp (Fig. 11) about half as long as
distal part of st.

Remarks: This species is ascribed to the genus
Chorebus Haliday in spite of the 3-dentate mandi-
bles, because of the dense, nearly dirty white tomen-
tum of the propodeum and the metapleuron (rosette
of radiating setae around a central swelling).

ACKNOWLEDGMENTS

Financial support for this paper was provided from
the Junta de Castilla y Le6n, project SA 18/96, and the
Fundaci6n Entomol6gica "Torres-Sala".

REFERENCES CITED

FISCHER, M. 1973. Das Tierrich. Hymenoptera, Bra-
conidae, Opiinae (Palarktische Region). Lief. 91: I-
XII. Walter de Gryter, Berlin.
FISCHER, M. 2002. Ubersicht tiber die Gattungen der
Aspilota-Genusgruppe mit Neubeschreibung von
Grandilota no. gen. sowie Redeskription von Rege-
tus Papp (Hymenoptera, Braconidae, Alysiinae). Z.
Arb. Gem. Osterreich. Ent. 54: 99-108.
GRIFFITHS, G. C. D. 1964. The Alysiinae (Hym., Bra-
conidae) parasites of the Agromyzidae (Diptera). I.
General questions of taxonomy, biology and evolu-
tion. Beitr. Ent. 14: 823-914.
GRIFFITHS, G. C. D. 1968a. The Alysiinae (Hym., Bra-
conidae) parasites of the Agromyzidae (Diptera). V.
The parasites of Liriomyza Mik and certain genera
of Phytomyzinae. Beitr. Ent. 18: 5-62.
GRIFFITHS, G. C. D. 1968b. The Alysiinae (Hym., Bra-
conidae) parasites of the Agromyzidae (Diptera). VI.
The parasites of Cerodontha Rondani s.l. Beitr. Ent.
18:63-152.
NIXON, G. E. J. 1943. A revision of the European Dac-
nusini (Hym., Braconidae, Dacnusinae). Entomolo-
gist's mon. Mag. 79: 20-34, 159-168.
TOBIAS, V. I. 1986. Subfamily Alysiinae, pp. 156-386 In
G. S. Medvedev [ed.] Keys to the Insects of the Euro-
pean Part of the URSS. Vol. III. Hymenoptera. Part
V. Science Publishers, Inc., Lebanon (original in Rus-
sian, transl. 1995 in English).

Florida Entomologist 87(3)

September 2004

FEEDING EFFECTS OF ISCHNODEMUS VARIEGATUS
(HEMIPTERA: BLISSIDAE) ON PHOTOSYNTHESIS AND GROWTH
OF HYMENACHNE AMPLEXICAULIS (POACEAE)

WILLIAM A. OVERHOLT1, SHARON M. L. EWE2, RODRIGO DIAZ', ERIC C. MORGAN1 AND ONOUR E. MOERI1
'University of Florida, IFAS, 2199 South Rock Road, Fort Pierce, FL 34945

2Florida International University, Southeast Research Center, Miami, FL 33199

ABSTRACT

The influence ofIschnodemus variegatus feeding on photosynthesis and growth of the inva-
sive semi-aquatic grass, Hymenachne amplexicaulis, was investigated in field and green-
house environments. In the field, carbon dioxide assimilation of infested plants was
approximately 35% less than that of non-infested plants, and the rate of assimilation was re-
lated to I. variegatus density. The relative growth rate of infested plants in the greenhouse
was 77% of that of non-infested plants, and biomass of infested plants was significantly less
than for non-infested plants 79 days after infestation. The value of I. variegatus as a fortu-
itous biological control agent of H. amplexicaulis is discussed.

Key Words: invasive plants, biological control, photosynthesis, wetlands.

RESUME

La influencia de la alimentaci6n de Ischnodemus variegatus sobre la fotosintesis y el desa-
rrollo del past invasive semi-acuatico Hymenachne amplexicaulis, fue investigado en am-
bientes de campo e invernadero. En el campo, la asimilaci6n del di6xido de carbon por
plants infestadas fue aproximadamente 35% menos que en las plants no infestadas y la
tasa de asimilaci6n fue relacionada con la densidad de I. variegatus. La tasa de crecimiento
relative de plants infestadas en el invernadero fue 77% menos que las plants no infestadas
y la biomasa de plants infestadas fue significativamente menos en plants no infestadas a
los 79 dias despu6s de la infestaci6n. Se discute sobre el valor de I. variegatus como un
agent de control biol6gico fortuito.

Hymenachne amplexicaulis Rudge (Nees)
(Poaceae), commonly referred to as West Indian
Marsh Grass, is an exotic, perennial, semi-
aquatic grass which was first seen in Florida in
1957 (University of Florida Herbarium 2003).
The native range of the grass is tropical Central
and South America (Bogman 1977). Hymenachne
amplexicaulis reproduces and grows from stolons
or seeds in areas with fluctuating water levels. It
can survive long periods of flooding, but will only
persist along the edges of permanent deep water
(Tejos 1980). Csurhes et al. (1999) stated that the
plant preferred low lying fresh water wetlands
and flood plains, and grew most prolifically in
wetlands which receive high nutrient and sedi-
ment influx.
In the 1970s and 80s, H. amplexicaulis began
invading wetlands in southern and central Flor-
ida (Langeland & Craddock-Burks 1998). The
Florida Exotic Pest Plant Council has listed H.
amplexicaulis as a Category I invasive plant
(FLEPPC 2003), and it is included on the Florida
Department of Environmental Protection's list of
noxious plants (DEP 2003). Although no quanti-
tative studies have yet been conducted to exam-

ine the effect of H. amplexicaulis on wetland
biodiversity, it has clearly displaced native plant
species in some areas, particularly in marshes in
Myakka River State Park where large monocul-
tures of the grass occur (Langeland & Craddock-
Burks 1998; R. Diaz unpublished data).
In 2000, a biologist at Myakka River State
Park noticed an insect causing considerable dam-
age to H. amplexicaulis in the park (P. Benshoff,
Park Naturalist, Myakka River State Park, pers.
comm.). Specimens of the insect sent to the Flor-
ida Department of Agriculture and Consumer
Services were identified as Ischnodemus variega-
tus Signoret (Hemiptera: Blissidae), a new record
for Florida (Halbert 2000). Previously, I. variega-
tus had been reported from several countries in
Central and South America (Baranowski 1979;
Slater 1987). Hymenachne amplexicaulis is the
only host mentioned for I. variegatus in South
America, although Baranowski (1979) cites a 'sit-
ting' record on Thalia geniculata L. (Maranta-
ceae) from Suriname. The objective of the present
study was to quantify the effect of I. variegatus
feeding on photosynthesis and growth of H. am-
plexicaulis.

Overholt et al.: Effect of variegatus on H. amplexicaulis

MATERIALS AND METHODS

Field Measurements

A portable infra-red gas exchange system
(CIRAS-1, PP Systems, Massachusetts, USA) was
used to measure leaf photosynthesis (i.e., net car-
bon dioxide (CO,) assimilation). Gas exchange was
measured on plants growing along the banks of
Fisheating Creek (Glades Co.) (26.95N, 81.14W)
on the western side of Lake Okeechobee on three
days (28/8, 4/9, 18/9) during August and Septem-
ber 2003. On each sampling date, photosynthesis
was measured on 27-66 H. amplexicaulis plants. In
order to increase the chance of having both in-
fested and non-infested plants in the sample,
plants were selected according to leaf color. Previ-
ous observations (W. Overholt, unpublished data)
on laboratory infested plants indicated that feed-
ing by I. variegatus induced a change in color of
H. amplexicaulis leaves from green to dark red. On
each sampling date, an approximately equal num-
ber of plants were sampled from patches ofH. am-
plexicaulis showing no damage symptoms and
patches with red leaves. After measuring gas ex-
change, culms were excised at water level and dis-
sected to count nymphs and adults ofL. variegatus.

Plants

Stolons and seeds ofH. amplexicaulis were col-
lected in Myakka River State Park from October
to December, 2002, and used to propagate plants
in a greenhouse in Fort Pierce. Plants were grown
in 1-L plastic pots in commercial potting soil from
rooted stolon cuttings or seeds. Pots were placed
in solid-bottomed trays, to which water was added
and maintained at a depth of 4-6 cm.

Insects

Adults and nymphs of variegatus were col-
lected in Myakka River State Park and taken to
the laboratory. Hymenachne amplexicaulis plants
(~30 cm in height) were inoculated with 10 I. var-
iegatus adults/nymphs. Plants in pots were
placed in trays with water, and maintained inside
a PVC framed cage covered with fine organdy
cloth.

Greenhouse Bioassay

The bioassay was conducted under ambient
conditions (22.2-37.2C, mean temperature of
27.1C, natural lighting) in a greenhouse at the
University of Florida's Indian River Research and
Education Center in Fort Pierce. Plants used for
the bioassay were grown from seed planted on the
same day, and grown under the same conditions
for 80 days. All plants were grown in 1-L plastic
pots containing commercial potting soil, and at

the time of infestation were approximately the
same size. Six plants were randomly selected
from this group, and infested with 20 I. variega-
tus second instars, and six plants were selected as
non-infested controls. In addition, six plants were
removed from their pots, dried, and weighed to es-
timate initial biomass. Infested and non-infested
plants were caged in open-bottomed acrylic cylin-
ders (46 cm x 14.5 cm, height x diameter) in which
the top was covered with 300 p mesh nylon cloth.
Holes (8.5 cm diameter) were cut at 6 locations in
the sides of the tubes and replaced with the same
nylon cloth to allow ventilation. Plants and their
cages were placed in trays and water was added
to a depth of 4-6 cm. Water was replenished daily
to maintain this depth throughout the course of
the experiment.
Net CO2 assimilation was measured once or
twice a week on the second fully expanded leaf
from the top of the plant with the CIRAS-1 instru-
ment. The first measurements were taken just
prior to infestation, and the last measurements
were made at 79 days after infestation. After 79
days, infested plants were dissected and all L var-
iegatus individuals removed, classified by age
nymphall instars 1-5 or adult), and counted. Eggs
were difficult to locate due to their small size and
cryptic coloration, and were not counted.
At harvest, the numbers of leaves and culms
were counted. Basal diameter of each culm and
the length and width of the largest leaf of each
plant were measured with a micrometer. All
growth medium was then washed off the plants.
Leaves were separated from the roots and all
leaves digitally photographed. Leaf area was de-
termined from the digital images with ImageJ
software (ImageJ shareware, NIH, Bethesda, MD).
The proportion of damaged area also was as-
sessed by this method. Plants were then dried in
an oven at 65C for two weeks and weighed to ob-
tain measurements of biomass.

Data Analysis

CO, assimilation in the field was analyzed
with two-way analysis-of-covariance (ANCOVA)
with date and infestation status (infested vs. non-
infested, where infested plants had one or more
nymphs and/or adults ofl. variegatus) as main ef-
fects and light level as a covariate (PROC GLM,
SAS Institute 2001). The covariate was included
in the model because light intensity varied
greatly among observations, ranging from 502 to
1964 pmol photons m2s-1. The number ofL varie-
gatus was also regressed on CO, assimilation
(PROC REG, SAS Institute 2001). Greenhouse gas
exchange was analyzed with repeated measures
analysis-of-variance (ANOVA) (PROC GLM, SAS
Institute, 2001). We used t-tests to compare leaf
area, morphometric parameters and growth rates
between infested and control plants.

Florida Entomologist 87(3)

RESULTS

20.0

Field Measurements

Mean CO, assimilation was different between
sampling dates (F= 53.1, df = 2, 132, P < 0.0001)
and between infested plants (8.5 0.5 pmol CO2
m-2s-1) and non-infested plants (12.9 0.6 pmol
CO, mMs-1) (F= 42.3, df = 4, 132, P < 0.0001). The
covariate light was also significant (F= 5.12, df=
1, 132, P < 0.025). A regression of CO, assimila-
tion on number of insects showed a decline in pho-
tosynthesis as insect numbers increased (F= 21.5,
df = 1, 135, P < 0.0001, R2 = 0.13) (Fig. 1).

Greenhouse Bioassay

The number of variegatus found on plants at
harvest ranged from 50 to 149, with a mean of 97
+ 13 (SE). Approximately 86% of the individuals
removed from the plants were either first (70.1%)
or second (15.9%) instars. As the plants were in-
fested with 20 second instars, this represented a
population increase of about 2.5 to 7.5 times dur-
ing the 79-day experiment. A generation of var-
iegatus is completed in approximately 60 days (R.
Diaz, unpublished), and therefore, the insects
found at harvest were most likely the F, progeny
of those released.
Growth patterns of the infested plants were
different from those of the control plants (Fig. 2,
Table 1). The amount of damage, as quantified by
the amount of red leaf area, in the infested plants
was higher (F = 4.722, df = 1, 10, P < 0.01) than
non-infested plants (Table 1).
The relative growth rate of infested plants was
77% that of the control plants, which resulted in

30

25
E
o 20
E

o 15
E
; 10

o
0 5

0

Figu
the field

y = -0.55 x +11.9

3 15.0

c 10.0
E
o
m 5.0

0.0

* stems/leaves
E roots

Infested

Unifested

Figure 2. Average biomass ( SEM) allocated to roots
and shoots for treatment and control plants.

much larger control plants (Table 1). Both root and
shoot biomass were greater in the controls relative
to the infested plants (roots: F = 3.437, df = 1,10,
P < 0.01; shoots: F = 1.968, df = 1,10, P < 0.05)
(Fig. 2). On average, control plants were more
than 1.5 times larger than the infested plants.
Neither infested nor non-infested plants flowered
during the experiment, and no plants died.
Morphometric differences were observed be-
tween the two treatments. Control plants had
larger total leaf area, longer leaves and thicker
culms than the infested individuals (Table 1). The
number of culms, however, was not different be-
tween treatments.
Carbon dioxide assimilation rates were higher
in the control plants during the first seven sam-
pling periods (days 4-29), but were not different
after day 29 (Fig. 3). Repeated measures ANOVA
indicated a difference between treatments (F =
6.92, df = 1,10, P < 0.05, power = 0.660).

DISCUSSION

Sr = 0.3 Feeding by Ischnodemus variegatus adults and
nymphs clearly affected the overall growth of
i H. amplexicaulis. Both above and below ground
parts of infested plants were smaller than those
of uninfested plants. Infested plants also had a
higher proportion of damaged leaves relative to
t the controls. In addition to the effect of infestation
on biomass, the majority of leaves of infested
plants were red or brown at harvest. The reddish
discoloration of the leaves, suggestive of a break-
* down and/or disruption in the function of plant
photosynthetic pigment complexes, is similar to
t damage symptoms on corn (Zea mays L.) and buf-
-- - --- falograss (Buchloe dactyloides (Nuttall)) caused
0 5 10 15 20 by feeding of Blissus spp. (Hemiptera: Blissidae)
mbeof variegatus (Negron & Riley 1990; Baxendale et al. 1999).
In the greenhouse bioassay, CO, assimilation
re 1. Carbon dioxide assimilation of plants in was lower in infested plants for the first 29 days
With variable densities of I. variegatus. after infestation. It was somewhat surprising

September 2004

*

Overholt et al.: Effect of variegatus on H. amplexicaulis

TABLE 1. AVERAGE ( SEM) VALUES OF MEASURED PARAMETERS IN PLANTS WITH I. VARIEGATUS AND CONTROL PLANTS.
SIGNIFICANT P-VALUES FROM T-TEST COMPARISONS ARE SHOWN IN BOLD.

Infested Control P-value

Leaf area (cm2):
Damaged 69 9 17 1 0.000
Undamaged 201 30 441 42 0.001
Total 270+ 29 458 43 0.005
Largest leaf (cm):
Length 18.8 0.7 22.3 0.5 0.003
Width 1.2 0.1 1.16 0.0 0.429
Culm:
Number 6.8 0.4 8.5 1.1 0.171
Thickness (mm) 3.4 0.1 4.0 0.1 0.002
Relative growth rate (g/g/week)' 0.167 + 0.01 0.215 0.01 0.008

Grams biomass gained/grams initial plant biomass/week.

that C
infeste
ter inf
nated
acrylic
tively
infeste
the fir
have b
The sn
change
Inse
through
trials
(pierci
sects,E
derma
(Wallii
hibit

18
16
E 14
S12
r 10
0
8
E 6
4
S 2

Figu
ilation
for eaci

02 assimilation was not different between herbivory (Meyer & Whitlow 1992). Johnson &
id and non-infested plants from 32 days af- Knapp (1996) concluded that photosynthetic inhi-
estation until the experiment was termi- bition of Spartina falicus (Link) (Poaceae) caused
on day 79. We suspect that the size of the by Ischnodemus falicus (Say) was consistent with
tubes covering the plants may have nega- xylem feeding. Our field and greenhouse results
influenced growth. Both infested and non- clearly demonstrated that I. variegatus decreased
id plants grew to the top of the tubes within photosynthetic capacity of H. amplexicaulis. Al-
st month, after which their growth may though the tissues accessed during feeding were
een impaired by the size of the containers, not identified, we are doubtful that this insect is a
tall chamber size may also explain the color xylem feeder. Press & Whittaker (1993) stated
es in leaves of non-infested plants (Table 1). that there is little evidence to support xylem feed-
ect herbivores access plant resources either ing of insects other than cercopids, cicadids, and
h consumption of foliage or other solid ma- some cicadellids. Moreover, we saw no evidence of
(chewing insects) or by ingesting plant sap copious amounts of excreted liquids typically as-
ng/sucking insects). Piercing/sucking in- sociated with xylem feeding (Press & Whittaker
such as blissids, feed in phloem, xylem, epi- 1993).
1, or mesophyll paraenchyma tissues Determining the value ofL. variegatus as a bio-
ig 2000). Xylem feeding is reported to in- logical control agent ofH. amplexicaulis requires
photosynthesis more than other types of additional research. The insect undoubtedly af-
fected photosynthesis and plant growth, but even
at relatively high initial densities of 20 I. varieg-
atus per plant, which increased to an average of
97 insects per plant during the course of the ex-
periment, plants were not killed. Densities of .
variegatus monitored in the field in 2002/2003
rarely surpassed 20 insects per plant, and were
most often much lower (Overholt, unpublished
[ I data). However, in the field, plants are stressed by
SI a variety of factors, including climate, water, soil
Nutrient levels, pathogens, herbivores, and com-
petition with other plants. Hymenachne amplexi-
caulis has low drought tolerance (Medina &
Motta 1990) and thus a combined effect of low
water availability and insect damage may have
0 20 40 60 80 additive negative effects on H. amplexicaulis
Time (a) growth. Additionally, I. variegatus may influence
flowering and seed production, which were not
ire 3. Average rates of carbon dioxide net assim- measured in our experiments. A negative impact
( SEM) in infested (*) and control ([) plants on seed production could conceivably slow the
Sample day. spread ofH. amplexicaulis in Florida's wetlands.

Florida Entomologist 87(3)

Finally, the value of L variegatus to natural re-
source management and agriculture in Florida
will depend on its host range. In South America,
I. variegatus has been recorded only from H. am-
plexicaulis (Baranowski 1979), and there are no
native members of this genus in Florida or the
USA (reference). However, no detailed studies of
the insect's biology have been conducted. We are
currently investigating the host range ofL. varie-
gatus by measuring survivorship on a large num-
ber of native and economically important grasses.
If variegatus is restricted to Hymenachne, there
is little threat of its shifting to more distantly re-
lated grasses (Pemberton 2000).

ACKNOWLEDGMENTS

The authors thank the staff at Myakka River State
Park, particularly Paula Benshoff and Diana Donaghy,
for allowing access to marshes in the park for collection
of H. amplexicaulis and I. variegatus. We also appreci-
ate the taxonomic assistance provided by Julieta Bram-
bila and Richard Baranowski for identification of I.
variegatus. We thank members of the Wetland Ecosys-
tem Ecology Laboratory at Florida International Uni-
versity for reviewing an earlier draft of this paper. This
research was supported by the Florida Agricultural Ex-
periment Station, and a grant from the Florida Depart-
ment of Agriculture and Consumer Services (DACS
7276186-12) and approved for publication as Journal
Series No. R-09938.

REFERENCES CITED

BARANOWSKI, R. M. 1979. Notes on the biology of
Ischnodemus oblongus and I fulvipes with descrip-
tions of the immature stages. Ann. Entomol. Soc.
Amer. 72: 655-658.
BAXENDALE, F. P., T. M. HENG-MOSS, AND T. R. RIOR-
DAN. 1999. Blissus occiduus (Hemiptera: Lygaeidae):
a chinch bug pest new to buffalograss turf. J. Econ.
Entomol. 92: 1172-1176.
BOGMAN, A. V. 1977. Tropical Pasture and Fodder
Plants. Longman, New York. 475 pp.

