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Shapiro & McCoy: Nematodes us D. abbreviatus
SUSCEPTIBILITY OF DIAPREPES ABBREVIATUS
(COLEOPTERA: CURCULIONIDAE) LARVAE TO DIFFERENT
RATES OF ENTOMOPATHOGENIC NEMATODES IN THE
GREENHOUSE
D. I. SHAPIRO1 AND C. W. McCoY
University of Florida, Citrus Research and Education Center
700 Experiment Station Road, Lake Alfred, FL 33850
1Current address: USDA-ARS, SAA. 21 Dunbar Rd., Byron, GA 31008
ABSTRACT
The Diaprepes root weevil, Diaprepes abbreviatus, is an important field and nursery
pest of citrus and ornamentals in Florida and the Caribbean. Entomopathogenic nem-
atodes, Heterorhabditis indica Poinar, Kanunakar, and David and H. bacteriophora Poi-
nar, and Steinernema riobrave (Cabanillas, Poinar, and Raulston) were compared at
different rates for their ability to parasitize D. abbreviatus under greenhouse condi-
tions. Nematodes (0, 11, 22, 54, and 108 infective juveniles per cm2) were applied to
Candler sandy soil (9% moisture = approximately -0.035 bars), contained in plastic pots
with one D. abbreviatus larva, and a citrus seedling for food. The experiments were con-
ducted at two temperature ranges (22-25C and 26-30C). Steinernema riobrave caused
higher larval mortality compared with H. bacteriophora and H. indica, and was more
virulent at higher temperatures. At the higher temperature, smaller larvae (ca. 7th in-
star) were more susceptible to S. riobrave and H. bacteriophora than later instars (ca.
11th instar). Our results indicate that, under greenhouse conditions, S. riobrave has the
potential for achieving >90% weevil control at a rate of 22 infective juveniles per cm2.
Key Words: Biological control, Diaprepes abbreviatus, Steinernema riobrave, Heter-
orhabditis bacteriophora, H. indica, entomopathogenic nematodes
RESUME
El barrenador de raiz de la cana azuicar (Diaprepes abbreviatus) es una plaga im-
portante de los citricos y cultivos ornamentales en Florida y en el Caribe. Los nemi-
todos entomopatog6nicos, Heterorhabditis indica Poinar, Kanunakar y David, H.
bacteriophora Poinar y Steinernema riobrave (Cabanillas, Poinar y Raulston), fueron
empleados a diferentes niveles para evaluar su capacidad de parasitar a D. abbrevia-
tus bajo condiciones de invernadero. Los nematodos (a raz6n de 0, 11, 22, 54 y 108 ju-
veniles infectivos por cm2) se usaron en suelo arenoso chandler (con un contenido de
humedad de 9%) empleando macetas de plastico con una larva de D. addreviatus y
una plantula de de citrico como fuente de alimento. Los experiments se llevaron a
cabo bajo dos rangos de temperature, 22-25C y 26-30C. Steinernema riobrave caus6
mayor mortalidad de larvas que H. bacteriophora y H. indica, al mismo tiempo que
fue mas virulento en el rango alto de temperature. En el rango alto de temperature,
las larvas mas pequenas (ca. 70 instar) fueron mas susceptibles a S. riobrave y H. bac-
teriophora que larvas mas desarrolladas (ca. 11v instar). Nuestros resultados indican
que S. riobrave tiene el potential de lograr un control del barrenador superior al 90%
bajo condiciones de invernadero empleando 22 juveniles infectivos por cm2.
Florida Entomologist 83(1)
March, 2000
The Diaprepes root weevil, Diaprepes abbreviatus (L.), causes severe damage to
citrus, vegetables, sugarcane, and ornamentals in the Caribbean and Florida (McCoy
1995; 1999). This insect is potentially the most damaging weevil in Florida citrus
(Schroeder 1994). Diaprepes abbreviatus can be found infesting plants both in field
and nursery settings (McCoy et al. 1995). Infestation of nursery stock is of particular
significance because movement of seedlings and plants is one way D. abbreviatus is
spread from one area to another (Schroeder 1994; McCoy et al. 1995). Adult weevils
feed on foliage and deposit eggs between leaves within the canopy (Schroeder 1992).
Upon hatching, neonates fall to the ground and enter the soil where all instars feed
on the roots causing damage to the rhizosphere (Schroeder 1992).
Various root weevils, including D. abbreuiatus, are susceptible to entomopatho-
genic nematodes (Grewal & Georgis 1998). These nematodes are obligate parasites in
the genera Steinernema and Heterorhabditis that kill insects with the aid of a mutu-
alistic bacterium carried in the nematode's intestine (Poinar 1990). The nematodes
complete 2-3 generations within the host resulting in new free-living infective juve-
niles emerging from the host (Poinar 1990). Numerous biotic and abiotic factors can
affect nematode efficacy (Grewal & Georgis 1998).
Field applications of entomopathogenic nematodes can reduce larval populations
of D. abbreviatus (Schroeder 1990; Downing et al. 1991; Schroeder 1992; Duncan &
McCoy 1996; Duncan et al. 1996; Bullock et al. 1999). Four species of entomopatho-
genic nematodes have been sold commercially to suppress D. abbreviatus in citrus: S.
carpocapsae (Weiser), S. riobrave (Cabanillas, Poinar, and Raulston), H. bacterio-
phora Poinar, and H. indica Poinar, Karunakar, and David. Previous studies have in-
dicated clearly that S. carpocapsae is relatively inferior for control of D. abbreviatus
(Schroeder 1994, Duncan et al. 1996).
Previous comparisons between the heterorhabditids and S. riobrave, however, may
not have portrayed natural differences in species pathogenicity. Duncan et al. (1996)
and Duncan & McCoy (1996) reported S. riobrave to be superior to H. bacteriophora
in field suppression of D. abbreviatus larvae. It is not known, however, if the observed
differences in efficacy were due to innate characteristics of the nematodes or differ-
ences in production and formulation. In the laboratory, Shapiro et al. (1999) compared
S. riobrave, H. bacteriophora, and H. indica against D. abbreviatus and found differ-
ences in parasitism among the species that depended on larval age and temperature.
The results of these laboratory bioassays were not reflective of natural conditions par-
ticularly because nematode searching was limited to a maximum depth of 3.5 cm. In
sandy soils D. abbreviatus larvae have been found at depths greater than 3 m below
the soil surface (McCoy 1999). Additionally the study by Shapiro et al. (1999) was con-
ducted without a natural food source and at a single rate of nematodes. To further elu-
cidate the pathogenicity among candidate nematodes, we compared H. bacteriophora
and H. indica with S. riobrave at different rates under greenhouse conditions. The re-
sults indicate the potential for the use of entomopathogenic nematodes for larval con-
trol in container-grown plants.
MATERIALS AND METHODS
Larvae of Diaprepes abbreviatus (reared on artificial diet) were obtained from the
USDA-ARS Horticultural Laboratory (USDA-ARS, Orlando, FL). Heterorhabditis
bacteriophora (Lewiston strain) and H. indica (Homl) were obtained from Integrated
BioControl Systems, Inc. (Lawrenceburg, IN). Steinernema riobrave (Biovector 355)
was obtained from Thermo Triology Corporation (Columbia, MD). Before experimen-
tation, passage of nematodes through live hosts did not exceed five transfers. All nem-
atodes were reared at approximately 25C in last instar greater wax moth larvae,
Shapiro & McCoy: Nematodes us D. abbreviatus
Galleria mellonella (L.), according to procedures described in Woodring & Kaya
(1988). After harvesting, S. riobrave and H. bacteriophora were stored in tap water at
10C (Kaya & Stock, 1997) and H. indica at 15C (unpublished data) for up to 8 d be-
fore use. Viability of all nematodes was >95% at the time of application.
Experimental units consisted of plastic pots (4 cm i.d., 20 cm deep). Each pot con-
tained sand at 9% moisture (approximately -0.035 bars), one D. abbreviatus larva,
and one citrus seedling (Sun Shu Sha, approximately 0.5 cm diameter at the base).
For convenience, the seedling was cut off at the base approximately three days prior
to nematode application. Four rates of nematodes (11, 22, 54, and 108 infective juve-
niles per cm2) were applied in 1 ml of water using a micropipette. One ml of water was
added to control pots. After nematode application, the pots were tightly covered with
white plastic to inhibit soil moisture loss, and muslin cloth to provide shading. Water
was added to the soil every 3-4 d based on observed weight changes in a random se-
lection of eight pots.
Heterorhabditis bacteriophora and S. riobrave were compared at two temperature
regimes using two stages of larvae. In the first experiment, the nematodes were ap-
plied to pots in a greenhouse at a temperature range from 26-30C. In the second ex-
periment, the temperature ranged from 22-25C. In both experiments one half of the
pots received 7th instars and one half contained 11th instars; the stage of the insect
was determined by head capsule size and larval weight (Quintela et al. 1998). There
were three replicates often pots for each of the nine treatments (4 rates of two nem-
atodes and a control) and each of the two larval stages i.e., 540 pots per experiment.
Each experiment was repeated once (resulting in two trials per experiment). Larval
mortality was recorded 12 and 15 d post-treatment for the first and second trial, re-
spectively.
A third experiment compared H. indica and S. riobrave at two temperature ranges
simultaneously at the same temperatures as above (i.e., 26-30C and 22-25C). The
results of the previous experiments indicated that the effects of larval size were min-
imal compared to the nematode species effect. Therefore, only one stage (7th instar)
of D. abbreviatus was used in the third experiment. The third experiment was re-
peated once (i.e., two trials) and larval mortality was determined after 12 and 13 d for
the first and second trials, respectively.
The temperatures at which all experiments were conducted are reflective of soil
temperatures beneath the tree canopy in a Florida citrus grove during periods appro-
priate for nematode application (spring to fall). Soil temperatures of 22-25C are typ-
ical 15 cm below the surface under shaded or mature citrus trees (DuCharme 1971).
Soil temperatures of 26-30C are typical 15 cm below the surface in unshaded groves
or under young or damaged trees (DuCharme 1971).
Analysis of variance and Student-Newman-Keuls multiple range test (SAS 1985)
were used to analyze nematode effect for all rates combined, at each rate separately
(nematode x rate). Analysis of variance was also used to test differences due to tem-
perature and susceptibility of larval stages. Regression analysis (SAS 1985) was con-
ducted to determine the relationship between rate of nematode application and larval
mortality.
RESULTS
In experiment one (26-30C), for both larval stages, the nematode effect (for all
rates combined) was significant; S. riobrave caused greater mortality in D. abbrevia-
tus than H. bacteriophora (F = 329.7; df = 1,37; P < 0.0001, and F = 131.0; df = 1,40;
P < 0.0001, for 7th and 11th instars, respectively). Furthermore, S. riobrave caused
greater mortality than H. bacteriophora at each of the rates tested (Figs. 1A and B).
Florida Entomologist 83(1)
*Hb
DSr
a a a a 3 RControl
control 11 22 54 108
nematodes / cm2
100
80
60
40
20
control 11 22 54 108
Hb
Sr
Control
nematodes / cm2
Fig. 1. Nematode induced mortality of 7th (A) and 11th (B) instar D. abbreviatus
at 26-30C. Letters above bars indicate statistical significance (P < 0.05). Control, wa-
ter; Hb, Heterorhabditis bacteriophora; Sr, Steinernema riobrave.
Steinernema riobrave induced mortality (mean + SE) was greater in 7th instars (99.2
+ 2.8) than 11th instars (88.3 + 2.5) (F = 23.4; df = 1,44; P < 0.0001). Heterorhabditis
bacteriophora induced mortality (mean + SE) was also greater in 7th instars (50.5 +
March, 2000
Shapiro & McCoy: Nematodes us D. abbreviatus
3.7) than 11th instars (35.4 + 2.8) (F = 11.4; df = 1,41;P < 0.0016). Although the slopes
were small, a positive linear relationship was observed between rate of S. riobrave
andD. abbreviatus mortality in both stages of larvae (B, = 0.5 + 0.16; t = 7.6;P = 0.005;
R2 = 0.22, and B, = 0.5 + 0.15; t = 3.3; P = 0.0026; R2 = 0.25 for 7th and 11th instars,
respectively). Similar relationships were observed between the rate of H. bacterio-
phora andD. abbreviatus mortality (B, = 0.3 + 0.1; t = 3.3;P = 0.003; R = 0.28, andB,
= 0.25 + 0.07; t = 3.5;P = 0.0016;R2 = 0.28 for 7th and 11th instars, respectively).
In experiment two (at 22-25C), for both larval stages, the nematode effect (for all
rates combined) was significant; S. riobrave caused higher mortality in D. abbreviatus
than H. bacteriophora (F = 34.2; df = 1,40; P < 0.0001, and F = 26.1; df = 1,40; P <
0.0001, for 7th and 11th instars, respectively). Additionally, at most individual rates
tested, S. riobrave caused higher mortality than H. bacteriophora (Figs. 2 A and B).
Steinernema riobrave induced mortality (mean + SE) in 7th instars (84.1 + 2.9) was
not significantly different than 11th instars (81.7 + 3.9) (F = 0.06; df= 1,44;P < 0.81).
Additionally, H. bacteriophora induced mortality (mean + SE) was not significantly
different in 7th instars (57.1 + 4.4) compared with 11th instars (51.7 + 4.4) (F = 0.5;
df = 1,44; P < 0.49). Although the slopes were small, a positive linear relationship be-
tween rate of S. riobrave and D. abbreviatus mortality was observed in both stages of
larvae (B1 = 0.06 + 0.01; t = 4.2; P = 0.0002; R = 0.37, and B, = 0.05 + 0.02; t = 3.4; P
= 0.0021; R' = 0.27 for 7th and 11th instars, respectively). Similar relationships were
observed between the rate of H. bacteriophora andD. abbreviatus mortality (B = 0.05
+ 0.01; t = 4.3;P = 0.0002;R2 = 0.38, and Bl = 0.03 + 0.02; t = 2.7; P = 0.011; R = 0.18
for 7th and 11th instars, respectively).
In the third experiment, at both temperatures, the nematode effect (for all rates
combined) was significant; S. riobrave caused higher mortality than H. indica (F =
27.15; df = 2,45; P < 0.0001, and F = 84.91; df = 2,45; P < 0.0001, for the lower and
higher temperature regimes, respectively). Steinernema riobrave also caused higher
mortality than H. indica at most rates (Figs. 3 A and B). A positive linear relationship
between rate of Steinernema riobrave and D. abbreviatus mortality was detected at
both temperature regimes (B, = 0.4 + 0.12; t = 3.6;P = 0.0014; R = 0.29, and B, = 0.56
+ 0.12; t = 4.5; P = 0.0001; R = 0.40 for the lower and higher temperature regimes, re-
spectively). Similar relationships were observed between the rate of H. indica and D.
abbreviatus mortality (B, = 0.28 + 0.10; t = 2.8; P = 0.0101; R' = 0.19, and B, = 0.30 +
0.13; t = 2.5; P = 0.033; R2 = 0.18 for lower and higher temperature regimes, respec-
tively). Mortality caused by S. riobrave was greater at the higher temperature regime
compared with the lower temperature regime (B, = 40.61; df = 5,90; P < 0.0001).
DISCUSSION
Our comparisons of pathogenicity were more reflective of the natural or intrinsic
abilities of entomopathogenic nematodes to suppress D. abbreviatus than previous
field and laboratory studies. Previous research (Duncan et al. 1996, Duncan & McCoy
1996) found greater field suppression of D. abbreviatus with S. riobrave compared
with H. bacteriophora. In those studies, however, the two nematodes were produced
and formulated under different conditions. Therefore, differences in field efficacy in-
volved both nematode production and formulation technology as well as species dif-
ferences. We demonstrated that S. riobrave is innately more virulent to D. abbreviatus
than H. bacteriophora and H. indica when the nematodes are cultured and compared
in parallel.
Host stage may affect the susceptibility of insect hosts to entomopathogenic nem-
atodes (Fuxa et al. 1988, Shapiro et al. 1999). Shapiro et al. (1999) reported that older
Florida Entomologist 83(1)
100
80
S60
E 40
o.R
control 11 22 54 108
nematodes / cm2
*Hb
EOSr
R Control
control 11 22 54 108
nematodes / cm2
Fig. 2. Nematode induced mortality of 7th (A) and 11th (B) instar D. abbreviatus
at 22-25C. Letters above bars indicate statistical significance (P < 0.05). Control, wa-
ter; Hb, Heterorhabditis bacteriophora; Sr, Steinernema riobrave.
instars of D. abbreviatus are more susceptible to entomopathogenic nematodes than
younger instars. This study confirmed the above finding at warmer temperatures but
not at cooler temperatures. The cause of this discrepancy between temperatures is not
EIHb
OSr i
S Control|
March, 2000
Shapiro & McCoy: Nematodes us D. abbreviatus
a a
control 11 22 54 108
nematodes / cm2
control 11 22 54 108
nematodes / cm2
Fig. 3. Nematode induced mortality of 7th instar D. abbreviatus at 26-30C (A) and
22-25C (B). Letters above bars indicate statistical significance (P < 0.05). Control,
water; Hi, Heterorhabditis indica; Sr, Steinernema riobrave.
known but we observed that all variables (species, larval size) were more pronounced
at warmer temperatures providing more power to the statistical analyses.
Our results indicate that S. riobrave is more virulent to D. abbreviatus at warmer
temperatures. Similarly, Grewal et al. (1994) reported that S. riobrave infectivity
100
80
60
E 40
20
0
* Hi
lCSr
B Control
100
80
60
40
20
0
9 Control
Florida Entomologist 83(1)
March, 2000
(nematode penetration) in G. mellonella, increased continually with temperature up
to 35C. Our results did not detect an effect of temperature on H. indica within the
ranges tested. Shapiro et al. (1999) reported that both S. riobrave and H. indica had
greater virulence against D. abbreviatus at 24C and 27C relative to 21C.
Rate of application is critical to entomopathogenic nematode efficacy (Grewal &
Georgis 1998). Field efficacy against D. abbreviatus has been achieved using high rates
of 108 infective juveniles (Ijs) per cm2 or more (Downing et al. 1991, Duncan & McCoy
1996, Duncan et al. 1996, Bullock 1999). Field rates currently recommended by com-
mercial companies that sell nematodes for control of D. abbreviatus are substantially
lower (from 11 to 25 Ijs per cm2). Successful field application in most other commodities
has required rates of 25 Ijs per cm2 or higher (Georgis & Hague 1991, Grewal & Georgis
1998). In the present study, the heterorhabditid species did not provide >80% suppres-
sion of D. abbreviatus under any conditions. Contrarily, in the warmer greenhouse, S.
riobrave provided high levels of mortality (>80%) to D. abbreviatus at rates as low as
11 Ijs per cm2. However, insects are generally less susceptible to nematode parasitism
in the field than in the laboratory or greenhouse under controlled conditions (Georgis
et al. 1991, Grewal & Georgis 1998). We are currently conducting research to deter-
mine optimum rates ofS. riobrave and H. indica under field conditions.
In addition to being severe pests of field crops, D. abbreviatus is also an important
pest of citrus and woody ornamentals in both nurseries and greenhouses (McCoy et al.
1995). Our data indicate that S. riobrave is superior to H. indica (Homl) and H. bac-
teriophora (Lewiston) in reducing larval populations of D. abbreviatus under green-
house conditions. In addition, we found that the virulence of several other strains of
H. bacteriophora (Baine, Hb, HbL, and HP88) and H. indica (original strain) are not
significantly different from the strains used in this study (unpublished data). The
value of nursery stock dictates an extremely low economic threshold. Although S. ri-
obrave provided up to 100% larval control with rates as low as 11 Ijs per cm2, further
research is required to determine what rates can achieve adequate root protection for
container-grown plants in greenhouses.
ACKNOWLEDGMENTS
We thank I. Jackson, A. Hoyte and S. Hoobin for technical assistance and Drs. J. P.
Michaud, K. Nguyen, and G. C. Smart for reviewing an earlier draft of this manu-
script. We are also very grateful to the USDA-ARS Horticultural Research Laboratory
(Orlando, FL) and K. Crosby for providing us with D. abbreviatus larvae. Florida Ag-
ricultural Experiment Station Journal Series No. R-07004.
REFERENCES CITED
BULLOCK, R. C., R. R. PELOSI, AND E. E. KILLER. 1999. Management of citrus root wee-
vils (Coleopetera: Curculionidae) on Florida citrus with soil-applied ento-
mopathogenic nematodes (Nematoda: Rhabditida). Florida Entomol. 82: 1-7.
DOWNING A. S., C. G. ERICKSON, AND M. J. KRAUS. 1991. Field evaluations of ento-
mopathogenic nematodes against citrus root weevils (Coleoptera: Curculion-
idae) in Florida citrus. Florida Entomol. 74: 584-586.
DUNCAN, L. W., AND C. W. MCCOY. 1996. Vertical distribution in soil, persistence, and
efficacy against citrus root weevil (Coleoptera: Curculionidae) of two species of
entomogenous nematodes (Rhabditida: Steinernematidae; Heterorhabditidae).
Environ. Entomol. 25: 174-178.
DUNCAN, L. W., C. W. MCCOY, AND C. TERRANOVA. 1996. Estimating sample size and
persistence of entomogenous nematodes in sandy soils and their efficacy
against the larvae of Diaprepes abbreviatus in Florida. J. Nematol. 28: 56-67.
Shapiro & McCoy: Nematodes us D. abbreviatus
DUCHARME, E. P. 1971. Soil temperature in Florida citrus groves. Agric. Exp. Stat.
Inst. Food Agric. Sci. University of Florida, Gainesville. Bull. no. 747. pp. 1-15.
FUXA J. R., F. AGUDELO-SILVA, AND A. R. RICHTER. 1988. Effect of host age and nem-
atode strain on susceptibility of Spodoptera frugiperda to Steinernema feltiae.
J. Nematol. 20: 91-95.
GEORGIS, R., AND N. G. M. HAGUE. 1991. Nematodes as biological insecticides. Pesti-
cide Outlook 2: 29-32.
GEORGIS, R., H. K. KAYA, AND R. GAUGLER. 1991. Effect of steinernematid and heter-
orhabditid nematodes (Rhabditida: Steinernematidae and Heterorhabditidae)
on nontarget arthropods. Environ. Entomol. 20: 815-822.
GREWAL, P. S., S. SELVAN, AND R. GAUGLER. 1994. Thermal adaptation of ento-
mopathogenic nematodes: niche breadth for infection, establishment, and re-
production. J. Therm. Biol. 19: 245-253.
GREWAL P., AND R. GEORGIS. 1998. Entomopathogenic nematodes. In Hall, F. R., and
J. J. Menn (eds.), Methods in Biotechnology, Vol. 5: Biopesticides: Use and De-
livery. Humana Press, Totowa, NJ.