CSURHES, S. M., A. P. MACKEY, AND L. FITZSIMMONS.
1999. Hymenache (Hymenachne amplexicaulis) in
Queensland. Queensland Government, Department
of Natural Resources and Mines. 39 pp. http://www.
nrm.qld.gov.au/pests/psas/pdfs/Hymenachne.pdf
DEP 2003. Florida Department of Environmental Pro-
tection. Invasive Plants of the Thirteen Southern
States. http://www.invasive.org/seweeds.cfm
FLEPPC. 2003. Florida Exotic Pest Plant Council. List
of invasive plants. http://www.fleppc.org/Plantlist/
031ist.htm
HALBERT, S. E. 2000. Entomology section. Trilogy 39(5)
http://doacs.state.fl.us/~pi/enpp/00-sep-oct.htm#ent.
JOHNSON, S. R., AND A. K. KNAPP. 1996. Impact of
Ischnodemus falicus (Hemiptera: Lygaeidae) on pho-
tosynthesis and production of Spartina pectinata
wetlands. Environ. Entomol. 25: 1122-1127.
LANGELAND, K. A., AND K. CRADDOCK-BURKS. 1998.
Identification and Biology of Non-native Plants in
Florida's Natural Areas. University Press of Florida,
Gainesville. 165 pp.
MEDINA, E., AND N. MOTTA. 1990. Metabolism and dis-
tribution of grasses in tropical flooded savannas in
Venezuela. J. Tropical Ecology 6: 7-89.
MEYER, G. A., AND T. H. WHITLOW. 1992. Effects of leaf
and sap feeding insects on photosynthetic rates of
goldenrod. Oecologia 92: 480-489.
NEGRON, J. F., AND T. J. RILEY. 1990. Long-term effects
of chinch bug (Hemiptera: Heteroptera: Lygaeidae)
feeding on corn. J. Econ. Entomol. 83: 618-620.
PRESS, M. C., AND J. B. WHITTAKER. 1993. Exploitation
of the xylem stream by parasitic organisms. Phil.
Trans. Royal Soc., London B 341: 101-111.
SLATER, J. A. 1987. The taxonomic status of Ischnode-
mus oblongus (Fabricius) and Ischnodemus variega-
tus (Signoret) (Hemiptera: Lygaeidae: Blissinae). J.
N.Y. Entomol. Soc. 95: 294-297.
TEJOS, M. R. 1980. Production of water straw grass (Hy-
menachne amplexicaulis (Rudge) Nees) during a sa-
vanna period. Congress Venezolano Zootecnia
Guanare (Venezuela) p. 24.
UNIVERSITY OF FLORIDA HERBARIUM. 2003. Collections
catalogue. http//www.flmnh.ufl.edu/scripts/dbs/herbs_
project/herbsproject/herbs_pub_proc.asp.
WALLING, L. L. 2000. The myriad of plant responses to
herbivores. J. Plant Growth Regulation 19: 195-216.

September 2004

Hoddle et al.: Checklist of California Thrips

THYSANOPTERA RECORDED FROM CALIFORNIA, U.S.A.: A CHECKLIST

MARK S. HODDLE', LAURENCE A. MOUND2 AND SUEO NAKAHARA3
'Department of Entomology, University of California, Riverside, CA 92521, U.S.A.

2Honorary Research Fellow, CSIRO Entomology, GPO Box 1700, Canberra, ACT 2601, Australia
and Scientific Associate, The Natural History Museum, London

3Systematic Entomology Laboratory, USDA, Agricultural Research Service, Beltsville, MD 20705-2350, U.S.A.

ABSTRACT

In California U.S.A., 238 named species of the insect Order Thysanoptera, in 87 genera and
eight families, are listed as having been found in this state. Inspection of museum collections
indicates many undescribed species ofthrips exist. Little is known of the host plants of native
California thrips species, due to imprecise collecting methods such as sweep netting swaths
of mixed vegetation. At least 40 (-17%) of the listed species in California are introduced from
other parts of the world. Two terebrantian families (Adiheterothripidae and Fauriellidae),
and one genus (Orothrips) in a third terebrantian family (Aeolothripidae), have a remarkably
disjunct distribution between California and the European Mediterranean region.

RESUME

En el estado de California EEUU, estan listadas 238 species descritas en el ord6n de insec-
tos Thysanoptera, pertenecientes a 87 g6neros y ocho families, apuntadas de haber sido en-
contrada en este estado. Una revision de las colecciones en los museos indica que existe mas
species de trips no descritas. Las plants hospederas de las species de trips nativas de Ca-
lifornia son poco conocidas, debido a los m6todos imprecisos de recolectar, tal como pasar una
red sobre vegetaci6n mezclada. Por lo menos 40 (~17%) de las species mencionadas en Ca-
lifornia son introducidas de otras parties del mundo. Dos families terebrantianas (Adihete-
rothripidae y Fauriellidae), y un g6nero (Orothrips) en una tercer familiar terebrantiana
(Aeolothripidae), tienen una distribuci6n desarticulada entire California y la region mediter-
ranea europea.

The foundation publication concerning Thysan-
optera diversity was by Heinrich Uzel from Bohe-
mia in 1895. Uzel's (1895) publication was followed
by Dudley Moulton's (1907) first paper on Califor-
nian thrips at the start of his long career in agricul-
ture in this State. Moulton's taxonomic studies
culminated 61 years later in a posthumous publi-
cation (Arnaud & Lee 1973). Stanley Bailey, at the
University of California, Davis, published exten-
sively on thrips between 1937 and 1968, and en-
couraged contributions from two students, H. E.
Cott (1956) and A. G. Gentile (Gentile & Bailey
1968). Although primarily involved in pest control,
Bailey produced several valuable bibliographic
treatments concerning the publications of other
North American thrips workers. Tokuwo Kono was
employed at the California Department of Food
and Agriculture in Sacramento to study thrips,
aphids and mites. Kono prepared a large slide col-
lection of thrips and published an introduction to
the more common species (Kono & Papp 1977). In
contrast, William Ewart, a Professor at the Univer-
sity of California, Riverside developed an extensive
knowledge of thrips together with a beautifully
prepared collection of slide-mounted specimens
and library. Unfortunately, Ewart's published con-
tribution on Thysanoptera was negligible.

Given this extensive and prolonged investment
of expertise in the study of Thysanoptera in Cali-
fornia, it is surprising that as many as 12 new spe-
cies of Thysanoptera have been described from
California in the past 10 years, particularly since
the authors involved carried out no new field stud-
ies but merely described taxa available in museum
collections. It seems that earlier Californian work-
ers lacked the opportunity, or the passion, for the
extensive field studies that are so evident in the
work of J. D. Hood at Cornell University (Ithaca,
New York, U.S.A.). Certainly, the technical exper-
tise of Hood in preparing microscope slides of
thrips was rarely matched. The slides of Moulton
and Bailey are often inadequate for critical study of
structural details. This lack of technical expertise,
together with the lack of devotion to field biology, is
presumably the origin of the very high synonymy
rate of some early workers on this group of insects.
Moulton, for example, published 510 species-group
names for thrips from around the world, but 178 of
these (35%) are now considered synonyms.
The two most recent revisionary studies of the
Californian thrips fauna, Bailey (1957) on the
Terebrantia and Cott (1956) on the Tubulifera,
are now totally inadequate due to the generic
classification that they used having been greatly

Florida Entomologist 87(3)

changed in recent years, and many species now
being placed in synonymy. Moreover, neither pub-
lication gives any indication of the extraordinary
biological interest in these insects, the remark-
able biogeographical distributions, the host plant
associations, or the seasonality of various species.
Both papers are essentially "descriptive taxon-
omy" in the most pedestrian sense, concerned
with statements of fact with no attempt to convey
the fascination of the biological diversity exhib-
ited by this group of insects.
The checklist provided here is intended to lay
the foundations for a modern approach to the
study of California Thysanoptera. The insect
fauna of this state is diverse, as is the range of ec-
osystems that thrips inhabit. But the lack of ade-
quate field surveys for thrips in different
ecosystems and at appropriate times of year re-
sults in it being impossible to gauge how accu-
rately this list reflects the native and exotic thrips
fauna. Despite this, the substantial number of
sorted but unidentified species in the Ewart Col-
lection at the University of California at River-
side suggests that the Thysanoptera of California
is considerably richer than the following list
might suggest.

HOST PLANT RELATIONSHIPS

The host plant relationships of Californian
thrips are poorly known, many species being
known from too few specimens for any serious in-
formation to be available on their host plants and
seasonality. Three of the species of Dactuliothrips
and both species of Orothrips are known from the
flowers of Ceanothus (Rhamnaceae), but whether
these species breed in (or even only in) these flow-
ers is unclear. In many species of thrips, even
wingless adults may be transported readily by
winds, and adults can be taken commonly from
plants on which they are not able to breed. Many
of the "host plants" recorded in the published lit-
erature cannot be relied upon as indicating that a
thrips species can reproduce on a particular
plant, let alone that it is dependent on that plant
species to maintain its populations. It is essential
to find and recognize the larvae of thrips species,
and to collect repetitively at different localities, in
order to establish the biological dependence of
such insects on particular plant species.
Two genera listed below, Aeolothrips and Lep-
tothrips, involve species that are presumed to be
predatory, but it seems unlikely that so many
closely related predatory species should co-exist
in this area. If these species prove to be both valid
and obligate predators, then niche apportionment
among them will be an interesting field for study.
However, it seems likely that at least some of the
Aeolothrips species are actually phytophagous,
and probably facultative predators with some
level of host-specificity.

BIOGEOGRAPHIC RELATIONSHIPS

The thrips fauna of the southwestern U.S.A.
includes taxa with distributions that are remark-
ably disjunct. Orothrips in the Aeolothripidae is
known from three species; one from European
Mediterranean countries and two from Califor-
nia. The Adiheterothripidae includes three gen-
era, one from the eastern Mediterranean to India
and two from California. The Fauriellidae in-
cludes four genera, one Mediterranean, one Cali-
fornian, and two from southeastern Africa. At
least 17% of the species in this checklist appear to
be non-native to California, and most of the na-
tive species appear to be found in the southern
and eastern areas of the state. However, the avail-
able locality information and "host plant" records
for collected species are not adequate to make any
broad generalizations concerning the thrips
fauna of California.

THRIPS COLLECTIONS IN CALIFORNIA

Several of the most important reference collec-
tions of world Thysanoptera are housed within
California research institutes. One of the smallest
collections, but in terms of the quality of slide-
mounted material, the most useful, is the Ewart
Collection at the University of California at Riv-
erside. The Ewart Collection has approximately
450 named species and many flagged and group-
organized but unnamed species from California.
The Moulton Collection at the Californian Acad-
emy of Sciences, San Francisco, is particularly
rich, with type material of 640 species and over
25,000 slides. The Bailey Collection at the Univer-
sity of California at Davis includes representa-
tives of almost 750 named species. The Cott
Collection at the University of California at Ber-
keley has about 170 species. Finally, the collection
at the California Department of Food and Agricul-
ture, Sacramento California, largely developed by
Kono, has about 630 species.

CHECKLIST

Although based largely on published litera-
ture, this list includes a considerable number of
previously unpublished State records, derived pri-
marily from the Ewart Collection at the Univer-
sity of California at Riverside, but also from the
United States Museum of Natural History collec-
tions, held at USDA, Beltsville, Maryland. Some
of the literature records seem likely to involve
misidentifications, particularly that of Oxythrips
quercicola, and some of the museum records are
based on few and old specimens, eg. Frankliniella
tritici and Fr. williamsi. Other problems for future
work include the currently unsatisfactory distinc-
tions among several genera of leaf-feeding phlaeo-
thripine species, e.g., Liothrips, Rhynchothrips

September 2004

Hoddle et al.: Checklist of California Thrips

and Pseudophilothrips. The objective of this list is
to provide a starting point for further work.
Within the Order Thysanoptera, two suborders
are recognized, Terebrantia and Tubulifera, and
both of these major groups are well represented in
California. The Terebrantia includes eight fami-
lies worldwide, of which only the monotypic, trop-
ical, Uzelothripidae has not been found in
California. The Tubulifera includes a single large
family, the Phlaeothripidae, with two subfamilies,
the Idolothripinae and Phlaeothripinae, both of
which are represented in California.
In the checklist below, an asterisk (*) indicates
species that presumably are not native to Califor-
nia. The original generic combination, when this
differs from the current one, is indicated in
square brackets [ ] after a species entry.

Merothripidae

This family of three genera, with about 15 fun-
gus-feeding species that live on dead twigs and in
leaf-duff, is found mainly in the Neotropics.
Merothrips Hood, 1912: 132
floridensis Watson, 1927: 60
morgani Hood, 1912: 132

Melanthripidae

The four genera now placed in this family until
recently were considered to be members of the Ae-
olothripidae. They are found in the northern and
southern hemisphere temperate regions, and in-
clude a total of about 65 flower-feeding species.
Ankothrips Crawford, 1909: 100
aequalis Moulton, 1926: 20
gracilis Moulton, 1926: 19
notabilis Bailey, 1940: 101
robustus Crawford, 1909: 100
yuccae Moulton, 1926: 119
Melanthrips Haliday, 1836: 450
digitus Bailey, 1954: 79

Adiheterothripidae

The three genera in this family have a remark-
ably disjunct distribution, one with four species
breeding in the flowers of date palms in western
Asia, and the two listed here from California.
Heratythrips Mound & Marullo, 1998: 88
sauli Mound & Marullo, 1998: 89
Oligothrips Moulton, 1933: 139
oreios Moulton, 1933: 139

Fauriellidae

Four genera and five species are placed in this
family, one Mediterranean with two species, and

two from southeastern Africa together with the
one listed here.

Parrellathrips Mound & Marullo, 1998: 83
ullmani Mound & Marullo, 1998: 85

Heterothripidae

The four genera and 70 species recognized in
this family are all from the New World. These spe-
cies are almost all flower-feeding, 65 of them be-
ing placed in Heterothrips, but one Brazilian
species that is placed in a monobasic genus is ec-
toparasitic on an homopteran.

Heterothrips Hood, 1908: 361
pectinifer Hood, 1915: 5
prosopidis Crawford, 1943: 93
salicis Shull, 1909: 220
uitifloridus Bailey & Cott, 1954: 616

Aeolothripidae

Most of the 190 species in this family of about
23 genera are found in the temperate areas of the
northern and southern hemispheres, although
most of the genera are from tropical countries.
The tropical species, in genera such as Franklino-
thrips and Stomatothrips, are mainly obligate
predators of other arthropods, whereas most of
the temperate area species in the genus Aeolo-
thrips are flower-living facultative predators.
Aeolothrips Haliday, 1836: 451
albicinctus Haliday, 1836: 451
auricestus Treherne, 1919: 184
brevicauda Hood, 1935: 105
brunneipictus Bailey, 1951: 53
clarus Bailey, 1951: 53
collariss Priesner, 1919: 119
crucifer Hood, 1935: 104
duuali Moulton, 1927: 186
*ericae Bagnall, 1920: 60
fasciatus (Linnaeus), 1758: 266 [Thrips]
fuscus Watson, 1931: 340
hartleyi Moulton, 1927: 185
hesperus Bailey, 1951: 58
kuwanaii Moulton, 1907: 47
*melaleucus (Haliday), 1852: 1117 [Coleothrips]
metacrucifer Bailey, 1951: 61
montanus Bailey, 1951: 62
nasturtii Jones, 1921: 2
nitidus Moulton, 1946: 59
occidentalis Bailey, 1951: 63
terrestris Bailey, 1951: 64
vittipennis Hood, 1912: 129

Dactuliothrips Moulton, 1931: 173
boharti Bailey, 1937: 122
diversus Bailey, 1939: 170
spinosus Moulton, 1931: 174
xerophilus Bailey, 1937: 122

Florida Entomologist 87(3)

Erythrothrips Moulton, 1911: 34
arizonae Moulton, 1911: 21
fasciculatus Moulton, 1929: 224
keeni Moulton, 1929: 226

Franklinothrips Back, 1912: 75
orizabensis Johansen, 1974: 249
vespiformis Crawford, 1909: 109

Orothrips Moulton, 1907: 45
kelloggii Moulton, 1907: 43
yosemetii Moulton, 1911: 13

Rhipidothrips Uzel, 1895: 66
*brunneus Williams, 1913: 216
*gratiosus Uzel, 1895: 46

Stomatothrips Hood, 1912: 63
flavus Hood, 1912: 64

Thripidae

More than 2000 species in 290 genera are
placed in this family worldwide. Most of them are
phytophagous on higher plants, with a few spe-
cies on ferns. A few species are obligate predators
(e.g., Scolothrips sexmaculatus), but some poly-
phagous pest thrips can behave as facultative
predators (e.g., Frankliniella occidentalis). Four
subfamilies within the Thripidae are currently
recognized worldwide, and each of these is repre-
sented in California.

Thripidae-Panchaetothripinae

Wilson (1975) provided an account of the mem-
bers of this subfamily that is now considered to in-
clude 125 species in 35 genera. The name
Hercothrips occurs in earlier literature in Califor-
nia, but this is a synonym of Caliothrips.

Caliothrips Daniel, 1904: 296
fasciatus (Pergande), 1895: 391 [Heliothrips]
marginipennis (Hood), 1912: 136 [Heliothrips]
(bromi Moulton, 1927: 31 [Heliothrips])
phaseoli (Hood), 1912: 113 [Heliothrips]

Heliothrips Haliday, 1836: 443
*haemorrhoidalis (Bouche) 1833: 42 [Thrips]

Hercinothrips Bagnall, 1932: 506
*femoralis (Reuter), 1891: 166 [Heliothrips]

Monilothrips Moulton, 1929: 93
*kempi Moulton, 1929: 94

Parthenothrips Uzel, 1895: 170
*dracaenae (Heeger), 1854: 365 [Heliothrips]

Thripidae-Dendrothripinae

More than 90 species, in 10 genera, are recog-
nized worldwide in this subfamily. All of the spe-

September 2004

cies live on young leaves, and they are usually
small and jump when disturbed.
Asprothrips Crawford, 1938: 109
*seminigricornis (Girault), 1926: 2 [Euthrips]
Dendrothrips Uzel, 1895: 159
ornatuss (Jablonowski), 1894: 93 [Thrips]
Leucothrips Reuter, 1904: 107
furcatus Hood, 1931: 153
*nigripennis Reuter, 1904: 108
pierce (Morgan), 1913: 19 [Microthrips]

Thripidae-Sericothripinae

This subfamily includes worldwide at least 90
species in 10 genera. Most of these genera are
subdivisions of the genus Sericothrips that have
been recognized relatively recently. Moreover, in
contrast to earlier authors, the genus Scirtothrips
is not considered now to be related to Serico-
thrips. The species are all phytophagous in flow-
ers and on leaves.
Neohydatothrips John, 1929: 33
albus (Jones), 1912: 6 [Sericothrips]
catenatus (Hood), 1957: 51 [Sericothrips]
collaris (Hood), 1936: 91 [Sericothrips]
chrysothamni (Hood), 1936: 85 [Sericothrips]
moultoni (Jones), 1912: 7 [Sericothrips]
opuntiae (Hood), 1936: 88 [Sericothrips]
setosus (Hood), 1927: 135 [Sericothrips]
variabilis (Beach), 1896: 220 [Thrips]

Thripidae-Thripinae

This is a large group of over 1700 species in
235 genera, although almost 50% of these genera
remain monotypic. The species exhibit a wide
range of biologies, and most of the pest thrips are
included in this subfamily.
Anaphothrips Uzel, 1895: 142
obscuruss (Muller), 1776: 96 [Thrips]

Apterothrips Bagnall, 1908: 185
apteris (Daniel), 1904: 295 [Sericothrips]
(=stanfordi Moulton 1907: 43 [Sericothrips])
secticornis Trybom, 1896: 620 [Thrips]

Aptinothrips Haliday, 1836: 445
Rufuss (Haliday), 1836: 445 [Thrips]
*stylifer Trybom, 1894: 43

Arorathrips Bhatti, 1990: 194
mexicanus (Crawford), 1909: 114 [Chirothrips]
spiniceps (Hood), 1915: 12 [Chirothrips]

Arpediothrips Hood, 1927: 197
mojave Hood, 1927: 198

Baileyothrips Kono & O'Neill, 1964: 1
arizonensis (Morgan), 1913: 12 [Anaphothrips]
minutusus Moulton: 1929, 127 [Anaphothrips])

Hoddle et al.: Checklist of California Thrips

Bregmatothrips Hood, 1912: 66
venustus Hood, 1912: 67
(=sonorensis Stannard, 1956: 71)

Chaetanaphothrips Priesner, 1926: 204
*orchidii (Moulton), 1907: 52 [Euthrips]

Chilothrips Hood, 1916: 119
occidentalis Stannard, 1973: 110
pini Hood, 1916: 120
rotrameli Stannard, 1973: 114

Chirothrips Haliday, 1936: 444
*aculeatus Bagnall, 1927: 567
falsus Priesner, 1925: 312
*manicatus (Haliday), 1836: 444 [Thrips]
patruelis Hood, 1940: 550
secalis Moulton, 1936: 173
simplex Hood, 1927: 128

Drepanothrips Uzel, 1895: 213
*reuteri Uzel, 1895: 213

Echinothrips Moulton, 1911: 37
americanus Morgan, 1913: 14

Ewartithrips Nakahara, 1996: 233
californicus Nakahara, 1996: 236
dispar Nakahara, 1996: 239
ehrhornii (Moulton), 1907: 52 [Euthrips]
flavidus Nakahara, 1996: 244
longirostrum (Jones), 1912: 10 [Euthrips]
salviae Nakahara, 1996: 248

Frankliniella Karny, 1910: 46
davidsoni Sakimura & O'Neill, 1979
deserticola Sakimura & O'Neill, 1979
ewarti Sakimura & O'Neill, 1979
fusca (Hinds), 1902: 154 [Euthrips]
fuscicauda Hood, 1927: 197
gossypiana Hood, 1936: 68
insignis Moulton, 1936: 170
insularis (Franklin), 1908: 715 [Euthrips]
minute (Moulton), 1907: 56 [Euthrips]
occidentalis (Pergande), 1895: 393 [Euthrips]
conspicuaua Moulton, 1935: 173)
tenuicornis (Uzel), 1895: 99 [Physopus]
tritici (Fitch), 1855: 385 [Euthrips]
tuttlei Sakimura & O'Neill, 1979: 30
williamsi Hood, 1915: 19
yuccae Moulton, 1936: 171

Kurtomathrips Moulton, 1927: 187
morrilli Moulton, 1927; 188

Limothrips Haliday, 1836: 444
*angulicornis Jablonowski, 1894: 45
*cerealium (Haliday), 1836: 445 [Thrips}

Microcephalothrips Bagnall, 1926: 113
*abdominalis (Crawford), 1910: 157 [Thrips]

Mycterothrips Trybom, 1910: 158
albus (Moulton), 1911: 39 [Euthrips]
(=corni Moulton, 1927: 34 [Rhopalandrothrips])

(=albipennis Moulton, 1929: 129 [Taeniothrips])
aureus (Moulton), 1946: 59 [Taeniothrips]

Odontanaphothrips Moulton, 1926: 24
tricolor (Moulton), 1911: 17 [Anaphothrips]

Odontothrips Amyot & Serville, 1843: 642
lotii (Haliday), 1852: 1108 [Thrips]

Oxythrips Uzel, 1895: 133
*quercicola Bagnall, 1926: 282

Plesiothrips Hood, 1915: 129
perplexus (Beach), 1897: 217 [Sericothrips]

Proscirtothrips Karny, 1921: 237
zeae (Moulton), 1911: 28 [Anaphothrips]
(=longipennis Crawford, 1910: 150
[Anapho thrips])
Prosopoanaphothrips Moulton, 1926; 22
reticulatus (Moulton), 1907: 50 [Sericothrips]

Pseudanaphothrips Karny, 1921: 242
*achaetus (Bagnall), 1916: 398 [Pseudothrips]

Psilothrips Hood, 1927: 198
pardalotus Hood, 1927: 198
priesneri (Moulton), 1926: 123 [Anaphothrips]

Scirtothrips Shull, 1909: 222
aceri Moulton, 1926: 122
albus (Jones), 1912: 15 [Anaphothrips]
citri (Moulton), 1909: 119 [Euthrips]
ewarti Bailey, 1964: 341
inermiss Priesner, 1933: 186
*longipennis (Bagnall), 1909: 173 [Euthrips]
*perseae Nakahara, 1997: 189
solaris, Bailey, 1964: 344
tehachapi Bailey, 1964: 345

Scolothrips Hinds, 1902: 157
*longicornis Priesner, 1926: 239
pallidus (Beach), 1896: 226 [Thrips]
sexmaculatus (Pergande), 1890: 539 [Thrips]
Taeniothrips Amyot & Serville, 1843: 644
*inconsequens (Uzel), 1895: 117 [Physopus]
orionis Treherne, 1924: 86
Tenothrips Bhatti, 1967: 18
*frici (Uzel), 1895: 126 [Physopus]

Thrips Linnaeus, 1758: 457
albogilvus Nakahara, 1994: 28
australiss (Bagnall), 1915: 592 [Isoneurothrips]
brevipilosus Moulton, 1927: 194
graminae Moulton, 1936: 106
*hawaiiensis (Morgan), 1913: 3 [Euthrips]
helvolus Nakahara, 1994: 67
heraclei Moulton, 1926: 25
konoi Nakahara, 1994: 77
madronii Moulton, 1907: 57
magnus Moulton, 1911: 36
*nigropilosus Uzel, 1895: 198
paramadronii Nakahara, 1994: 97

Florida Entomologist 87(3)

pruni Nakahara, 1994: 105
sierrensis Gentile & Bailey, 1968: 45
*simplex (Morison), 1930: 12 [Physothrips]
*tabaci Lindeman, 1888: 61
*trehernei Priesner, 1927: 356
(=hukkineni Priesner, 1937: 108)
*uulgatissimus Haliday, 1836: 447
(=lemanis Treherne, 1924: 87)
Toxonothrips Moulton, 1927: 30
gramineae Moulton, 1927: 30
Trichromothrips Priesner, 1930: 9
*cyperaceae (Bianchi), 1945: 283 [Taeniothrips]
*xanthius (Williams), 1917: 59 [Physothrips]

Xerothrips Nakahara, 1996: 209
dissimilis Nakahara, 1996: 210

Phlaeothripidae

This is the only family recognized in the Tubu-
lifera and includes more than 3200 species world-
wide, primarily in the warmer parts of the world.
Two subfamilies are recognized, and both are well
represented in California.

Phlaeothripidae-Idolothripinae

The smaller of the two subfamilies includes at
least 700 species in about 80 genera, mainly in
tropical countries. All of these species feed by im-
bibing whole fungal spores, as is evident from
their gut contents. The larger species can be par-
ticularly common on dead leaves that remain
hanging on broken branches, but many smaller
species live on the ground in leaf duff.
Allothrips Hood, 1908: 372
aureus Stannard, 1955: 155
Bactrothrips Karny, 1912: 131
hesperus (Moulton), 1907: 65 [Megalothrips]
Bolothrips Priesner, 1926: 90
rachiphilus Cott, 1956: 181
Compsothrips Reuter, 1901; 214
hookeri (Hood), 1916: 64 [Oedaleothrips]
jacksoni (Hood), 1925: 137 [Oedaleothrips]
tristis (Cott), 1956: 186 [Oedaleothrips]
yosemitae (Moulton), 1929: 135 [Formicothrips]
Cryptothrips Uzel, 1895: 228
carbonarius Hood, 1908: 376
rectangularis Hood, 1908: 307
sordidatus Hood, 1927: 199
Megalothrips Uzel, 1895; 224
picticornis Hood, 1927: 204
Megathrips Targioni-Tozzetti, 1881: 124
timidus Cott, 1956: 177
Priesneriella Hood, 1927: 198
citricauda Hood, 1927: 199

Phlaeothripidae-Phlaeothripinae

Worldwide, more than 2500 species in 350 gen-
era are placed in this subfamily, although 50% of
these genera remain monotypic. Probably about
half of the species are fungus-feeding on dead
wood or in leaf duff. However, species of a few gen-
era live in flowers, and a large number of tropical
species are leaf-feeding, some inducing galls.

Acanthothrips Uzel, 1895: 259
albivittatus Hood, 1908: 374
argentifer (Cott), 1956: 141 [Notothrips]
nodicornis (Reuter), 1880: 16 [Phloeothrips]

Adraneothrips Hood, 1925: 54
ephippium Stannard, 1956: 24
faustus Stannard, 1956: 21
saturatus Cott, 1956: 82
vacuus Stannard, 1956: 23

Amynothrips O'Neill, 1968: 175
*andersoni O'Neill, 1968: 179

Bagnalliella Karny, 1920: 41
desertae Hood, 1927: 201
mojave Hood, 1927: 200
yuccae (Hinds), 1902: 194 [Cephalothrips]
Cephalothrips Uzel, 1895: 244
hesperus Hood, 1941: 197
*monilicornis (Reuter), 1880: 21 [Phloeothrips]

Goniothrips Hood, 1927: 202
denticornis Hood, 1927: 202
Gynaikothrips Zimmermann, 1900: 13
*ficorum Marchal, 1908: 252 [Phloeothrips]
Haplothrips Amyot & Serville, 1843: 640
halophilus Hood, 1915: 29
*leucanthemi (Schrank), 1781: 298 [Thrips]
(=niger Osborn, 1883: 154 [Phloeothrips])
malifloris Hood, 1916: 121
robustuss Bagnall, 1918: 209
ruber (Moulton), 1911: 42 [Trichothrips]
*uerbasci (Osborn), 1897: 228 [Phloeothrips]

Hoplandrothrips Hood, 1912: 145
armiger (Jones), 1912: 23 [Phloeothrips]
costano Hood, 1942: 567
lissonotus Hood, 1942: 561
salicacearum Hood, 1942: 564
Hoplothrips Amyot & Serville, 1843: 640
bailey Cott, 1956: 40
Karnyothrips Watson, 1923: 23
flavipes (Jones), 1912: 18 [Anthothrips]
longiceps (Hood), 1908: 364 Z .*.. '!.1..
Leptothrips Hood, 1909: 249
distalis (Hood), 1925: 103 [Haplothrips]
fasciculatus (Crawford), 1909: 105 [Phyllothrips]
heliomanes Hood, 1927: 202
larreae Hood, 1939: 207

September 2004

Hoddle et al.: Checklist of California Thrips

mali (Fitch), 1855: 807 [Phloeothrips]
oribates Hood, 1939: 205
purpuratus (Hood), 1925: 101 [Haplothrips]

Liothrips Uzel, 1895: 261 (=Rhynchothrips)
breuitubus Kono, 1964: 4
corni Moulton, 1926: 124
cunctans (Cott), 1956: 68 [Rhynchothrips]
dumosa (Moulton), 1907: 3 [Trichothrips]
eremicus Cott, 1956: 60
gaviotae (Moulton), 1929: 132 [Haplothrips]
ilex (Moulton), 1907: 62 [Trichothrips]
invisus (Cott), 1956: 65 [Rhynchothrips]
lepidus Cott, 1956: 62
monoensis Kono, 1964: 6
*vaneeckei Priesner, 1920: 211
varicornis Hood, 1912: 74
xanthocerus Hood, 1927: 203

Macrophthalmothrips Karny, 1922: 34
*argus (Karny), 1920: 38 [Ophthalmothrips]

Neurothrips Hood, 1924: 315
apache Hood, 1957: 58
magnafemoralis (Hinds), 1902: 199 [Acantho-
thrips]

Phlaeothrips Haliday, 1836: 442
karnyi Hood, 1914: 20 [Trichothrips]
coriaceuss Haliday, 1836: 442

Plectrothrips Hood, 1908: 370
crocatus Cott, 1956: 80

Poecilothrips Uzel, 1895: 264
albopictuss Uzel, 1895: 264
dens (Moulton), 1907: 60 [Trichothrips]

Scopaeothrips Hood, 1912: 70 (=Rhopalothrips)
bicolor (Hood), 1912: 72 [Rhopalothrips]

Stephanothrips Trybom, 1912: 42
bradleyi Hood, 1927: 204

Stictothrips Hood, 1925: 295
maculatus (Hood), 1909: 250 [Phloeothrips]

Trachythrips Hood, 1930: 317
astutus Cott, 1956: 196

ACKNOWLEDGMENTS

We thank Cheryl Barr, Essig Museum, University of
California at Berkeley, for access to the Cott Collection.
Ray Gill, California Department of Food and Agricul-
ture, Sacramento California, allowed unlimited access
to the Kono collection. The California Avocado Commis-
sion and Avocado Brainstorming Committee provided
some financial assistance for this project.

REFERENCES CITED

ARNAUD, P. H., AND V. F. LEE. 1973. Types of Thysan-
optera in the collection of the California Academy of
Sciences. Occasional Papers of the California Acad-
emy of Sciences 105: 1-138.
BAILEY, S. F. 1957. The Thrips of California. Part I: Sub-
order Terebrantia. Bulletin of the California Insect
Survey 4 (5): 143-220.
COTT, H. E. 1956. Systematics of the Suborder Tubu-
lifera (Thysanoptera) in California. University of
California Publications in Entomology 13: 1-216.
GENTILE, A. G., AND S. F. BAILEY. 1968.A Revision of the
Genus Thrips Linnaeus in the World with a Catalogue
of the World Species (Thysanoptera: Thripidae). Uni-
versity of California, Berkeley, Publications in Ento-
mology 51: 1-95.
KONO, T., AND C. S. PAPP. 1977. Handbook of Agricul-
tural Pests. Aphids, Thrips, Mites, Snails and Slugs.
California Department of Food and Agriculture, Di-
vision of Plant Industry, Laboratory Services-Ento-
mology. 205 pp.
MOULTON, D. 1907. A contribution to our knowledge of
the Thysanoptera of California, Technical series,
USDA Bureau of Entomology 12/III: 39-68.
UZEL, H. 1895. Monographie der Ordnung Thysanop-
tera. 472 pp. Konigratz.

Florida Entomologist 87(3)

September 2004

MORTALITY OF ANT (HYMENOPTERA: FORMICIDAE)
PEST SPECIES EXPOSED TO SODIUM HYDROGEN CARBONATE

MARK A. BRINKMAN AND WAYNE A. GARDNER
Department of Entomology, University of Georgia, College of Agricultural and Environmental Sciences
Griffin Campus, 1109 Experiment Street, Griffin, GA 30223-1797 USA

ABSTRACT

Laboratory bioassays enabled us to determine the mortality of Argentine ant (Linepithema
humile [Mayr]) workers, and red imported fire ant (Solenopsis invicta Buren) workers ex-
posed to sodium hydrogen carbonate (NaHCO3, sodium bicarbonate). The median lethal con-
centration (LC,,) of NaHCO, for Argentine ants was 5.64 mg per cm2 after 5 d exposure and
3.96 mg per cm2 after 6 d. Cumulative mortality for Argentine ants exposed to 28 mg
NaHCO, per cm2 was 89.5% on day 6. Workers of both species were exposed to concentrations
of 9.92, 17.70, or 152.00 mg NaHCO, per cm2 in separate tests. Mortality of Argentine ants
was significantly higher than that of fire ants following exposure to 9.92 mg NaHCO, per
cm2, while mortality for the two species did not differ following exposure to the two higher
concentrations. Mortality of both species treated with the highest concentration exceeded
99% at 6 d. In tests with equivalent amounts of sodium in NaHCO, and NaC1 treatments,
mortality for fire ants exposed to NaHCO, was about 46% after 6 d. Mortality for fire ants
exposed to NaC1 was about 15% and was similar to that for untreated ants. Argentine ants
were provided sugar water baits containing a range of NaHCO, concentrations. Argentine
ant mortality after 6 d exposure to 5% NaHCO,-sugar water treatment was about 50%. Mor-
tality was not higher for workers exposed to higher concentrations of NaHCO, in sugar wa-
ter baits. Enzymatic dysfunction caused by unfavorable increases in internal pH is the most
likely explanation for worker mortality following exposure to NaHCO,.
Key Words: Sodium bicarbonate, bicarbonate of soda, Argentine ant, red imported fire ant,
pest ant, laboratory bioassays, Gut pH.

RESUME

Los bioensayos del laboratorio nos permiten determinar la mortalidad de las trabajadoras de
la hormiga Argentina (Linepithema humile [Mayr]), y la hormiga de fuego roja importada,
(Solenopsis invicta Buren) expuestas al hidr6xido carbonate del sodio (NaHCO, hidrogeno-
carbonato del sodio). La concentraci6n media letal (LC5s) del NaHCO, para la hormiga Ar-
gentina fue 5.64 mg por cm2 despu6s de exponerlas por 5 dias y fue 3.96 mg por cm2 despu6s
de 6 dias. La mortalidad acumulativa de las hormigas Argentinas expuestas a 28 mg de Na-
HCO, por cm2 fue 89.5% en el dia 6. Las trabajadoras de ambas species fueron expuestas a
concentraciones de 9.92, 17.70, o 152.00 mg de NaHCO, por cm2 en pruebas separadas. La
mortalidad de las hormigas Argentinas fue significativamente mas alta que la mortalidad de
las hormigas de fuego roja importada despu6s de exponerlas al 9.92 mg de NaHCO, por cm2,
mientras que la mortalidad de las dos species no fue diferente despu6s de exponerlas a las
dos concentraciones mas altas. La mortalidad de ambas species tratadas con la mas alta
concentraci6n alcanzo el 99% al dia 6. En pruebas con cantidades equivalentes de sodio en
los tratamientos de NaHCO, y NaCl, la mortalidad de las hormigas de fuego roja importadas
expuestas al NaC1 fue aproximadamente 15% y fue similar a la mortalidad en las hormigas
no tratadas. Las hormigas Argentinas fueron proveidas con cebos de agua azucarada que te-
nian varias concentraciones de NaHCO,. La mortalidad de la hormiga Argentina despu6s de
exponerlas por 6 dias al tratamiento del agua azucarada con 5% de NaHCO, fue aproxima-
damente 50%. La mortalidad no fue mas alta para las trabajadoras expuestas al concentra-
ciones mas altas de NaHCO, en cebos de agua azucarada. La disfunci6n enzimatica causada
por aumentos no favorables en el pH es la explicaci6n mas probable para la mortalidad de
las trabajadoras despu6s de exponerlas al NaHCO,.

The Argentine ant, Linepithema humile dangerous pests because of their aggressive be-
(Mayr), and red imported fire ant, Solenopsis in- havior and sting. In surveys of South Carolina
victa Buren, are indigenous to South America. residents conducted by Lemke & Kissam (1989),
Both have become important pests in urban and 87% of respondents felt that they had a severe fire
agricultural areas in the southern United States ant problem on their property, and 89% reported
(Callcott & Collins 1996; Suarez et al. 1999). Fire having one or more members of their immediate
ants infest lawns and are nuisances as well as family stung by fire ants. Although Argentine

Brinkman & Gardner: Argentine Ant and Fire Ant Mortality

ants do not sting humans and livestock, they are
considered a nuisance pest because they invade
homes in search of food and nesting sites. Argen-
tine ants are opportunistic feeders and will forage
in garbage receptacles and pet food dishes (Rust
et al. 2003).
Ant control in urban environments usually is
accomplished with chemical insecticides (Pereira
& Stimac 1997). Argentine ant control strategies
have focused on the use of baits and the applica-
tion of contact and barrier sprays and granules
(Rust et al. 2003); however, most toxic or repellent
barriers fail to provide long-term control, and
commercial baits are not always accepted by for-
aging Argentine ants (Rust et al. 2003). Retreat-
ments are often necessary, adding to the expense
of ant control. Many homeowners find extensive
use of insecticides in and around the home unde-
sirable. Therefore, additional control methods
with low toxicity are needed for urban pest ant
management (Klotz et al. 1997a).
Brinkman et al. (2004) previously determined
that S. invicta workers were susceptible to so-
dium hydrogen carbonate (NaHCO3, also known
as sodium bicarbonate) placed on surfaces and in
liquid baits. Workers were not repelled by concen-
trations of NaHCO3, and mortality was over 78%
in treated arenas with liquid bait. They further
reported that the median lethal concentration
(LCs,) decreased from 9.66 mg per cm2 on day 5 to
8.16 mg per cm2 on day 6. Vinson (1970) tested the
preferences of fire ants (S. richteri Forel) for vari-
ous electrolytes (including NaHCO,) in solution,
but did not report on potential mortality following
ingestion of those electrolytes. If effective against
S. invicta and Argentine ants, NaHCO, could
prove to be a safe alternative to conventional in-
secticides. The objective of this research, there-
fore, was to compare the mortality of Argentine
ants and red imported fire ants after exposure to
NaHCO3in simultaneous laboratory tests.

MATERIALS AND METHODS

Fire ant workers used in this study were ob-
tained from monogyne field populations in Grif-
fin, GA (Spalding Co.), and were removed from
soil by procedures described by Jouvenaz et al.
(1977). Argentine ants were collected from nests
in logs and leaf litter on the Georgia Experiment
Station campus. Although these ants were col-
lected from different areas on the campus, they
likely belonged to the same unicolony (Giraud
2002). These laboratory colonies were maintained
in plastic trays containing artificial nests con-
structed of plastic Petri dishes (150 x 10 mm) with
dental plaster on the bottom to maintain mois-
ture (Stimac et al. 1993). Fluon (Northern Prod-
ucts Inc., Woonsocket, RI) was applied to the
inside walls of trays to prevent ant escape. Ants
were fed 10% sugar water (v/v) and tuna in oil.