KAYA, H. K., AND S. P. STOCK. 1997. Techniques in insect nematology. In Lacey, L. A.
[ed.], Manual of Techniques in Insect Pathology. Academic Press, San Diego, CA.
McCoY, C. W. 1995. Past and current IPM strategies to combat the spread of Di-
aprepes abbreviatus (L.) in Florida citrus. Proc. Caribbean Food Crops Soc. 30:
247-256.
McCoY, C. W. 1999. Arthropod pests of citrus roots. In Timmer, L. W., and L. W. Dun-
can (eds.), Citrus Health Management. Am. Phytopathol. Soc., St. Paul, MN.
pp. 149-156.
McCoY, C. W., E. D. QUINTELA, S. E. SIMPSON, AND J. FOJTIK. 1995. Effect of surface-
applied soil-incorporated neonate larvae of Diaprepes abbreviatus in container-
grown citrus. Proc. Fla. Stat. Hort. Soc. 108: 130-136.
POINAR, G. 0. 1990. Biology and taxonomy of Steinernematidae and Heterorhabditi-
dae. pp 23-62. In Gaugler, R., and H. K. Kaya (eds.), Entomopathogenic Nema-
todes in Biological Control. CRC Press, Boca Raton, FL.
QUINTELA, E. D., J. FAN, AND C. W. McCOY. 1998. Development of Diaprepes abbre-
viatus (Coleoptera: Curculionidae) on artificial and citrus root substrates.
J. Econ. Entomol. 91: 1173-1179.
SAS. 1985. SAS Users Guide: Version 5 ed. SAS Institute, Cary, NC.
SCHROEDER, W. J. 1990. Suppression of Diaprepes abbreviatus Coleoptera: Curculion-
idae) adult emergence with soil application of entomopathogenic nematodes
(Nematoda: Rhabditida). Florida Entomol. 73: 680-683.
SCHROEDER, W. J. 1992. Entomopathogenic nematodes for control of root weevils of cit-
rus. Florida Entomol. 75: 563-567.
SCHROEDER, W. J. 1994. Comparison of two steinernematid species for control of the
root weevil Diaprepes abbreviatus. J. Nematol. 26: 360-362.
SHAPIRO, D. I., J. R. CATE, J. PENA, A. HUNSBERGER, AND C. W. McCOY. 1999. Effects
of temperature and host age on suppression of Diaprepes abbreviatus (Co-
leoptera: Curculionidae) by entomopathogenic nematodes. J. Econ. Entomol.
92: 1088-1092.
WOODRING, J. L., AND H. K. KAYA. 1988. Steinernematid and heterorhabditid nema-
todes: A handbook of biology and techniques. Southern Cooperative Series Bul-
letin 331., Arkansas Agric. Exp. Stat., Fayetteville, NC.
Florida Entomologist 83(1)
March, 2000
SOIL-FREE COLLECTION OF ARGENTINE ANTS
(HYMENOPTERA: FORMICIDAE) BASED ON FOOD-DIRECTED
BROOD AND QUEEN MOVEMENT
JULES SILVERMAN'2 AND BAKISI NSIMBA1
1Clorox Technical Center, 7200 Johnson Drive, Pleasanton, CA 94588 U.S.A.
2Current address: Department of Entomology, North Carolina State University
Raleigh, NC 27695-7613
ABSTRACT
The movement of Argentine ant, Linepithema humile (Mayr), colonies was studied
in the laboratory. Workers transported brood from the main colony to satellite nests
within 2 h. Queens also moved into the satellite nests. Up to 70% of the brood were
moved out of the main colony by 48 h. Although most of the brood and queens mi-
grated to a satellite nest 60 cm from the main nest, a substantial number of brood and
queens moved 12.2 m to a nest 60 cm from a food source. We subsequently employed
these findings to induce a portion of a field colony ofL. humile to enter artificial colony
dishes within the laboratory. Workers, brood, and queens were collected continuously
and effortlessly using this technique.
Key Words: Argentine ant, Linepithema humile, colony movement, soil-free, collection
RESUME
Se estudi6 el movimiento de colonies de la hormiga Argentina (Linepithema hu-
mile Mayr) bajo condiciones de laboratorio. Las hormigas trabajadoras comenzaron a
transportar a las hormigas j6venes desde la colonia principal a nidos satelite en me-
nos de dos horas. Las reinas tambien se mobilizaron hacia los nidos satelite. Hasta un
70% de las hormigas j6venes fueron sacadas de la colonia principal en un lapso de 48
horas. Aunque la mayoria de las hormigas j6venes y reinas emigraron hacia nidos sa-
telites ubicados a 60 cm del nido principal, una cantidad sustancial de hormigas j6ve-
nes y reinas se mobilize 12.2 m para ubicarse en un nido a 60 cm de una fuente de
alimento. Estos resultados sirvieron para inducir a una porci6n de una colonia de
campo de L. humile a penetrar en platos de colonies artificiales dentro del laboratorio.
Esta t6cnica permiti6 colectar trabajadores, hormigas j6venes y reinas con much fa-
cilidad y de manera continue.
Colony migrations are common in a number of ant species. Entire colonies may
move to a new location in response to a major disturbance to the nest, divide into sub-
colonies with a continuous exchange of foragers (satellite formation), or multiply
when one or more fertilized queens depart the nest with a cadre of workers, ultimately
establishing independent colonies (Holldobler & Wilson 1990). Colony migrations
commonly occur in temperate woodland ant species without obvious provocation
(Smallwood & Culver 1979, Smallwood 1982, Herbers 1985). However, colony emigra-
tion may also be induced by competition (Holldobler 1976), predation (Droual & Topoff
1981) and the need to find food (Topoff & Mirenda 1980).
The Argentine ant, Linepithema humile, is a pest of urban, agricultural and ripar-
ian woodland habitats which has spread widely, particularly in Mediterranean and
Silverman & Nsimba: Soil-Free Ant Collection
subtropical regions (Markin 1970a, Ward 1987, Holldobler & Wilson 1990). The polyg-
ynous and polydomous colonies of L. humile occur over vast areas of California devel-
oped by human activity (Markin 1968a). Like other tramp ant species, L. humile
tends to have fragile nest sites (Passera 1994) and has been reported to partially or
completely abandon their nests in response to adverse conditions such as excess mois-
ture or dryness (Markin 1968a). In addition, colony foundation via migration from the
original colony has been reported in L. humile with new nests occasionally con-
structed near a food supply (Newell & Barber 1913).
Laboratory study of L. humile biology, behavior and control requires initial field
collection of colonies, or colony fragments, containing one or more fertile queens,
brood and workers. The standard collection process is fairly laborious, involving first
the location of the colony followed by its excavation and transport to the laboratory.
The final step, perhaps the most time-consuming activity, requires the separation of
ants from the often large amounts of soil excavated with the ants (Markin 1968b,
Baker et al. 1985, Knight & Rust 1990).
Movement of Argentine ant brood and queens was mentioned earlier (Newell &
Barber 1913, Wilson 1971). Herein, we report more detailed experimental evidence
about the movement of laboratory colonies of L. humile proximal and distal to a food
source. Furthermore, we describe a continuous, soil-free method for collecting field
ants which exploits brood and queen transport behavior. This method is simple and al-
lows the investigator to procure large numbers of ants, which are more likely to ex-
press field characteristics than long-standing laboratory colonies.
MATERIALS AND METHODS
Collection of Original Colonies
Laboratory colonies were established from nest sites in soil excavated from an
open field bordering a suburban housing development in Alameda County, California,
using a method similar to Markin (1968b) and Knight & Rust (1990). Soil containing
L. humile workers, brood and queens was spread out in a 55 cm by 40 cm by 30 cm
plastic container coated with teflon (E. I. Du Pont de Nemours Co. Wilmington, Dela-
ware) to prevent ant escape. Artificial colony dishes were constructed in a manner
similar to Markin (1970b). Plastic petri dishes (9 cm dia.) were filled with casting
plaster to a depth of 2 cm and affixed to the lid of a 200 ml glass jar. A 13 mm dia. hole
was drilled through the dish and jar lid and a piece of plastic tubing (20 mm length)
was glued to the hole. The petri dish-jar lid was fitted to ajar with water, and a length
of cotton dental wick was inserted through the plastic sleeve. The plastic sleeve al-
lowed the sealed plaster chamber housing the ants to maintain a high humidity with-
out the plaster becoming saturated. Grooves were etched into the plaster to increase
the surface area of the artificial nest. Two nest entrances were fitted with truncated
plastic pipette tips so that tubing could be attached to the nest for experiments. An
opaque cover was placed over the nests and they were placed within the container
holding the ants and soil. As the soil dried, the colony moved into the constructed
nests within 14 days.
Laboratory Investigation of Brood and Queen Movement
We determined the rate of queen and worker-assisted brood migration from their
original colony dish to satellite nests in the absence of an environmental disturbance.
A nest containing ca 2000 workers, 1000 brood pieces and 25 queens was placed inside
a teflon-coated 243 cm by 150 cm by 5 cm arena (Fig. 1). Plastic tubing (12.2 m by 1.2
Florida Entomologist 83(1)
March, 2000
12.2 m
60 cm
60 cm
Fig. 1. Diagram of the nest relocation experiment showing the locations of the
main colony (MC) satellite nests (SN) and food (F).
cm inside dia.) was attached to one nest entrance, while the other was blocked with
modeling clay. Food (0.25 M sucrose plus cockroaches [Blattella germanica]) was pro-
vided at the tubing port distal to the colony. A 30 cm length of tubing was attached via
a y-connector to the main foraging line 30 cm from the colony entrance and 30 cm from
the food. Satellite nests (see colony dish description above) were attached to each of
the ends of these branches. Access to the satellite nests was blocked for three days
while a foraging trail was established between the main colony and the food. There-
after, ants had access to the satellite dishes. The number of brood and queens in the
satellite nests were counted at 2, 4, 8, 16, 24 and 48 h intervals. Afterwards, the num-
ber of brood and queens remaining in the main colony were counted and the percent
of brood and queen movement over time was calculated. Ten replicates (colonies) were
conducted. Near-colony v near-food brood and queen distributions at 48 h were com-
pared with paired Wilcoxon signed-rank tests (BBN Software Co. 1995).
Establishing Continuous Recruitment of Field Ants into the Laboratory
A L. humile trail from a field colony was first noted September, 1996 along the out-
side edge of a threshold at a remote corner of our insectary. We attempted to induce
L. humile workers to trail just inside the insectary for the purpose of conducting fairly
realistic food acceptance studies for ant bait development, and collecting all stages of
field ants for other laboratory studies. Synthetic cis-9-hexadecenal (Aldrich Chemical
Co., Milwaukee, Wisconsin), the major trail pheromone component of L. humile, was
applied at a rate of 200 ng/100 cm (Key & Baker 1982) in a continuous line between
the existing trail onto the top of a wooden table (80 cm by 80 cm by 100 cm high). Drop-
lets of 0.25 M sucrose were placed sequentially along the chemical trail every 10 cm
to encourage recruitment. Workers reaching the table top were provided freshly killed
cockroaches (B. germanica) along with 0.25 M sucrose in a cotton-stoppered vial. A
moistened, plaster-filled petri dish with an opaque cover was placed along the trail in
an effort to attract and capture queens and brood. A study was initiated in December,
1998 to quantify L. humile movement indoors. The number of workers, brood and
queens moving into each of three dishes within a 24-h period was determined once on
each of 10 successive weeks.
Silverman & Nsimba: Soil-Free Ant Collection
RESULTS AND DISCUSSION
Laboratory Investigation of Brood and Queen Movement
Workers explored the satellite nests within 5 minutes, once access was allowed.
Within 2 hours, both brood and queens were observed in both satellite colony dishes,
with numbers increasing in the new nests through 48 hours (Fig. 2). Although more
brood were transported to the new nest closer to the colony than to the food, the
counts were not significantly different at 48 h (Wilcoxon statistic = 14; critical value
= 8; P > 0.05). Also, the distribution of queens between the 2 new nests was not sig-
nificantly different (Wilcoxon statistic = 12.5; critical value = 8; P > 0.05). Mechanical
disturbance, flooding, or light or air currents entering the brood chambers generally
causes an immediate response by the colony, either in the form of a retreat into the
nest interior or emigration from the nest (Holldobler & Wilson 1990). We allowed a 3-
d acclimation period, and were careful not to disturb the colonies or foraging conduits,
yet some brood and queens exited the main nest within a relatively short period of
time. We considered that brood and queen relocation in our study may have been in
response to high nest density and/or suboptimal environmental conditions such as hu-
midity or moisture. Smallwood & Culver (1979) speculated that colony emigration
may be in response to the build-up of waste products in the nest. This was based on
the laboratory observation that ants will abandon a fouled artificial nest in favor of an
alternative clean nest. However, if the nest environment was unfavorable, we would
have expected complete, or nearly complete, evacuation of the primary nest. In our
studies, no more than 70% of the brood was transported from the primary nest, and
in 8 of the 10 colonies less than 50% of the brood was moved. Therefore, it appears that
L. humile inherently exploits new habitats, including those close to a reliable, abun-
dant food source.
Establishing Continuous Recruitment of Field Ants into the Laboratory
Worker ants from the field colony followed the pheromone trail into the laboratory,
along the door frame, and onto the top of the table. Recruitment was rapid and forag-
ing activity was intense once the food was located (Fig. 3a, b). Although we used both
trail pheromone and food to effect recruitment, it is quite possible that one or the
other could have directed workers to the table top. Consequently, this approach may
35
30
S---Brood near colony
0 20 ---Brood near food
10 -1M--Queens near colony
5 --Queens near food
2 4 8 16 24 48
Time After Satellite Nest Access (h)
Fig. 2. Distribution of L. humile brood and queens in satellite nests 60 cm (near
colony) from the main nest and 12.2 m (near food) from the main nest. Each data point
represents the mean (+SEM) fraction of the total brood and queen population (n = 10
colonies) in the satellite nests.
Florida Entomologist 83(1)
March, 2000
-M r
Fig. 3. Continuous movement of a L. humile field colony between an outdoor nest
and a table top within the laboratory. A) Ant foraging surface with food (0.25 M su-
crose [back left], German cockroaches [back center]) and collection dishes (fore-
ground). B) L. humile trail along door frame, including queen (arrow). C) Collection
dish containing workers and brood (arrow).
be effective in ant species for which no synthetic trail pheromone is available. Worker
activity was restricted to the table top as long as cockroaches and sucrose were con-
tinuously provided.
Silverman & Nsimba: Soil-Free Ant Collection
10000
1000
: !-4-V Workers
|Brood
L I -A--- Queens
S,10
1 2 3 4 5 6 7 8 9 10
Week
Fig. 4. Total L. humile field workers, brood and queens collected in 3 petri dishes
within 24 h at each of 10 weekly time points.
De-alated queens and workers carrying brood were observed on some occasions
(Fig. 3b) moving between the colony and food source. Initially, workers entered and ex-
plored the artificial harborage, but neither queens nor brood were collected. However,
after several weeks, queens, brood and workers moved into the harborage. This sys-
tem was established in September, 1996. Since that time, we have continuously col-
lected workers, queens and all stages of brood (Fig. 3c). Ten collections, each over a 24-
h period between December, 1998 and March, 1999 revealed several thousand work-
ers and brood, and over 10 queens (Fig. 4). When the plaster collection dishes were
filled, the ants were transferred to larger holding containers until used in behavioral
and efficacy experiments.
Our findings corroborate earlier observations of Newell & Barber (1913) that L.
humile transported colony members close to a continuous food source. To some degree
this behavior resembles the habit of a nomadic ponerine ant, Amblyopone pallipes,
where larvae are often transported to raided food instead of vice versa (Wilson 1958).
This food procurement strategy would appear to be more energetically efficient than
food transport in species which construct temporary nests and where the food supply
is reliable. A collection method which exploits this behavior should apply broadly to L.
humile in other settings and possibly to other polygynous ant species that expand
their colonies through partial emigration.
REFERENCES CITED
BAKER, T. C., S. E. VAN VORHIS KEY, AND L. K. GASTON. 1985. Bait preference tests for
the Argentine ant (Hymenoptera: Formicidae). J. Econ. Entomol. 78: 1083-1088.
BBN SOFTWARE PRODUCTS. 1995. RS/1 User's Guide, Release 5.2. Cambridge, MA.
DROUAL, R., AND H. TOPOFF. 1981. The emigration behavior of two species of the ge-
nus Pheidole (Formicidae: Myrmicinae). Psyche. 88: 135-150.
HERBERS, J. M. 1985. Seasonal structuring of a north temperate ant community. In-
sectes soc. 32: 224-240.
Florida Entomologist 83(1)
March, 2000
HOLLDOBLER, B. 1976. Recruitment behavior, home range orientation and territorial-
ity in harvester ants, Pogonomyrmex. Behav. Ecol. and Sociobiol. 1: 3-44.
HOLLDOBLER, B., AND E. 0. WILSON. 1990. The Ants. The Belknap Press of Harvard
University Press, Cambridge, Mass. 732 pp.
KEY, S. E. VAN VORHIS, AND T. C. BAKER 1982. Trail following responses of the Ar-
gentine ant, Iridomyrmex humilis (Mayr), to a synthetic trail pheromone com-
ponent and analogs. J. Chem. Ecol. 8: 3-14.
KNIGHT, R. L., AND M. K. RUST. 1990. Repellency and efficacy of various insecticides
against foraging workers in laboratory colonies of the Argentine ant (Hy-
menoptera: Formicidae). J. Econ. Entomol. 83: 1402-1408.
MARKIN, G. P. 1968a. Nest relationship of the Argentine ant, Iridomyrmex humilis
(Hymenoptera: Formicidae). J. Kans. Entomol. Soc. 41: 511-516.
MARKIN, G. P. 1968b. Handling techniques for large quantities of ants. J. Econ. Ento-
mol. 61: 1744-1745.
MARKIN, G. P. 1970a. The seasonal life cycle of the Argentine ant, Iridomyrmex humi-
lis (Hymenoptera: Formicidae), in Southern California. Ann. Entomol. Soc.
Amer. 63: 1238-1242.
MARKIN, G. P. 1970b. Food distribution within laboratory colonies of the Argentine
ant, Iridomyrmex humilis (Mayr). Insectes. Soc. 17: 127-158
NEWELL, W., AND T. C. BARBER. 1913. The Argentine ant. USDA Bureau of Entomol-
ogy Bulletin 122.
PASSERA, L., 1994. Characteristics of tramp species. IN: Exotic Ants. Biology, Impact,
and Control of Introduced Species. (D. Williams, Ed.), Westview Press, Boulder,
San Francisco, Oxford. pp. 21-43.
SMALLWOOD, J. 1982. Nest relocations in ants. Insectes soc. 29: 138-147.
SMALLWOOD, J., AND D. C. CULVER. 1979. Colony movements of some North American
ants. J. Anim. Ecol. 48: 373-382.
TOPOFF, H. R., AND J. MIRENDA. 1980. Army ant on the move: relation between food
supply and emigration frequency. Science. 207: 1099-1100.
WARD, P. S. 1987. Distribution of the introduced Argentine ant (Iridomyrmex humilis)
in natural habitats of the lower Sacramento Valley and its effects on the indig-
enous ant fauna. Hilgardia. 55: 1-16.
WILSON, E. 0. 1958. The beginnings of nomadic and group predatory behavior in the
ponerine ants. Evolution. 12: 24-36.
WILSON, E. 0. 1971. The Insect Societies. The Belknap Press of Harvard University
Press, Cambridge, Mass. 548 pp.
Taylor & Wood: Hydrometra: Food and Substrate Effects 17
REARING HYDROMETRA MARTINI (HETEROPTERA:
HYDROMETRIDAE): FOOD AND SUBSTRATE EFFECTS
STEVEN J. TAYLOR1 AND D. L. WOOD2
1Center for Biodiversity, Illinois Natural History Survey
607 East Peabody Drive, Champaign, Illinois 61820 USA
2Department of Biology, Sul Ross University, Alpine, Texas 79832 USA
ABSTRACT
Hydrometra martini Kirkaldy was reared using two food treatments (Sminthu-
rides malmgreni [Tullberg] or Drosophila melanogaster Meigen) and two substrate
treatments (filter paper or duckweed) to investigate the effects of differing food and
substrate on stadium and survivorship. Food, substrate, and the interaction of food
and substrate affected survivorship and stadium lengths, but effects varied among in-
stars. To maximize laboratory survivorship, the data indicate that the more effective
food was Sminthurides on a filter paper substrate and Drosophila on a duckweed sub-
strate.
Key Words: Hydrometra martini, laboratory rearing, survivorship, stadium
RESUME
Hydrometra martini Kirkaldy fue criada empleando dos fuentes de alimento
(Sminthurides malmgreni [Tullberg] o Drosophila melanogaster Meigen) y dos sus-
tratos (papel filtro o "duckweed"). El objetivo del studio fue determinar los posibles
efectos de distintas fuentes de alimento y diferentes sustratos en la duraci6n y super-
vivencia de cada estadio. La fuente de alimento, sustrato y la interacci6n de fuente de
alimento y sustrato afectaron la supervivencia y duraci6n de cada estadio, pero los
efectos variaron entire instars. Los resultados indicaron que las mejores fuentes de ali-
mento fueron Sminthurides sobre sustrato de papel filtro y Drosophila sobre sustrato
de "duckweed".
Our knowledge of hydrometrid biology and ecology in North America is based pri-
marily on Sprague's (1956) monographic study of the biology and morphology of Hy-
drometra martini Kirkaldy, Lanciani's (1971, 1975, 1991, 1995) studies of Hydrometra
australis Say and its relationship with water mites, and Wood and McPherson's
(1995) life history study of Hydrometra hungerfordi Torre-Bueno.
Lanciani (1991) compared H. australis reared on springtails (Collembola: Smin-
thuridae: Sminthurides sp.) with those he had reared earlier (Lanciani 1975 [as Hy-
drometra myrae Torre-Bueno]) on fruit flies (Diptera: Drosophilidae: Drosophila
melanogaster Meigen). He found that hydrometrid stadia were shorter and survivor-
ship was higher when springtails were used as food. He suggested that aquatic Col-
lembola may provide important nutrients that are lacking in fruit flies. Lanciani
reared the animals under identical temperature and photoperiod regimes, but the two
studies were conducted using differing substrates (paper in 1975, duckweed in 1991).
Lanciani (1991), using a duckweed substrate, successfully reared H. australis
through 2nd instar on collembolans, with subsequent instars receiving Drosophila as
Florida Entomologist 83(1)
March, 2000
food, while a control group reared exclusively on Drosophila failed to reach adults.
The survivorship differences related to food seem plausible, but we felt that some af-
fect could be attributed to the rearing substrates. We investigated this possibility by
rearing H. martini under both of the food and substrate conditions employed by Lan-
ciani (1975, 1991). Food and survivorship were then examined as factors influencing
survivorship and stadia.