The LC5s of NaHCO, against Argentine ants
was established in laboratory bioassays. Test are-
nas were clear 35-ml plastic cups. Each cup had a
5-mm diam hole in the bottom and contained den-
tal plaster to about 10% of total cup volume. Lids
for the cups were plastic and had a 1.2-cm diam
hole to allow for air exchange. Fluon was applied
to the inside walls of cups and undersides of lids.
Ten cups were randomly assigned to each of the
treatments.
Treatment concentrations were 0, 0.85, 1.7, 3.5,
7.0, 14.0, and 28.0 mg NaHCO, per cm2. The
NaHCO, was deposited as powder on the surface of
dental plaster in the appropriate cups. Cups were
lightly tapped to evenly distribute the material on
the surface. Ten Argentine ant workers were
placed in each container with a small quantity of
sugar water for food. Cups were placed on a wet
foam pad to maintain moisture within cups over
the duration of the tests. Initially, the NaHCO3
treatments were dry, but as water was drawn up
through the dental plaster, they became slightly
moistened. Mortality was checked daily for 6 d;
dead workers were removed each day. Treatments
were replicated 10 times in a randomized complete
block design (RCBD). These tests were conducted
four times between 03 October and 15 December
2003. Data were subjected to probit analysis (SAS
Institute 1985) to obtain estimates of lethal con-
centrations and associated parameters. Concen-
tration of NaHCO, was transformed by log (x + 1)
prior to regression analysis and graphing of ant
mortality data (SPSS Inc. 1998).
Potential differences in mortality of the two
ant pest species from NaHCO, exposure also were
determined in laboratory tests. Test arenas, ap-
plication of treatments, and maintenance of ants
and arenas were the same as previously de-
scribed. In this test, fire ants and Argentine ants
were exposed to 9.92 mg NaHCO, per cm2, a con-
centration that approximated the LC5o for fire ant
workers following 5 d of exposure (Brinkman et
al. 2004). Groups of 10 workers of each species
were placed in the appropriate arenas and main-
tained as previously described. Mortality was
checked daily for 7 d in the treatment and control
arenas. Dead ants were removed each day. Treat-
ments were replicated 5 to 10 times in a RCBD
with each arena being a replicate. These experi-
ments were repeated five times between 21 July
and 5 August 2003.
Two higher concentrations were tested in sep-
arate assays by methods previously described.
Both were compared to an untreated control. The
concentration of 17.7 mg NaHCO3 per cm2 was
evaluated three times between 18 December 2003
and 15 January 2004. The highest concentration
of 152.0 mg NaHCO, per cm2 was evaluated in five
experiments between 16 January and 27 January
2004. Data resulting from these experiments
were analyzed by the PROC MIXED procedure

Florida Entomologist 87(3)

with repeated measures in SAS (Littell et al.
1996); means were separated with LSD (P = 0.05).
A range of concentrations of NaHCO3 was
tested in sugar water baits on Argentine ants.
Test arenas and maintenance of ants and arenas
were the same as previously described. A stock so-
lution of sugar water was prepared by mixing
8.37 g (10 ml) of granulated sugar with 90 ml ster-
ile distilled water. Concentrations of 0, 1, 5, 7.5,
and 10% NaHCO--sugar water (v/v) were pre-
pared (Table 2). Treatments were pipetted into
0.65-ml microcentrifuge tube lids, and these were
individually placed on the dental plaster in cups.
Treatments were replicated 10 times in a RCBD.
Mortality was checked daily for 6 d. Dead ants
were removed from cups each day. These tests
were conducted three times between 20 February
and 8 March 2004. Data were analyzed by the
PROC MIXED procedure, and means were sepa-
rated with LSD (P = 0.05).
Tests were conducted with equivalent amounts
of sodium in the form of NaHCO, and sodium
chloride (NaC1) to determine whether or not fire
ant mortality would be similar for the two com-
pounds. The total amount of either NaHCO, or
NaCl placed in each test arena was 84.0 mg
(11.898 mg per cm2) of NaHCO, and 58.0 mg
(8.215 mg per cm2) of NaC1. Formula weight of
NaHCO, is 84.00687 and is 58.44277 for NaCl
(Whitten & Gailey 1981). Untreated arenas (con-
trol) were also included in these tests. Test are-
nas, treatment application, and maintenance of
ants were the same as previously described.
Treatments were replicated 10 times in a RCBD.
Mortality was checked daily for 6 d, and dead ants
were removed from cups each day. These experi-
ments were repeated five times between 30 Octo-
ber 2003 and 18 January 2004 using fire ants
from four different colonies. Data were analyzed
by the PROC MIXED procedure with repeated
measures in SAS (Littell et al. 1996), and means
were separated with LSD.

RESULTS AND DISCUSSION

A positive linear relationship (R2 = 0.3665; F1,278
= 160.81; P < 0.0001) occurred between NaHCO,
concentration on surfaces and Argentine ant mor-
tality (Fig. 1). Probit analysis of the concentra-
tion-mortality response of workers after 5 d

y = 17.91 + 44.38x
R2 = 0.3665
P < 0.0001

50 -

0.00 0.27 0.43 0.65 0.90 1.18 1.46
mg NaHCO3 per cm2 (Log x + 1)

Fig. 1. Linear regression for NaHCO, concentration
effects on Argentine ant mortality in test cups (Day 6).
Vertical lines represent SEM. Treatments were an un-
treated control, 0.85, 1.70, 3.50, 7.00, 14.00, and 28.00
mg NaHCO, per cm2. Concentration of NaHCO, was
transformed by log (x + 1) prior to regression analysis
and graphing of ant mortality data.

exposure to NaHCO3 yielded a LCs0 of 5.64 mg per
cm2 and 3.96 mg NaHCO, per cm2 after 6 d (Table
1). This LC50 is lower than that obtained for red
imported fire ants on day 5, as reported by Brink-
man et al. (2004). Argentine ant LC50 followed a
similar trend as that observed with fire ants by
decreasing over time. Furthermore, fire ant mor-
tality following exposure to 28 mg NaHCO, per
cm2 for 6 days was 66.0% (Brinkman et al. 2004),
while Argentine ant mortality following 6 days of
exposure to 28 mg NaHCO, per cm2 was 89.5%.
These results suggest that less NaHCO, is re-
quired to kill Argentine ant workers than fire ant
workers.
Cumulative mortality for Argentine ants ex-
posed to 9.92 mg NaHCO, per cm2 was (F = 9.85;
df = 3,6; P = 0.0001) higher than mortality of fire
ants exposed to the same concentration over the 7
d of exposure. On day seven, cumulative mortal-
ity among Argentine ants exposed to NaHCO,
was 38.0% (5.5) and was 35.6% (4.9) for fire
ants exposed to NaHCO, (Fig. 2A).

TABLE 1. CONCENTRATION-MORTALITY OF WORKER ARGENTINE ANTS AFTER EXPOSURE TO NAHCO, FOR 5 TO 6 D (N
= 400 IN EACH TREATMENT).

mg per cm2

Day LC5, (95% CL) LC,, (95% CL) Slope SE y2 P > 2

5 5.64 (2.74-13.10) 210.0 (50.0-26930.0) 1.05 0.21 24.6 0.0001
6 3.96 (1.84-7.60) 150.0 (40.0-7700.0) 1.04 0.20 28.2 0.0001

September 2004

Brinkman & Gardner: Argentine Ant and Fire Ant Mortality

Untreated Fire Ants
NaHC3 Fire Ants
Untreated Argentine Ant!
NaHCO3 Argentine Ants

so

ioo

20

40

20

1 2 3 4 5 6 7
Days of Exposure

Fig. 2. Mortality of fire ants and Argentine ants ex-
posed to a concentration of(A) 9.92, (B) 17.7, (C) 152.0 mg
NaHCO, per cm2 on dental plaster in test cups. Untreated
workers of both species also were kept as controls.

Mortality of Argentine ants and fire ants ex-
posed to 17.7 mg NaHCO, per cm2 was (F = 24.20;
df = 3,6; P = 0.0001) higher than mortality for
their respective untreated controls over the 7 d of
the test (Fig 2B). Argentine ant mortality did not
differ (P > 0.05) from fire ant mortality following
exposure to 17.7 mg NaHCO, per cm2. Cumula-
tive mortality at day 7 for Argentine ants was
59.3% (6.9) and 58.7% (7.1) for fire ants. This
concentration was the predicted LC7, for Argen-

tine ants after 6 d of exposure to NaHCO3, but
mortality for workers of both species was lower
than 75%. The reason for the lower mortality is
not known, but it was consistent for both ant spe-
cies at this concentration.
Mortality for Argentine ants and fire ants ex-
posed to 152.0 mg NaHCO3 per cm2 was (F =
592.02; df = 3,5; P = 0.0001) higher than mortality
for their respective untreated controls over the 6 d
of the test. Following correction for control mortal-
ity (Abbott 1925), Argentine ant mortality was
99.09% and fire ant mortality was 99.47% after 6
days of continuous exposure to 152.0 mg NaHCO,
per cm2 (Fig. 2C, non-corrected mortality). This
concentration was the predicted LC95 for Argentine
ants following 6 d exposure to NaHCO,. However,
mortality for both species was higher than 95% in
less than 6 d. In fact, almost all workers of both
species were killed by this concentration after only
4 d of exposure. These results suggest that, at
lower concentrations, there may be small differ-
ences in mortality of workers of these two species;
however, as concentration of NaHCO3 is increased,
the mortality of the two species is similar.
Cumulative mortality for fire ants provided
untreated sugar water was (F = 14.46; df = 4,5; P
= 0.0001) lower than for the three highest concen-
trations of NaHCO, in sugar water at 6 d. The
highest corrected mortality was 49.56% in the
5.0% NaHCO,-sugar water treatment (Table 2,
non-corrected mortality). However, this was not
(P > 0.05) different from ant mortality for the
7.5% NaHCO,-sugar water treatment. Corrected
Argentine ant mortality in the highest concentra-
tion of NaHCO, in sugar water was 29.20% after
6 d. A range of concentrations of NaHCO, mixed
in sugar water was tested, yet the greatest mor-
tality was observed in the 5% NaHCO,-sugar
water treatments. A concentration-dependent re-
lationship did not occur beyond this level. A simi-
lar trend was observed with fire ants provided
sugar water treatments containing NaHCO,
(Brinkman et al. 2004). Brinkman et al. (2004)
concluded that excess NaHCO, had settled out of
solution in the higher concentrations and was not
available for ant consumption. In this study, some
precipitate was observed in the bottoms of lids

TABLE 2. CUMULATIVE MORTALITY FOR ARGENTINE ANTS (N = 100 PER TREATMENT PER TEST) PROVIDED SUGAR WATER
AND NAHCO,.

Food Treatment Mean # Dead (day 6)

Untreated sugar water 24.67 3.31a
0.113 g NaHCO, in 9.9 ml sugar water (1%) 30.33 3.47a
0.563 g NaHCO, in 9.5 ml sugar water (5%) 62.00 4.11c
0.844 g NaHCO, in 9.25 ml sugar water (7.5%) 55.67 4.86c
1.125 g NaHCO, in 9.00 ml sugar water (10%) 46.67 4.53b

Means (+ SEM) followed by same letter are not different (LSD, P > 0.05).

Florida Entomologist 87(3)

containing 10% NaHCO,-sugar water treatment,
yet mortality for Argentine ants exposed to this
concentration was significantly higher than mor-
tality for Argentine ants provided untreated
sugar water. Therefore, we concluded that work-
ers were not repelled by the higher concentra-
tions of NaHCO, in sugar water. Vinson (1970)
found that fire ants workers preferred NaHCO, in
solution over NaCl in solution. Preferential re-
sponse to sodium was variable in comparison
with other cations (Vinson 1970). Brinkman et al.
(2004) conducted tests in arenas in which fire
ants could feed on sugar water or sugar water
containing NaHCO,. In those tests, fire ant mor-
tality was much higher in arenas with both sugar
water and sugar water containing NaHCO3, than
it was in arenas with sugar water only. Brinkman
et al. (2004) concluded that fire ants were not re-
pelled by NaHCO, in food.
Fire ant mortality following exposure to NaCl
was (F = 22.76; df = 2,5; P = 0.0001) lower than
mortality occurring among those workers exposed
to NaHCO, (Fig. 3). Worker mortality in response
to NaCl was 15.4% at 6 d and did not differ (P >
0.05) from mortality of untreated ants. Fire ant
mortality following 6 d exposure to NaHCO, was
46.2%. Brinkman et al. (2004) found that whole-
body pH of fire ant workers exposed to NaHCO,
increased with increasing concentration of
NaHCO,. They theorized that fire ants ingested
NaHCO, while cleaning appendages and that the
resultant changes in internal pH were unfavor-
able to normal enzymatic functions. According to
Tortora & Grabowski (1996), sodium hydrogen

0o

1 2 3 4 5 6
Days of Exposure
Fig. 3. Mortality of fire ants exposed to NaHCO, and
NaCl treatments. Untreated workers of both species
also were kept as controls. NaHCO, and NaC1 treat-
ments that were placed in respective arenas contained
equal amounts of sodium.

carbonate contributes hydroxide ions (OH ) to so-
lutions causing increases in pH. However, Bigner
et al. (1997) attributed the alkalinizing action of
NaHCO3 to Na' and they based this on the strong
ion difference theory. In the theory of strong ion
difference in acid-base physiology (Stewart 1983),
addition of non-metabolizable, positively charged
cations to a body fluid compartment raises the pH
of that compartment. Bigner et al. (1997) tested
three Na compounds to determine which was best
for treating metabolic acidosis in dairy cattle.
Blood pH and blood HCO3 increased in the
NaHCO, treatment, and was much higher than
that observed for NaC1. They assumed, based on
the theory, that the NaCl treatment did not alter
blood pH because both the positively charged cat-
ion Na' and the negatively charged anion Cl
were absorbed equally well and added no net
charge to the blood fluid compartment. This sug-
gests that Na' may have played a role in killing
fire ants by raising pH, but only when delivered
in the form of NaHCO,, and not as NaC1. Accord-
ing to Audesirk et al. (2002), salts dissociate into
ions in solution, and may then form bonds with
enzymes and interfere with the enzymes' normal
three-dimensional structure. Also, changes in pH
may modify the structure of enzymes and
strongly alkaline solutions can denature enzymes
(Conn & Stumpf 1976).
Hertel (1997) tested NaCl and KC1 as pro-
tectants for pinewood against attack of a long-
horn beetle species [Hylotrupes bajulus (L.)].
Both compounds were effective, but NaCl pro-
vided better protection than KC1. Dehydration of
beetle larvae after feeding on salt treated wood
was offered as a possible explanation for mortal-
ity. In our study, the role of dehydration in deaths
of fire ants exposed to NaCl and NaHCO, on sur-
faces was minimal because workers had unre-
stricted access to untreated sugar water.
Optimal procedures for use of NaHCO3 as an
ant control treatment in the home have yet to be
determined. According to Klotz et al. (1997a),
dusts are an excellent formulation for insecticides
because ants readily pick up dusts that are ap-
plied to their trails. This may be an acceptable ap-
plication strategy for NaHCO3 in that Brinkman
et al. (2004) determined that fire ants were not re-
pelled by NaHCO, and would readily forage over
treated areas. Crust will develop on NaHCO,
powder if it is exposed to moisture and then dries.
Therefore, retreatment may be necessary on un-
protected ant trails. Klotz et al. (1997a) suggest
that dusts could be applied during home construc-
tion when there is easy access to wall voids.
Knight & Rust (1990) reported that repellency of-
ten determines how much contact an insect will
have with a toxicant and that very low repellency
treatments may produce high kill, even with only
intermediate toxicity, because of increased con-
tact with the treatment.

* Untreated
A NaHC03
* NaC1

September 2004

Brinkman & Gardner: Argentine Ant and Fire Ant Mortality

Sugar water has been used as a bait carrier for
boric acid against fire ants (Klotz et al. 1997b) and
Argentine ants (Klotz et al. 2002). Sucrose solu-
tions are attractive to Argentine ants and are a
means of transporting toxicants into the colony
(Hooper-Bui & Rust 2000). Sodium hydrogen car-
bonate is inexpensive, easy to handle, and gener-
ally recognized as safe (GRAS) for use in foods
(Montville & Goldstein 1987). Thus, sugar water
baits containing NaHCO, could be used safely in
the homes with children or pets. Toxicants that are
effective in baits exhibit delayed action, are readily
transferred between ants and kill the recipient,
and are not repellent (Stringer et al. 1964). Per-
haps an ant trail treatment with NaHCO, powder,
sucrose baits containing NaHCO,, or a combina-
tion of both, may provide safe methods of Argen-
tine ant control in and around homes.

ACKNOWLEDGMENT

We thank G. David Buntin and Jerry Davis for assis-
tance with statistical analysis of data.

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Florida Entomologist 87(3)

September 2004

ASIAN CITRUS PSYLLIDS (STERNORRHYNCHA: PSYLLIDAE)
AND GREENING DISEASE OF CITRUS: A LITERATURE REVIEW
AND ASSESSMENT OF RISK IN FLORIDA

SUSAN E. HALBERT1 AND KEREMANE L. MANJUNATH2
'Division of Plant Industry, Florida Department of Agriculture and Consumer Services
P.O. Box 147100, Gainesville, FL 32614-7100

2University of Florida Department of Plant Pathology, Gainesville, FL 32611

ABSTRACT

The Asian citrus psyllid, Diaphorina citri Kuwayama, was discovered in Florida in 1998. It
can be one of the most serious pests of citrus if the pathogens that cause citrus greening dis-
ease (huanglongbing) are present. Citrus greening recently has been reported in Brazil by
Fundecitrus, Brazil. The establishment of D. citri in Florida increases the possibility that
the disease may become established. Diaphorina citri can be separated from about 13 other
species of psyllids reported on citrus. The biology of D. citri makes it ideally suited to the
Florida climate. Only two species, D. citri and Trioza erytreae (del Guercio), have been impli-
cated in spread of citrus greening, a disease caused by highly fastidious phloem-inhabiting
bacteria. The disease is characterized by blotchy mottle on the leaves, and misshapen, poorly
colored off-tasting fruit. In areas where the disease is endemic, citrus trees may live for only
5-8 years and never bear usable fruit. The disease occurs throughout much of Asia and Africa
south of the Sahara Desert, on several small islands in the Indian Ocean, and in the Saudi
Arabian Peninsula. Transmission of citrus greening occurs primarily via infective citrus
psyllids and grafting. It is transmissible experimentally through dodder and might be trans-
mitted by seed from infected plants and transovarially in psyllid vectors. Citrus greening
disease is restricted to Citrus and close citrus relatives because of the narrow host range of
the psyllid vectors. Management of citrus greening disease is difficult and requires an inte-
grated approach including use of clean stock, elimination of inoculum via voluntary and reg-
ulatory means, use of pesticides to control psyllid vectors in the citrus crop, and biological
control of psyllid vectors in non-crop reservoirs. There is no place in the world where citrus
greening disease occurs that it is under completely successful management. Eradication of
citrus greening disease may be possible if it is detected early. Research is needed on rapid
and robust diagnosis, disease epidemiology, and psyllid vector control.

Key Words: Diaphorina citri Kuwayama, Asian citrus psyllid, citrus greening disease, huang-
longbing, citrus psyllids, Citrus.

RESUME

El psilido Asidtico de citricos, Diaphorina citri Kuwayama, fue descubierto en Florida en
1998. Esta puede ser una de las plagas de citricos mas series si los pat6genos que causan la
enfermedad "greening" de los citricos (huanglongbing) estan presents. Recientemente, la
entermedad "greening" de los citricos ha sido reportada en Brasil por fundecitrus (Brasil). El
establecimiento de D. citri en Florida aumenta la posibilidad que la enfermedad pueda esta-
blecerse. Diaphorina citri puede ser separado de aproximadamente 13 otras species de
psilidos reportadas en citricos. La biologia de D. citri lo hace idealmente adaptable al clima
de Florida. Solamente dos species, D. citri y Trioza erytreae (del Guercio), han sido implica-
das en la dispersion del "greening" de citricos, una enfermedad causada por una bacteria al-
tamente fastidiosa que habitat el floema. La enfermedad se caracteriza por causar areas
moteadas en las hojas, y frutas mal formadas, mal coloradas y con sabor normal. En areas
donde la enfermedad es end6mica, los arboles de citricos pueden vivir por solamente 5-8 anos
y nunca dar fruta provechosa. La enfermedad ocurre en la mayor parte de Asia, en Africa al
sur del Desierto Sahara, en varias islas pequenas del Oc6ano Indico, y en la Peninsula de
Saudi Arabia. La transmisi6n de "greening" de citricos ocurre principalmente por medio de
psilidos infectados y por injertar las plants. Puede ser transmisible experimentalmente a
trav6z de cuscuta, posiblemente transmitida por la semilla de plants infectadas y transo-
variolmente en los vectores psilidos. La enfermedad de "greening" de citricos es restringida
al Citrus y sus relatives cercanos debido al rango estrecho de hospederos de los vectores psi-
lidos. El manejo de la enfermedad de "greening" de citricos es dificil y require una estrate-
gia integrada incluyendo el uso de plants no contaminadas, la eliminaci6n de in6culo por
medios voluntarios y regulatorios, el uso de pesticides para controlar los vectores psilidos en
los huertos de citricos, y el control biol6gico de los vectores psilidos en dep6sitos de plants

Halbert & Manjunath: Diaphorina citri and Citrus Greening Disease

que no son cultivos. No hay ningun lugar en el mundo donde ocurre la enfermedad de "gree-
ning" de citricos que est6 completemente bajo un manejo exitoso. La erradicaci6n de la en-
fermedad de "greening" de citricos puede ser possible si la enfermedad esta detectada
tempranamente. Se necesita investigaci6n sobre un diagn6stico rdpido y robusto, la epide-
miologia de la enfermedad, y el control del vector psilido.