Lanciani (1975, 1991) used H. australis in his studies, but the widespread occur-
rence of character states intermediate between those of H. australis and H. martini
(Bennett & Cook 1981; Gonsoulin 1973; S. J. Taylor, unpublished data) suggests that
these two species are synonymous (Polhemus & Chapman 1979; J. T. Polhemus 1996,
Colorado Entomological Museum, Englewood, personal communication). Thus, our
findings should be comparable to Lanciani's (1975, 1991) work. Following Smith
(1988), we treat Illinois specimens as H. martini.
MATERIALS AND METHODS
Forty-nine micropterous (sensu Polhemus & Polhemus 1987) adult H. martini
were collected from Crab Orchard Lake (Williamson County, Illinois) on September 6,
1991, within 2 m of the shoreline from shallow (<0.3 m), still, unshaded water with
abundant floating and emergent vegetation. The specimens (32 2 9, 17 6 6) were di-
vided randomly into four screen-covered, one-quart mason jars, each with about 3 cm
of dechlorinated tap water and three floating plastic disks. Disks were 4 cm in diam-
eter, each with five 5.5 mm diameter holes. The disks provided a dry retreat and ovi-
position substrate. Frozen D. melanogaster were provided ad libitum to each container.
Each day, fruit flies were replaced and the disks rinsed, dried and returned to the jars.
Oviposition containers were incubated at a constant photoperiod (12L:12D) and tem-
perature (28 + 1C), which was the same temperature and photoperiod used by Lan-
ciani (1975, 1991). Three "daylight" fluorescent lamps provided approximately 2800
lux. Eggs from the ovipositional containers were removed daily and distributed in
equal numbers into each of four experimental groups described below. Sufficient eggs
were collected in four days to rear 40 individuals in each of four treatments.
Screw top, straight-sided plastic containers (4.25 cm tall and 4.8 cm inside diam-
eter) were used to test duckweed substrate and filter paper substrate treatments. The
duckweed substrate treatment consisted of 80 containers filled approximately half
full (2 cm) of dechlorinated tap water that was covered with a dense layer of Lemna
minor L., Spirodela polyrhiza (L.), and Wolffia papulifera Thompson (Lemnaceae),
collected from a pond in Carbondale, Illinois. These species are widespread in Illinois
(Weik & Mohlenbrock 1968). One H. martini egg was placed in the center of each con-
tainer on a large S. polyrhiza leaf. Containers were covered with a piece of fiberglass
screening (1 mm2 mesh) secured with a rubber band. The screen top duplicated con-
ditions of Lanciani (1991).
The filter paper substrate treatment consisted of 80 containers with a 4.8 cm di-
ameter circular piece of Eaton-Dikeman (Mt. Holly Springs, PA) grade 617 filter paper
placed in the bottom of each container. These containers were tilted at an 8 angle and
moistened with dechlorinated tap water to a maximum depth of 3 to 5 mm to approx-
imate Lanciani's (1975) rearing conditions. Each of these containers received one H.
martini egg, placed in the center of the filter paper, out of the pooled water. These con-
tainers were loosely covered with a screw cap to prevent the filter paper from drying
out. This also duplicated conditions of Lanciani (1975).
Containers were checked daily, and water was added to maintain appropriate lev-
els described above for each substrate treatment. As eggs hatched, each treatment
Taylor & Wood: Hydrometra: Food and Substrate Effects 19
group (duckweed and filter paper substrates) was further divided into two food treat-
ments: fruit fly and springtail. Each day, containers in the fruit fly treatment received
two frozen D. melanogaster, and those in the springtail treatment about 20 live Smin-
thurides malmgreni T.ll.... (Collembola: Sminthuridae), approximating Lan-
ciani's (1975, 1991) feeding regimes. Dead fruit flies were removed daily; dead
springtails were removed if they did not appear fresh, and new food items were pro-
vided as needed to maintain numbers of individuals.
Fruit fly cultures were maintained in the laboratory on a commercially available
culture medium (Ward's Natural Science, Rochester, New York) and were killed by
freezing no more than two days prior to their use. Preliminary work indicated that
flies frozen for prolonged periods became dehydrated. Springtails were obtained by re-
peatedly passing a plastic box slowly over the surface of a duckweed covered pond, as
described by Lanciani (1991). Springtail colonies were maintained at 28 + 1C in
quart jars, following the methods of Purrington et al. (1991). Additional springtails
were collected and added to the colonies every 1-3 days.
Statistical analyses were carried out using SAS procedures (SAS Institute 1988).
Survivorship (percent of individuals molting to the next instar) was examined using
a general linear model (PROC GLM) with data coded as 0 or 1. Stadia and trans-
formed stadia for nymphal instars were not normally distributed. We used the two
way ANOVA's to compare stadia among treatments for first through fourth instars.
This procedure is fairly robust to deviations from normality (Glass et al. 1972, Srivas-
tava 1959, Tiku 1971, Zar 1984). Post hoc comparisons, stadia of fifth instars, and to-
tal length of development were examined using t-tests. Numbers of eggs hatching and
the proportion of the stadia available for calculation in the two substrate treatments
were examined using chi-square tests. The significance level was 0.05 for all tests.
Voucher specimens are housed in the Southern Illinois University at Carbondale
Entomology Collection and the collections of the authors.
RESULTS
First through fifth instar H. martini nymphs in both duckweed food treatments
were observed on several occasions feeding on arthropods other than Sminthurides
and Drosophila, most often upon emerging or recently (<24 h) emerged adult Chirono-
midae (Diptera). Several early anisopteran instars (Odonata), larval Chironomidae
and one small larval Dytiscidae (Coleoptera) were removed from rearing containers in
the course of the experiment, but we found no evidence that these insects were prey-
ing upon H. martini.
During rearing, molting occasionally was overlooked, particularly in early instars
of the two duckweed treatments where exuviae were difficult to find. This resulted in
some stadium data being lost (Table 1). Missed molts were discovered later when in-
dividuals molted to later instars; the animals were then assigned to the correct instar.
To examine the effect of substrate on our ability to detect molts, we compared the sam-
ple sizes for numbers of individuals surviving each stage with the number of individ-
uals of each stage for which stadia could be calculated. The proportion of the stadia
available for calculation was greater on filter paper (98%, 327 of 334 stadia) than on
duckweed (72%, 219 of 303 stadia) (Z2 = 83.1, df = 1, P < 0.001), indicating that our
ability to detect exuviae was influenced by the substrate.
Survivorship for each treatment decreased at nearly every instar (Table 1). Survi-
vorship from egg to adult differed among treatments (F = 11.28, df = 3,156, P =
0.0001): substrate, food, and the interaction of food and substrate were all significant
(P = 0.007, 0.0459, and 0.0001, respectively). Survivorship from egg to adult differed
TABLE 1. STADIUM (DAYS) AND SURVIVORSHIP OF H. MARTINI NYMPHS REARED ON TWO SUBSTRATES AND UNDER TWO FEEDING REGIMES AT 28 +
1C.
Survivorship
Stadium Length Number Percentb
Substrate Food Stage N" X + SE Range N, N2 %
Filter Paper
Sminthurides 1st instar
2nd instar
3rd instar
4th instar
5th instar
Total of 1st through 5th
Total of egg through 5th
Drosophila 1st instar
2nd instar
3rd instar
4th instar
5th instar
Total of 1st through 5th
Total of egg through 5th
73 5.6 + 0.1 5-6
37 2.0 + 0.0 1-2
36 1.0 + 0.0 1-2
34 1.4 + 0.1 1-2
27 1.9 + 0.2 1-4
16 3.8 + 0.3 2-5
17 9.9 + 0.2 8-10
17 15.4 + 0.2 14-16
35 2.1 + 0.1 1-4
32 1.9 + 0.1 1-4
24 2.2 + 0.2 1-4
13 2.8 + 0.2 2-4
0
0
0
"Includes only individuals for which stadium length could be calculated.
'Percent entering stage (NI) that survived to enter next (N ); includes individuals lacking stadium data.
80 76 95.00
39 37 94.87 3.
37 36 97.30
36 34 94.44 ?
34 28 82.35
28 17 60.71
39 17 43.59
40 17 42.50 "
37 37 100.00 0
37 32 86.49
32 24 75.00
24 13 54.17
13 0 0.00
37 0 0.00
40 0 0.00
t3
TABLE 1. (CONTINUED) STADIUM (DAYS) AND SURVIVORSHIP OF H. MARTINI NYMPHS REARED ON TWO SUBSTRATES AND UNDER TWO FEEDING RE-
GIMES AT 28 -+ 1C.
Survivorship
Stadium Length
Number
Percent
Percent1'
Stage
Sminthurides 1st instar
2nd instar
3rd instar
4th instar
5th instar
Total of 1st through 5th
Total of egg through 5th
Drosophila 1st instar
2nd instar
3rd instar
4th instar
5th instar
Total of 1st through 5th
Total of egg through 5th
N' X SE I
63 6.6+ 0.1
15 2.1 + 0.2
10 1.1 + 0.1
16 1.4 + 0.2
17 1.8 + 0.2
14 2.9 + 0.1
tange N N2 %
5-9 80 72 90.00
1-3 32 27 84.38
1-2 27 26 96.30 C
1-3 26 24 92.31 3
1-3 24 21 87.50
2-4 21 15 71.43
14 9.0 + 0.2 8-10 32 15 46.88
15 15.7 + 0.3 13-17 40 15 37.50 Q.
18 2.2 + 0.2 1-3 33 25 75.76 Q
13 1.6 + 0.2 1-3 25 25 100.00 C
15 1.7 0.1 1-2 25 24 96.00
18 1.8 + 0.1 1-3 24 23 95.83
20 2.5 + 0.1 2-3 23 21 91.30
21 9.3 + 0.2 8-11 33 21 63.64
21 15.8 + 0.2 14-17 40 21 52.50 't
aIncludes only individuals for which stadium length could be calculated.
'Percent entering stage (N ) that survived to enter next (N); includes individuals lacking stadium data.
Substrate
Duckweed
Florida Entomologist 83(1)
March, 2000
between food treatments within the filter paper treatment (42.5% versus 0% survivor-
ship; F = 28.8, df = 1,78, P = 0.0001) but not in the duckweed treatment (37.5% versus
52.5% survivorship; F = 1.8, df = 1,78, P = 0.182), and between substrate treatments
in the fruit fly treatment (52.5% versus 0% survivorship; F = 43.1, df = 1,78, P =
0.0001) but not in the springtail treatment (37.5% versus 42.5% survivorship; F =
0.20, df -= 1,78, P = 0.653).
Egg stadia (Table 1) were 15% shorter on filter paper than on duckweed (t = 8.24,
df = 91.5, P < 0.001), but hatching success did not differ (Z2 = 1.441, df = 1,P = 0.230).
The first stadium did not differ by either food or substrate treatments (Table 2).
The second and third stadia were 40% and 28% shorter, respectively, for individuals
reared on springtails. The interaction of food and substrate was significant for the
third stadium; post hoc comparisons revealed a substrate difference in stadia of fruit
fly treatments (2.2 versus 1.7 days; t = -2.56, df = 37, P = 0.015) but not in stadia of
springtail treatments (1.4 versus 1.4 days; t = 0.16, df = 48, P = 0.877). Both food and
substrate affected the length of the fourth stadium, and the interaction term was also
significant; post hoc comparisons revealed a substrate difference in stadium lengths
of fruit fly treatments (2.8 versus 1.8 days; t = -4.67, df = 29, P < 0.001) but not in
springtail treatments (1.9 versus 1.8 days; t = -0.53, df = 42, P = 0.596), and a food dif-
ference in stadia on filter paper (2.8 versus 1.9 days; t = -3.51, df = 38, P = 0.001) but
not on duckweed (1.8 versus 1.8 days; t = -0.343, df = 33, P = 0.734).
No individuals in the filter paper/fruit fly treatment reached adults. Therefore,
stadia for fifth instars and total length of development (with and without egg stage)
were tested separately, using only the duckweed treatments to examine food effects
and only the springtail treatments to examine substrate effects.
The fifth stadium in the springtail treatments was 24% shorter on duckweed than
on filter paper (t = -2.83, df -= 22.0, P = 0.010). No difference in food treatments was
detected for fifth stadium on duckweed (t = 1.96, df = 32, P = 0.058), perhaps because
of the small sample size for the springtail fed individuals.
The length of total development (egg through fifth instar) did not differ between
substrates in springtail treatments (t = 1.18, df -= 30, P = 0.247) or by food in duckweed
treatments (t = -0.08, df = 34, P = 0.936). Total length of nymphal development (first
through fifth instars) was 9% shorter on duckweed than on filter paper in springtail
treatments (t = -3.84, df = 29, P = 0.001), but did not differ between foods in duckweed
treatments (t = -1.18, df = 33, P = 0.247).
DISCUSSION
Differences between treatment groups in survivorship from egg to adult were af-
fected by the interaction between food and substrate. To maximize survival of labora-
tory colonies, our survivorship data suggest that when filter paper was used as a
substrate, springtails were a more effective food source, and when fruit flies were
used as a food source, duckweed was the more effective rearing substrate. When sta-
dia differences between springtail and fruit fly treatments were detected (in the third
stadium and on filter paper in the fourth stadium), the springtail treatments had
shorter stadia, corroborating Lanciani's (1991) observations for springtail treat-
ments. However, differences between substrate treatments also were found in our
study. When stadium differences between substrate treatments were detected (in
third and fourth instar fruit fly treatments, and in springtail treatments in the fifth
instar and total nymphal development), stadia were shorter on duckweed. These data
indicate that the shorter stadia Lanciani (1991) found for springtail reared samples
in comparison to fruit fly reared samples (Lanciani 1975) may actually reflect a dif-
ference in rearing substrates in his two studies.
Taylor & Wood: Hydrometra: Food and Substrate Effects 23
TABLE 2. TWO-WAY ANOVAS (UNBALANCED DESIGN) OF STADIA WITHIN INSTARS OF H.
MARTINI REARED ON TWO SUBSTRATES AND UNDER TWO FEEDING REGIMES AT
28 + lC'.
Instar Source df F P > F
First Substrate 1 0.43 0.512
Food 1 1.18 0.279
Substrate*Food 1 0.03 0.853
Error 101
Second Substrate 1 0.93 0.338
Food 1 30.17 <0.001
Substrate*Food 1 2.31 0.132
Error 87
Third Substrate 1 3.83 0.054
Food 1 15.16 <0.001
Substrate*Food 1 4.63 0.034
Error 85
Fourth Substrate 1 10.74 0.002
Food 1 8.61 0.005
Substrate*Food 1 6.30 0.014
Error 71
'Fifth instar not included because no individuals in filter paper/Drosophila treatment reached adult.
Only the egg stadium was shorter on filter paper than on duckweed. Some Het-
eroptera have eggs that develop on damp ground or in water (e.g., Notonecta trigut-
tata Say, Gerris lacustris latiabdominalis Miyamoto, and Gerris gracilicornis
gracilicornis Horvath). Mori (1986) noted that the egg stadium increased when water
uptake was experimentally reduced and emphasized the apparent importance of wa-
ter absorption in the embryonic development of these taxa. We suspect that the waxy
coating on the duckweeds created a substrate condition that inhibited water absorp-
tion, whereas the moist filter paper facilitated water uptake by the eggs.
We found that filter paper was clearly a more suitable choice for rearing H. martini
eggs than was duckweed. The choices were less clear for the nymphal instars.
Nymphal stada often were shorter on duckweed, but potential contamination of duck-
weed with a wide array (Rathke 1979) of other organisms, and the greater difficulty
with which exuviae were detected, may make this substrate less suitable for some lab-
oratory studies. Our data were not consistent with a general trend of nutritional aug-
mentation due the presence of other taxa in duckweed treatments; the effect of these
taxa appeared to be negligible. However, it is possible to rear more nearly sterile mo-
nocultures of duckweed (Landolt & Kandeler 1987).
The sometimes shorter stadia observed in springtail reared H. martini may not be
sufficient reason to reject fruit flies as food organisms. Cultures of Drosophila melan-
ogaster are readily available and easy to maintain, allowing more repeatable experi-
ments. Collembola are more difficult to obtain and culture, and collecting the same
species as used in previous studies may be difficult. Additionally, the assumption that
Florida Entomologist 83(1)
March, 2000
shorter stadia are indicative of healthier or more natural development in Hydrometra
has not been demonstrated.
We have shown that food and substrate affect the stadia and survival of H. mar-
tini. The advantages of an artificial substrate (cleanliness, repeatability, control, ease
of observation) should be weighed against the advantages of duckweed (more closely
replicating field conditions and, in some cases, shorter stadia) before decisions regard-
ing rearing conditions are made. Drosophila may be more effective for laboratory
rearing than springtails for Hydrometra even though, as suggested by Lanciani
(1991), there may be nutritional differences between these two food species.
Average total developmental time for H. martini in the laboratory was shorter
than for several other North American gerromorphans. Another hydrometrid, H. hun-
gerfordi, took 25.6 d at 28C (Wood & McPherson 1995). Mesovelia cryptophila Hun-
gerford, a mesoveliid, required 28.6 d at 26.7C to complete development (Taylor &
McPherson 1998). The veliid Microvelia pulchella Westwood, took 34.1 d (at 23.3C)
(Taylor & McPherson 1999). Gerris argenticollis Parshley had a longer developmental
period, 58.3 d at 21C (Korch & McPherson 1987).
Detailed life history studies have been conducted only for a small portion of the
North American heteropteran fauna (Schaeffer 1990, Spence & Andersen 1994). We
are fortunate to know more about the biology of H. australis/H. martini than is known
for most Heteroptera.
ACKNOWLEDGMENTS
We thank J. E. McPherson (Southern Illinois University at Carbondale) for provid-
ing us with the facilities to carry out this study and for critiquing an early version of this
manuscript. Thanks to reviews by C. A. Lanciani (University of Florida), R. W. Sites
(University of Missouri), M. J. Wetzel and R. E. DeWalt (Illinois Natural History Sur-
vey), many improvements to this manuscript were implemented. R. J. Snider (Michigan
State University) kindly identified the springtails for us. A. C. Driskell (University of
Chicago), P. B. Elmore, and J. Mouw (Southern Illinois University at Carbondale) pro-
vided helpful discussion and advice on experimental design and data analysis.
LITERATURE CITED
BENNETT, D. V., AND E. F. COOK. 1981. The semiaquatic Hemiptera of Minnesota
(Hemiptera: Heteroptera). Minnesota Agric. Expt. Sta. Tech. Bull. 332: 1-59.
GLASS, G. V., P. D. PECKHAM, AND J. R. SANDERS. 1972. Consequences of failure to meet
assumptions underlying the fixed effects analysis of variance and covariance.
Rev. Educ. Res. 42: 239-288.
GONSOULIN, G. J. 1973. Seven families of aquatic and semiaquatic Hemiptera in Lou-
isiana. Entomol. News 84: 9-16.
KORCH, P. P., AND J. E. MCPHERSON. 1987. Life history and laboratory rearing of Ger-
ris argenticollis (Hemiptera: Gerridae) with descriptions of immature stages.
Great Lakes Entomol. 20: 193-204.
LANCIANI, C.A. 1971. Host exploitation and synchronous development in a water mite
parasite of the marsh treader Hydrometra myrae (Hemiptera: Hydrometridae).
Ann. Entomol. Soc. Am. 64: 1254-1259.
LANCIANI, C. A. 1975. Parasite-induced alterations in host reproduction and survival.
Ecology 56: 689-695.
LANCIANI, C. A. 1991. Laboratory rearing of Hydrometra australis (Hemiptera: Hy-
drometridae). Florida Entomol. 74(2): 356-357.
LANCIANI, C. A. 1995. Effect of a parasitic water mite on the per capital rate of increase
of its host Hydrometra australis (Hemiptera, Hydrometridae). Florida Ento-
mol. 78: 357-359.
Taylor & Wood: Hydrometra: Food and Substrate Effects 25
LANDOLT, E., AND R. KANDELER. 1987. Biosystematic investigations in the family of
duckweeds (Lemnaceae). 4 Volumes. The family Lemnaceae a monographic
study. Volume 2. Phytochemistry, physiology, application, and bibliography.
Veroffentlichungen des Geobotanisches Institute ETH, Stiftung Rubel, Zurich,
Switzerland. Heft 95.
MORI, H. 1986. Water absorption by eggs and serosal specialization as clues to evolu-
tionary trends in Heteroptera. Ann. Entomol. Soc. Am. 79: 456-459.
POLHEMUS, J. T., AND H. C. CHAPMAN. 1979. The semiaquatic and aquatic Hemiptera
of California, families Hebridae, Mesoveliidae, Hydrometridae, Macroveliidae,
Veliidae, and Gerridae, pp. 39-42 in A. S. Menke [ed.] The semiaquatic and
aquatic Hemiptera of California (Heteroptera: Hemiptera). Bull. California In-
sect Surv. 21: 1-166.
POLHEMUS, J. T., AND D. A. POLHEMUS. 1987. Terrestrial Hydrometridae (Heteroptera)
from Madagascar, and the remarkable thoracic polymorphism of a closely re-
lated species from Southeast Asia. J. New York Entomol. Soc. 95: 509-517.
PURRINGTON, F. F., P. A. KENDALL, J. E. BATER, AND B. R. STINNER. 1991. Alarm pher-
omone in a gregarious Poduromorph Collembolan (Collembola: Hypogastru-
ridae). Great Lakes Entomol. 24: 75-78.
RATHKE, M. S. 1979. The invertebrate fauna associated with three species of Lem-
naceae in southern Illinois. Unpublished M.S. thesis, Southern Illinois Univer-
sity at Carbondale, Carbondale, Illinois. 87 pp.
SAS INSTITUTE. 1988. SAS/STAT user's guide, version 6, 4th ed. Vols. 1 & 2. SAS In-
stitute, Cary, North Carolina.
SCHAEFER, C. W. 1990. The Hemiptera of North America: what we do and do not know,
pp. 105-188 in M. Kosztarab and C. W. Schaefer [eds.] Systematics of the North
American insects and arachnids: status and needs. Virginia Agricultural Ex-
periment Station Information Series 90-1. Virginia Polytechnic Institute and
State University, Blacksburg, Virginia.
SMITH, C. L. 1988. Family Hydrometridae Billberg, 1820, pp. 156-158 in T. J. Henry
and R. C. Froeschner [eds.] Catalog of the Heteroptera, or true bugs, of Canada
and the continental United States. E. J. Brill, New York. 958 pp.
SPENCE, J. R., AND N. M. ANDERSEN. 1994. Biology of water striders: Interactions be-
tween systematics and ecology. Annu. Rev. Entomol. 39: 101-128.
SPRAGUE, I. B. 1956. The biology and morphology of Hydrometra martini Kirkaldy.
Univ. Kansas Sci. Bull. 38: 579-693.
SRIVASTAVA, A. B. L. 1959. Effects of non-normality on the power of the analysis of
variance test. Biometrika 46: 114-122.
TAYLOR, S. J., AND J. E. MCPHERSON. 1998. Laboratory rearing of Mesovelia crypto-
phila (Heteroptera: Gerromorpha: Mesoveliidae). Entomol. News 109: 95-98.
TAYLOR, S. J. AND J. E. MCPHERSON. 1999. Morphological variation and polyvoltinism
of Microvelia pulchella (Heteroptera: Veliidae) in southern Illinois, USA. Acta
Societaris Zoologicae Bohemicae 63: 237-249. [in press]
TIKU, M. L. 1971. Power function of F-test under non-normal situations. J.Amer. Stat-
ist. Assoc. 66: 913-916.
WEIK, K. L., AND R. H. MOHLENBROCK. 1968. Contributions to a flora of Illinois. No.
3. Lemnaceae. Trans. Illinois State Acad. Sci. 61: 382-399.
WOOD, D. L., AND J. E. MCPHERSON. 1995. Life history and laboratory rearing of Hy-
drometra hungerfordi Torre-Bueno (Heteroptera: Hydrometridae) with de-
scriptions of immature stages. Proc. Entomol. Soc. Washington 97: 717-728.
ZAR, J. H. 1984. Biostatistical analysis, Second Edition. Prentice Hall, New Jersey.
718 pp.
Florida Entomologist 83(1)
March, 2000
PUBLIC PERCEPTION OF A TRAP TO LOCALLY REDUCE
YELLOW FLY (DIPTERA: TABANIDAE) NUISANCE IN
RESIDENTIAL AREAS OF NORTHEASTERN FLORIDA
J. E. CILEK1 AND G. MEDRANO2
'John A. Mulrennan, Sr. Public Health Entomology Research and Education Center
Florida A & M University, 4000 Frankford Avenue, Panama City, FL 32405
2East Flagler Mosquito Control District, 24 Utility Drive, Palm Coast, FL 32137
ABSTRACT
A mail survey was conducted to measure perception of seasonal yellow fly
(Diptera: Tabanidae) nuisance by residents of the East Flagler Mosquito Control Dis-
trict (Flagler County, FL) before and after using adhesive-coated black beach balls as
traps to capture these outdoor biting fly pests. A total of 72 (36%) completed question-
naires were received from 200 initially mailed. The majority of survey respondents
(70%) reported that annoyance (nuisance) from yellow flies had decreased after using
this trap. Relative reduction of nuisance did not appear to have been significantly
(P > 0.05) influenced by number of trapped flies observed on traps. Fly nuisance was
not related to length of residence in the county or number of years a person had used
the beach ball traps. Most respondents (66.0%) reported that they used one trap per
residence with the majority of traps (48.0%) placed in the backyard. No significant re-
lationship existed between initial nuisance ranking and number of traps used. Sixty-
six percent of survey respondents reported that the trap was very easy to use, while
98.6% stated this method of control was worth the effort expended.
Key Words: Biting flies, Diachlorus ferrugatus, Chrysops
RESUME
Se realize una encuesta por correo para medir el grado de molestia causado por la
mosca amarilla (Diptera: Tabanidae) a los residents de East Flagler Mosquito Con-
trol District, en el Condado de Flagler, Florida. Se midi6 la eficacia de utilizar pelotas
de playa pintadas de color negro y cubiertas de un adhesive para atrapar a los mos-
quitos. De un total de 200 cuestionarios enviados, 72 (36%) fueron contestados y usa-
dos para clasificar las respuestas. La mayoria de los encuestados que respondieron
(70%) report que la molestia causada por las moscas amarillas disminuy6 despues de
instalarse las trampas. Sin embargo, la reducci6n en el grado de molestia no fue in-
fluida de manera significativa (P > 0.05) por el numero de moscas atrapadas. Tampoco
se observaron diferencias significativas cuando se compare el grado de molestia con el
tiempo de residencia de los encuestados en el Condado o con el numero de anos que la
persona hubiera utilizado las trampas. La mayoria de las personas (66%) report que
utilizaron una trampa por residencia. La mayoria de las trampas (48%) fue colocada
en el patio trasero de la casa. No se encontr6 una relaci6n significativa entire el nivel
de molestia inicial y el numero de trampas empleadas. Segun el 66% de los encuesta-
dos, la trampas fueron muy faciles de usar, y el 98.6% de encuestados consider justi-
ficado el esfuerzo empleado en este m6todo de control.
As a group, "yellow flies" consist of about a dozen species of yellow-bodied biting
flies in the family Tabanidae. From early spring through mid-fall these blood-sucking
flies (primarily Diachlorus and Chrysops spp.) frequently become pests in northern
Cilek & Medrano: Yellow Fly Nuisance in Residential Areas 27
Florida. These insects persistently attack the head region, shoulders and extremities
of people. This host-seeking behavior is not only discomforting, but the bite can be
painful and allergic reactions have been reported (Banks 1904, Mease 1943).
From 1993-1995 personnel of the East Flagler Mosquito Control District (EFMCD)
provided to residents a "yellow fly trap" that consisted of a glossy black beach ball (51
cm diam) coated with an adhesive as a method to control these flies (Cilek 1993). A set
of written directions on how to set up the trap was provided. The ball was suspended
about head-height (1.5 m) to allow free movement with wind currents. The District
provided a 120-ml packet of adhesive per trap for residents to apply to each beach ball.
Diachlorus ferrugatus (F.), and some species of Chrysops, have been observed to land
on this trap, presumably influenced by movement of the ball's silhouette and/or re-
flected sunlight along its curved surfaces. Attraction to such objects has been reported
for Tabanidae (e.g., Bracken et al. 1962).
The beach ball trap program has appeared to be a popular one during the yellow
fly season (April-June) (J. Cash, Director, EFMCD pers. comm.). However, no quanti-
tative information has been available on client satisfaction relative to trap use and re-
duction of fly nuisance. As a result, a mail survey was conducted during the summer
of 1995 to gauge the public's perception of yellow fly annoyance before and after using
the beach ball trap.
MATERIALS AND METHODS
A total of 200 questionnaires was sent to residents of EFMCD in Palm Coast who
had participated in the beach ball yellow fly trap program at any time from 1993
through 1995. The questionnaire contained 19 fill-in-the-blank questions plus a dia-
gram of a house surrounded by a rectangular "lawn" to indicate placement of beach
ball traps on their property (Fig. 1). Each questionnaire included a self-addressed
stamped envelope for return and a cover letter explaining the survey.
Participants provided their address, and a statement at the top of the page assured
them that answers to all questions remained confidential and anonymous. Data were
collected on length of residence in the state and county, length of time in program,
time of day yellow flies were most bothersome, perceived sources from which yellow
fly nuisance/infestation originated, placement and number of traps used, and allergic
reactions to bites. Respondents ranked nuisance (annoyance) from yellow flies prior to
and after using the beach ball trap on a scale of 1 = extreme nuisance to 10 = no prob-
lem. Because yellow flies accumulated on traps and could produce a bias in nuisance
ranking, respondents were asked to quantify total number of flies captured per ball as
0-25, 25-50, 100+. We also asked if "non-target" organisms (i.e. other insects, birds,
etc.) were captured on these traps and if so, what kind. If beneficial organisms are
caught, in addition to the pest, this may have an adverse impact on public relations-
especially for publicly funded agencies. The survey period covered approximately one
month (June 20 through July 15, 1995).
Results are presented as frequency of response or means where appropriate. Data
on length of residence in county (i.e., <5 yr or >5 yr) and number of years (i.e., 1, 2, or
3 yr) respondents participated in the trap program were separately subjected to anal-
ysis of variance (PROC GLM, SAS Institute 1990) to determine if either variable sig-
nificantly (P < 0.05) influenced relative perception of yellow fly nuisance before or
after the beach ball trap was used. A linear regression (PROC REG, SAS Institute
1990) was performed on initial nuisance ranking versus number of beach ball traps
placed at each residence with trap as the dependent variable (Sokal & Rohlf 1981). A
similar but separate regression analysis was conducted on level of nuisance after trap
use versus number of flies captured per trap with fly as the dependent variable.
Yellow Fly Trap Survey
ALL RESPONSES WILL BE KEPT CONFIDENTIAL AND ANONYMOUS
PLEASE RESPOND BY JULY 15, 1995
1. Your street address
2. How long have you lived at this address?_
3. How long have you lived in Flagler County?__
4 Are you a native Floridian? Yes_ No
5. Where do you think the yellow fly source is in your
area?
6 Did any member of your family visit a physician as a result of yellow fly bites?
Yes_ No
7. Did any member of your family experience an extreme reaction (severe swelling,
breathing problems) as a result of a yellow fly bite? Yes_ No
8. Rate the yellow fly problem in your area before you began trapping (1= very bad,
1 =no problem) _
9. Rate the yellow fly problem in your area after you began using the yellow fly trap
(1 = very bed, 10=no problem) __
10. At what time of day do yellow fies cause you the most problems?____
11 During daylight, when are yellow flies least bothersome?
12. How many years have you participated in the yellow fly program? __
13. How many traps did you set out? __
14. Do you feel that the yellow fly trap reduced or eliminated the yellow fly problem in
your immediate area? Yes_ No_
Fig. 1. Questionnaire used as survey instrument.
15. Estimate the number of flies per trap? 0-25 25-100 100+
16. How convenient is it to construct the trap? Very easy some effort
very difficult__
17. Suggestions to improve the trap design or construction?
18, Is this program worth your time and effort? Yes_ No_
19 Did you capture any other animal on the trap? Yes___ No What?
20 Please show the approximate location of yellow fly trap(s) on your property. If you
located one in the garage or in a door entry, please note
Cilek & Medrano: Yellow Fly Nuisance in Residential Areas 29
RESULTS AND DISCUSSION
A total of 72 respondents (36%) returned completed questionnaires, of which
93.2% were not native Floridians. Although the trap program was available for 3
years (i.e., 1993 through 1995), the majority of survey respondents (52.8%) had par-
ticipated for one year, followed by 26.4% for two years and 20.8% for three years.
Approximately 66% of respondents identified perceived sources of yellow fly nui-
sance. The majority (31.0%) reported wood lots adjacent to, or in the vicinity of, their
property as a source of fly production. Subsequent field investigations by District per-
sonnel revealed that most persons were located near forests that bordered freshwater
wetlands several hundred meters away. We presumed that these wetland habitats
were the probable source of yellow fly infestation. Only 27% associated their yellow fly
annoyance with lakes, ditches or canals, while approximately 23% reported the prob-
lem coming from freshwater swamps and/or brackish/salt marshes. Jones and An-
thony (1964) reported that developmental areas for most yellow flies in Florida, such
as D. ferrugatus and Chrysops sp., were primarily aquatic or semi-aquatic.
Most survey respondents reported that yellow flies were most bothersome in late
afternoon (46%) and least bothersome in the morning (47%). This suggested that their
primary nuisance species was probablyD. ferrugatus as these data corresponded with
findings of Cilek (1993) and Cilek & Schreiber (1999) relative to peak diel host seeking
activity of D. ferrugatus. Approximately 84% of survey respondents bitten by yellow
flies did not visit a physician although 52% reported that they had experienced an ex-
treme allergic reaction from a bite. An extreme allergic reaction was defined in the
questionnaire as severe swelling and/or breathing problems. Of the 16% that visited
a physician, 92% experienced extreme allergic reactions.
The majority of respondents most frequently rated their level of nuisance (annoy-
ance) from yellow flies as "1" which was categorized as extreme nuisance (Fig. 2). After
using the beach ball trap, nuisance was most frequently rated as 8 (no problem had a
rating of 10). Number of years living in the county and number of years participating
in the trap program did not significantly (P > 0.05) influence rating.
Seventy percent of respondents believed that the beach ball trap decreased their
yellow fly nuisance. Interestingly, 15% reported no improvement or that fly annoy-
ance was worse. However, later in the questionnaire when respondents were asked if
traps helped to reduce annoyance, 92.8% (64 out of 69) said yes. Number of flies cap-
tured on traps did not significantly influence nuisance ranking (F = 0.86, df = 60, P =
0.36). In addition to yellow flies, no organisms (e.g., birds or other vertebrates) other
than flying insects were reported trapped on the adhesive-coated beach balls.
Most people (47.9%) used one beach ball trap on their property, followed by 36.6%
with two and 8.5% with three. Seven percent of survey respondents used more than 3
traps. No significant relationship existed between initial annoyance ranking and
number of traps placed in yards (F = 1.64, df = 71, P = 0.20). However, number of traps
per yard was probably limited by lot size, (avg. 36 m length by 25 m width). Most per-
sons (43%) placed traps in the backyard. Location probably reflected where they spent
most of their time when outdoors.
The majority (66%) of respondents reported that the trap was very easy to use,
32% reported some effort had to be expended to use this technique, while 2% said the
trap was difficult to use. Overall, 98.6% believed that the trap was worth using.
From the data obtained in this survey, most persons perceived their level of yellow
fly nuisance (i.e. annoyance) had been substantially reduced after using the traps.
Whether or not actual population levels of the pestiferous yellow fly species (in this
case, D. ferrugatus) were reduced remains to be determined and warrants further in-
vestigation.
Florida Entomologist 83(1)
March, 2000
50
MBefore rAfter
40
30
I 20
L)
10
1 2 3 4 5 6 7 8 9 10
Nuisance Ranking
(1=extreme nuisance, 10=no problem)
Fig. 2. Frequency distribution of relative yellow fly nuisance rating as reported by
survey respondents of East Flagler Mosquito Control District (65 records) before us-
ing beach ball adhesive trap and after (1 = extreme nuisance, 10 = no problem).
ACKNOWLEDGMENTS
We thank Joe Cash, Director, East Flagler Mosquito Control District for providing
encouragement and financial assistance in conducting this survey. We also thank the
staff of this District for assistance in administration of this study as well as J. Cough-
lin, J. A. Mulrennan, Sr. Public Health Entomology Research and Education Center,
Florida A & M University, Panama City, for assistance in compiling result summaries.
REFERENCES
BANKS, N. 1904. The "yellow-fly" of the Dismal swamp. Entomol. News 15: 290-291.
BRACKEN, G. K., W. HANEC, AND A. J. THORSTEINSON. 1962. The orientation of horse
flies and deer flies (Tabanidae: Diptera) II. The role of some visual factors in the
attractiveness of decoy silhouettes. Can. J. Zoology 40: 685-695.
CILEK, J. E. 1993. The yellow-biting flies of Florida. J. A. Mulrennan, Sr. Res. Lab.,
Florida A & M Univ. EntGuide #1.
CILEK, J. E., AND E. T. SCHREIBER. 1999. Diel host-seeking activity of adult Diachlo-
rus ferrugatus (F.) (Diptera: Tabanidae) in northwestern Florida. J. Entomol.
Sci. 34: 462-466.
JONES, C. M., AND D. W. ANTHONY. 1964. The Tabanidae of Florida. USDA, ARS Tech.
Bull. 1295.
MEASE, J. A. 1943. Deer fly desensitization. J. Amer. Med. Assoc. 122: 227.
SAS INSTITUTE. 1990. SAS user's guide: statistics, version 6 ed. SAS Institute, Cary, NC.
SOKAL, R. R., AND F. J. ROHLF. 1981. Biometry (2 ed.) W. H. Freeman & Co., San Fran-
cisco, CA.
Weekley: A Gall-Making Wasp on Blackbead
THE NATURAL HISTORY OF TANAOSTIGMODES
PITHECELLOBIAE (HYMENOPTERA: TANAOSTIGMATIDAE),
A GALL-MAKER ON BLACKBEAD (PITHECELLOBIUM
KEYENSE)
CARL WEEKLY
Archbold Biological Station, P.O. Box 2057, Lake Placid, FL 33862
ABSTRACT
Tanaostigmodes pithecellobiae LaSalle, a chalcidoid wasp, induces foliar galls on
Pithecellobium keyense Britton ex Britton & Rose, a mimosoid legume native to South
Florida. This paper provides the first description of the gall-maker's natural history:
it is monophagous and multivoltine; its phenology varies with the season of gall initi-
ation; and it is preyed upon by chalcidoid parasitoids and by an unusual microlepi-
dopteran "gall-miner".
Key Words: insect gall-makers, cecidology, plant galls, gall-making wasps
RESUME
Tanaostigmoides pithecellobiae LaSalle es una avispa que induce la formaci6n de
agallas en hojas de Pithecellobium keyense Britton ex Britton y Rose, una plant le-
guminosa originaria del sur de la Florida. Este trabajo represent la primera descrip-
ci6n de la historic natural de este insecto. Esta especie es mon6faga, multiovular y su
fenologia varia con las 6pocas de producci6n de agallas. Es parasitada y devorada por
chalcicoides y por un microlepid6ptero poco comun que causa minas en las agallas.
Tanaostigmodes pithecellobiae LaSalle (Hymenoptera: Tanaostigmatidae) induces
foliar galls on Pithecellobium keyense Britton ex Britton & Rose, blackbead, a mi-
mosoid legume native to South Florida. The gall-maker was named and described in
LaSalle's (1987) taxonomic revision of the New World Tanaostigmatidae, a small but
well-circumscribed family of gall-making chalcidoids. It is indicative of the present
state of knowledge of the Tanaostigmatidae that of the 74 New World species treated
in LaSalle's monograph, two-thirds (49) were new to science. The present paper is
among the first to characterize the biology of a tanaostigmatid.
Blackbead is an arborescent, evergreen shrub of the coastal scrub zone and of pine-
land and hammock margins (Tomlinson 1980). Its leaves are bipinnately compound,
with four to eight leaflets in two pairs (Tomlinson 1980). The leaflets are elliptical to
obovate, 4-5 cm long, and dark green and leathery at maturity. New growth is pro-
duced in recurrent flushes throughout the year, but appears least abundant during
the dry season. During the initial stage of leaf development, which lasts about 1 week,
opposite leaflets are oriented with their upper surfaces facing one another, leaving the
lower surfaces exposed (personal observation).
The congeneric P. unguis-cati (L.) Benth., catsclaw, is also listed by LaSalle as a
host species for T pithecellobiae. Catsclaw closely resembles blackbead in leaf and
flower morphology and occupies similar coastal habitats (Wunderlin 1998, Tomlinson
1980). Blackbead and catsclaw occur sympatrically in the Florida Keys, but their
Florida Entomologist 83(1)
March, 2000
ranges diverge on the mainland. Blackhead occurs on the Atlantic Coast to Martin
County, while catsclaw occurs on the Gulf Coast to Hillsborough County (Wunderlin
et al. 1996, Isely 1990, Little 1978).
This paper establishes the host specificity of T pithecellobiae, provides the first de-
scription of its natural history, and examines seasonal variation in gall density and
patterns of development.
MATERIALS AND METHODS
Host Specificity
Host-plant specificity was determined by a survey of 463 individuals of the two
candidate species at nineteen sites in South Florida, extending from Key West to
Sanibel Island on the Gulf coast and to Juno on the Atlantic coast. I examined black-
bead and catsclaw plants in areas where they occurred together and in areas where
one or the other was absent. Each plant surveyed was scrutinized for the presence of
galls, and where galls were present I quantified gall density per plant by haphazardly
censusing 100 leaflets. Per site gall density was estimated by calculating the mean
percentage of galled leaflets based on all galled plants censused at a given site.
Natural History
Study site. The primary study site was the Deering Estate, part of the Metro-Dade
Park system, in Miami, Fl. I monitored about 20 blackbead plants growing along the
shoulders of a roadway through a coastal pine rockland/oak hammock established on
Miami oolitic limestone. Average temperatures in Miami range between 10 and 32C
(Tomlinson 1980), with an annual average of ~23C (Migliaccio 1987). Rainfall aver-
ages ~1500 mm per year, with about 70% of the annual precipitation occurring during
the May-to-October rainy season (Migliaccio 1987).
Gall-maker phenology. To determine gall-maker phenology, I followed the develop-
ment from oviposition to gall-maker emergence of successive cohorts of galled leaflets.
Between July 1991 and March 1993, I1 marked seven cohorts (designated I-VII) of newly
galled leaflets. Each cohort consisted of at least 100 galled leaflets. I monitored four
of these cohorts (I, II, V and VII) weekly from first emergence of the gall-maker to de-
pletion of the cohort (with an 8 week gap in the case of cohort V). I have only partial
data for cohorts III and IV, and cohort VI was destroyed by Hurricane Andrew (24 Au-
gust 1992) prior to maturation.
Gall demographics. From November 1991 to March 1993, I periodically collected
samples of 30 leaflets with mature galls for rearing in the lab. I set up 23 such sam-
ples, comprising 690 leaflets and approximately 5,000 galls. Each leaflet was main-
tained in its own 16 oz plastic container with a clear plastic lid for a minimum of 2
weeks. Moist tissue paper was kept in each container to maintain humidity. Temper-
ature in the lab was approximately 20C.
For each leaflet, I recorded the initial number of exited and unexited galls and
marked the exited galls. I censused emerging wasps by species and sex and preserved
voucher specimens of all wasps obtained. At the end of the rearing period, unexited
galls were dissected and gall contents were recorded. M. E. Schauff of the U.S. Depart-
ment of Agriculture (USDA) Agricultural Research Service/Systematic Entomology
Laboratory provided species determinations.
I periodically collected additional leaflets with mature or immature galls for obser-
vation and dissection. Galled leaflets with leaf mines that encircled or invaded devel-
Weekley: A Gall-Making Wasp on Blackbead 33
oping galls were also collected. I reared the caterpillars obtained from these "gall-
mines" and sent larvae, pupae and moths to R. W. Hodges of the USDA Agricultural
Research Service/Systematic Entomology Laboratory for identification.
Data Analysis
I constructed a phenology chart to show the duration of successive cohorts of galls
and the timing of gall-maker emergence at the Deering Estate over a period of 22
months. To highlight seasonal variations in patterns of emergence, percent exited
galls was plotted against the age of the galls (in weeks) for early, mid- and late season
cohorts. To see if the proportion of emerging wasps per month differed statistically for
early, mid- and late season cohorts, I used x2 contingency tables. Analysis of variance
(ANOVA) was used to evaluate differences in gall density per cohort among early, mid-
and late season cohorts.
To determine the statistical significance of the sex ratios for the wasps reared in
the lab, I performed Z2 goodness-of-fit tests.
All statistical tests were conducted using SAS version 6.1 (SAS Institute, 1990).
RESULTS AND DISCUSSION
Tanaostigmodes pithecellobiae is monophagous (host- specific) and multivoltine.
The phenology of gall-maker development varies seasonally and within a cohort. T
pithecellobiae is parasitized by at least two other chalcidoids and is preyed upon by an
unusual "gall-mining" microlepidopteran.