Asian citrus psyllid (Diaphorina citri Kuwa-
yama, Sternorrhyncha: Psyllidae) may be the
most serious pest of citrus in the world if any of
the pathogens that cause citrus greening also are
present. If none of the pathogens are present, the
psyllids usually are minor pests. Citrus greening
was reported in Brazil in July 2004 by Funde-
citrus. This is the first report of the disease in the
Western Hemisphere (Anon. 2004).
The Asian citrus psyllid causes damage to the
crop primarily by transmission of the pathogen
that causes greening, or "huanglongbing" ( '. 1. .,
which means "yellow dragon disease" in Chinese.
Huanglongbing has been translated loosely as
yellow shoot disease in English language publica-
tions because of characteristic yellow shoots
caused by the disease. In addition to yellow
shoots, the disease also causes mottling, chlorosis
resembling zinc deficiency, twig dieback and re-
duced fruit size and quality. Fruit do not color
properly, leading to the name greening. Fruit from
diseased trees have a bitter taste. Other names
include citrus vein phloem degeneration, and
. i (likubin), which means immediate wither-
ing disease. Australian citrus dieback, a disease of
unknown etiology, is suspected to be caused by a
similar psyllid-transmitted pathogen (Broadbent
2000). Although the official name of the disease is
huanglongbing (anon. 1996), we use the name
"citrus greening disease" throughout this review
because it is the name commonly used in the
United States, and by our audience for this paper.
Citrus greening probably is the worst disease
of citrus caused by a vectored pathogen. The dy-
namics, epidemiology, and molecular characteris-
tics of the complex are poorly understood. Trioza
erytreae (del Guercio) (Sternorrhyncha: Triozi-
dae) in Africa and Diaphorina citri Kuwayama
(Sternorrhyncha: Psyllidae) in Asia are the only
known vectors of the two forms of the disease,
namely African and Asian citrus greening, respec-
tively. Two species of fastidious phloem-limited
bacteria (Candidatus Liberibacter africanus and
asiaticus), are thought to be the causal organ-
isms, but Koch's postulates have not been fulfilled
because the bacteria have not been cultured yet.
(The term Candidatus is used for bacteria species
that cannot be cultured. If Candidatus is used,
the actual genus and species are not italicized.)
The pathogens prevalently transmitted by the
two psyllids are different, but both psyllid species
will transmit either pathogen under experimen-
tal conditions (Lallemand et al. 1986). The patho-
gens at present are extremely difficult to detect

and characterize, although great strides have
been made in recent years with development of
detection methods based on polymerase chain re-
action (PCR) and DNA hybridization.
Excellent reviews of citrus greening disease
complex have been published (da Graca 1991;
Garnier & Bove 1993, 2000a; Mead 1977; Rois-
tacher 1991; Viraktamath & Bhumannavar
2002). We do not intend to duplicate these earlier
efforts. The recent introduction of D. citri into
Florida (Halbert 1998) has greatly increased the
threat of citrus greening disease for North Amer-
ican citrus. The intent of this paper is to provide a
convenient summary of information that is rele-
vant to risk assessment for the Florida citrus in-
dustry and possible eradication of citrus greening
disease. The emphasis will be on recognition of
citrus psyllids, host range information, detection,
epidemiology, and management.

BIOLOGY OF ASIAN CITRUS PSYLLID

Systematics and Recognition of Psyllids Reported
on Citrus

Diaphorina citri (=Euphalarus citri (Kuway-
ama 1908)) was described from citrus in
Shinchiku, Taiwan in 1907 and published in a
double volume in 1908. Species of Diaphorina
usually are separated based on the pattern of
maculation in the forewings and the shape of the
genal cones. Diaphorina citri has a distinct pat-
tern on the forewings and can be separated easily
from most of the other species reported on citrus
and its relatives.
There are six other obscure species of Diapho-
rina also reported from citrus and other closely
related plants: Diaphorina amoena Capener
1970b (reported on citrus by da Graca 1991),Dia-
phorina auberti Hollis 1987a (reported on citrus
in original description), Diaphorina communis
Mather 1975 (reported on citrus in original de-
scription) and Aubert (1987), Diaphorina murrayi
Kandasamy 1986 (reported on citrus in original
description), Diaphorina punctulata (Pettey
1924) (reported on citrus in original description),
and Diaphorina zebrana Capener 1970b (re-
ported on citrus by Catling & Atkinson 1974).
Diaphorina auberti was described (Hollis
1987a) from the Comoro Islands. The host is cit-
rus, on which nymphs concentrate on the upper
surfaces of young leaves near the midribs. This
causes the lateral margins of the leaves to curl
upwards and inwards, sometimes forming an en-

Florida Entomologist 87(3)

closed leaf-roll (Dr. B. Aubert, pers. comm., in Hol-
lis 1987a). Hollis (1987a) placed D. auberti in the
D. amoena species group. The wing patterns ofD.
auberti are very similar to those ofD. amoena (see
Fig. 10 and Fig. 11 (amoena) compared with Fig.
22 and Fig. 23 (auberti) in Hollis (1987a)); how-
ever, the genae of auberti are much shorter than
those of amoena (see Fig. 1 and Fig. 7 of Hollis
(1987a)). The host for D. amoena is 'r, .. ....... in-
nocua Delile (Loganiaceae (Strychnaceae)). It is
not reported from citrus or citrus relatives either
in Hollis (1987a) or in the original description
(Capener 1970b). Thus, reports of D. amoena on
citrus probably can be attributed to D. auberti or
possibly D. citri. Both D. amoena and D. auberti
can be separated from D. citri by the pattern on
the forewings.
Diaphorina communis was described from a
long series of specimens collected in Uttar
Pradesh, India (Mather 1975). It is reported to be
common on Murraya koenigii and occurs occa-
sionally on citrus. It is mentioned as a possible
species on citrus by Burckhardt (1994a). The
forewings ofD. communis are almost totally dark,
making it easily separable from D. citri.
Diaphorina murrayi was described by Kanda-
samy (1986) from 11 specimens taken on Murraya
exotica L. in Madras (now Chennai, Tamilnadu),
India. According to the original description, it is
closely related to D. citri but differs in having a
slightly different wing pattern and slightly differ-
ent tarsal spine formula. So far, it is reported only
from M. exotica. Further study is needed to deter-
mine whether it differs sufficiently from D. citri to
be considered a separate species.
Diaphorina punctulata (=Euphalarus punctu-
latus Pettey 1924) was described from a female
specimen collected in southern Africa. The host
was Sclerocarya caffra Sond. (Anacardiaceae)
Capener (1970a). The original description says
that the species also has been found on Chorda
[sic] caffra Sond. (Boraginaceae) and Clausena
inaequalis (DC.) Benth. (=anisata (Willd.) Hook,
S. ex Benth.) (Rutaceae). The description is very
brief (barely 13 lines long) and includes no figures
or designation of paratypes. Capener (1970a), ap-
parently with access to Pettey's notes, said that
the species was described from seven specimens -
1 male, 6 females. Seven specimens (evidently not
entirely from the type series because sexes do not
match, but determined by Pettey) still exist in the
National Collection of Insects, Pretoria. There is
some doubt as to whether all of this material is
the same species. Catling & Atkinson (1974) men-
tion that D. punctulata was found on citrus in
Swaziland (Mead 1977) but was a non-vector of
citrus greening. If the specimens reported from
Clausena (above) are in fact D. punctulata, it is
plausible that this species could infest citrus occa-
sionally. Pettey (1924) (original description), Cap-
ener (1970a), and Catling & Atkinson (1974) do

not include a thorough description or figure of
D. punctulata, so it is not possible to explain from
the descriptions how to separate it from D. citri.
Photos of identified specimens of D. punctulata,
including a paratype, kindly provided by Ian
Millar, ARC-Plant Protection Research Institute,
South African National Collection of Insects,
Queenswood, Pretoria, South Africa, and by Dr.
G. J. Begemann, Transvaal Sugar Ltd, Komati-
poort, South Africa, show thatD. punctulata looks
very similar to D. citri. The two species can be
separated by a difference in the maculation pat-
tern on the wings. Both species have a dark band
around the edge of the wings, with a clear area in
the middle containing irregular spots. The dark
outer band on D. citri has a definite break near
the terminus of the Rs vein. The band on
D. punctulata lacks that break. In addition to the
wing pattern, the wing shape is more angular in
D. punctulata, and the genal processes of
D. punctulata are more massive and irregularly
tapered than those of D. citri (Daniel H. Burck-
hardt, Naturhistorisches Museum, Basel, Swit-
zerland, pers. comm.).
Diaphorina zebrana was described from Ozo-
roa paniculosa (Sond.) R.& A. (Anacardiaceae).
Additional specimens that varied slightly in the
intensity of wing banding were collected from
Ozoroa reticulata (Bak. f.) R. & A. Rernandes. Di-
aphorina zebrana, like D. punctulata, was men-
tioned as a citrus infesting species and a non-
vector of greening in Swaziland (Mead 1977) by
Catling & Atkinson (1974). There is no mention of
infestations on citrus or related plants in the orig-
inal description. Diaphorina zebrana, as its name
suggests, has striped forewings and thus is
readily separable from D. citri.
In addition to the seven species of Diaphorina
reported on citrus, there are six other psyllid spe-
cies reported to occur on citrus: Mesohomotoma
lutheri (Enderlein 1918) (=Udamostigma lutheri
Enderlein), Psylla citricola Yang & Li 1984,
Psylla citrisuga Yang & Li 1984, Psylla murrayi
Mathur 1975, Trioza citroimpura Yang & Li 1984,
Trioza erytreae (del Guercio 1918) (= Aleurodes
erytreae del Guercio, = Trioza citri Laing, = Trioza
merwei Pettey, = Spanioza merwei (Pettey), =
Spanioza erythreae (del Guercio) (Hollis 1984)),
and Trioza litseae Bordage 1898 (=Trioza eastopi
Orian 1972).
Mesohomotoma lutheri was described from
Peradeniya, Ceylon (Sri Lanka) from collections
made in 1910 by Dr. Luther (Enderlein 1918). It
was re-described carefully by Mathur (1975). The
host was Urena lobata L. (Malvaceae), and it also
may infest Hibiscus (also Malvaceae). There is
some doubt about the synonymy for this species.
Hollis (1987b) said that there is confusion about
the validity of the species currently placed in Me-
sohomotoma because of variation in size and color
among collections of the same species. The varia-

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Halbert & Manjunath: Diaphorina citri and Citrus Greening Disease

tion does not correlate well with host plant and
distribution data. Hollis (1987b) suspects that
several of the species, including M. lutheri, may
in fact all be synonyms of Mesohomotoma hibisci
(Froggatt). Aubert & Quilici (1984) reported that
adults ofM. lutheri were seen on citrus leaves for
short feeding periods, but that this was extremely
rare, and no eggs were laid. They reported that
the preferred host of M. lutheri was Hibiscus.
Psylla citricola and P citrisuga were described
from Citrus grandis (L.) Osbeck (now Citrus max-
ima (Burm.) Merr.) and Citrus medical L. in Yun-
nan Province in China (Yang & Li 1984). The two
species are very similar and apparently occur to-
gether in mixed colonies on the hosts. Yang & Li
(1984) suggest that a report ofPsylla alni on citrus
in Sichuan Province may actually be P citrisuga.
There is a report by Cen et al. (1999) that P citri-
cola occurs in Guangzhou. Further study is needed
to determine whether these are distinct species.
Psylla murrayi normally feeds and reproduces
on leaves of Murraya koenigii (L.) Sprengel
(Mather 1975), but adults have been observed on
citrus in Malaysia (Lim et al. 1990). Based on il-
lustrations in the descriptions, the male genitalia
appear to be distinct from those of the two Chi-
nese Psylla spp.
Trioza citroimpura also was described from
Yunnan Province in China. The host was Citrus
reticulata Blanco. Both male and female genitalia
appear distinct from those of T erytreae, based on
figures given in the description.
Trioza erytreae is the well-known African cit-
rus psyllid. It was described as a whitefly, Aleu-
rodes erytreae del Guercio 1918; however, the
drawing of the nymph is clearly a psyllid, and the
photograph of the damage is that of T erytreae. It
is part of a species group that includes at least ten
species that are very difficult to separate morpho-
logically but have different host plant preferences
(Hollis 1984). Hosts of T erytreae are listed as
Clausena anisata (Willd.) Oliv. (=Clausena
inaequalis (DC.) Benth.), Citrus spp., Vepris un-
dulata (Thunb.) Verdoorn & C.A. Smith (=Todda-
lia lanceolata Lam.) and Fagara spp. There is
extensive literature about this serious pest, and
particularly about its relationship to African cit-
rus greening disease. Trioza erytreae can be found
throughout much of Africa south of the Sahara, in
Saudi Arabia and Yemen in the Saudi Peninsula,
in Mauritius and Reunion, and in Madeira
(Toorawa 1998). A key to African Trioza, along
with additional characters useful in separating
species in the T erytreae group can be found in
Hollis (1984). It is easily separated from D. citri
because it has clear forewings that are pointed at
the tips. Nymphs of T erytreae live in individual
depressions on the undersides of citrus leaves,
whereas nymphs of D. citri tend to colonize the
stems of new growth and never produce individ-
ual pits on the leaves.

Trioza litseae Bordage was described based on
its damage to vanilla and Litsea (Lauraceae) on
Reunion Island (Bordage 1898). There has been
some confusion about the synonymy with T east-
opi. Orian (1972) determined that T litseae was a
nomen dubium because the description was
sketchy; however, the International Code of Zoo-
logical Nomenclature (2000) (Articles 1.2.1,
12.2.8, 23.3.2.3, and 72.5.1) allows descriptions
based on the "works" (e.g., damage) of an animal if
the description was published prior to 1931.
Therefore, Bordage's (1898) description, which in-
cludes details of the economic damage to vanilla,
and also damage to Litsea, which he considers the
original host, qualifies, and T litseae Bordage is a
good species. Thus, T eastopi Orian 1972 becomes
a junior synonym of T litseae Bordage. There is
some further question as to whether this species
actually occurs on citrus. Hollis (1984) reported
that the usual host is Litsea glutinosa C.B. Robin-
son (=L. laurifolia Cordem) (Lauraceae), where
nymphs damage floral parts of the plant. Adults
can damage Vanilla planifolia Andrews (Orchi-
daceae). Aubert & Quilici (1984) reported both
adults and nymphs of T litseae (as T eastopi) on
leaves of citrus, avocado, papaw, and vanilla
leaves. Apparently, the favored host was Litsea
chinensis Jacq., a common weed. When popula-
tions on these weeds reached very high levels, the
insects began to infest young flush of other plants,
including citrus. Nymphs formed pits similar to
those of T erytreae. Trioza litseae can be separated
from T erytreae with the key in Hollis (1984).
Trioza is an extremely large and difficult artifi-
cial genus. There are no keys to world fauna. Thus,
host plant association is of utmost importance in
determining the species. The thorough re-descrip-
tion and key in Hollis (1984) would be useful for
diagnosis of T erytreae, along with Burckhardt
(1994b), which keys psyllid genera that occur in
Chile, along with various potential exotic pests in-
cluding T erytreae. The Trioza spp. can be sepa-
rated from D. citri because the radius, media and
cubitus veins in the forewings diverge at the same
point trifurcatee) in Trioza spp., whereas the me-
dia and cubitus share a common stem in D. citri.
Psylla loranthi Capener 1973 is not reported to
feed on citrus or citrus relatives, but it feeds on
Loranthus zeyheri Harv, a parasitic plant that
sometimes attacks citrus. There is a small possi-
bility that P loranthi might potentially transmit
citrus greening bacteria via the parasitic plant, so
the species is included in this list. However, we
note that no phloem connection may exist be-
tween the parasitic plant and its host (Salle
1983). It can be distinguished from other Psylla
species associated with citrus by the long slender
genitalia, especially of the female (Capener 1973),
and by the presence of immatures on its parasitic
host plant. Psylla loranthi would not be found
where its host does not occur.

Florida Entomologist 87(3)

Finally, Leuronota fagarae Burckhardt 1988,
the wild lime psyllid, showed up in Florida in July
2001. Its only known host is Zanthoxylum fagara
(L.) Sarg., a citrus relative. The psyllid is native to
South America. Damage consists of rolled leaf
edges that enclose the nymphs. We have surveyed
citrus growing near infested Z. fagara and have
not found any L. fagarae on citrus. Leuronota fa-
garae is very slender and has dark wings. It is not
likely to be confused with D. citri or any other cit-
rus psyllids.

Life Cycle

Mead (1977) has an excellent annotated sum-
mary of the life cycle of D. citri. Eggs are laid on
"feather flush" and hatch in 2-4 days (Chavan &
Summanwar 1993). There are five nymphal in-
stars (Aubert 1987), which are completed in 11-15
days (Chavan & Summanwar 1993). The total life
cycle takes 15-47 days, depending upon the tem-
perature. Adults may live several months and the
females lay as many as 800 eggs in a lifetime
(Mead 1977). Catling (1970) provided further in-
formation on life cycle and biology. Life table pa-
rameters at different temperatures have been
studied for Florida D. citri (Liu & Tsai 2000).
Time for completion of the life cycle was the same
as Mead (1977) reported. The optimum develop-
ment temperature range was found to be 25-28C.
Liu & Tsai (2000) found that the maximum aver-
age number (748.3) of eggs produced per female
occurred at 28C.

Climatic Requirements

Aubert (1987) states that Diaphorina citri does
not tolerate frost very well; however, we have ob-
served that populations have overwintered in
Gainesville, FL, where temperatures dropped to at
least -5C on several nights. Populations ofD. citri
in the Florida panhandle have been limited so far
to Murraya and Citrus plants for sale at discount
outlets, so it is not known whether D. citri can over-
winter north of Gainesville. Aubert (1987) also
states that populations ofD. citri do not tolerate hu-
midity close to the saturation point because it pro-
motes fungal epizootics, to which the nymphs are
very susceptible; however, high humidity in Florida
has not prevented extremely high summer popu-
lations of D. citri in local groves and backyards.
Similarly, few D. citri regulatory samples sent to
Florida Department of Agriculture and Consumer
Services, Division of Plant Industry (DPI) have ca-
davers resulting from fungal infection. Diaphorina
citri was not found above 1300-1500 m in elevation
in various places searched in Asia, presumably be-
cause of occasional frosts (Aubert 1987). Popula-
tions ofD. citri moved north in China in the 1980s
as a result of more citrus plantings and higher win-
ter temperatures (Qiu et al. 1996).

Distribution and Possible Source of the Florida Infestation

Diaphorina citri can be found in all of south-
east Asia and the Indian subcontinent, the is-
lands of Reunion and Mauritius, Saudi Arabia,
Brazil (da Graca 1991), southern Iran near the
border with Pakistan (Danet, pers. comm., ex
Toorawa 1998), Venezuela (Cermeli et al. 2000),
and Argentina (DPI records). In early 1998, it was
discovered in the island of Guadeloupe in the Car-
ibbean (Etienne et al. 1998). It also was discov-
ered in Florida in Palm Beach, Broward, and
Martin Counties in June 1998 and has since
spread throughout the state, wherever citrus oc-
curs (Halbert et al. 2002). We have seen speci-
mens from Texas (French et al. 2001), Cayman
Islands, and several Bahamian islands (Halbert
& Nifiez 2004). There is a report in the literature
that D. citri is present in Honduras (Burckhardt
1994b), which is based upon an interception of
D. citri in France on citrus trees from Honduras
in 1989 (Burckhardt & Martinez 1989). This re-
ported Central American infestation has been dif-
ficult to substantiate in Honduras itself. We do
not doubt that the insects intercepted were D.
citri, but the actual source of the infested plants
remains an open question.
There are two likely scenarios for the introduc-
tion ofD. citri into Florida. First, D. citri has been
established in South America for many years.
Therefore, it could have spread naturally through
Central America and the Caribbean, and ulti-
mately found its way to Florida. If the intercep-
tion record from Honduras is true, it provides
support for the gradual spread ofD. citri through-
out the Western Hemisphere. A USDA/APHIS/
PPQ record of an interception of D. citri from
Mexico in April, 1996, if true, also lends credence
to gradual spread from South America. If the
Florida D. citri population came from Latin
America, it is very likely to be free of the greening
pathogen.
Alternatively, D. citri could have been intro-
duced directly from Asia. The USDA/APHIS/PPQ
database has records of 170 interceptions of live
D. citri from Asian countries at ports in the USA
between 1985 and November 2003. There are an
additional 73 records of interceptions of live Dia-
phorina spp. on rutaceous plants from Asia. Many
of these populations probably were D. citri. In
most cases, there were only one or two specimens
found, but one collection intercepted in Des
Plaines, Illinois contained 46 live D. citri from In-
dia. In most cases, these insects were intercepted
on Murraya plant material, especially M. koenigii,
but infested citrus also has been observed.
Interception reports for the most part reflect
the known distribution ofD. citri. An interception
report in the USDA/APHIS/PPQ database of D.
citri from roots of Colocasia esculenta (L.) Schott
(Araceae) from Cameroon probably is a misidenti-

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Halbert & Manjunath: Diaphorina citri and Citrus Greening Disease

fiction rather than an indication thatD. citri is es-
tablished in Western Africa. Several interceptions
reported from the Caribbean Basin indicate that
D. citri already is moving in cargo within five years
of known establishment. If citrus greening disease
ever became established anywhere in the Carib-
bean Basin, the potential for movement is high.

Direct Plant Damage

Direct plant damage occurs as a result of high
populations of psyllids. Copious amounts of hon-
eydew and moderate leaf distortion have been ob-
served on infested plants (Aubert 1987). In
Florida, after the initial invasion ofD. citri, new
growth on some citrus plantings was severely
damaged. Feeding by Asian citrus psyllid caused
leaves to be curled and notched. In cases of severe
infestation, newly emerged sprouts were killed.
Lateral leaf notching is particularly characteris-
tic ofD. citri damage. In dry weather, we have ob-
served curled waxy secretions from nymphs.
Heavy oviposition or larval activity sometimes
will kill developing terminals or cause abscission
of leaves or entire terminals (Michaud 2004).
Populations can reach extremely high levels. A
survey technique reported by Ahmad (1961) con-
sisted of spraying citrus trees in West Pakistan
with insecticide and collecting the psyllids on a
white sheet beneath the tree. This method yielded
an average of 41,561 adults per tree! OnMurraya
paniculata hedges in Reunion, catches of 200
adults per m2 were obtained with a D-VAC ma-
chine (Aubert 1987).

BIOLOGY OF THE GREENING PATHOGENS

Nature and Classification of the Pathogens

The greening pathogens are thought to be
highly fastidious phloem-inhabiting bacteria in
the genus Candidatus Liberibacter. Although the
bacteria have not been cultured for completion of
Koch's postulates, circumstantial evidence points
strongly to a bacterial disease agent because cit-
rus greening symptoms abate temporarily when
trees are injected with antibiotics (Buitendag &
von Broembsen 1993; Lim et al. 1990; Su et al.
1986). The isolate from South Africa has been
named Candidatus Liberibacter africanus, and
the isolate from Asia has been named Candidatus
Liberibacter asiaticus (Garnier et al. 2000). A
subspecies of Candidatus L. africanus, Candida-
tus L. africanus subsp. capensis, has been de-
scribed from the Western Cape Region of South
Africa from Calodendrum capensis Thunb., a na-
tive South African plant. This subspecies also in-
fects citrus (Gamier et al. 2000). Garnier et al.
(2000) changed the generic name from Libero-
bacter to Liberibacter, following the International
Code of Nomenclature of Bacteria, which states

that since "bacter" is of masculine gender and
"Liber" is of Latin origin, the connecting vowel
should be an "i."
It is widely accepted that both species ofbacte-
ria multiply in both of the psyllid vectors, but this
has not been demonstrated with molecular evi-
dence. However, Moll & Martin (1973) noticed
marked increases in the number of citrus green-
ing bacteria in T erytreae vectors over 9 days
time, and concluded that the bacteria were multi-
plying in the vectors. Neither species of citrus
greening bacteria has been cultured on artificial
media. Molecular analysis indicates genetic dif-
ferences between the two species, and specific
DNA probes have been developed for each (Bove
et al. 1993, 1996; Garnier & Bove 1996; Harakava
et al. 2000; Tian et al. 1996).
African greening manifests symptoms prima-
rily under cool conditions (below 25C), whereas
Asian greening does well under hot conditions
(Gamier & Bove 1993). African greening does not
show symptoms above 27C under glasshouse
conditions. In South Africa, the greening symp-
toms are more pronounced in winter than in sum-
mer. Similarly, the African citrus greening
symptoms are severe in elevations above 700 m,
whereas they are absent in low-lying hot areas.
Indian greening does well in hot conditions, above
25C. Asian citrus greening symptoms are less
pronounced and disappear above 1500 m, possi-
bly because the vector is absent (Aubert 1987). In
a laboratory study, Bove et al. (1974) showed that
symptoms of African citrus greening were moder-
ate to severe at 22 to 24C and disappeared at
27 to 32C, whereas symptoms of Asian citrus
greening from India and Philippines were ex-
pressed strongly at both temperature regimes.
Candidates Liberibacter asiaticus is pre-
sumed to be Asian and may have developed with
citrus, while Candidatus L. africanus probably
came from native African rutaceous plants, since
citrus is an introduced species in Africa. A native
plant, Toddalia lanceolata, was found to be a good
host of both Candidatus L. africanus and its nat-
ural vector, T erytreae (Gamier & Bove 1996). Lin
& Lin (1990) postulate that Asian citrus greening
originated in the northeastern part of Guangdong
Province in China. It is also possible that the
Asian greening pathogen has a geographical ori-
gin similar to that of its primary vector, D. citri,
which probably evolved with similar species ofDi-
aphorina in the Indian subcontinent.

Distribution

It is important to keep an updated file on the
known distribution of citrus greening disease be-
cause rutaceous plants or citrus psyllids from
those locations may harbor the pathogens.
Toorawa (1998) compiled a summary of countries
known to have citrus greening in his Table 3. Each

Florida Entomologist 87(3)

entry in his table is referenced by literature cita-
tion, and he notes the laboratory that did the mo-
lecular confirmation. Locations listed below are
from Toorawa (1998) unless noted otherwise. Asian
countries include: China (including Hong Kong),
Indonesia, southern islands of Japan, Malasia,
Philippines, Taiwan, Thailand, and Vietnam. Evi-
dently citrus greening disease is spreading in Ja-
pan. Subandiyah et al. (2000) have confirmed
citrus greening using molecular diagnosis in four
places in Okinawa. Prior to this survey, citrus
greening was known only from the southernmost
island of Iriomote. Countries with citrus greening
in the Indian subcontinent include Bangladesh,
Bhutan, India, Nepal, and Pakistan. In the Indian
Ocean, citrus greening disease is found in Sri
Lanka, the Comoros Islands, Madagascar, Mauri-
tius, and R4union. All of these places have estab-
lished populations of D. citri and Asian citrus
greening. Mauritius and Reunion also have Afri-
can citrus greening and T erytreae. Similarly, in
the Saudi Arabian peninsula, Saudi Arabia and
Yemen have both species of vectors and both
pathogens. In Africa, Burundi, Cameroon, Central
African Republic, Ethiopia, Kenya, Malawi,
Rwanda, Somalia, South Africa, Swaziland, Tan-
zania, and Zimbabwe all have African citrus green-
ing and Trioza erytreae. Diaphorina citri is not
known to be established in the African mainland.
Although D. citri has been observed in Iran (Danet,
pers. comm., ex Toorawa 1998), it is not known if
citrus greening disease occurs there. Additionally,
Varma & Atiri (1993) reported that over 50% of
plants in some areas of Nigeria show symptoms of
citrus greening. Symptoms have been observed all
over Nigeria, but presence of the pathogen has not
been confirmed by molecular analysis. The CABI
map 766 (1998) additionally lists Laos and Myan-
mar as positive for Candidatus L. asiaticus. It
states that there is an unconfirmed report for
Syria. Garnier & Bove (2000b) added Cambodia to
the list of countries where citrus greening is
present. Citrus greening disease was found in
Papua New Guinea in 1999 (Lee 2002). The status
of citrus greening in Afghanistan, Brunei, and Sin-
gapore is unknown. In July 2004, as this paper was
in press, citrus greening disease was reported in
Brazil by Fundecitrus (Anon. 2004).

Plant Damage

Citrus greening is a very destructive disease. A
survey conducted over an 8-year period in
Reunion Island indicated that 65% of the trees
were badly damaged and rendered unproductive
within 7 years after planting (Aubert et al. 1996).
In Thailand, citrus trees generally decline within
5-8 years after planting due to citrus greening
(Roistacher 1996). Roistacher (1996) showed that
groves must live for a minimum of about 10 years
in order to make a profit. Infected trees are

stunted and sparsely foliated. The symptoms can
resemble nutritional stress, especially zinc defi-
ciency symptoms on recent growth; however, a
more diagnostic mottle usually occurs on slightly
older leaves that resembles symptoms of luteovi-
ruses in dicots (e.g., Potato leafroll luteovirus).
The mottle differs from nutrition-related mot-
tling in that greening induced mottling usually
crosses leaf veins, whereas nutrition-related mot-
tling usually occurs between or along leaf veins.
Off-season bloom, fruit drop, and twig dieback are
other symptoms. Fruit are small, lopsided, hard,
and have a bitter flavor. Seed abortion is common
(Capoor et al. 1974). Citrus greening disease may
predispose plants to other pest problems such as
the citrus longhorned beetle, Anoplophora chin-
ensis Forster (Aubert 1990b). A combination of
citrus greening, citrus longhorned beetle, and as-
sociated Phytophthora fungi are common in ad-
vanced citrus greening epidemics (Aubert 1990b).
Toorawa (1998) attempted to compile global in-
fection statistics. He estimated 50 million trees
infected in south and southeast Asia, three mil-
lion trees infected in Indonesia, and ten million
trees infected in Africa. In India and Saudi Ara-
bia, there has been a marked decline in citrus in-
dustries as a result of citrus greening disease.

DETECTION

Vector

In low numbers, Diaphorina citri is an incon-
spicuous pest of citrus. The adults are the most
easily observable stage. They are about 3-4 mm
long. The wings have distinct bars on the top and
bottom, giving the insects a flattened X-pattern
when viewed laterally. Characteristically, they sit
at a 450 angle to the shoot or leaf on which they
feed. Adults jump readily when approached. It is
best to collect them either by using an aspirator,
or by bagging the entire shoot. Another way to col-
lect specimens in excellent condition is to place an
inverted empty test tube above an infested shoot
while disturbing the colony. The adults will jump
up into the tube and remain there.
Nymphs are difficult to see. They are flat and
tend to wrap themselves around the shoot where
they feed. Superficially, they look similar to scale
insects. Nymphs may be green or orange in color,
but, unlike scale insects, they have large wing
pads. Eggs, bright yellow or orange and shaped
like a pointed football, are attached in the plant
tissue at one end. Eggs are deposited on the
"feather flush" of the host. It is very difficult to see
eggs without a hand lens.

Pathogen

It is only within the last few years that reliable
detection of the greening pathogens has been

September 2004

Halbert & Manjunath: Diaphorina citri and Citrus Greening Disease

available. DNA probes now have been used suc-
cessfully to detect Candidatus Liberibacter spp.
both in infected plants and in psyllid vectors (Bove
et al. 1993; Tian et al. 1996). The bacteria also can
be detected with an electron microscope, ELISA
(Gamier & Bove 1993), and by biological assay.
Roistacher (1991) gives a detailed methodology for
preparing specimens for electron microscopy.
Unfortunately, infected trees may be over-
looked if symptoms alone are used for detection.
Aubert (1990b) estimated that 15% to 20% of the
infected plants are overlooked by nursery inspec-
tors who rely only on visual inspection.
Lafleche & Bove (1970) using a transmission
electron microscope observed a "mycoplasma-like
organism" in citrus phloem tissue infected with
citrus greening disease. The organisms were
about 2000 nm long and 100-200 nm in diameter.
Similar bodies soon were observed in both vectors
of the citrus greening disease, T erytreae (Moll &
Martin 1973) and D. citri (Chen et al. 1973). A fur-
ther comparison of the greening organism (Saligo
et al. 1971) with citrus stubborn, a spiroplasma,
showed that the outer membrane of the greening
organism was much thicker (25 nm) than that of
the spiroplasma (10 nm).
Further studies showed the bacterial nature of
the greening organism, and a peptidoglycan- con-
taining outer membrane of gram negative bacte-
rial type was identified (Gamier et al. 1984).
Molecular information provided the basis for ac-
curate nomenclature for the two species. The bac-
terium was recognized as a new 'Candidatus'
genus Liberibacter, in the alpha subdivision of
proteobacteria (Jagoueix et al. 1994).
Monoclonal antibodies raised against proteins
purified from infected greening tissue from Africa,
China, and India reacted selectively with the source
antigens and a few other isolates of citrus greening,
demonstrating the existence of several serotypes of
greening (Gamier et al. 1987; Gao et al. 1993).
These monoclonal antibodies are too isolate-specific
to be used for general detection of greening.
Molecular approaches such as PCR and strain-
specific DNA probes now have been used success-
fully to detect and differentiate Candidatus
Liberibacter spp. both in infected plants and in
psyllid vectors (Bove et al. 1993; Jagoueix et al.
1996; Tian et al. 1996). Unfortunately, detection
is not always reliable. Sometimes trees with clas-
sic greening symptoms test negative with PCR
(Toorawa 1998).
Molecular detection methods have been diffi-
cult to develop since the greening organism has
not yet been cultured. Villechanoux et al. (1992)
isolated total DNA from periwinkle plants in-
fected with Indian greening, and digested it with
restriction enzyme, HindIII. The digested DNA
was cloned and the clones were screened by differ-
ential hybridization with DNA from both healthy
and infected tissues. They identified three clones

with 2.6, 1.9, and 0.6 kb inserts to be specific to
the greening bacterium. The two larger clones re-
acted with all the Asian forms, but not with the
African isolates, while the 0.6 kb clone reacted
only with the Indian greening. Villechanoux et al.
(1993) sequenced and analyzed the three green-
ing specific clones. The larger 2.6 kb clone con-
tained the genes of the nusG-rplKAJL-rpoBC
operon, confirming the eubacterial nature of the
greening organism at the molecular level. The 1
kb insert contained sequences for a bacterio-
phage-type DNA polymerase. The sequences from
the 0.6 kb insert did not match anything in the
database of known sequences.
Since the bacterial nature of the greening or-
ganism was established, Jagoueix et al. (1996)
used universal primers for general amplification
of prokaryotic 16S rDNA. Based on sequence in-
formation, primers have been developed to amp-
lify a 1,160 bp region of ribosomal DNA for
detection of greening by PCR. Further differentia-
tion of Asian and African forms of greening can be
achieved by restriction enzyme XbaI digestion.
The XbaI digestion of an 1160 bp fragment from L.
africanus yields three fragments of 520 bp, 506 bp,
and 130 bp, while the Asian greening, L. asiaticus,
yields only two fragments of 640 bp and 520 bp.
Ribosomal DNA primers have been used
widely for detection of both forms of greening.
These primers have been shown not to amplify
16S ribosomal sequences of other citrus patho-
gens (Jagoueix et al. 1996).
Additionally, some citrus species, such as
sweet oranges and mandarins, produce a com-
pound (gentisic glucoside) as a result of infection.
Gentisic acid glows violet under UV light and can
be seen directly in the fruit albedo of sweet or-
anges. A bark extract procedure (Roistacher
1991) can be used with other commercial citrus
species (mandarin and tangelo). Results are not
consistent for lemon, lime, pummelo, and grape-
fruit. Gentisic acid analysis sometimes produces
false negatives and false positives, so it cannot be
used alone for definitive diagnosis. However, re-
sults are fairly consistent for sweet oranges, so
the technique can be useful in conjunction with
other more reliable (but also more expensive and
time-consuming) tests (Hooker et al. 1993).
For many years, biological indexing has been
used for citrus greening diagnosis. Miyakawa
(1980) found that ponkan (Citrus reticulata Blanco)
and Orlando tangelo (Citrus tangelo J. Ingram & H.
Moore) are the best indicators, particularly if se-
vere forms of Citrus tristeza virus (CTV) are
present and may confound symptom expression.
Detection of citrus greening pathogens from
asymptomatic tissue is inconsistent by any known
method. Similarly, the molecular assays some-
times are complicated to run, and results are not
always believable. Clearly, more accurate, timely,
and robust detection methodologies are needed.

Florida Entomologist 87(3)

EPIDEMIOLOGY

Since it has only been in the last several years
that citrus greening pathogens could be detected
reasonably reliably by means of molecular meth-
ods, some of the basic characteristics of transmis-
sion and epidemiology are poorly understood.
There are reports of transmission via psyllid vec-
tors, grafting, dodder, and seed.

Psyllid Transmission

Psyllid transmission is the primary means of
spread in the field. Acquisition times of 30 min for
Asian psyllids (Roistacher 1991) and 24 h for Af-
rican psyllids (Buitendag & von Broembsen 1993)
have been reported. In some experiments, acqui-
sition feeding of 5-7 h was sufficient to transmit
citrus greening pathogens, while feeding periods
of 1-3 h were not (Xu et al. 1988). The pathogen
probably multiplies in the vector (Aubert 1987;
Moll & Martin 1973; Xu et al. 1988), but this has
not been demonstrated by molecular experi-
ments. It is not known if psyllids can be infected
simultaneously by both bacteria species (Garnier
et al. 1996), although both psyllid species trans-
mit both pathogens experimentally (Lallemand et
al. 1986; Massonie et al. 1969). Adults and fourth
and fifth instar Asian citrus psyllids are able to
transmit the pathgen after a latent period as
short as one day or as long as 25 days (Roistacher
1991; Xu et al. 1988). Fourth and fifth instars
were able to retain the pathogen as adults, which
were able to transmit the disease immediately af-
ter emergence (Xu et al. 1988). First through
third instars were unable to transmit citrus
greening (Xu et al. 1988). A latent period of 24 h
has been reported for African greening (Bui-
tendag & von Broembsen 1993). Transmission is
thought to occur via salivary secretions (Aubert
1987). Serial transfer experiments by van den
Berg et al. (1992) suggest that young nymphs of
T erytreae can acquire the bacteria even though
they do not transmit them.
Candidates Liberibacter spp. potentially
should be considered pathogens of the insect as
well as the plant, if in fact they multiply in the
psyllid vectors, as suggested by Xu et al. (1988)
and Moll & Martin (1973). There are conflicting
reports as to whether Candidatus Liberibacter
spp. are transmitted transovarially (Buitendag &
von Broembsen 1993; Roistacher 1991; van den
Berg et al. 1992; Xu et al. 1988). Xu et al. (1988)
reported that there is no evidence for transovarial
transmission, because D. citri nymphs collected
immediately after hatching on diseased plants
did not transmit citrus greening disease to indica-
tor plants. The most extensive studies on transo-
varial transmission of citrus greening pathogens
were done with T erytreae. van den Berg et al.
(1992) allowed immature psyllids to develop on

heavily infected plants. When adults emerged,
they were allowed to feed and mate on infected
plants. After 14 days, the mouthparts of 100 of the
females were severed. Ten of these females were
placed on each of ten healthy indicator plants,
where they laid eggs. Adults from those eggs were
allowed to feed on the same plants for 30 days af-
ter emergence. Plants were later sprayed, kept in-
sect-free, and tested for citrus greening disease
after six months. One of the ten plants developed
citrus greening disease. In another experiment,
oviposition was allowed to occur on the infected
plants. Crawlers were removed immediately after
hatching and prior to feeding and placed on indi-
cator plants. Five of the 24 plants on which these
psyllids completed development became infected
with citrus greening disease. The most logical ex-
planation for these infections is transovarial
transmission; however, the authors postulate
that the plant in the first experiment could have
been infected via oviposition, and those in the sec-
ond experiment could have been infected as a re-
sult of absorption of greening bacteria from the
infected host by the egg. These experiments
should be repeated with D. citri. To our knowl-
edge, there are no studies on sexual transmission
of Candidates Liberibacter spp. in psyllids. Simi-
larly, it is not known if parasites that develop in
infected psyllids can transmit the pathogen to the
hosts of their offspring. Hoy et al. (2001) has a
good review of relevant literature about transmis-
sion of plant pathogens via parasites of vectors.
Candidates Liberibacter spp. can be detected
in single psyllids (Bove et al. 1993). Experimental
data showing detection of citrus greening patho-
gens in psyllids indicate that percent transmis-
sion by psyllids that feed on infected trees may be
variable. Thirty-nine percent of psyllids collected
in Malaysia in September 1991 tested positive for
the pathogen, whereas less than 1% of those col-
lected in February 1992 in India had positive
DNA hybridization reactions for citrus greening
(Bove et al. 1993). Toorawa (1998) also found a
higher percentage of D. citri that had positive
DNA hybridization reactions in the fall. The rela-
tionship between positive detection of the patho-
gen in the psyllids and ability to infect indicator
plants is not known. Field infectivity experi-
ments, in which adult psyllids are trapped alive
and allowed to feed on indicator plants, are badly
needed. These kinds of experiments, though labor
intensive, would provide valuable information on
infectivity and seasonality of transmission.

Graft Transmission

The citrus greening pathogens are graft trans-
mitted (Bove et al. 1996; van Vuuren 1993); how-
ever, graft transmission ofCandidatus Liberibacter
spp. is variable, depending upon the plant part used
for grafting, the amount of tissue used, and the

September 2004

Halbert & Manjunath: Diaphorina citri and Citrus Greening Disease

pathogen isolate. With single buds, graft transmis-
sion of African greening varied from 0 to 50%, de-
pending upon the isolate used (van Vuuren 1993).
Side grafts with twigs were even more efficient at
transmitting the pathogen, whereas fruit stems and
bark strips were not effective (van Vuuren 1993).
Lin & Lin (1990) reported some early experi-
ments performed but apparently not previously
published by Chen Qi-bao. Seven months after
grafting diseased buds on healthy rootstock, 58%
of grafts had survived, and of those, 20% showed
citrus greening symptoms. In another experi-
ment, 10-16% of grafts with buds from asymptom-
atic branches on diseased trees developed
symptoms, while 40% of grafts from symptomatic
branches developed symptoms of citrus greening
in 3-9 months.

Seed Transmission

There is little information on seed transmis-
sion. Most fruit is lost, and that which remains
has a high proportion of aborted seed; however,
Tirtawidjaja (1981) collected normal and green-
ing-affected (very small) fruit and harvested nor-
mal-looking seeds from each. No symptoms were
observed on seedlings from seed taken from nor-
mal fruit, even when they were collected from in-
fected plants; however, seeds derived from
smaller, greening-affected fruit produced some
stunted chlorotic seedlings. Three of the seedlings
had the same appearance as insect-inoculated
seedlings. This experiment bears repeating. Miy-
akawa et al. (1990) reported that greening-in-
fected Troyer citrange trees showed few leaf
symptoms and bore a good crop, although there
were relatively high numbers of aborted seeds. If
seed transmission occurs in cultivars like cit-
range that are used for citrus rootstocks, spread
could occur through liners as well as by budding.

Timing, Patterns, and Rates of Spread

Many of the parameters necessary to develop
epidemiological models of citrus greening disease
spread are not known. Little is known about how
soon after infection by psyllids the pathogens can
be detected in the infected plant; however, symp-
toms of African greening developed 40 cm back to-
wards the trunk of the tree from the vector
feeding site on infected shoots within 12 months
(van Vuuren 1993). Pathogens became detectable
in shoots between 2.5 and 3.5 months after leaves
emerged from buds on diseased trees, and symp-
toms expressed themselves in a similar period of
time (Su & Huang 1990). Pathogens could be de-
tected in the root system of Luchen seedlings five
months after graft inoculation (Su & Huang 1990).
The time interval between the infection of a citrus
shoot and the possibility of subsequent acquisi-
tion of the pathogen by new vectors is not known.