Host Specificity
Eighty-two percent of the 266 blackbead plants censused between Key West and
Juno had galls (Table 1). The percentage is even higher (96%) if the 30 blackbeads sur-
veyed north of Boca Raton, on which no galls were found, are excluded. I found no
galls on the 197 catsclaws censused between Big Pine Key and Sanibel Island.
In populations of blackbead containing galls, the mean percentage of galled leaf-
lets per site (based on haphazard censuses of 100 leaflets per galled plant) varied from
<10 to >40% (Table 1).
In addition to blackbead (P. keyense), LaSalle (1987) lists the sympatric catsclaw
(P. unguis-cati) as a host plant for T pithecellobiae. But LaSalle examined only mu-
seum specimens of T pithecellobiae galls, and the congeneric putative host plants are
often confused. From my survey of blackbead and catsclaw plants growing throughout
most of their South Florida ranges, I conclude that only blackbead is a host for T pith-
ecellobiae, and that the gall-maker is therefore monophagous in the strictest sense
(i.e., a single host-plant species).
At present, T pithecellobiae is recorded only from Florida (LaSalle 1987). The dis-
tribution of its host plant is, however, complicated by taxonomic uncertainties. Long
& Lakela (1976) list P. keyense as a South Florida endemic. Wunderlin et al. (1996)
and Wunderlin (1998), using the same binomial, do not consider the taxon a Florida
endemic, but fail to specify its range beyond Florida. Other authors (e.g., Little 1978,
Tomlinson 1980, Isely 1990) refer to blackbead as P. guadalupense (Pers.) Chapm.,
with a distribution which includes the Yucatan peninsula and the West Indies. Fur-
ther clarification of the degree of host specificity of T pithecellobiae requires resolu-
tion of the taxonomic status and geographical distribution of its Florida host plant.
TABLE 1. A SURVEY OF 463 INDIVIDUALS OF BLACKBEAD AND CATSCLAW AT NINETEEN SITES FROM KEY WEST TO SANIBEL ISLAND ON THE GULF
COAST AND TO JUNO ON THE ATLANTIC COAST. SHOWN ARE THE TOTAL NUMBER OF PLANTS CENSUSED AT EACH SITE; THE NUMBER OF
EACH SPECIES CENSUSED; THE PERCENT OF INDIVIDUALS OF EACH SPECIES WITH GALLS; AND, FOR BLACKBEAD, THE MEAN PERCENT OF
GALLED LEAFLETS PER SITE (BASED ON CENSUSES OF 100 LEAFLETS PER GALLED PLANT AT EACH SITE).
Blackhead Catsclaw
Total Mean %
number % Plants galled % Plants
plants Number with galled leaflets Number with galled
Date Site Location surveyed plants leaflets per site plants leaflets
12/31/91 Harry Harris Rd. Key Largo 100 60 92 24.3 + 18.8 40 0
12/31/91 Easement PP181 Key Largo 49 42 100 18.1 + 9.7 7 0
12/31/91 Dynamite Docks Key Largo 50 12 100 9.3 + 5.7 38 0
12/31/91 Old SR 905 Key Largo 2 2 100 NA 0 0
06/10/92 Deering Estate Miami 20 20 100 NA 0 0
06/26/93 Cactus Hammock Big Pine Key 30 5 100 36.2 + 13.97 25 0
06/26/93 Wilder Blvd. No Name Key 10 10 100 25.9 + 9.2 0 0
06/26/93 Blue Hole Big Pine Key 10 10 100 42.3 + 19.2 0 0
06/26/93 Roadway Little Torch Key 10 10 90 13.4 + 7.3 0 0
06/26/93 Roadway Sugarloaf Key 10 10 100 19.4 + 9.1 0 0
06/26/93 Little Hamaca Park Key West 10 10 100 37.0 + 13.9 0 0
07/17/93 Catsclaw Trail Rookery Bay 36 0 0 NA 36 0
07/17/93 Delnor-Wiggins Pass Naples 21 0 0 NA 21 0
07/17/93 Ding Darling NWR Sanibel 30 0 0 NA 30 0
07/31/93 H. T. Birch State Park Ft. Lauderdale 25 25 100 43.1 + 13.0 0 0
07/31/93 Red Reef Park Boca Raton 9 9 78 17.8 + 19.9 0 0
07/31/93 Gumbo Limbo EnvCnt Boca Raton 2 2 0 NA 0 0
07/31/93 MacArthur Beach SP N. Palm Beach 19 19 0 NA 0 0
07/31/93 AlA N of Marcinski Juno 20 20 0 NA 0 0
Totals 463 266 82 197 0
Weekley:A Gall-Making Wasp on Blackbead 35
The absence of T pithecellobiae galls from the 30 blackbead plants surveyed north
of Boca Raton suggests that the gall-maker may be excluded from the northernmost
parts of its host plant's range.
Gall-maker Phenology
Tanaostigmodes pithecellobiae females oviposit on the lower surface of expanding
leaflets within 1 week of bud break. One bladder of the encyrtiform egg is inserted be-
neath the lower epidermis of the rapidly growing young leaflet; the other bladder, con-
nected to the first by a short stalk, remains on the leaflet surface for 1 or 2 days.
Apparently the inserted bladder absorbs the contents of the external one, which dis-
appears. Within a few days the eggs hatch and larval feeding begins.
Gall development parallels leaflet development. It takes 8 to 10 weeks for leaflets
to become dark green and leathery. During this time the galls develop from pimple-
like eruptions on the upper surface of the leaflet to tumor-like swellings. Galls mature
in about 10 weeks and do not change in physical appearance until emergence of the
adult gall-maker (or one of its parasitoids). Gall-maker emergence begins only after
14 weeks (later for overwintering galls). Exited galls necrose and once all the galls are
exited the leaflet abscises prematurely.
Since blackbead produces flushes of new growth throughout the rainy season, T
pithecellobiae is able to initiate several (overlapping) generations per year. A mass
emergence of overwintering gall-makers may result in high densities of galls (per leaf-
let) on the first rainy season flush. Because of differential rates of gall-maker devel-
opment within a cohort, emergences may be staggered to take advantage of the
patchier availability of oviposition sites as the season progresses.
The time required for the development of insect gall-makers from oviposition to
eclosion of the adult varies from a few days to over a year (Mani 1964) and may be pro-
longed by diapause (Mani 1964, Abrahamson and Weis 1987). T pithecellobiae galls
initiated in early or mid-season (March-July) may complete their emergence in as few
as 14 weeks. Some mid-season wasps, as well as wasps oviposited late in the season,
apparently undergo larval diapause and thus avoid emergence in the dry season when
oviposition sites are unavailable.
Gall Demographics
Between February 1992 and March 1993, I reared 892 wasps from galls collected
at the Deering Estate. Excluding 4 unidentified wasps of uncertain role, 65% were T
pithecellobiae and 35% were parasitoids belonging to 2 chalcidoid genera in the Eu-
lophidae (Table 2). Chrysonotomyia sp. outnumbered Aprostocetus sp. by 2 to 1. Nei-
ther has been identified to species (M. E. Schauff personal communication). I obtained
pupae of both parasitoid species from dissected galls and it appears that both are en-
doparasitoids on the later stages of gall-maker development.
Sex ratios of the gall-maker and its 2 major parasitoids showed a statistically sig-
nificant 60:40 female bias (Table 2).
The only predator obtained was an undescribed microlepidopteran in the Cosmop-
terygidae (R. W. Hodges personal communication). The caterpillar mines into devel-
oping galls and consumes both gall tissue and the gall-maker, leaving only the upper
and lower epidermis of the leaflet.
The "gall-mining" caterpillar is of interest both taxonomically-it may represent a
new genus within the family Cosmopterygidae (Hodges personnel communication)-
and ecologically. Mani (1964) recognized "cecidophages" (i.e., "gall-eaters") as a
Florida Entomologist 83(1)
March, 2000
TABLE 2. A SUMMARY OF WASPS REARED OVER A 13 MONTH PERIOD (FEBRUARY 1992 TO
MARCH 1993) FROM GALLED LEAFLETS COLLECTED AT THE DEERING ESTATE,
MIAMI. SEX RATIOS ARE SIGNIFICANTLY FEMALE-BIASED; SEX RATIOS AMONG
THE THREE SPECIES DID NOT DIFFER. TOTAL PERCENT PARASITISM = 35.4%.
Sex ratios % of galls
yielding
Number Number Total each
Species females males number % female species
T pithecellobiae 345 231 576 59.9' 64.6
Chrysonotomyia sp. 126 90 216 58.32 24.2
Aprostocetus sp. 61 39 100 61.03 11.2
Totals 532 360 892 59.64 100.0
'X'(1) = 22.16, p < 0.01.
'(1) = 5.67, p < 0.025.
S(1) = 19.36, p < 0.01.
S'(2) = 0.246, p > 0.88.
"highly specialized group that feed either preferentially or obligatorily on galls". He
singled out "cecidophagous insects [which] bore into the tissues of galls, eating the en-
tire flesh [of the gall] and leaving only the outer skin in the form of an empty bag, in-
side of which they even pupate". Several microlepidoptera are mentioned by Mani as
belonging to this category.
Gall Season and Cohort Longevity
There was a distinct seasonality to gall-maker development as shown by the 7 co-
horts monitored at Deering Estate over a 22 month period (Fig. 1). Gall season, the pe-
riod of gall initiation and active development, corresponds roughly to the traditional
South Florida rainy season (Chen and Gerber 1990), anticipating it by 2 months
(March-April) during which mean precipitation increases from the November-Febru-
1991 1992 AND REW 19 93
JA SON D JF MAMJJ SON D JF MAM
--I-
Fig. 1. A 22-month history of seven successive cohorts of galls at the Deering Es-
tate, Miami (July 1991 to June 1993). Gall season (March to October) is indicated by
stippled background. Width of horizontal bars indicates duration of cohort. Stars
show first confirmed emergence of T pithecellobiae; dots show weeks for which addi-
tional exits-either T pithecellobiae or parasitoids-were recorded. Heavy vertical
line represents Hurricane Andrew (August 24, 1992).
Weekley: A Gall-Making Wasp on Blackbead 37
ary low. Within the gall season, I distinguish 3 periods: early (March-April), mid
(May-July) and late (August-September). Each of the 7 cohorts was initiated during
one of these three periods. Cohort VI was destroyed by Hurricane Andrew prior to
maturation and is excluded from the following analysis.
The 2 early season cohorts, cohorts III (early March 1992) and IV (mid April 1992),
showed first emergences in their 14th and 16th weeks, respectively (though for cohort
IV, I do not have a confirmed gall-maker exit for that period) (Fig. 1). Data are not
available for these 2 cohorts from mid June to late August. But on August 21, with
only 18% of its original 1,195 galls present (80% of which were exited), cohort III had
essentially completed its development within 24 weeks. Similarly, only 14% of cohort
IV's original 1,141 galls remained on August 21, its 16th week, and of these 16%
showed exit holes. It is likely that many (if not most) of these galls were exited before
August 21 and their leaflets abscised. Further development of these cohorts was cut
short by Hurricane Andrew.
The 2 mid season cohorts, cohorts I (mid-July 1991) and V (mid-June 1992), also
produced gall-maker adults after 14 weeks, but emergence was discontinuous, with a
hiatus during the dry season (Fig. 1). For cohort I there was a 12 week gap (November-
February), after which emergences resumed and continued until April. Data are lack-
ing for cohort V from November to early January, but I have records for weekly emer-
gences from January to March (Fig. 2). Thus cohort V deviated from the pattern set
0 o- N=- -- - -
20 -- -............- ....
A
.S- /
o -/ - V -
/ A:
3 40 -- ---a - -- -
| t E n Cohort III: N= 176
20 .... .......... . Cohort V: N =166.
a Cohort VII: N= 225
late(VIlsi aedasout cohorts o galls inhEta iateroent 1exited gber bas
I I|- -I --- I---I i -
14 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
Gall age (weeks)
-I- CohortlIl e-CohortV --. CohortVII
Fig. 2. Seasonal variation in patterns of gall-maker emergence. A comparison of the
seasonal variation in patterns of gall-maker emergence among early (III), mid- (V) and
late (VII) season cohorts of galls at the Deering Estate, Miami. Percent exited galls based
on total number of exited galls recorded. Dotted lines for cohorts III and V indicate weeks
for which data are unavailable. Cohort III galls were initiated about 1 March 1992; cohort
V galls initiated about 10 July 1992; cohort VII galls initiated about 1 September 1992.
Florida Entomologist 83(1)
March, 2000
by cohort I by yielding gall-makers during the dry season. For both cohorts gall-maker
emergence extended over a period from 14 to 32+ weeks.
The two late season cohorts, cohorts II (mid- September 1991) and VII (early Sep-
tember 1992), were both initiated within 8 weeks of the onset of the dry season (Fig.
1). Cohort II yielded wasps only after 21 weeks, while cohort VII began to show exits
at week 20 (Fig. 2). Both cohorts produced continuous weekly emergences at least
through their 30th weeks. In both cases gall-maker emergence was delayed by the on-
set of the dry season. However, cohort VII wasps began to emerge in January 1993,
about 2 months earlier than cohort II wasps had emerged the previous year.
The earlier emergences of cohort V and cohort VII gall-makers compared to the
corresponding cohorts of the previous year correlate with higher temperatures (Fig. 3)
and greater rainfall (Fig. 4) in January 1993 compared to January 1992.
Seasonal Variation in Patterns of Development and Gall Density
Comparison of early, mid-, and late season cohorts revealed distinctly different
seasonal patterns of emergence (Fig. 2). Cohort III gall-makers developed more rap-
idly than cohort V or cohort VII gall-makers, as measured by the proportion of exited
galls per month for the three cohorts (X2(2) = 528.2, p < 0.001). Gall densities, the
mean number of galls per leaflet, also varied with the season, being significantly
greater for early season than for either mid- or late season galls (Table 3).
28
i '"',.***
| 26 ,......-.; ., ,,
"J 24 ...... .....
S22
c ,
20
SEPT OCT
NOV DEC
Month
I I
JAN FEB
-- 1991-92 --- 1992-93
Fig. 3. A comparison of average monthly temperatures in C for South Dade
County for the winter of 1991-92 versus 1992-93. The sharp increase in monthly av-
erage temperature for January 1993 compared to January 1992 corresponded to the
early emergence of overwintering gall-makers in cohorts V and VII. Temperature av-
erages computed from data collected in Homestead and supplied by the U.S. Weather
Service.
Weekley: A Gall-Making Wasp on Blackbead
/r
500
400
E 300
0 200
I-
SEPT OCT NOV
SEPT OCT NOV
DEC JAN FEB
Month
1991-92 -^- 1992-93
Fig. 4. A comparison of total monthly rainfall in mm for South Dade County for the
winter of 1991-92 versus 1992-93. The sharp increase in rainfall for January 1993
compared to January 1992 corresponded to the early emergence of overwintering gall-
makers in cohorts V and VII. Rainfall totals computed from data collected in Home-
stead and supplied by the U.S. Weather Service.
Gall densities and patterns of gall-maker emergence varied among early, mid- and
late season cohorts. Early season cohorts had statistically greater gall densities (per
leaflet) and completed development more rapidly than either mid- or late season co-
horts (Table 3, Fig. 2). Greater gall densities per leaflet early in the season were re-
lated to the mass emergence of overwintering wasps.
TABLE 3: A COMPARISON OF THE MEAN NUMBER OF GALLS PER LEAFLET FOR EARLY (III),
MID- (V), AND LATE (VII) SEASON COHORTS OF GALLS AT THE DEERING ESTATE.
THE MEAN NUMBER OF GALLS PER LEAFLET WAS SIGNIFICANTLY GREATER FOR
EARLY SEASON COHORT III THAN FOR MID-SEASON COHORT V OR LATE SEASON
COHORT VII.
Cohort Number galled leaflets Mean number galls/leaflet'
III 106 11.23 + 16.4
V 91 5.5 +4.5
VII 93 4.2 + 2.8
F(2, 287) = 13.34, p < 0.001.
Florida Entomologist 83(1)
March, 2000
Emergence schedules were protracted in mid- and late season cohorts compared to
early season cohorts. Most early season wasps emerged within 24 weeks, with the first
emergences at 14 weeks (Fig. 2). Some mid-season wasps also emerged in 14 weeks,
but some overwintered and resumed emergence over a period from 26 to 32 weeks. No
wasps emerged in 14 weeks in either of the two late season cohorts. Emergences be-
gan only after 20 weeks for cohort II and 21 weeks for cohort VII, and for both cohorts
emergences continued for more than 30 weeks.
Insect gall-makers co-opt host plant resources and are thus dependent on the
availability of those resources (Hovanitz 1959, Abrahamson & Weis 1987, Hori 1992).
Seasonal variation in patterns of gall-maker development on blackbead are undoubt-
edly related to plant resource allocation which varies from wet to dry season. Within-
cohort variations may be due to environmental stimuli, condition of the host plant,
gall density per leaflet, per leaf, or per plant, or some combination of these factors.
Comparison of T pithecellobiae's phenology to that of other gall-making tanaostig-
matids is precluded for lack of information on other species. A non-gall-making
tanaostigmatid from India, T cajaninae LaSalle, ecloses in less than three weeks
(Lateef et al. 1985).
ACKNOWLEDGMENTS
This research was conducted in partial fulfillment of the requirements for a Mas-
ter of Science in Biology at Florida International University (FIU) and was supported
by an FIU Teaching Assistantship and by a Grant-in-Aid of Research from Sigma Xi,
The Scientific Research Society. For their support and advice, I thank the members of
my graduate committee: Suzanne Koptur (chairperson) and Steve Oberbauer of FIU
and Jorge Pena of the Tropical Research and Education Center (Institute of Food and
Agricultural Sciences/University of Florida). For species determinations, I thank M.
E. Schauff and R. W. Hodges of the USDA Agricultural Research Service/Systematic
Entomology Laboratory. For permission to work at the Deering Estate, I thank Metro-
Dade Natural Areas Management. I also thank Gary Steck, John LaSalle, and an
anonymous reviewer for their editorial comments and advice.
REFERENCES CITED
ABRAHAMSON, W. G., AND A. E. WEIS. 1987. Nutritional ecology of arthropod gall mak-
ers, pp. 235-258 in F. Slansky and J. G. Rodriquez [eds]. Nutritional ecology of
insects, mites, spiders and related invertebrates. John Wiley & Sons, Inc., New
York, NY. 1016 pp.
CHEN, E., AND J. F. GERBER. 1990. Climate, pp. 11-34 in R. L. Meyers and J. J. Ewel
[eds]. Ecosystems of Florida. Univ. Central Florida Press, Orlando, FL. 765 pp.
HORI, K. 1992. Insect secretions and their effect on plant growth, with special refer-
ence to Hemipterans, pp. 157-170 in J. D. Shorthouse and 0. Rohfritsch [eds].
Biology of insect-induced galls. Oxford University Press, New York, NY. 285 pp.
HOVANITZ, W. 1959. Insects and plant galls. Scientific American. 201: 1511-162.
ISELY, D. 1990. Vascular flora of the southeastern United States. Vol. 3, Part 2 Legu-
minosae (Fabaceae). Univ. North Carolina Press, Chapel Hill, NC. 277 pp.
LASALLE, J. 1987. New World Tanaostigmatidae (Hymenoptera, Chalcidoidea). Con-
tributions of the American Entomological Institute. 23: 1-181.
LATEEF, S. S., W. REED, AND J. LASALLE. 1985. Tanaostigmodes cajaninae LaSalle
sp. n. (Hymenoptera: Tanaostigmatidae), a potential pest of pigeon pea in In-
dia. Bull. ent. Res. 75: 305-313.
LITTLE, E. L., Jr. 1978. Atlas of United States trees. Vol 5: Florida. U.S. Government
Printing Office, Washington, DC.
Johanowicz & Mitchell: Sweet Alyssum 41
LONG, R. W., AND 0. LAKELA. 1976. A flora of tropical Florida. Univ. Miami Press, Mi-
ami, FL. 963 pp.
MANI, M. S. 1964. Ecology of plant galls. Dr. W. Junk Publishers, The Hague, The
Netherlands.
MIGLIACCIO, C. P. 1987. Dade County's natural environment, pp. 4-25 in S. Ross, D. M.
Ross and J. E. Podgor, Jr. [eds]. The Dade County environmental story. Envi-
ronment Information Service of Friends of the Everglades, Miami Springs, FL.
255 pp.
STATISTICAL ANALYSIS SYSTEM (SAS). 1990. SAS/STAT user's guide. Version 6. SAS
Institute Inc., Cary, NC.
TOMLINSON, P. B. 1980. The biology of trees native to tropical Florida. Harvard Uni-
versity Printing Office, Allston, MA. 480 pp.
WUNDERLIN, R. P., B. F. HANSAN, AND E. L. BRIDGES. 1996. Atlas of Florida vascular
plants. Institute for Systematic Botany, University of South Florida, Tampa,
FL.
WUNDERLIN, R. P. 1998. Guide to the vascular plants of Florida. University Press of
Florida, Gainesville, FL. 806 pp
Johanowicz & Mitchell: Sweet Alyssum
EFFECTS OF SWEET ALYSSUM FLOWERS ON THE
LONGEVITY OF THE PARASITOID WASPS COTESIA
MARGINIVENTRIS (HYMENOPTERA: BRACONIDAE) AND
DIADEGMA INSULARE (HYMENOPTERA: ICHNEUMONIDAE)
DENISE L. JOHANOWICZ' AND EVERETT R. MITCHELL2
'Department of Entomology and Nematology, University of Florida
P.O. Box 110620, Gainesville, FL 32611 USA
2Center for Medical, Agricultural and Veterinary Entomology
U.S. Department of Agriculture, Agricultural Research Service
P.O. Box 14565, Gainesville, FL 32604 USA
ABSTRACT
The effects of sweet alyssum (Lobularia maritima) (Brassicaceae) flowers on the
longevity of two augmentatively-released parasitoids, Cotesia marginiventris (Cres-
son) (Hymenoptera: Braconidae) and Diadegma insulare (Cresson) (Hymenoptera:
Ichneumonidae), were studied in a greenhouse experiment. C. marginiventris and
D. insulare survived approximately 4.8 and 12.7 times longer, respectively, when pro-
visioned with honey or with sweet alyssum than with water alone. Sweet alyssum
planted in northern Florida cabbage fields may be one way to improve biological con-
trol by augmentatively-released natural enemies of lepidopteran pests by increasing
adult parasitoid longevity during times when few wild plants are in bloom.