Percent citrus greening disease transmission by
psyllids raised on infected plants is variable. Effi-
ciency may vary from around 1% to 80% for single
insects (Xu et al. 1988). Xu et al. (1988) list several
conditions that enhance transmission efficiency,
including psyllid-inoculated source plants, young
(3-4 leaves) indicator plants, psyllids raised on in-
fected plants in the laboratory, and control of shade
and temperature in the greenhouse where indica-
tor plants are kept. The genetic makeup of the
pathogen and vector also may account for some of
the variation in that some populations of citrus
psyllids may be inherently better vectors, and
some populations of citrus greening bacteria may
be inherently more transmissible.
Although patterns of spread in groves have
been studied (Gottwald et al. 1991a,b), there has
not been an attempt to match disease spread in-
formation with a reproducible measurement of
vector abundance. It is significant that Gottwald
et al. (1991a) found that the source of infection
was a small planting near a farmhouse of 24 trees
with severe disease in a study in China. The inci-
dence of detectable citrus greening disease rose to
14% in the first 5 years after planting. They esti-
mate that the disease would have reached its
asymptote in the next 2-4 years, and thus, the
productive life of the grove would be less than 10
years, even with a clean start.
In another Chinese study in Shantou, Guang-
dong, ingress into densely planted groves showed
a typical edge effect. Twenty percent of the plants
were lost to greening by the fifth year, and the
groves lost their commercial value by the time
they were seven to eight years old (Aubert 1990b).
There are robust experimental data for dis-
persal and infestation patterns for T erytreae, the
African citrus psyllid; however, we could not find
similar data for D. citri. Samways & Manicom
(1983) severely pruned a citrus grove and in-
spected it carefully for initial psyllid infestation
in the spring. The initial distribution was random
on a tree-to-tree basis, but the side of the grove
closest to the neighbor's infested grove had a
higher density of T erytreae, suggesting that the
source of the infestation was the neighboring
grove. Results showed that even after the initial
invasion, there was considerable tree-to-tree
movement, which potentially can spread the
pathogens further. Trioza erytreae readily in-
vaded the whole grove within days.
There is good experimental evidence for flight
distance of T erytreae, but not for D. citri. van den
Berg & Deacon (1988) released clean T erytreae in
an area that had no citrus. Yellow traps were
placed in a grid at various distances from the re-
lease site. From these data, it was determined
that T erytreae could fly at least 1.5 km in the ab-
sence of their host plants. A similar estimate was
made for D. citri, but it was not based on experi-
mental evidence (Tolley 1990).

Florida Entomologist 87(3)

Infected plants were clustered within groves,
possibly indicating that most D. citri normally do
not fly very far (Aubert et al. 1996; Gottwald et al.
1991a,b). Similarly, Toorawa (1998) says that in
Mauritius, D. citri are not very mobile. This asser-
tion is based on the very low percentage (0.33%)
of D. citri captured on M. paniculata that were
contaminated with the citrus greening pathogen.
An estimate of maximum flight distance for infec-
tive vectors is needed for determining safe isola-
tion distance for quarantine and eradication
purposes, and this is not well known. A 30-km
separation was sufficient in Nepal (Regmi et al.
1996) but not in Vietnam (Bove et al. 1996).
Although the distance D. citri can fly is poorly
known, experiments on height of capture and
color preference have been done. Aubert & Hua
(1990) reported that "brown yellow" traps worked
better for collecting D. citri than other colors on
cloudy days. However, plain yellow traps worked
better on sunny days. Maximum catch occurred at
1.5 m above the ground.

Host Range and Vector Specificity

The host range of D. citri includes many of the
close citrus relatives (Table 1). DPI's Citrus Arbo-
retum in Winter Haven, Florida provided a good
opportunity to determine which plants serve as
field hosts of D. citri in Florida. Two species of na-
tive Zanthoxylum are represented at the facility.
No D. citri were ever found on Zanthoxylum clava-
hercules L; however, Zanthoxylum fagara (L.)
Sarg. may be an occasional host. Zanthoxylum fa-
gara nearly always has suitable flush, sporting a
nearly year-around population of Toxoptera citri-
cida (Kirkaldy), the brown citrus aphid; however,
we found D. citri nymphs present only once, and
in very low numbers. Similarly, no D. citri were
found on Z. fagarae growing next to an infested
lime grove in South Florida. Zanthoxylum spp.
may be non-hosts, or as in the case of Z. fagara,
very poor hosts, of D. citri. Another apparent non-
host, based on our observations at the DPI Citrus
Aboretum, is Casimiroa edulis Llave & Lex.,
white sapote. Both Zanthoxylum and Casimiroa
are of Western Hemisphere origin, suggesting a
preference by D. citri for Old World Rutaceae.
There are many observations about preferred
hosts of D. citri, but only one comparative labora-
tory study (Tsai & Liu 2000). In their study, Tsai
& Liu (2000) tested Murraya paniculata (L.) Jack
(orange jasmine), Citrus jambhiri Lushington
(rough lemon), Citrus aurantium L. (sour or-
ange), and Citrus xparadisi Macfad. (grapefruit).
Grapefruit was the best host, followed by the
other hosts, among which there was no statistical
difference.
There is not much information on the host
range of the pathogens because of the difficulty in
measuring the presence of the pathogen with cer-

tainty (Table 2). Most, if not all, Citrus spp. ap-
parently are susceptible to some degree, although
some species (Citrus indica Tan. and Citrus mac-
roptera Montr.) remained symptom-free under
heavy inoculum pressure (Bhagabati 1993). Cit-
rus limetta remained symptom-free after labora-
tory inoculation (paper does not specify means of
inoculation) (Nariani 1981).
Murraya paniculata is a preferred host of D.
citri; however, there is not agreement on whether
it is a host for the greening pathogens. Careful
work using dot hybridization by Hung et al.
(2000) indicates that Asian greening pathogens
from Taiwan will not multiply in M. paniculata or
M. koenigii. Toorawa (1998), who worked in Mau-
ritius, concurs. On the other hand, Tirtawidjaja
(1981) was able to observe consistent external
and internal symptoms on 25-33% of inoculated
M. paniculata plants. Asian greening may be
caused by a population of bacterial strains with
somewhat differing host ranges. The fact that
Murraya spp., which are native to the Indian sub-
continent (Coile 1995) and are good hosts of D.
citri, are resistant or at least tolerant to citrus
greening disease further supports a South Asia
origin for the pathogens.
Several citrus relatives have been shown with
modern detection methods to harbor greening
pathogens, including Severinia buxifolia (Poiret)
Ten. (Hung et al. 2000), Limonia acidissima L.
(Koizumi et al. 1996; Su et al. 1995; Hung et al.
2000), and Toddalia lanceolata Lam (Korsten et
al. 1996). Many other citrus relatives are impli-
cated as hosts of citrus greening pathogens, but
symptoms have been the only criteria (Table 2).
Citrus greening has been transmitted experi-
mentally to several hosts outside the Rutaceae.
Greening can be transmitted by dodder (Cuscuta
sp.) (Convolvulaceae (Cuscutaceae)) to non-Ruta-
ceous plants such as Catharanthus roseus L. G.
Don (Apocynaceae) (periwinkle) (Tirtawidjaja
1981) and Nicotiana tobacum L. cv. 'Xanthii'
(Solanaceae) (tobacco) (Garnier & Bove 1993),
suggesting a wide physiological host range for the
pathogens. The pathogens even multiplied in the
dodder itself (Ghosh et al. 1977; Su & Huang
1990).
As with plant hosts, vector specificity of Candi-
datus Liberibacter spp. may be low, in that both
Asian and African citrus psyllids (two different
psyllid families) can transmit both species of
greening organisms. The relatively narrow host
and vector associations observed in the field may
be determined by the restricted host ranges of the
psyllid vectors rather than by the potential host
and vector associations for the pathogens. After
obtaining successful transmission of greening to
Catheranthus by dodder, Tirtawidjaja (1981) at-
tempted to inoculate Catharanthus with D. citri
and was unsuccessful, presumably because the
psyllids would not feed normally on a non-host.

September 2004

Halbert & Manjunath: Diaphorina citri and Citrus Greening Disease

TABLE 1. HOST LIST FOR DIAPHORINA CITRI KUWAYAMA.

Species Source Comments

Aegle marmelos (L.) Corr.
Aeglopsis chevalieri Swingle
Afraegle gabonensis Engl.
Afraegle paniculata (Schaum.) Engl.
Artocarpus heterophyllus Lamarck
(Moraceae)
Atalantia missions Oliver
Atalantia monophylla (L.) Corr.
Atalantia sp.
Balsamocitrus dawei Stapf
Citropsis gilletiana Swingle &
M. Kellerman
Citropsis schweinfurthii (Engl.)
Swingle & Kellerm.
Citrus aurantifolia (Christm.) Swingle
Citrus aurantium L.
Citrus deliciosa Tenore
Citrus grandis (L.) Osbeck

Citrus hystrix DC.
Citrus jambhiri Lushington
Citrus limon (L.) Burm. f.
Citrus madurensis Loar.
Citrus maxima (Burm.) Merr.

Citrus medical L.
Citrus meyeri Tan
Citrus x nobilis Lour.
Citrus obovoidea Hort. ex Tanaka cv
'Kinkoji'
Citrus xparadisi Macfad.

Citrus reticulata Blanco

Citrus sinensis (L.) Osbeck
Citrus spp.
Clausena anisum-olens Merrill

Clausena excavata Burm. f.
Clausena indica Oliver
Clausena lansium (Lour.) Skeels

Eremocitrus glauca (Lindley) Swingle
Eremocitrus hybrid
Fortunella crassifolia Swingle
Fortunella margarita (Lour.) Swingle
Fortunella polyandra (Ridley) Tanaka
Fortunella spp.

Limonia acidissima L.
Merrillia caloxylon (Ridley) Swingle

Microcitrus australasica (F.J. Muell.)
Swingle
Microcitrus australis (Planch.) Swingle
Microcitrus papuana H.F. Winters

Viraktamath & Bhumannavar 2002
Koizumi et al. 1996
DPI Citrus Arboretum survey
DPI Citrus Arboretum survey
Shivankar et al 2000

Tirtawidjaja 1981
DPI Citrus Arboretum survey
Koizumi et al. 1996; Aubert 1990a
Koizumi et al. 1996
DPI Citrus Arboretum survey

Chavan & Summanwar 1993

Aubert 1987, 1990a; Florida surveys
Florida surveys
Aubert 1987
Aubert 1987

Aubert 1987; Lim et al. 1990
Florida surveys
Aubert 1987, 1990a
Aubert 1990a
Aubert 1990a

Aubert 1987, 1990a
Florida surveys
Aubert 1987; Florida surveys
Florida surveys

Aubert 1987; Florida surveys;
Tsai & Liu 2000

Aubert 1987, 1990a, Koizumi et al.
1996; Florida surveys
Aubert 1987, 1990a; Florida surveys
Aubert 1990a; Florida surveys
Aubert 1990a

Aubert 1990a; Lim et al. 1990
Aubert 1990a
Koizumi et al. 1996; Aubert 1990;
Florida surveys

Koizumi et al. 1996
DPI Citrus Arboretum Survey
DPI Citrus Arboretum Survey
DPI Citrus Arboretum Survey
DPI Citrus Arboretum Survey
Aubert 1987, 1990a

Koizumi et al. 1996
Lim et al. 1990; Aubert 1990a

Koizumi et al. 1996; Aubert 1987,
1990a; DPI Citrus Arboretum survey
DPI Citrus Arboretum survey
DPI Citrus Arboretum survey

adult feeding only (Aubert)

good host

preferred host

common
occasional, C. grandis is considered
a junior synonym of C. maxima
occasional

common

occasional, but observed nymphal
development
common

common

common; a preferred host in Florida
(DPI); best host in laboratory assays
(Tsai & Liu)
common

common
common host
occasional host, observed nymphal
development

adult feeding in laboratory
poor host (Koizumi et al.); common
host (Aubert); population highly
variable (FL surveys)
poor host, but plant died

occasional; nymphal development,
laboratory only (Aubert 1990)

cage in laboratory only (Lim et al.);
adult feeding in laboratory (Aubert)
common; observations in laboratory
(Aubert 1990a)

Florida Entomologist 87(3)

TABLE 1. (CONTINUED) HOST LIST FOR DIAPHORINA CITRI KUWAYAMA.

Species Source Comments

Microcitrus sp. 'Sidney' DPI Citrus Arboretum survey
Murraya exotica L. Aubert 1990a adult feeding in laboratory
Murraya koenigii (L.) Sprengel Koizumi et al. 1996; Aubert 1987; good host (Koizumi); occasional
1990a; Lim et al. 1990; Florida sur- host; no eggs observed (Aubert
veys 1987); good host with nymphal de-
velopment (Aubert 1990a); not an
excellent host but will support a
small population, including eggs
(FL surveys)
Murraya paniculata (L.) Jack Koizumi et al. 1996; Aubert 1987, a preferred host
Florida surveys
Naringi crenulata (Royb.) Nicholson DPI Citrus Arboretum survey
Pamburus missions (Wight) Swingle DPI Citrus Arboretum survey
Poncirus trifoliata (L.) Raf. Koizumi et al. 1996; Aubert 1987, occasional; eggs, but no nymphs
1990a) (Aubert 1987, 1990a)
Severinia buxifolia (Poiret) Ten. Koizumi et al. 1996; Florida surveys
Swinglea glutinosa (Blanco) Merr. Garnier & Bov6 1993; Florida sur-
veys
Toddalia asiatica (L.) Lam Aubert 1987, 1990a occasional; no eggs observed
Triphasia trifolia (Burm. f.) P. Wilson Koizumi et al. 1996; Aubert 1987; poor host (Koizumi); occasional host
DPI Citrus Arboretum survey; (Aubert); all stages and damage evi-
Aubert 1990a dent (FL surveys)
Vepris lanceolata G. Don Aubert 1987, 1990a occasional; no eggs observed
Zanthoxylum fagara (L.) Sarg. DPI Citrus Arboretum Survey plenty of suitable new shoots; very
few D. citri found; possible non-host.

Apparent non-hosts:
Casimiroa edulis Llave & Lex. DPI Citrus Arboretum Survey plenty of suitable new shoots; no
D. citri found
Zanthoxylum clava-herculis L. DPI Citrus Arboretum Survey plenty of suitable new shoots; no
D. citri found

The potentially wide physiological host range
of the pathogens, combined with low vector-
pathogen specificity, has potential implications
for the epidemiology of the disease. A naturally-
occurring native Candidatus Liberibacter sp.,
normally spread by native psyllids in plants unre-
lated to citrus, could be inoculated into citrus in a
rare event. This scenario has been postulated for
Australian citrus dieback, a disease of unknown
etiology (Miyakawa & Yuan 1990; Broadbent
2000; Broadbent et al. 1976). Once in citrus, the
citrus psyllids might spread the pathogen further
within the crop, causing major damage.

MANAGEMENT

Control ofD. citri and citrus greening disease
will involve all aspects of an integrated pest man-
agement program. The following is a summary,
based on a standard IPM approach.

Chemical Control

If both the insect and the pathogen are
present, the world literature is basically in agree-

ment that it is necessary to control psyllids with
pesticides (Tolley 1990). It is important to control
psyllids, even on apparently disease-free plants
(Aubert 1990b). Aubert (1987) recommended pro-
tecting spring flush. Populations are considered
high when they reach three nymphs and five
adults per twig. A Chinese program to rehabili-
tate citrus production in an area affected with cit-
rus greening disease requires 10-13 sprays per
year during flush periods (Roistacher 1996). In
Thailand, procedures to monitor for psyllids and
spray when necessary are recommended (Rois-
tacher 1996). Su et al. (1986) recommended
spraying at 10-20 day intervals during critical in-
fection periods. Gonzales & Viias (1981) recom-
mend spraying young trees at weekly intervals
during the rainy season and every ten days dur-
ing the dry season. Aubert (1990b) indicates that
it is very important for farmers in a citrus produc-
tion area to synchronize chemical applications.
Timing of pesticides is critical. Aubert (1988)
suggests using yellow sticky cards for monitoring
D. citri in order to time control action. In Florida,
this method may be too slow. Based on our trap-
ping collections in Florida, the peak spring flights

September 2004

Halbert & Manjunath: Diaphorina citri and Citrus Greening Disease

TABLE 2. HOST LIST FOR CANDIDATES LIBERIBACTER SPP.

Species Source Comments

Aeglopsis chevalieri Swingle
Atalantia missions Oliver
Balsamocitrus dawei Stapf.
Calodendrum capensis Thunb.
Catharanthus roseus (L.) G. Don
(Apocynaceae)
X Citroncirus webberi J. Ingram
& H. E. Moore
Citrus amblycarpa Ochse
Citrus aurantifolia (Christm.)
Swingle
Citrus aurantium L.
Citrus depressa Hayata
Citrus grandis (L.) Osbeck

Citrus hassaku Hort. ex Tanaka
Citrus hystrix DC.
Citrus ichangensis Swingle
Citrus jambhiri Lushington
Citrus junos Sieb. ex Tanaka
Citrus kabuchi Hort. ex Tanaka
Citrus limon (L.) Burm. f.

Citrus x limonia Osbeck

Citrus xnobilis Lour. 'Ortanique'
Citrus x nobilis Lour.
Citrus oto Hort. ex Tanaka
Citrus xparadisi Macfad.
Citrus reticulata Blanco

Citrus sinensis (L.) Osbeck
Citrus sunki Hort. ex Tanaka
Citrus unshiu (Mack.) Marc
Citrus sp. (mandarins)
Citrus sp. (pomelo/shaddock)
Clausena indica Oliver
Clausena lansium (Lour.) Skeels

Cuscuta australis R. Br. (Convol-
vulaceae (Cuscutaceae))
Fortunella spp.
Limonia acidissima L.

Microcitrus australasica (F. J.
Muell.) Swingle
Murraya koenigii (L.) Sprengel

Murraya paniculata (L.) Jack

Nicotiana tabacum L.'Xanthii'
(Solanaceae)

Koizumi et al. 1996
Tirtawidjaja 1981
Koizumi et al. 1996
Gamier et al. 2000
Tirtawidjaja 1981

Miyakawa & Yuan 1990;
Nariani 1981
Tirtawidjaja 1981
Miyakawa & Yuan 1990;
Tirtawidjaja 1981
Miyakawa & Yuan 1990
Miyakawa & Yuan 1990
Miyakawa & Yuan 1990;
Su & Huang 1990

Miyakawa & Yuan 1990
Miyakawa & Yuan 1990
Miyakawa & Yuan 1990
Tirtawidjaja 1981
Miyakawa & Yuan 1990
Miyakawa & Yuan 1990
Miyakawa & Yuan 1990

Miyakawa & Yuan 1990;
Tirtawidjaja 1981
Koizumi et al. 1996
Koizumi et al. 1996
Miyakawa & Yuan 1990
Miyakawa & Yuan 1990
Miyakawa & Yuan 199;
Tirtawidjaja 1981
Miyakawa & Yuan 1990
Miyakawa & Yuan 1990
Miyakawa & Yuan 1990
Miyakawa & Yuan 1990
Miyakawa & Yuan 1990
Miyakawa & Yuan 1990
Tirtawidjaja 1981; Koizumi
et al. 1996
Su & Huang 1990

Miyakawa & Yuan 1990
Koizumi et al. 1996; Su et al.
1995; Hung et al. 2000

Koizumi et al. 1996

Hung et al. 2000

Tirtawidjaja 1981; Aubert
et al. 1985; Miyakawa 1980;
Hung et al. 2000, Koizumi
et al. 1996;Toorawa 1998

Gamier & Bove 1993

questionable symptoms
symptoms only, vector transmission
symptoms only; vector transmission
molecular characterization
symptoms, electron microscopy; (dodder transmis-
sion only)
symptoms (few) stunting, seed abortion (Miya-
kawa & Yuan); symptoms fairly intense (Nariani)

mild symptoms

symptoms
symptoms
symptoms; pomelo-infecting strain prevalent since
1970s (Su & Huang). C. grandis is considered a
junior synonym of C. maxima
symptoms
symptoms
symptoms

symptoms
symptoms
symptoms, presence of putative pathogen in tissue;
plant reported tolerant to disease, but source of
vectors (Lee 1996)
symptoms

symptoms
symptoms
symptoms
symptoms
symptoms

symptoms, presence of putative pathogen in tissue
symptoms
symptoms
symptoms
symptoms
symptoms (stunting)
symptoms only, vector transmission

observed to multiply in stems, haustoria and
flower stalks
symptoms
symptoms only; vector transmission; DNA hybrid-
ization (Su et al.); infection apparently temporary
(Hung et al.)
stunting

no detection by dot hybridization after attempted
graft transmission; no symptoms (Hung et al.)
Mixed results: symptoms only (external and inter-
nal), vector transmission (Tirtawidjaja); can har-
bor greening organism (Aubert et al.). EM negative
(Miyakawa); No detection by dot hybridization af-
ter attempted graft transmission (Hung et al.); no
symptoms (Koizumi et al.); not a host (Toorawa)
symptoms, dodder transmission only

Florida Entomologist 87(3)

TABLE 2. (CONTINUED) HOST LIST FOR CANDIDATES LIBERIBACTER SPP.