Key Words: biological control, conservation, augmentation, Brassicaceae
RESUME
Se estudiaron los efectos de flores de Lobularia maritima (Brassicaceae) en la lon-
gevidad de dos parasitoides, Cotesia marginiventris (Cresson) (Hymenoptera: Braco-
nidae) y Diadegma insulare (Cresson) (Hymenoptera: Ichneumonidae), liberados de
Florida Entomologist 83(1)
March, 2000
manera incremental bajo condiciones de invernadero. C. marginiventris y D. insulare
sobrevivieron aproximadamente 4.8 y 12.7 veces mas tiempo, respectivamente, cuando
se les aliment6 con miel o con flores de L. maritima, que cuando se les aliment6 s6lo
con agua. En el Norte de Florida, la siembra de plants de L. maritima dentro de cul-
tivos de col podria ser una manera de mejorar el control biol6gico de plagas lepid6p-
teras. De esta manera, la longevidad de los parasitoides adults se incrementaria
cuando existan pocas plants de L. maritima creciendo de manera silvestre.
Conservation of adult parasitoid populations in an agroecosystem so that they
may be available at times of increased pest densities is an important consideration in
the implementation of biological control programs. Adult parasitoid wasps visit wild
flowers in the field (Leius 1960), and access to these and other (i.e. host fluids, ho-
mopteran honeydew) carbohydrate sources may increase parasitoid longevity (e.g.
van Emden 1963a, 1963b, 1964, 1965, Leius 1967; van den Bosch & Messenger 1973;
Syme 1975). Clausen (1956) suggests that some failures of biological control programs
may have been due to the lack of suitable food for the adult parasitoids. Therefore, di-
rect provisioning of a carbohydrate source in agroecosystems may help maintain local
populations of natural enemies for biological control of pests.
In cabbage fields in northern Florida, augmentative biological control programs
are being implemented as one tactic in a pilot Integrated Pest Management (IPM)
program to control lepidopterous pests such as the diamondback moth, Plutella xylos-
tella (L.) (Lepidoptera: Plutellidae), and the cabbage looper, Trichoplusia ni (Htibner)
(Lepidoptera: Noctuidae) (Mitchell et al. 1997a). Other tactics include the use of pher-
omone for mating disruption (Mitchell et al. 1997c), and surrounding fields with col-
lards as a trap crop for diamondback moth management (Mitchell et al. 1997b).
Biological control agents often are released prior to outbreaks of larval populations so
that they may be immediately available whenever pest outbreaks occur. Cotesia mar-
giniventris (Hymenoptera: Braconidae) is a polyphagous parasitoid of early-instar
lepidopteran larvae that is released to help manage cabbage looper populations. Dia-
degma insulare (Cresson) (Hymenoptera: Ichneumonidae) is a native host-specific
parasitoid of the diamondback moth that is augmentatively-released earlier in the
season than it normally appears. Previous studies demonstrated that the effective-
ness of parasitoids may be influenced by the presence of wildflowers adjacent to Bras-
sica crops (Idris & Grafius 1993, Zhao et al. 1992).
We have observed that few plants are in bloom during much of the cabbage grow-
ing season in northern Florida, so the direct provisioning of carbohydrate sources may
be one way to enhance biological control by augmentatively-released D. insulare and
C. marginiventris. Idris (1995) studied the effects of wild flowering plants on the lon-
gevity of D. insulare. Some flowering species were less effective than others, in part
because the flower shape probably did not allow access to the nectar by these short-
tongued wasps and/or because the nectar quality differed among the species. Two
plants which significantly increased the longevity and fecundity of D. insulare were
wild mustard (Brassica kaber (L.)) and wild carrot (Daucus carota (L.)). However, in-
tegrating these particular plants into cabbage agroecosystems in our area may be
problematic because wild mustard is considered a weed by local growers, and wild car-
rot may not flower rapidly enough if planted at the same time as the cabbage.
A possible alternative flowering plant to include in the cabbage agroecosystem is
sweet alyssum (Lobularia maritima) (L.) (Brassicaceae). Sweet alyssum is a non-
weedy, hearty winter annual, which flowers rapidly and attracts large numbers of
Johanowicz & Mitchell: Sweet Alyssum
natural enemies, including parasitic Hymenoptera, syrphids, and predatory bugs
(Chaney 1998). Sweet alyssum is being used on a limited basis in California as an "in-
sectary" for beneficial insects in lettuce (Chaney 1998), and is included in many "in-
sectary seed blends" available commercially (e. g. Good Bug BlendTM, Peaceful Vally
Farm Supply, Grass Valley, CA; Border PatrolTM, Garden City Seeds, Hamilton, MT).
The first step in assessing the utility of using sweet alyssum to enhance natural ene-
mies populations in cabbage is to determine the effects of this plant on the longevity
of augmentatively-released parasitoid wasps. The goal of this study was to evaluate
the longevity of D. insulare and C. marginiventris adult females provisioned with
sweet alyssum as compared to the longevity of wasps supplied with honey or with no
carbohydrate source.
MATERIALS AND METHODS
All studies were conducted in cages located in a glasshouse under ambient light at
the USDA-ARS Center for Medical, Agricultural and Veterinary Entomology in
Gainesville, Florida. The cages were square, 30 x 30 x 30 cm with four sides of fine or-
gandy cloth for ventilation. The cages were partially shaded with black shadecloth to
protect against the afternoon sun. The in-cage temperatures ranged between 23 and
30C. Studies were conducted between December, 1998 and April, 1999.
C. marginiventris were reared at the Gast Rearing Facility, USDA-ARS, Missis-
sippi State University, MS, and shipped as pupae to our laboratory. D. insulare were
reared at our laboratory from diamondback moth larvae feeding on collard leaves.
Sweet alyssum (white-flowered) was grown from seed in our greenhouse or purchased
from a local nursery which reportedly did not apply insecticides to the plants. The
plants were used when they reached approximately 10 x 10 cm.
Ten newly-emerged female parasitoids were housed per cage. The parasitoids were
housed with one of the following three treatments: a potted sweet alyssum plant plus
a water-soaked cotton ball, honey plus a water-soaked cotton ball, or a water-soaked
cotton ball. In the honey treatment, fresh honey (Sue Bee wildflower honey) was
streaked on the cage screen every 2 days. Fresh water was provided to each cage daily.
The alyssum was watered daily. Soil-filled pots were added to the cages without the
sweet alyssum and watered daily to reduce effects of soil or humidity differences. Four
replicates of each treatment were conducted for each species.
Cages were monitored daily to record the number of surviving wasps in the cage.
Longevity was measured in days until mortality by recording the number of wasps
alive on a given day; the remaining number were recorded as dead. The mean number
of days until mortality per replicate for each treatment was calculated, an analysis of
variance was conducted (JMP, SAS Institute 1996) and the means (n = 4 per treat-
ment) compared using the Tukey-Kramer HSD means separation test (JMP, SAS In-
stitute 1996) at alpha = 0.05.
RESULTS
Cotesia marginiventris
The addition of carbohydrate sources had a significant effect on the longevity of
C. marginiventris (F = 49.49; df = 11; p < 0.0001). The longevity was significantly dif-
ferent between wasps provided water (x + S.E; 4.0 + 0.2; range 2-5 days) and those
Florida Entomologist 83(1)
March, 2000
provided honey (18.6 + 1.6; range 3-33 days) and between wasps provided water and
those provided sweet alyssum (19.4 + 1.1; range 4-30 days) (Fig. 1). There was no sig-
nificant difference in longevity between wasps provided with honey or sweet alyssum.
Based on these results, Cotesia marginiventris survived on average approximately 4.8
times longer when provisioned with honey or sweet alyssum than with water alone.
Diadegma insulare
The addition of carbohydrate sources had significant effects on the longevity of D.
insulare (F = 74.66; df = 11; p < 0.0001). The longevity was significantly different be-
tween wasps provided water (x + S.E; 2.2 + 0.3; range 1-4 days) and those provided
honey (27.2 + 1.0; range 2-51 days) and between wasps provided water and those pro-
vided sweet alyssum (27.3 + 2.7; range 1-53 days) (Fig. 2). There was no significant dif-
ference in longevity between wasps provided honey and those provided sweet
alyssum. Based on these results, D. insulare survived on average approximately 12.7
times longer when provisioned with honey or sweet alyssum than with water alone.
DISCUSSION
Providing a carbohydrate source in the form of honey or sweet alyssum to C. mar-
giniventris and D. insulare extended their longevity well beyond that when provided
water alone. There were no significant differences in the longevity of either C. mar-
giniventris or D.insulare when caged with honey or with sweet alyssum flowers.
The longevity of wasps provided a nectar source in the field may not be as great as
it was in the greenhouse, because environmental conditions are expected to be more
severe. The longevity may vary even under greenhouse conditions, since the average
longevity of D. insulare in this study was slightly higher than that of those provided
honey or appropriate flowers in a previous study, also conducted in a greenhouse (Id-
ris 1995). In addition to variations in environmental conditions, longevity may be af-
fected by whether or not the female has been exposed to hosts (Hohmann et al. 1988).
Studies are planned which address the effects of sweet alyssum on biological con-
trol by C. marginiventris and D. insulare in commercial cabbage fields. Preliminary
observations conducted in an experimental field plot and in a commercial cabbage
field indicate that D. insulare does visit sweet alyssum flowers. Although a positive
correlation was found between longevity and fecundity when fed appropriate nectar
(Idris 1995), we will not know if this will translate into improved biological control by
D. insulare or by C. marginiventris until field studies are completed. To test for in-
creased parasitism in the field, we will plant areas of sweet alyssum in the field mar-
gins and record parasitism at various distances from the flowers throughout the
season. Diamondback moth populations are highest in the field margins (Hu et al.
1997), and are particularly high in cooperating growers' fields because of their adop-
tion of a collard trap crop technique in which collards, a favored host plant, are
planted in the cabbage field peripheries (Mitchell et al. unpublished data).
In order to implement the planting of sweet alyssum in commercial cabbage in our
area, we also will need to determine whether sweet alyssum is compatible with the
current commercial cabbage growing operations, whether it flowers long enough and
survives common agricultural practices, whether it will flower when necessary,
whether it becomes weedy, and whether it may increase pest populations by providing
food to adult moths. Preliminary observations indicate that sweet alyssum planted
from seed in October started flowering as soon as three weeks after being planted,
that it did not spread or become weedy, and that flowers persisted for approximately
Johanowicz & Mitchell: Sweet Alyssum
Cotesia marginiventris Longevity
Sweet Alyssum
b
Water
Honey
Fig. 1. Mean longevity of female Cotesia marginiventris provided sweet alyssum
flowers, honey, or water alone. Error bars show S.E.M. Bars with same letter are not
significantly different (p < 0.05).
5-6 months (March-April). Chaney (1998) reported that of all flowering plants tested
in California as nectar sources for natural enemies of aphids, none bloomed as quickly
as sweet alyssum or attracted as many desirable beneficial species while attracting
relatively few pest species.
Based on the results of our study, on our preliminary observations, and on the re-
sults of Chaney (1998), we are encouraged to proceed with further studies of this tac-
tic in commercial cabbage fields. Releases ofD. insulare have been somewhat effective
in managing the diamondback moth, and the addition of a food source for these and
other released adult parasitoids shows promise as an improvement to augmentative
biological control of lepidopteran pests in cabbage.
ACKNOWLEDGMENTS
We thank Joyce Leach, Charlie Stuhl, and Amanda Bishop for rearing Diadegma
insulare and Plutella xylostella, Victor Chew and M. Sidney Mayer for helpful com-
ments on the data analysis, and Gary Leibee, Robert Meagher, Jr., Sanford Porter,
John Sivinski, and anonymous reviewers for helpful comments on the manuscript.
This article reports the results of research only. Mention of a proprietary product does
not constitute an endorsement or the recommendation for its use by USDA.
Florida Entomologist 83(1)
Diadegma insulare Longevity
March, 2000
30 --- -
25 -
'U 20
| 15
')
10
5 -
0 -
Sweet Alyssumrn
a
--I
Honey
b
Water
Fig. 2. Mean longevity of female Diadegma insulare provided sweet alyssum flow-
ers, honey, or water alone. Error bars show S.E.M. Bars with same letter are not sig-
nificantly different (p < 0.05).
REFERENCES CITED
CHANEY, W. E. 1998. Biological control of aphids in lettuce using in-field insectaries,
pp. 73-83 in Pickett, C. H. and R. L. Bugg, [eds.], Enhancing biological control-
Habitat management to promote natural enemies of agricultural pests. Uni-
versity of California Press, Berkeley, CA.
CLAUSEN, C. P. 1956. Biological control of insect pests in the Continental United
States. Dept. Agr. Tech. Bull. 1139.
HOHMANN, C. L., R. F. LUCK, AND E. R. OATMAN. 1988. A comparison of longevity and
fecundity of adult Trichogramma platneri (Hymenoptera: Trichogrammatidae)
reared from eggs of the cabbage looper and the Angumouis grain moth, with
and without access to honey. J. Econ. Entomol. 81: 1307-1312.
Hu, G. Y., E. R. MITCHELL, AND J. S. OKINE. 1997. Effect of habitat types on popula-
tion densities and parasitism of the diamondback moth (Lepidoptera: Plutel-
lidae) larvae in cabbage fields. J. Entomol. Sci. 32: 56-71.
IDRIS, A. B. 1995. Ecology and behavior of Diadegma insulare (Cresson), a biological
control agent of diamondback moth, Plutella xylostella (L.). Dissertation, Mich-
igan State University, 205 pages.
IDRIS, A. B., AND E. GRAFIUS. 1993. Field studies on the impact of pesticides on the di-
amondback moth Plutella xylostella (L.) (Lepidoptera: Plutellidae) and parasit-
ism by Diadegma insulare (Cresson) (Hymenoptera: Ichneumonidae). J. Econ.
Entomol. 86: 1196-1202.
Johanowicz & Mitchell: Sweet Alyssum
LEIUS, K. 1960. Attractiveness of different foods and flowers to the adults of some hy-
menopterous parasitoids. Can. Entomol. 92: 369-376.
LEIUS, K. 1967. Food sources and preferences of adults of a parasite, Scambus buoli-
anae (Hymenoptera: Ichneumonidae) and their consequences. Can. Entomol.
99: 865-871.
MITCHELL, E. R., F. C. TINGLE, R. C. NAVASARO-WARD, AND M. KEHAT. 1997a. Dia-
mondback moth (Lepidoptera: Plutellidae) parasitism by Cotesia plutellae (Hy-
menoptera: Braconidae) in cabbage. Florida Entomologist 80: 1-13.
MITCHELL, E. R., G. Y. HU, AND J. S. OKINE. 1997b. Diamondback moth (Lepidoptera:
Plutellidae) infestation and parasitism by Diadegma insulare (Hymenoptera:
Ichneumonidae) in collards and adjacent fields. Florida Entomologist 80: 54-62.
MITCHELL, E. R., G. Y. HU, J. S. OKINE, AND J. R. MCLAUGHLIN. 1997c. Mating dis-
ruption of diamondback moth (Lepidoptera: Plutellidae) and cabbage looper
(Lepidoptera: Noctuidae) in cabbage using a blend of pheromones emitted from
the same dispenser. Journal of Entomological Sciences 32: 120-137.
SAS INSTITUTE. 1996. JMP Start Statistics: A Guide to statistics using JMP and JMP
IN Software. Duxbury Press, Belmont, CA.
SYME, P. D. 1975. The effects of flowers on the longevity and fecundity of two native par-
asites of the European pine shoot moth in Ontario. Environ. Entomol. 4: 337-346.
VAN DEN BOSCH, R., AND P. S. MESSENGER. 1973. Biological Control. Intext Educa-
tional Publishers, New York.
VAN EMDEN, H. F. 1963a. A preliminary study of insect numbers in field and hedgerow.
Entomol. Mon. Mag. 98: 255-259.
VAN EMDEN, H. F. 1963b. An observation on the effect of flowers on the activity of par-
asitic Hymenoptera. Entomol. Mon. Mag. 98: 265-270.
VAN EMDEN, H. F. 1964. The role of uncultivated land in the biology of crop pests and
beneficial insects. Sci. Hortic. 42: 121-136.
VAN EMDEN, H. F. 1965. The effect of uncultivated land on the distribution of the cab-
bage aphid (Brevicoryne brassicae) on an adjacent crop. J. Appl. Ecol. 2: 171-196.
ZHAO, J. Z., G. S. AYERS, E. J. GRAFIUS, AND F. W. STEHR. 1992. Effects of neighboring
nectar-producing plants on populations of pest Lepidoptera and their parasi-
toids in broccoli plantings. Great Lakes Entomol. 25: 253-258.
Florida Entomologist 83(1)
March, 2000
INSTABILITY OF SANDY SOIL ON THE LAKE WALES RIDGE
AFFECTS BURROWING BY WOLF SPIDERS (ARANEAE:
LYCOSIDAE) AND ANTLIONS (NEUROPTERA:
MYRMELEONTIDAE)
MICHELLE M. HALLORAN, MARGARET A. CARREL AND JAMES E. CARREL
Division of Biological Sciences, 105 Tucker Hall
University of Missouri-Columbia, Columbia, MO 65211-7400
ABSTRACT
Tests with Geolycosa spiders revealed that these arachnids may be excluded
largely from the Ridge Sandhill-turkey oak ecosystem on the Lake Wales Ridge be-
cause their burrows quickly collapse in the unstable natural soil (Astatula sand).
Comparable results were obtained in tests of pit construction by antlion larvae
(Myrmeleontidae), which may serve as bioindicators of soil stability.
Key Words: Geolycosa, Myrmeleon, Florida scrub, sandhill, ecology, behavior
RESUME
Pruebas con la arania Geolycosa demuestran que esta especie puede ser excluidas
del ecosistema de "Southern Ridge Sandhill-turkey oak" en la loma de Lake Wales,
dado que sus madrigueras se derrumban rdpidamente en el suelo natural inestable
(arena "Astatula"). Resultados semejantes fueron obtenidos en pruebas de hoyos ex-
cavados por larvas de la hormiga le6n (Myrmeleontidae), lo cual podria ser utilizado
como un bio-indicador de la estabilidad del suelo.
The scrub and sandhill ecosystems on the Lake Wales Ridge in central Florida are
major centers ofendemism that now harbor many rare and endangered species (Dey-
rup & Eisner 1993, 1996, Dobson et al. 1997, Ando et al. 1998). These xeric, upland
communities consist of a complex patchwork of approximately 15 distinct vegetative
associations, most of which depend on periodic fire to maintain species diversity
(Abrahamson et al. 1984).
Quantitative field studies conducted annually from 1993-1999 at Archbold Biolog-
ical Station, located at the southern terminus of the Lake Wales Ridge, reveal that two
burrowing wolf spiders endemic to Florida scrub, Geolycosa xera archboldi and G.
hubbelli, are numerous in all but one vegetative association, namely Ridge Sandhill
with turkey oak (RSt) (J. Carrel, unpublished results). This observation is quite sur-
prising because other wolf spiders (genus Lycosa) are plentiful in the RSt habitat and
Geolycosa themselves are numerous in all neighboring habitats, such as Hickory
Scrub (RSh) and Scrubby Flatwoods (SF) (See Richman et al. 1995 for a list of local
wolf spiders). In addition, because all of the study sites had been burned several years
before our studies as part of the station's fire management plan (Main & Menges
1997), there were many patches of barren sand suitable for Geolycosa to colonize (Car-
rel 1995, Marshall 1995a, Marshall et al. 1999).
Halloran et al.: Unstable sand affects soil arthropods
We reasoned that the excessive instability of dry soil present in the RSt habitat
might make it unsuitable for Geolycosa either to construct or to maintain their simple
burrows. The burrows are open tubes, 2-15 mm in diameter, lined with silk only at the
top, which extend vertically down 4-15 cm, ending in a bulbous chamber (McCrone
1963, Wallace 1942, Corey 1991, J. Carrel, unpublished data). Moreover, we hypothe-
sized that antlion larvae (Myrmeleon crudelis Walker) might be particularly useful as
bioindicators of soil instability because it is known that these insects will actively
seek out fine grained, stable sands for pit construction and that their pits made in fine
grain sand are less symmetrical than those made in coarse grained sands (Lucas
1982, 1986, 1989). To evaluate our ideas, we analyzed published survey data for soils
found in the RSt and SF habitats, we determined persistence of artificial spider bur-
rows constructed in both habitats, and we studied burrowing by spiders and antlion
larvae in the different soils.
MATERIALS AND METHODS
Soil and Weather Data
We conducted our tests during the dry season (February) at the Archbold Biological
Station, Highlands County, Florida. We analyzed data on the Astatula soil in the RSt ec-
osystem and, for comparison, on Satellite soil in the SF ecosystem published by Carter
et al. (1989) in a recent soil survey of Highlands Country. They used the Archbold Bio-
logical Station as a primary reference site for these sandy upland soils because the man-
aged ecosystems at the Station, for the most part, represent presettlement conditions
on the Lake Wales Ridge. We obtained weather information daily during our tests from
the local weather center, which has been in operation at the Station since 1932.
Tests Using Artificial Geolycosa Burrows
This experiment was designed to test whether artificial Geolycosa burrows con-
structed in Astatula soil within the RSt habitat would persist as long as those con-
structed in Satellite soil within the SF habitat.
On 5-II-1996, one day after a heavy (2.9 cm) rain had soaked the soil, we set up 10
stations at 10 m intervals along a transect on each soil type. We chose localities that
had been burned two or three times in the past two decades as part of a management
plan designed to simulate presettlement burning patterns. At each station we ex-
tracted 14 cores, 7 mm diameter by 150 mm deep, in the sand using a piece of tubular
steel taken from a television antenna, for a total of 140 cores/soil type. The cores were
comparable in size to natural Geolycosa burrows. Subsequently on day 1, 2, 4, 6, 8, 10,
or 12 thereafter we randomly selected one hole at each station and plumbed its depth
to the nearest mm with a narrow rod. During this test there was no precipitation ex-
cept on day 11 (1.3 cm rainfall) and air temperatures were relatively cool (average
~13C, range: -6 to 27C).
Tests Using Living Geolycosa
These tests were designed to determine two things: (1) whether the burrows con-
structed by Geolycosa spiders in Astatula soil from the RSt ecosystem are comparable
to those they make in Satellite soil from the SF ecosystem, and (2) whether, after re-
moval of the resident spiders, unoccupied burrows in Astatula soil would persist as
long as unoccupied burrows of comparable size made in Satellite soil.
Florida Entomologist 83(1)
March, 2000
We reconstructed natural profiles ofAstatula and Satellite soils to a depth of 12 cm
in plastic flower pots (15 cm diameter x 15 cm height, N = 10 for each soil type) by ex-
cavating three layers (0-2, 2-8, and 8-12 cm depth) of each soil separately and then
adding them in reverse order to the pots after passing each through a coarse (4 mm
mesh size) sieve to remove roots and debris. On 13-II-1995, the pots were partially
buried with sand in an open firelane near the weather station after they were ar-
ranged in five columns of four pots each using a complete random block design. To
each pot we added one adult or subadult Geolycosa hubbelli chosen at random from 20
spiders we had recently dug out of their burrows in Satellite sand and weighed to the
nearest mg. We also placed four or five dried leaves on the sand for each spider to use
to build the turrets that they characteristically construct around their burrow en-
trances. Each pot was tightly covered with a piece of nylon mesh fabric to retain the
spider and then entire assemblage of 20 pots was covered with a sheet of coarse hard-
ware cloth attached to a heavy wooden frame to prevent disturbance by raccoons and
other mammals.
We measured the depth of each spider burrow to the nearest mm at 2 days and
again at 10 days by plumbing it gently with a thin rod. Subsequently all spiders were
removed without damaging the burrows after we lured them out of their burrows with
a mealworm (the larva of the beetle Tenebrio molitor) tethered to a piece of thread.
The diameter of each burrow was measured to the nearest 0.1 mm with calipers. Fol-
lowing this, the pots were covered again with the nylon fabric and hardware cloth and
left in situ for 4 days before the depths of the unoccupied burrows were measured as
before.
On the first day of this experiment, shortly after the spiders were set up, there was
light rain (0.5 cm), followed by heavy rain (3.1 cm) on the next day. Thereafter it did
not rain until day 8 when a total of 2.8 cm precipitation fell. During these tests daily
air temperatures were relatively warm (average ~20C, range: 3 to 32C).
Tests Using Antlion Larvae
Antlion larvae (Myrmeleon crudelis, N ~ 50) were collected individually in vials on
28-II-1998, from sheltered areas beside buildings at the Station, as was done previ-
ously by Lucas (1986, 1989b), and brought into the laboratory (24-27C, 16L: 8 D). Af-
ter inspecting the head capsule for key characteristics (Lucas & Stange 1981), we
arranged them in order by body size and then chose 40 medium sized, second and
third instar larvae, returning the largest and smallest individuals to the field. We ran-
domly assigned the remaining larvae singly to plastic pots (11 cm diameter x 11 cm
height) filled to 10 cm depth either with Astatula soil from the RSt ecosystem or with
Satellite soil from the SF ecosystem. The soil originally was scraped from the upper-
most 10 cm in the field and air dried at room temperature for one week before sieving
to remove roots and debris.
At 24 and 48 hr we checked each pot for the presence or absence of an antlion pit
and relocation of a pit in the otherwise level sand. We classified an antlion larva as
having relocated by the presence of trails in the sand or the presence of a shallow de-
pression where the old pit had been located. After 48 hr we measured the diameter of
each pit on its two major axes, corresponding to the anterior-posterior and left-right
position of the antlion resting at the bottom of the pit, and the maximum depth of the
pit to the nearest mm using calipers (Lucas 1989b). To assess the asymmetry of each
pit, we calculated the arithmetic difference between the two diametric measurements.
Representative specimens of G. hubbelli and M. crudelis were preserved in the col-
lection of arthropods at the Archbold Biological Station.
Halloran et al.: Unstable sand affects soil arthropods
RESULTS
Interpretation of Soil Survey Data
By overlaying the vegetation map ofAbrahamson et al. (1984) with the general soil
map of Carter et al. (1989), we determined that the Ridge Sandhill with turkey oak
(RSt) ecosystem at the Archbold Biological Station is located predominantly on Astat-
ula soil and the Scrubby Flatwoods (SF) ecosystem is extensively found on Satellite
soil. As are all other soils of the upland ridges in Highlands County, both Astatula and
Satellite soils are nearly level or gently sloping and they are sandy to a depth greater
than 2 m. Astatula soil, prized for citrus production, is excessively well drained; in
contrast, Satellite soil is somewhat poorly drained (Carter et al. 1989).
The size distribution of soil particles in the upper 20 cm of Astatula soil is very dif-
ferent from Satellite and most other soils on the Lake Wales Ridge, otherwise these
soils all have remarkably similar properties. As shown in Table 1, Astatula soil is a
mixture of mostly medium and coarse sand. In contrast, Satellite soil has little coarse
sand, but much medium and fine sand. Biophysical calculations demonstrate that
larger sand particles are more likely to fall down a slope than smaller ones under dry
conditions (Lucas 1982), so the soil survey data led us to predict that burrows of spi-
ders and antlions in coarse Astatula soil would be inherently less stable than compa-
rable burrows made in fine Satellite soil. In addition, the small amount of clay present
only in Astatula soil might account for the slight crustiness of surficial material we
commonly detect in the RSt ecosystem that is absent from the SF ecosystem. Results
of tests reported here confirm our predictions.
Tests Using Artificial Geolycosa Burrows
Cylindrical holes in Astatula soil, constructed by us to simulate open Geolycosa
burrows, filled up with soil particles faster than those made in Satellite soil (Fig. 1).
The slope of the regression line decreased from 9.86 mm sand accumulated/d in the
Astatula soil to 5.45 mm sand accumulated/d in the Satellite soil. After 12 days the
holes in Astatula sand were significantly shallower than those in Satellite sand
(Mann-Whitney U-test or Student's t-test, P < 0.05). In fact, on day 12 the openings
for six of ten artificial burrows in the Astatula sand were barely detectable, whereas
only two of ten holes in Satellite sand were hard for us to see.
TABLE 1. PHYSICAL PROPERTIES OF TWO SOIL TYPES USED IN THIS STUDY*.
Particle size distribution (%)
Coarse & Fine &
Soil medium very fine
Habitat type series sand sand Silt Clay Drainage
Ridge sandhill Astatula 81.0 17.3 0.3 1.4 Excessive
with turkey oak
(RSt)
Scrubby Satellite 46.1 51.9 1.5 0.5 Somewhat
flatwoods (SF) poor
*Data from L. J. Carter et al. (1989).
Florida Entomologist 83(1)
Ast.: y = 150.9 + 9.86x
March, 2000
RA2 = 0.966
-75
-100-
-125-
-150
Sat.: y = 136.3 + 5.45x R^2 = 0.929
I -I
0 2 4 6 8 10 12
Elapsed time (days)
Fig. 1. Artificial Geolycosa spider burrows dug in Astatula soil (Ast., solid circles)
refill faster than those dug to the same depth in Satellite soil (Sat., open circles).
Means, standard errors, and best fit regression equations are indicated.
Tests Using Living Geolycosa
Geolycosa spiders burrowed equally well in both soils (Table 2). Within two days
each spider had constructed a complete burrow, as indicated by the fact that in the
subsequent 8 days they did not significantly deepen their burrows even though there
was sand remaining beneath them (Mann Whitney U-test or Student's t-test, P >
0.05). In addition, the burrow entrances in each soil type were equivalent in diameter
(11.4 + 0.8 mm for Astatula soil; 12.3 + 0.4 mm for Satellite soil; Mann-Whitney U-test
or Student's t-test, P > 0.1).
However, after removal of the wolf spiders, unoccupied burrows in Astatula soil
collapsed and filled in more extensively than those in Satellite soil (Table 2). This hap-
pened despite the fact that there were no rain storms or strong gusts of wind during
the four day interval and the firmly seated pots had a protective cover of netting and
Halloran et al.: Unstable sand affects soil arthropods
TABLE 2. BURROW CONSTRUCTION BY GEOLYCOSA SPIDERS AND PERSISTENCE OF UNOC-
CUPIED SPIDER BURROWS IN TWO SOIL TYPES.
Burrow depth (mm, X + SEM, N = 10)
Elapsed time
(days) Astatula soil Satellite soil P value*
2 89 6 85 + 8 n.s.
10 88 +7 93 5 n.s.
---------------------------- Spiders removed ----------------------------
14 48 + 9 71 + 7 <0.05
*Pairwise comparison by soil type in each row, Mann-Whitney U-test or Student's t-test, n.s.= not significant.
hardware cloth. At the end of the experiment (day 14) we did not notice any difference
in the entrances of the spider burrows or the surrounding sand in the pots, so sand
that accumulated within spider burrows had to be of subterranean origin.
Tests Using Antlion Larvae
The pits constructed by antlion larvae (M. crudelis) ranged from 20-40 mm in di-
ameter and 8-27 mm in depth, but overall there was no significant difference in size
between those made in Astatula and Satellite soils. However, we found that M. crude-
lis pits made in Astatula soil were more symmetrical than those made in Satellite soil
(Mann-Whitney U-test, U = 287.5, P < 0.02). Knowing that asymmetrical pits are a
design feature for improved prey capture whose implementation is impeded by large
grains of sand (Lucas 1982, 1989), our results indicate that Astatula soil was less suit-
able than Satellite soil for pit construction by antlion larvae.
We also found each day that twice as many antlions (6-8 larvae) in the coarse As-
tatula soil relocated their pits than those (3-4 larvae) in the relatively fine-grained
Satellite soil. The daily differences for each pit relocation by soil type were significant
(x2 = 7.75, P < 0.01, df = 1 for day 1; Z2 = 5.05, P < 0.05, df = 1 for day 2).
DISCUSSION
The absence of Geolycosa spiders from the Ridge Sandhill with turkey oak (RSt)
ecosystem at the Archbold Biological Station cannot be explained primarily by a lack
of colonizing spiders. Geolycosa spiders are abundant in the Hickory Scrub (RSh) and
the Scrubby Flatwoods (SF) that adjoin the somewhat more elevated RSt ecosystem
(J. Carrel, unpublished observations), so the source population is large. Although
Geolycosa endemic to scrub may exhibit limited dispersal (~0.4 m/day) (Marshall
1995b), given many months they can easily cover the 50-100 m distance needed to in-
vade the RSt ecosystem. In fact, in 1997 and 1998 we detected several Geolycosa bur-
rows located in the RSt, but never actually in the native vegetation: the spiders
always were restricted to footpaths where mats of centipede grass (Eremochloa ophi-
uroides) and wire grass (Aristida strict) reinforced the soil. Geolycosa are known to
invade and propagate extensively in SF ecosystems at the Archbold Biological Station
within one year after a burn rids the soil of leaf litter and many barren patches are
created (Carrel 1995).
Florida Entomologist 83(1)
March, 2000
Our tests indicate that Geolycosa spiders and antlion larvae can successfully build
burrows in the Astatula soil found in the RSt ecosystem, but soon thereafter the bur-
rows and pits begin to collapse. This suggests the long-term outlook for these arthro-
pods in the RSt ecosystem may be bleak: they must persistently work and expend
considerable energy to maintain their subterranean homes or risk burial by subsiding
sand. In addition, based on ecological studies of antlion larvae by Youthed & Moran
(1969) and Gotelli (1993), we suspect the temperature and moisture regimes in Astat-
ula soil on the Lake Wales Ridge may prove stressful to burrowing spiders and antlion
larvae.
One cannot help but wonder if soil instability drives the Geolycosa spiders and ant-
lion larvae to abandon their burrows in the RSt ecosystem. Both species of Geolycosa
living in their preferred habitats (i.e., different types of scrub) at the Archbold Biolog-
ical Station are known to relocate their burrows at a low frequency (-1-3% per day)
(Marshall 1995a, J Carrel, unpublished results). Likewise, antlion larvae relocate
their pits very infrequently unless they are disturbed (Heinrich & Heinrich 1984,
Matsura 1987). Perhaps after colonizing the RSt ecosystem these arthropods abandon
their burrows at such a high rate that there is a tendency for local populations to de-
cline or, in some instances, to go extinct. In particular, the act of relocating burrows
and actively maintaining existing ones probably puts the occupants at heightened
risk from attacks by enemies, such as birds, pompilid wasps, and spiders, including
cannibalistic Geolycosa (Marshall 1995b). To our knowledge, there are no published
reports on the affect of soil type on the distribution and survival of either Geolycosa
spiders or antlion larvae. Currently we are conducting field tests to determine rates
of site abandonment and survivorship of Geolycosa and antlion larvae introduced into
RSt and SF ecosystems at the Archbold Biological Station.
ACKNOWLEDGMENTS
We thank Drs. James Layne and Mark Deyrup for informative discussions about
the natural history of the Lake Wales Ridge, Nancy Deyrup for providing weather
data, the staff of the Archbold Biological Station for providing research facilities, and
Carrie McMahon, Heather Burgess, Margaret Janowski-Bell, and Thomas Carrel for
helping in the field. Funding for this work came in part from a grant from the Re-
search Council and Development Funds at the University of Missouri. Steve Latta
kindly provided the Spanish abstract.
REFERENCES CITED
ABRAHAMSON, W. G., A. F. JOHNSON, J. N. LAYNE, AND P. A. PERONI. 1984. Vegetation
of the Archbold Biological Station, Florida: an example of the southern Lake
Wales Ridge. Florida Scient. 47: 209-250.
ANDO, A., J. CAMM, S. POLASKY, AND A. SOLOW. 1998. Species distributions, land val-
ues, and efficient conservation. Science 279: 2126-2128.
CARREL, J. E. 1995. Fire ecology of rare burrowing wolf spiders in Florida scrub.
Trans. Missouri Acad. Sci. 29: 69-70.
CARTER, L. J., D. LEWIS, L. CROCKETT, AND J. VEGA. 1989. Soil survey of Highlands
County, Florida. Soil Conservation Service, USDA, p. 1-178.
COREY, D. T. 1991. Burrow structure and placement in Geolycosa xera (Araneae: Ly-
cosidae). Florida Scient. 54: 125-128.
DEYRUP, M., AND T. EISNER 1993. Last stand in the sand. Natural History 102 (12):
42-47.
Halloran et al.: Unstable sand affects soil arthropods
DEYRUP, M., AND T. EISNER. 1996. Description and natural history of a new pygmy
mole cricket from relict xeric uplands of Florida (Orthoptera: Tridactylidae).
Mem. Entomol. Soc. Washington 17: 59-67.
DOBSON, A. P., J. P. RODRIGUEZ, W. M. ROBERTS, AND D. S. WILCOVE. 1997. Geo-
graphic distribution of endangered species in the United States. Science 275:
550-553.
GOTELLI, N. J. 1993. Ant lion zones: Causes of high-density predator aggregations.
Ecology 74: 226-237.
HEINRICH, B., AND M. J. E. HEINRICH. 1984. The pit-trapping foraging strategy of the
ant lion, Myrmeleon immaculatus DeGeer (Neuroptera: Myrmeleontidae). Be-
hav. Ecol. Sociobiol. 14: 151-160.
LUCAS, J. R. 1982. The biophysics of pit construction by antlion larvae (Myrmeleon,
Neuroptera). Anim. Behav. 30: 651-664.
LUCAS, J. R. 1986. Antlion pit construction and kleptoparasitic prey. Florida Ent. 69:
702-710.
LUCAS, J. R. 1989. The structure and function of antlion pits: slope asymmetry and
predator-prey interactions. Anim. Behav. 38: 318-330.
LUCAS, J. R., AND L. A. STANGE. 1981. Key and descriptions to the Myrmeleon larvae
of Florida (Neuroptera: Myrmeleontidae). Florida Ent. 64: 207-216.
MAIN, K. N., AND E. S. MENGES. 1997. Station management plan. Archbold Biological
Station Land Management Publication 97-1.104 pp.
MARSHALL, S. D. 1995a. Natural history, activity patterns, and relocation rates of a
burrowing wolf spider: Geolycosa xera archboldi (Araneae, Lycosidae).
J. Arachnol. 23: 65-70.
MARSHALL, S. D. 1995b. Mechanisms of the formation of territorial aggregations of the
burrowing wolf spider Geolycosa xera archboldi McCrone (Araneae, Lycosidae).
J. Arachnol. 23: 145-150.
MARSHALL, S. D., W. R. HOEH, AND M. DEYRUP. 1999. Patterns of species diversity in
a genus of Florida endemics: a product of historical biogeography and habitat
destruction. J. Ins. Conserv (in press).
MATSURA, T. 1987. An experimental study of the foraging behavior of the pit-building
antlion larvae, Myrmeleon bore. Res. Popul. Ecol. 29: 17-26.
MCCRONE, J. D. 1963. Taxonomic status and evolutionary history of the Geolycosa
pikei complex in the southeastern United States. Am. Midl. Nat. 70: 47-73.
RICHMAN, D. B., J. S. MEISTER, W. H. WHITCOMB, AND L. MURRAY. 1995.A comparison
of populations of wolf spiders (Araneae, Lycosidae) on two different substrates
in southern Florida. J. Arachnol. 23: 151-156.
WALLACE, H. K. 1942. A revision of the burrowing spiders of the genus Geolycosa (Ara-
neae, Lycosidae). Am. Midl. Nat. 27: 1-62.
YOUTHED, G. J., AND V. C. MORAN. 1969. Pit construction by myrmeleontid larvae.
J. Insect. Physiol. 15: 867-875.
Florida Entomologist 83(1)
March, 2000
A NEW SPECIES OF PSYCHODA (DIPTERA:PSYCHODIDAE)
FROM CAVES IN GEORGIA
LAURENCE W. QUATE1
Natural History Museum of Los Angeles County
900 Exposition Blvd., Los Angeles, CA 90016, USA
1Mailing Address: 16271 Oak Creek Trail, Poway, CA 92064, USA
ABSTRACT
A new species of Psychoda, collected in caves in Georgia, U.S.A., is named and
adults and larvae described and illustrated.
Key Words: Psychoda, caves, Georgia
RESUME
En este trabajo se identifica y nombra una especie del g6nero Psychoda que fue co-
lectada en cuevas del estado de Georgia. Se described e ilustran adults y larvas de
esta nueva especie.
During thesis research on cave ecology, Will Reeves, a student at Clemson Univer-
sity, discovered a new species of Psychoda in several caves. This species is now named
and described to make the name available for Reeves' thesis.
Psychoda reevesi Quate, New Species
Figs. 1-7
Female. Eyes separated by 1-1.5 facet diameters; interocular suture absent; frons
hair patch extends dorsally between eyes to bottom of first facet row, slightly sepa-
rated from vertex hair patch; palpomeres 10:10:10:13. Antenna with 14 flagellomeres,
terminal 3 separated and unequal in size, 14 smaller than 12 and 13; ascoids Y-
shaped. Radial and medial forks of wing complete. Genitalia as figured; subgenital
plate with well defined lobes, sides of plate convergent basad of lobes, parallel at level
of lobes; prominent structure on inner face of plate, quadrate with apical lobes; genital
digit arises between lobes of this structure; spermatheca lacking lateral strut (bar
from inner margin of spermathecal sac to lateral margin).
Measurements. Antenna 1.01-1.08 mm (x = 1.03, N=7). Wing length 1.50-1.88
mm, width = 0.70-0.78 mm (x = 1.63, 0.73, n = 7).
Male. Eyes separated by 1 facet diameter. Genitalia as figured; hypandrium
arched above aedeagus, expanded into lobed projection on midline; paramere slender,
tapering to acute apex, little shorter than basiphallus; anterior gonocoxal apodeme
projecting posteriorly as large, setose lobe, upper margin curves anteriorly, well scle-
rotized; tergite 10 a small, rounded lobe; surstylus elongate.
Measurements. Antenna 1.19-1.34 mm (n = 3). Wing length = 1.63-1.73 mm, width
= 0.73-0.75 mm (x = 1.66, 0.74, n = 4).
Quate: Psychoda reevesi from Georgia Caves
1
3
Ut'9
II ~
7k
Figs. 1-7. Psychoda reevesil. 1. Female genitalia, internal view; 2. Male gonopods
and aedeagus, dorsal view; 3. Terminal 5 flagellomeres of female; 4. Siphon of larva;
5. Oral opening of larva, ventral view; 6. Antennal segments 5,6,7 of larva, dorsal view.
Larva. Antenna mushroom shaped and not distinctive; labrum sparsely covered
with setae; mandible with single tooth; many lightly sclerotized setae on ventral sur-
face. Body with sparse, simple setae. Pair of tergal plates only on last three penulti-
mate abdominal segments, i.e., 5, 6, 7; anterior plate smaller than posterior and
without true setae; segment 5 with pair of true setae on each side of midline; siphon
comparatively short, length about 1.3x maximum width; cylindrical processes bearing
posterior spiracles recessed and not protruding beyond apex of siphon.
Holotype 9, Monroe Gap Cave, Dade Co., Georgia, 3447'N 8528'W, 29.V.98, W.
Reeves; allotype 6, Newsome Gap Cave, Dade Co., Georgia, 3447'N 8528'W, 29.V.98,
W. Reeves (USNM). Paratypes, 1 larva, same data as holotype; 5 9, 5 6, 3 larvae,
same data as allotype; 2 9, same except 2.VIII.98; (Clemson Univ., Quate Colln). All
adults reared from larvae.
Etymology. Named to honor the collector.
Larvae were collected in caves by using sterilized human dung as bait. The bait
was placed on a rock ledge about 15 meters from the cave entrance in total darkness.
Adults were reared from the larvae. The life cycle in an artificial laboratory cave took
2.5 weeks at 19-21C. The laboratory colony was maintained on wet yeast extract and
Limburger cheese.
* I
Id
58 Florida Entomologist 83(1) March, 2000
Psychoda reevesi would key to P. cinerea in Quate's key (Quate 1955:194). Females
of these two species are separable by the shape of the subgenital plate and the struc-
tures on the inner face of the subgenital plate; in cinerea the apex of the plate is con-
cave without distinct apical lobes, but in reevesi the lobes are well developed; in
cinerea the inner face of the plate has indistinct, rugose patterns, while in reevesi
there is a conspicuous quadrate structure on the inner face. The males of cinerea have
a broad aedeagus and the surstyli are short and thick, while in reevesi the aedeagus
is rather slender and the surstyli are long and slender.
ACKNOWLEDGMENTS
I thank Mr. Will Reeves, Clemson University, for his efforts in collecting these
small flies and diligence in successively searching for the larvae and making them
available to me.
REFERENCES CITED
QUATE, L. W. 1955. A revision of the Psychodidae (Diptera) in America North of Mex-
ico. University California Publications Entomology 10(3): 103-273.
6666666666666666666666666666666666666666666666666666
Florida Entomologist 83(1)
March, 2000
LIFE HISTORY AND LABORATORY REARING OF
ARILUS CRISTATUS (HETEROPTERA: REDUVIIDAE)
IN SOUTHERN ILLINOIS
A. M. HAGERTY AND J. E. MCPHERSON
Department of Zoology, Southern Illinois University at Carbondale
Carbondale, Illinois 62901
ABSTRACT
The life history ofArilus cristatus (L.) was studied in southern Illinois from March
1997 to November 1998. The bug also was reared in the laboratory at 26 + 0.5C under
a 16:8 (L:D) photoperiod. This univoltine species overwintered as eggs. First instars
were found from early May to late June, second instars from mid-May to early June,
third instars from late May to early July, fourth instars from early June to mid-July,
fifth instars from early June to mid-August, and adults from early July to late Novem-
ber. In the laboratory, the five nymphal stadia averaged 15.64, 14.04, 15.17, 20.53, and
28.61 d, respectively. Also, the incubation periods of two egg clusters oviposited by two
field-collected females were 60 and 61 d.