Species Source Comments

Poncirus trifoliata (L.) Raf. Miyakawa 1980; Miyakawa back inoculations (Miyakawa, Miyakawa &Yuan)
& Yuan 1990; Nariani 1981;
Koizumi et al. 1996
Severinia buxifolia (Poiret) Ten. Hung et al. 2000; Koizumi DNA hybridization with specific probe; symptoms
et al. 1996
Swinglea glutinosa (Blanco) Tirtawidjaja 1981 symptoms only, vector transmission
Merr.
Toddalia lanceolata Lam Korsten et al. 1996 DNA/DNA hybridization, PCR
Triphasia trifolia (Burm. f.) Koizumi et al. 1996 severe stunting, vector transmission
P. Wilson
Possible non-hosts:
Citrus indica Tanaka Bhagabati 1993 no symptoms in the field in endemic area
Citrus limetta Risso Nariani 1981 no symptoms; laboratory inoculation (does not
specify how)
Citrus macroptera Montrons Bhagabati 1993 no symptoms in the field in endemic area

ofD. citri occur very suddenly, and without prior
incremental increase in numbers of adults col-
lected. In Florida, it would be better to monitor
buildup of nymphs on shoots, or to sample over-
wintered adults and observe when they become
gravid. (Their abdomens turn orange when egg-
laying is imminent.) In our opinion, scouting in
the spring should focus on nymphs, because by
the time adults emerge, the disease is already
spreading. This is true particularly in the case of
adults that emerge from nymphs that fed on in-
fected plants, because they can transmit citrus
greening bacteria immediately after emergence
(Xu et al. 1988).
As is the case with other phloem-sucking Ster-
norrhyncha, systemic pesticides are particularly
efficacious against D. citri. Trunk applications
have proven useful (Aubert 1988; Buitendag &
von Broembsen 1993). Two patent applicators are
available in South Africa that calibrate the dose
based on the diameter of the tree (Buitendag &
von Broembsen 1993). Supriyanto & Whittle
(1991) and Shivankar et al. (2000) also had suc-
cess with trunk applications. The best time to ap-
ply was just prior to spring flush.
A computer model indicated that even with
careful attention to inoculum reduction, at least
70% reduction in transmission is needed to delay
the epidemic significantly (Supriyanto & Whittle
1991). Unfortunately, there was no standard mea-
surement of psyllid abundance, so it is unclear
what constitutes 70% reduction; however, it is clear
that a pesticide with high efficacy is essential.
There has been little research with "soft" (en-
vironmentally friendly) pesticides, but Deacon et
al. (1989) have found that certain chitin synthesis
inhibitors work for eggs and first instars. Shivan-
kar et al. (2000) report about 90% control for sev-
eral botanicals, including neem formulations. Use
of these materials alone may not be wise in an

eradication effort, but they might be used effec-
tively against spring populations if timing were
just right.
Antibiotics injected into infected citrus trees
provide temporary remission of symptoms (Bui-
tendag & von Broembsen 1993; Lim et al. 1990;
Su et al. 1986). Injection with antibiotics is rec-
ommended as part of an integrated management
program in India (Nariani 1981). It is not known
whether the titre of citrus greening bacteria is re-
duced sufficiently to impact transmission by in-
sects or grafting. Symptoms reappear 1-1.5 years
after injection (Zhou 1981). Tetracycline also can
be used to treat budwood. The budwood is im-
mersed in 1,000 pg/ml tetracycline hydrochloride
for two h, or 500 pg/ml for three h (Zhou 1981).

Biological Control

Aubert (1987) indicated that pathogenic fungi
may be the most important mortality factor for
D. citri. Nymphal mortality of 60-70% could be ex-
pected where minimum daily relative humidity
exceeded about 87.9% in Reunion Island (Aubert
1987). Two fungal pathogens were reported, in-
cluding Cladosporium sp. nr. oxysporum Berk. &
M.A. Curtis and Capnodium citri Mont. (Aubert
1987). Etienne et al. (2001) said that the fungus
Hirsutella citriformis Speare was common during
periods when humidity was greater than 80%.
Use of insect pathogenic fungal sprays has not
been reported. In Florida, fungal cadavers of
D. citri have not been common in the hundreds of
submitted regulatory samples of D. citri that we
have seen in the past five years, in spite of the
high relative humidity that characterizes our
subtropical climate.
There are two well-known primary parasites of
D. citri. One is a eulophid ectoparasite, Tamarixia
(=Tetrasticus) radiata (Waterston). The other is

September 2004

Halbert & Manjunath: Diaphorina citri and Citrus Greening Disease

an encyrtid endoparasite, Diaphorencyrtus ali-
garhensis (Shaffee et al.). Tamarixia radiata ap-
parently is more efficient at parasitizing D. citri
than D. aligarhensis (Tang 1989). In surveys con-
ducted in Reunion, T radiata attacked 60-70% of
D. citri nymphs, whereas, D. aligarhensis parasit-
ism did not exceed 20% (Aubert 1987). Both para-
sites can be subject to high mortality due to
hyperparasitism (Aubert 1987; Garnier & Bove
1993). There is considerable Asian literature
about the parasite complex attacking D. citri, in-
cluding life cycle studies (Tang & Wu 1991; Xu &
Tang 1993), identification guides (Tang 1990;
Tang & Aubert 1990), and survey information. In-
troduction of T radiata into Reunion has im-
proved citrus production significantly on the
island (Aubert et al. 1996). While the success on
Reunion is spectacular, it has occurred in the pe-
culiar circumstances of an island environment in
the absence of hyperparasites. Experience in
Southeast Asia has shown that the same para-
sites are not able to similarly reduce transmission
(Supriyanto & Whittle 1991).
In Mauritius, biological control of T erytreae
was much more effective than biological control of
D. citri (Toorawa 1998). Toorawa (1998) postu-
lates several reasons for this. First, the initial
population of T erytreae was much lower than
that ofD. citri. Trioza erytreae reproduces princi-
pally on citrus, which is regularly treated with
pesticide, whereas D. citri utilizes M. paniculata,
which is unsprayed and is ubiquitous as an orna-
mental throughout the island. The climate on
much of the island also is more suitable toD. citri
than to T erytreae. Second, the parasite of T
erytreae (Tamarixia dryi (Waterston)) has an al-
ternate host in the common psyllid T litseae,
whereas T radiata, the parasite ofD. citri, has no
alternate host (Toorawa 1998).
Tamarixia radiata also was introduced into
Guadeloupe in January of 1999. The parasites
were imported from Reunion and released imme-
diately on arrival. The parasite apparently has
been quite successful (Etienne et al. 2001), al-
though release of any insects without prior quar-
antine is not recommended, particularly when
vectored pathogens may be present in the host
population.
Both T radiata and D. aligarhensis were re-
leased into Florida (McFarland & Hoy 2001), but
with mixed results. Apparently only T radiata
has established in Florida (Michaud 2002). Field
data reported by Michaud (2004) indicate that
parasitism by T radiata contributed 1.3%, 0.2%,
and 1.0% mortality of psyllid nymphs in three co-
horts, respectively, observed in central Florida.
The low rate of parasitism was due at least par-
tially to intraguild predation by coccinellids. Ex-
clusion of large predators from some of the
observed citrus terminals of cohort 3 increased
mummy formation about 20-fold (Michaud 2004).

Viraktamath & Bhumannavar (2002) list sev-
eral more parasites of D. citri in their Table 1 and
in the text on the proceeding page. Psyllaephagus
diaphorinae Lin & Tao probably is a primary
parasite. Syrphophagus taiwanus Hayat & Lin,
Syrphophagus (= Aphidencyrtus) diaphorinae
Myartseva & Tryapitsyn, and Marietta sp. nr. ex-
itiosa Compere probably are hyperparasites.Dia-
phorencyrtus diaphorinae Lin & Tao is listed
(Viraktamath & Bhumannavar 2002) as a hyper-
parasite, but it may be primary.
Predators ofD. citri are known from wherever
the psyllid occurs. One species of Scymnus (Coc-
cinellidae) has been reported in Brazil (Gravena
et al. 1996). Syrphids in the genus Allograpta
have been found in Reunion and Nepal (Aubert
1987) and in Florida (Michaud 2002). Several coc-
cinellids and chrysopids also have been reported
(Aubert 1987), but there is no information about
how much they actually reduce psyllid popula-
tions. In Florida, the most abundant predators
are Harmonia axyridis Pallas and Olla v-nigrum
Mulsant (Michaud 2001; Michaud 2002; Michaud
2004). Olla v-nigrum was a relatively rare species
prior to the arrival of D. citri, but it exhibited a
marked functional response to the establishment
of D. citri (Michaud 2001). Coccinellid predators
are by far the most important sources of biological
control for D. citri in Florida (Michaud 2002;
Michaud 2004). Both Michaud (2002, 2004) in
Florida and Al-Ghamdi (2000) in Saudi Arabia
have observed that spiders may be important
predators for D. citri. In Saudi Arabia, spiders ac-
counted for 33.6% of total predators (Al-Ghamdi
2000). Several other predators, including a his-
terid beetle, Saprinus chalcites Illiger and the
predaceous carabid, Egapola crenulata Dejean,
were important in Saudi Arabia (Al-Ghamdi
2000). A similar complex of predators, including
Coccinellidae, Chrysopidae, and Syrphidae exists
in Cuba (Gonzalez et al. 2003).
Biological control of vectors of pathogens may
have limited value in some circumstances, partic-
ularly in the case of a perennial tree crop like cit-
rus. Population fluctuations are inherent in any
predator-prey relationship. Some years the natu-
ral enemies predominate, and sometimes the pest
is more abundant. If citrus greening is present, in
years when citrus psyllids predominate, the en-
tire grove may be infected and subsequently de-
stroyed by citrus greening disease. Similarly, if
pesticides are needed for some other pest problem
such as whiteflies, mealybugs, scales, etc., natu-
ral enemies could be killed, and psyllid popula-
tions would increase dramatically. Once again, if
citrus greening disease were present, the entire
grove could be lost.
Biological control of the pathogen (cross-pro-
tection) has not been well-studied. It is known
that plants can become infected with both Asian
and African greening bacteria (Garnier et al.

Florida Entomologist 87(3)

1996). In South Africa, van Vuuren et al. (2000)
found that a population of several strains of CTV
was able to cross-protect citrus from African
greening. The isolate and its aphid transmitted
sub-isolates are under further study for potential
use in cross protection. Naidu & Govindu (1981)
did a greenhouse study on cross protection. Mild
isolates did not provide complete cross protection
when graft-inoculated sweet orange plants were
challenged with severe isolates. Moreover, iso-
lates that were mild in sweet orange were severe
in grapefruit in a subsequent host range test.

Host Plant Resistance

Although there is no real resistance in Citrus
spp. to citrus greening disease, some species and
cultivars are somewhat tolerant. Koizumi et al.
(1993) did extensive field surveys showing that
some cultivars were less susceptible to decline
than others. Most of the sweet orange trees became
infected with the pathogen and subsequently de-
clined, while grapefruit was more tolerant. In gen-
eral, sweet oranges, mandarins and tangelos are
most susceptible, grapefruit and lemon are more
resistant, and limes, Poncirus trifoliata and cit-
ranges are the most tolerant (Lee 1996).

Cultural Control

Management of citrus greening in areas where
the disease is endemic depends largely upon cul-
tural control. Infected limbs and trees should be
removed as symptoms appear. The pathogen ap-
parently moves fairly slowly within the plant af-
ter infection, so severe pruning can be helpful. For
African greening, Buitendag & von Broembsen
(1993) make the following recommendations: If
the infected tree is 5 years old or less, remove the
tree. If it is between 6 and 10 years, remove it if it
is 75% infected; otherwise remove branches. If it
is more than 10 years old, remove affected
branches up to 40% of the tree. Do not plant
young resets in old groves affected by greening.
The tendency for suckers that sprout after prun-
ing to be infected with greening depends upon the
diameter of the branches. Branches 10-19 mm in
diameter grew no suckers. Among branches 20
mm in diameter or more, the smallest ones were
most likely to produce infected suckers (86% for
branches 20-29 mm, as compared with 29% for
those that were 40-60 mm) (van Vuuren 1993).
Roistacher (1996) cited a Chinese program for
rehabilitation of citrus in Fujian Province in
which cultural control played a major part. Wind-
breaks were established to protect plants from
psyllid vectors (although the efficacy of barriers
for protection from a persistently transmitted
pathogen is questionable). Trees were examined
regularly for citrus greening disease, and all in-
fected trees were immediately removed and re-

placed with healthy trees from a certified citrus
stock program at the Fujian Academy of Agricul-
tural Sciences (Ke & Xu 1990). In another Chi-
nese program, part of the control program
involved hand-removal of summer flush in high
density citrus plantings following rice cultivation
(Aubert 1990b).

Regulatory Measures

If no citrus greening pathogen is present, D.
citri is not a major pest, and regulatory measures
are unnecessary; however, regulation of host ma-
terial is an essential part of managing citrus
greening disease. Initially, all citrus budwood and
liners should be tested and certified free of the
greening pathogens. Propagation material must
be kept isolated from psyllids and potential
sources of Candidatus Liberibacter spp. Lin &
Lin (1990) recommend eliminating all citrus and
citroids within 5-8 km of propagating nurseries.
In the Chinese program in Fujian discussed
above (Ke & Xu 1990), it was necessary to eradi-
cate all backyard citrus trees, as well as Murraya
and Clausena plants. The introduction of any cit-
rus or other Rutaceous plants into the area was
strictly forbidden. Additionally, all newly planted
trees were supplied by the Fujian Academy of Sci-
ences and certified free of greening.

Integrated Management

There is no place in the world where citrus
greening disease occurs that it is under com-
pletely successful management. In every place
where the disease occurs, life expectancy of citrus
trees is vastly reduced, and production losses are
significant to total. That having been said, in
many areas of the world, citrus production has
had to adapt to the presence of citrus greening.
The most successful management efforts combine
production of clean stock with psyllid control,
both within the grove and on alternative host
plants, and inoculum suppression after groves
are established. Taiwan is a case in point, where
Hung et al. (2000) and Su et al. (1986) state that
there are three main aspects to managing citrus
greening disease: Propagation of clean nursery
stock, psyllid control, and removal of potential in-
oculum sources. Many aspects of citrus greening
management are costly both in cash outlay, and in
lost production. The economic viability of citrus
production in a greening-endemic environment,
even with the best current management prac-
tices, certainly is not assured.

CAN CITRUS GREENING BE ERADICATED?

The success of any eradication program de-
pends upon the extent of the problem. Thus, early
detection is essential to the success of an eradica-

September 2004

Halbert & Manjunath: Diaphorina citri and Citrus Greening Disease

tion effort. Once the disease becomes widespread,
there is little hope of eradication, particularly if
the pathogen has become established in an un-
known number of native or ornamental non-cit-
rus hosts. Given an ideal situation with early
detection and very limited spread of the disease,
it may be possible to eradicate citrus greening dis-
ease successfully, especially in an island situa-
tion, but the outcome depends on a number of
factors.

Detection Capabilities

The success of any eradication program de-
pends on rapid and accurate diagnosis, preferably
in the field. It is unknown whether reliance on
symptoms, even by personnel with extensive
training in citrus greening symptom recognition,
will be sufficient to contain the problem. Cer-
tainty of diagnosis is vital, given today's legal cli-
mate (Gottwald et al. 2002; Schubert et al. 2001).
It is not known if vectors are able to transmit
greening pathogens from infected, but asymptom-
atic plants. If so, rapid diagnostic methods are
needed that can detect the presence of the patho-
gens prior to symptom expression in infected
plants. In any case, reliable, robust diagnostic
methods are needed to confirm infection with cer-
tainty if control action (i.e., tree removal) is nec-
essary. Research is needed in the area of rapid,
reliable diagnostics for citrus greening disease.
Detection of citrus greening disease in plants
is difficult because of the irregular distribution of
the pathogen in the host. While the currently
available molecular detection methods have pro-
vided us with a better understanding of the tax-
onomy of the organism and confirmation of the
disease in various parts of the world, there is a
need for robust universal diagnostic methods for
quarantine and eradication purposes. The pres-
ence of the vector in Florida and the increasing
numbers of interceptions of illegal plant materi-
als have made it impossible to neglect the need for
development of sensitive detection techniques for
citrus greening disease. The new PCR methods or
hybridization techniques should be sensitive
enough to detect very low levels of the pathogen
in both host and the vector, and not give false pos-
itives. This requires development of sequence in-
formation that is unique to citrus greening
pathogens. Citrus greening isolates are available
at present in the USDA quarantine facility, Belts-
ville, MD. Genome sequencing of citrus greening
should be given a high priority. This should en-
able us to develop better strategies for both detec-
tion and control.

Efficacy of Psyllid Control

Removal of infected and exposed host plants
could be extensive and expensive. It is not known

how far Asian citrus psyllid vectors can fly, but in-
formal estimates suggest that they might fly sev-
eral kilometers. Removal of all citrus trees within
a radius of several kilometers, especially in an ur-
ban environment, is likely to provoke extreme
public outcry. If psyllid vectors can be controlled
successfully, only infected plants would have to be
removed. Thus, safe and extremely effective psyl-
lid control probably is needed for successful erad-
ication. Depending upon the efficiency and
seasonality of transmission, it may not be neces-
sary to control citrus psyllids 100% all the time,
but research is needed on field infectivity of vec-
tors and seasonality of transmission.
Determining the host range of the psyllid vec-
tors is relatively easy compared with determining
the host range of the pathogens. Knowledge of
both, however, is needed for successful eradica-
tion. Hosts of vectors at least would need to be
treated to eliminate the insects within the regu-
lated area. Hosts of the pathogens would need to
be tested and removed if found to be infected.

Quarantines

Citrus greening pathogens are transmitted
only by psyllid vectors, grafting, dodder, and pos-
sibly seed. Dodder transmission probably can be
discounted in the field. Thus, only grafting, seed,
and vectors need to be considered in quarantine
regulations. Nurseries that produce hosts of ei-
ther pathogens or vectors would have to be quar-
antined very strictly, similar to citrus nurseries in
citrus canker quarantine areas (Florida Depart-
ment of Agriculture and Consumer Services
2000). Our experience has shown thatD. citri can
move on unprocessed fruit. Numerous D. citri
were intercepted in boxes of grapefruit picked in
the Bahamas and shipped to Ft. Pierce, Florida
for packing (Halbert & Nifiez 2004). Similarly, D.
citri certainly can move on leaf and twig material.
Thus, it may be necessary to quarantine all citrus
plant material within the regulated area, includ-
ing both citrus yard trash and fruit. Quarantine
treatments may be feasible for commercially pro-
duced fruit.
D. citri was able to colonize much of the state of
Florida as a result of shipments of orange jasmine
(M. paniculata) plants produced in southern Mi-
ami-Dade County and distributed through dis-
count chain stores (Halbert et al. 2002). During
the time that the distribution ofD. citri in Florida
was classified as limited, the DPI required pesti-
cide treatment of M. paniculata if D. citri was
found in a nursery. However, the actual producers
of the plants in Miami-Dade County frequently
were hard to find and proved impossible to regu-
late. It may be necessary to prohibit movement of
all potential hosts of citrus greening pathogens or
their vectors within the quarantine area. Mur-
raya paniculata now is considered a Category II

invasive plant (Florida Exotic Pest Plant Council
2003), which might give additional leverage to a
program to regulate its sale and distribution.

CONCLUSIONS

Citrus greening is a devastating disease, and
the prospects for maintaining an economically vi-
able citrus industry at current production levels
in Florida if citrus greening disease becomes es-
tablished are very poor, given current knowledge.
Keeping citrus greening pathogens out of Florida
should be given very high priority. In the mean-
time, surveys are necessary to find infected plants
as soon as possible if the disease becomes estab-
lished. Given a limited epidemic, eradication may
be possible, depending on circumstances. Scien-
tific research on the disease complex is greatly
needed, particularly in the areas of rapid field di-
agnosis, disease epidemiology and efficacy of psyl-
lid vector control.

ACKNOWLEDGMENTS

We thank John V. da Graca, Texas A&M University;
Mohammad Afunian, University of Florida, Lake Alfred;
Timothy S. Schubert, DPI; Wayne N. Dixon, DPI; Rich-
ard Lee, USDA, Riverside, California; Daniel Burck-
hardt, Naturhistorisches Museum, Basel, Switzerland;
Chester Roistacher, University of California, Riverside;
J. P. Michaud, Kansas State University; and Xiaoan
Sun, DPI, for reviews of the manuscript; Mark Garland
and Richard Weaver, both DPI, for botanical help; Dou-
glass Miller and Debra Creel, both USNM, and Daniel
Burckhardt (see above) for finding original descriptions
of obscure psyllids; Ian Millar, ARC-Plant Protection Re-
search Institute, South African National Collection of
Insects, Queenswood, Pretoria, South Africa and Dr.
G. J. Begemann, Transvaal Sugar Ltd., Komatipoort,
South Africa for photos of Diaphorina punctulata; and
Beverly Pope and Alice Sanders, both DPI for library as-
sistance. We thank Xiaoan Sun, DPI, for checking our
Chinese translations. We thank Dr. Thomas Dobbs,
USDA/APHIS/PPQ, Miami, for providing interception
information. We thank CSREES T-STAR for partial sup-
port for this project. This paper is Florida Agricultural
Experiment Station Journal Series No. R-10083.

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Florida Entomologist 87(3)