Key Words:Arilus cristatus, life history, southern Illinois, laboratory rearing
RESUME
El ciclo de vida deArilus cristatus (L.) fu6 estudiado en el sur de Illinois de Marzo
de 1997 a Noviembre de 1998. El insecto tambien fu6 criado bajo condiciones de labo-
ratorio a 26 + 0.5C y con un fotoperiodo de 16 horas dia/8 horas noche. Esta especie
uniovular pasa el invierno en estadio de huevecillo. Los primeros instars se encontra-
Hagerty & McPherson: Life history of Arilus cristatus
ron desde principios de Mayo hasta fines de Junio; los segundos instars desde media-
dos de Mayo hasta principios de Junio; los terceros instars desde fines de Mayo hasta
principios de Julio; los cuartos instars desde principios de Junio a mediados de Julio;
los quintos instars desde principios de Junio hasta mediados de Agosto y los adults
desde principios de Julio hasta fines de Noviembre. En el laboratorio, los cinco esta-
dios ninfales promediaron 15.64, 14.04, 15.17, 20.53 y 28.61 dias, respectivamente.
Asimismo, los periods de incubaci6n de grupos de huevecillos ovipositados por dos
hembras colectadas en el campo fueron de 60 y 61 dias.
The wheel bug, Arilus cristatus (L.), occurs from Ontario and New York south to
Florida and west to Iowa, Kansas, and New Mexico; it also has been reported from
Mexico and Guatemala (Froeschner 1988). Adults are recognized easily because of
their large size (26-36 mm), blackish brown body, reddish brown antennae, and a dis-
tinctive, high, toothed, median ridge on the pronotum. Although a common species,
most published information on its biology consists of scattered notes.
This species commonly is found on trees and shrubs (e.g., Barber 1920, Elkins
1951, Froeschner 1944, Readio 1926, Swadener & Yonke 1973) but can be collected
from other vegetation (Barber 1920, Blatchley 1926, Elkins 1951, Readio 1926,
Wheeler & Stimmel 1983, Whitcomb & Bell 1964). It is predaceous and feeds on a
wide variety of insects including, among others, the fall webworm, Hyphantria cunea
(Drury); imported cabbageworm, Pieris rapae (L.); Mexican bean beetle, Epilachna
varivestis Mulsant (Thompson & Simmonds 1965); orangedog, Papilio cresphontes
Cramer (Watson 1918); tent caterpillar, Malacosoma (Surface 1906); and bollworm,
Helicoverpa zea (Boddie) (Whitcomb & Bell 1964).
Arilus cristatus is univoltine, with five nymphal instars (Readio 1927, Todd 1937).
It overwinters as eggs (Froeschner 1944; Garman 1916; Readio 1926, 1927; Swadener
& Yonke 1973; Todd 1937) that are laid in clusters in the fall on the bark of tree trunks
and twigs (Barber 1920; Froeschner 1944; Garman 1916; Readio 1926, 1927; Swadener
& Yonke 1973). The eggs hatch the following spring, and nymphs are found from May
to July and adults from June to October (Froeschner 1944). Copulation occurs in the
fall (Barber 1920) and the eggs are laid shortly thereafter (Garman 1916; Readio 1926,
1927). Not unexpectedly, the life cycle is somewhat different in Florida; for example,
nymphs appear in April and some adults survive into the winter (Mead 1974).
Several egg parasites have been reported including the eupelmidAnastatus redu-
vii (Howard), and the encyrtids Ooencyrtus johnsoni (Howard) (Peck 1963) and 0. cli-
siocampae (Ashmead) (Swadener & Yonke 1973).
This species has been reared in an insectary under uncontrolled conditions (Todd
1937), and the eggs (Readio 1926, 1927) and nymphal instars, except the second
(Readio 1927), have been described.
In this paper, we present information on this insect's field life history in southern
Illinois and laboratory rearing under controlled conditions.
MATERIALS AND METHODS
Field life history.-This study was conducted from March 1997 to November 1998
in conjunction with a general survey of the Reduviidae of southern Illinois. Southern
Illinois was defined as the 11 southernmost counties (i.e., Jackson, Williamson,
Saline, Gallatin, Union, Johnson, Pope, Hardin, Alexander, Pulaski, and Massac)
(Fig. 1). Samples were collected weekly with the entire study area sampled 3 times per
Florida Entomologist 83(1)
March, 2000
Fig. 1. Southern Illinois map showing counties surveyed and the three collecting
subareas.
year (i.e., May-June, July-August, and September-October). However, because the
area was so large, it was subdivided into 3 smaller areas with the Southern Illinois
University campus serving as a home base (Fig. 1). During each of the 3 bimonthly
sampling periods, each subarea was sampled daily at various locations over a 4-day
period. Therefore, sampling of the entire study area per year occurred during 36 col-
lecting trips. Finally, additional sampling was conducted sporadically in Jackson
County during November 1997 and 1998 until the insects no longer were active.
Sampling was conducted along major roads with side trips to promising habitats.
Insects were collected by sweeping, beating foliage, and handpicking along roadsides,
grassy fields, and forest edges; preserved in 70% EtOH; and taken to the laboratory.
Field-collected nymphs were determined to instar by comparison with laboratory-
reared specimens. Field data (e.g., collection sites, times of occurrence of developmen-
tal stages, habitat types) were supplemented with data associated with specimens
housed in the Southern Illinois University Entomology Collection.
Laboratory rearing.-During November 1997 and January-March 1998, 12 egg
clusters were collected in Jackson, Williamson, and Union counties from the bark of
trees. The clusters were brought to the laboratory and each was placed on moistened
filter paper on the bottom of a petri dish (approximately 9 cm diam., 2 cm depth) and
covered with the lid. Approximately 4-6 drops of distilled water were added every 1-2
d to keep the filter paper moist.
Hagerty & McPherson: Life history of Arilus cristatus
Of the 12 clusters, 10 were heavily parasitized or contained several eggs that did
not hatch for unknown reasons. The remaining 2 contained 315 eggs (n = 123, 192),
252 of which hatched. Of these, 210 were chosen for further study based on their ap-
parent good health.
Nymphs were kept in petri dishes prepared similarly to those for egg clusters. One
Tenebrio sp. larva per nymph was provided daily as food. The dishes were examined
daily, molts recorded, and exuviae removed. Initially, nymphs were grouped by hatch
date at a density of 10 per dish. As molts occurred, nymphs were grouped by molting
dates to determine stadia accurately. Filter paper was moistened daily and replaced
when necessary, usually every 5-7 d.
To determine if eggs of Illinois populations could develop without a cold winter di-
apause, two pairs of adults were collected from the field during September 1998 and
brought to the laboratory. Each pair (1 6, 1 Y) was kept in a one-quart (approximately
0.95 liter) mason jar with a moistened disc of filter paper on the bottom and fed 2-3
Tenebrio sp. larvae every other day. A strip of bark (approximately 4 cm wide, 16 cm
long) was propped against the inner surface of the jar to provide additional walking
surface and to serve as a possible ovipositional site.
All specimens were kept in incubators maintained at 26 -+ 0.5C and a photoperiod
of 16:8 (L:D) (approximately 2,800 lux).
RESULTS AND DISCUSSION
Life history.-This species was collected in all 11 counties. It was univoltine and
overwintered as eggs, which were laid in hexagonal clusters and glued to the trunks
of sassafras (Sassafras albidum [Nuttall]), beech (Fagus grandifolia Ehrhart), and
maple (Acer sp.). First instars were found from early May to late June, second instars
from mid-May to early June, third instars from late May to early July, fourth instars
from early June to mid-July, fifth instars from early June to mid-August, and adults
from early July to late November (Fig. 2). Copulation (1 pair) was observed in Septem-
ber. Unhatched egg clusters were found as early as early October.
MAY JUNE JULY AUG. SEPT. OCT, NOV DEC
1STINSTAR
2ND INSTAR [
(N=2)
3RD INS7AR
4TH INSTAR
(N=84)
5TH INSTAR
Fig. 2. Field life cycle of A. cristatus in southern Illinois (combined 1997-1998
data). Periods represented by dashes lines indicate only probable occurrence because
no specimens were collected.
Florida Entomologist 83(1)
March, 2000
Nymphs were collected most often by sweeping weeds and short woody vegetation
along the margins of forested areas. Adults frequently were collected by sweeping or
beating the branches of trees.
Several prey were collected during the study, all of which had been captured by late
instars or adults. These items and the attacking stages included single adult speci-
mens of the cercopid Clastoptera proteus Fitch (fourth instar), the chrysomelid
Ophraella sp. (fifth instar), and a halictid (adult). Also, two bugs (1 fifth instar, 1 adult)
were observed with their beaks inserted in the cases ofbagworms (Thyridopteryx sp.?).
One adult male was seen inserting its beak into a flower of goldenrod (Solidago sp.).
As noted earlier, several field-collected egg clusters were heavily parasitized. The
parasitoids were identified as Ooencyrtusjohnsoni andAnastatus reduuii.
Laboratory rearing.-Field-collected eggs were dark brown to black cephalad, red
posterad, and attached by their posterior ends. Eye spots were not visible. The first in-
stars emerged through a circular opening in the cephalic end of the egg, pushing aside
a cap. They were orangish at this time but darkened to the more typical coloration
(i. e., head, thorax, and appendages black; abdomen red) within 3-4 h. They fed on
Tenebrio sp. larvae within 1 d.
The first, second, third, fourth, and fifth stadia averaged 15.64, 14.04, 15.17, 20.53,
and 28.61 d, respectively. The total development period averaged 93.99 d (Table 1).
Mortality during the nymphal stadia resulted from incomplete ecdysis, predation by
other nymphs, and unnatural causes (e. g., drowning in water condensation in the dishes).
The two females collected for ovipositional data each deposited a single egg cluster
on the wall of its jar. The clusters contained 79 and 48 eggs, which hatched in 60 (n =
58 eggs, 73.42%) and 61 (n = 23 eggs, 47.92%) d, respectively. Therefore, a cold period
apparently is not necessary for normal egg development. Sailer (1957) reported that
eggs he collected in late September hatched in early December, supporting our con-
clusion.
ACKNOWLEDGMENTS
We thank the following individuals for identifying the prey and egg parasitoids of
A. cristatus: Stephen W. Lingafelter (Systematic Entomology Laboratory, Beltsville,
MD), Ophraella sp.; Stephen W. Wilson (Central Missouri State University, Warrens-
burg), Clastoptera proteus; and Norman F. Johnson (Ohio State University, Colum-
bus), Anastatus reduuii and Ooencyrtus johnsoni. We also thank Beth A. Burke
(Southern Illinois University at Carbondale) for providing the laboratory culture of
Tenebrio sp.
TABLE 1. DURATION (IN DAYS) OF EACH NYMPHAL STADIUM OF A. CRISTATUS IN THE LAB-
ORATORY.
No. completing Cumulative
Stage stadium Range Mean + SE mean age
1st instar1 174 11-27 15.64 + 0.22 15.64
2nd instar 170 10-31 14.04 + 0.24 29.68
3rd instar 163 9-37 15.17+ 0.33 44.85
4th instar 135 12-47 20.53 + 0.52 65.38
5th instar 93 16-51 28.61+ 0.81 93.99
'210 began stadium.
Hagerty & McPherson: Life history of Arilus cristatus
REFERENCES CITED
BARBER, G. W. 1920. Notes on the oviposition and food of the wheel-bug (Arilus crista-
tus Linn.) (Hemip. Heter.). Entomol. News 31: 107.
BLATCHLEY, W. S. 1926. Heteroptera or true bugs of eastern North America with es-
pecial reference to the faunas of Indiana and Florida. Nature Pub. Co., India-
napolis. 1116 pp.
ELKINS, J. C. 1951. The Reduviidae of Texas. Texas J. Sci. 3: 407-412.
FROESCHNER, R. C. 1944. Contributions to a synopsis of the Hemiptera of Missouri, Pt.
III. Lygaeidae, Pyrrhocoridae, Piesmidae, Tingididae, Enicocephalidae, Phy-
matidae, Ploiariidae, Reduviidae, Nabidae. Am. Midland Nat. 31: 638-683.
FROESCHNER, R. C. 1988. Family Reduviidae Latreille, 1807. The assassin bugs, pp.
616-651. In T. J. Henry and R. C. Froeschner (eds.), Catalog of the Heteroptera,
or true bugs, of Canada and the continental United States. E. J. Brill, New
York, NY. 958 pp.
GARMAN, H. 1916. The locust borer (Cyllene robiniae) and other insect enemies of the
black walnut. Kentucky Agric. Exp. Stn. Bull. 200: 97-135.
MEAD, F. W. 1974. The wheel bug, Arilus cristatus (Linnaeus) (Hemiptera: Reduvi-
idae). Florida Dep. Agric., Div. Plant Industry, Entomol. Circ. 143: 1-2.
PECK, 0. 1963. A catalogue of the Nearctic Chalcidoidea (Insecta: Hymenoptera). Can.
Entomol. Suppl.: 1-1092.
READIO, P. A. 1926. Studies on the eggs of some Reduviidae (Heteroptera). Univ. Kan-
sas Sci. Bull. 16: 157-179.
READIO, P. A. 1927. Studies on the biology of the Reduviidae of America north of Mex-
ico. Univ. Kansas Sci. Bull. 17: 5-291.
SAILER, R. I. 1957. No title. Proc. Entomol. Soc. Washington 59: 203.
SURFACE, H. A. 1906. Order X. The Hemiptera: the bugs, lice, aphids, scale insects, ci-
cadas, and others. Pennsylvania Dep. Agric., Div. Zool., Mon. Bull. 4: 48-75.
SWADENER, S. O., AND T. R. YONKE. 1973. Immature stages and biology of Sinea com-
plexa with notes on four additional reduviids (Hemiptera: Reduviidae). J. Kan-
sas Entomol. Soc. 46: 123-136.
THOMPSON, W. R., AND F. J. SIMMONDS. 1965. A catalogue of the parasites and pred-
ators of insect pests. Section 4. Host predator catalogue. Commonwealth Inst.
Biol. Control, Ontario. 198 pp.
TODD, J. N. 1937. Life history of the wheel-bug, Arilus cristatus (Linn.) (Hemiptera:
Reduviidae). Entomol. News 48: 226-228.
WATSON, J. R. 1918. Insects of a citrus grove. Florida Agric. Exp. Stn. Bull. 148: 165-
267.
WHEELER, A. G., JR., AND J. F. STIMMEL. 1983. The phytophagous and predacious ar-
thropod fauna of soybean in Pennsylvania. Melsheimer Entomol. Ser. 33: 31-38.
WHITCOMB, W. H., AND K. BELL. 1964. Predaceous insects, spiders, and mites of Ar-
kansas cotton fields. Arkansas Agric. Exp. Stn. Bull. 690: 1-84.
Florida Entomologist 83(1)
March, 2000
USE OF AN ACOUSTIC EMISSIONS DETECTOR AND
INTRAGALLERY INJECTION OF SPINOSAD BY PEST
CONTROL OPERATORS FOR REMEDIAL CONTROL OF
DRYWOOD TERMITES (ISOPTERA: KALOTERMITIDAE)
ELLEN M. THOMS
Dow AgroSciences LLC, 3225 S. MacDill Ave. #129-258, Tampa, Florida 33629
ABSTRACT
During 1997, four pest control companies in Florida (FL) participated in experi-
mental use permit field trials to evaluate spinosad (NAF-85) for control of drywood
termites (DWT). Forty-four DWT infestations of Incisitermes snyderi (Light) and
Cryptotermes brevis (Walker) in 37 structures in FL were delineated using an acoustic
emissions detector (AED). These infestations were injected with a 0.5% spinosad sus-
pension concentrate formulation using a hand-held injector. The majority of these in-
festations were interior (68%) and were completely accessible (86%). The visible signs
most frequently associated with DWT infestations were pellets (93% of infestations).
A mean of 10 holes were drilled and 4.3 holes were injected with a total mean of 60.7
ml spinosad per infestation.
At a mean of 44 days post-treatment, the overall reduction in acoustic emission
(AE) counts/30 sec was 94%. AE activity was reduced by >90% at 89% (n = 40) of the
infestations and was completely eliminated at 61% (n = 27) of the infestations. The
mean time to monitor a DWT infestation using the AED was 23.4 min for the 1' visit
and 6.3 min for the 2nd visit. The mean time to drill, inject NAF-85, and plug drill holes
was 13.7 min per infestation. The mean total time per trial site was 58.6 min for the
1' visit and 13.1 min for the 2nd visit. Results demonstrated the combination of the
AED, spinosad and injector provided efficient and effective control of localized, acces-
sible DWT infestations.
Key Words: Incisitermes snyderi, Cryptotermes brevis, treatment time
RESUME
Durante 1997, cuatro companies de control de plagas de Florida participaron en
ensayos experimentales para evaluar la efectividad de spinosad (NAF-85) en el con-
trol de termitas de madera seca (drywood termites). Cuarenta y cuatro infestaciones
de Incisitermes snyderi (Light) y Cryptotermes brevis (Walker) fueron identificadas
mediante un detector de emisiones acusticas (DEA). En los sitios infestados se inyect6
una suspension concentrada de spinosad al 0.5% usando un inyector manual. El 68%
de las infestaciones estaba localizadas en interiores y eran completamente accesibles
(86%). El signo mas comunmente asociado con la infestaci6n de termitas fue la pre-
sencia de pellets (93% de los casos). En promedio, en cada sitio sitio infestado se hi-
cieron 10 perforaciones, de las cuales 4.3 se usaron para inyectar un promedio de 60.7
ml de spinosad por infestaci6n. En promedio, a los 44 dias post-tratamiento se detect
una reducci6n de 94% en el conteo de emisiones acusticas/30 segundos. En el 89% de
los sitios infestados (n = 40), las emisiones acusticas se redujeron en >90%, mientras
que no se detect emisi6n acustica en 61% de los sitios infestados (n = 27). El tiempo
promedio usado para monitorear una infestaci6n de termitas con el DEA fu6 23.4 mi-
nutos para la primera visit y 6.3 minutes para la segunda visit. En promedio, el
tiempo empleado en hacer las perforaciones, inyectar el spinosad, y sellar las perfora-
ciones fu6 de 13.7 minutes por sitio infestado. El tiempo total promedio por sitio ex-
Thoms: A Novel Local Treatment for Drywood Termites 65
perimental fue de 58.6 minutes para la primera visit y 13.1 minutes para la segunda
visit. Los resultados demostraron que la combinaci6n de DEA, spinosad e inyector lo-
graron un buen control de infestaciones accesibles y localizadas de termitas.
Drywood termites account for about 20% of the $1.5 billion estimated for annual
termite control expenditures in the United States (Su and Scheffrahn 1990). Florida
(FL) is one of the geographic areas within the United States in which drywood ter-
mites are considered important structural pests. Two species of drywood termites,
Cryptotermes brevis (Walker) and Incisitermes snyderi (Light), are the most widely
distributed and commonly occurring structure-infesting drywood termites in FL
(Scheffrahn et al. 1988).
These drywood termites (DWT), if left uncontrolled, will recolonize a structure until
the wood members and contents are severely damaged by numerous colonies. Struc-
tural fumigation with fumigants such as sulfuryl fluoride has been documented to be
more effective than currently available localized remedial chemical treatments for elim-
inating DWT infestations throughout a structure (Scheffrahn et al. 1997). Nonetheless,
structural fumigation is not always a treatment option for economic or logistical rea-
sons; infested structures cannot always be sealed to confine the fumigant or vacated of
people, animals, or sensitive materials. In addition, fumigation may not be necessary if
the DWT infestation is limited and confined to wood members accessible for an effective
localized treatment. A variety of insecticides are currently registered for application di-
rectly to infested wood; however, the efficacy of many of these treatments for remedial
control of DWT is inadequate or inconsistent (Scheffrahn et al. 1997, 1998).
One compound which has demonstrated consistent efficacy in research trials for
local remedial control of DWT is spinosad, a proprietary material of Dow Agro-
Sciences LLC (Indianapolis, IN). Spinosad is derived from the fermentation product
of a naturally-occurring soil bacterium (Saccharopolyspora spinosa) (Anonymous
1996). Spinosad has a favorable human and environmental toxicity profile, is nearly
odorless, and has long residual activity in wood galleries (Scheffrahn and Thoms
1999). In laboratory and research field trials in FL, spinosad injected into DWT gal-
leries has demonstrated consistent and excellent control of DWT infestations (Schef-
frahn et al. 1997, 1998, Scheffrahn and Thoms 1999). These field trials also validated
the use of a hand-held acoustic emissions detector (AED) for nondestructively delin-
eating DWT infestations and measuring DWT activity before and after treatment.
The AED confirms the presence of DWT in wood by detecting sound emitted as ter-
mites chew on wood fibers (Scheffrahn et al. 1993).
In 1997, a Federal Experimental Use Permit (EUP) was granted to Dow Agro-
Sciences for pest control operators (PCOs) to evaluate spinosad (NAF-85) for DWT con-
trol. The objectives of the EUP field trial in FL were to determine 1) if PCOs could obtain
control of localized DWT infestations similar to that reported by Scheffrahn et al. (1997)
and Scheffrahn and Thoms (1999), and 2) if the time required for PCOs to monitor and
treat DWT infestations using the AED and spinosad, respectively, would be comparable
to currently available local treatments. The results of the EUP trial are described below.
MATERIALS AND METHODS
PCO Cooperators
Four PCO companies (Hobelmann Inc., Terminix International, Truly Nolen of
America Inc., and Young Pest Control Inc.) located in Hillsborough and Pinellas Coun-
Florida Entomologist 83(1)
March, 2000
ties, FL, participated in the trials. All participating companies were licensed to fumi-
gate in FL and had extensive experience in controlling DWT by fumigation with
Vikane gas fumigant (Dow AgroSciences LLC, Indianapolis, IN). Some companies
also had experience with non-traditional localized treatment methods for DWT, such
as heat (CleanHeat by Terminix International) and borates (TruGuard by Truly
Nolen).
The PCO participants included technicians, managers, and technical personnel.
They were responsible for inspecting the trial site, using the AED to delineate active
DWT infestations, applying spinosad in these areas, and documenting the infestation
as required by state law and pest control company policy. Two contractors experienced
in the pest control industry were hired to observe and document the activities and
conditions at each trial site. The contractors completed their activities in a manner
that did not interfere with the PCO monitoring and treating the DWT infestations. All
materials and equipment, with the exception of ladders, used in these trials were pro-
vided by Dow AgroSciences and were maintained by the contractors during the trial
period.
All PCO participants and contractors were trained by the author and provided
with a reference manual on how to use the AED, and information and application in-
struction on spinosad. Initial inspection, treatment, and reinspections were con-
ducted from 4 September through 15 December, 1997. Three infestations were
retreated and had a second reinspection on 25 February, 1998.
Study Sites
Trial sites selected by PCOs included residential and commercial structures. Sites
had to contain at least 1 active DWT infestation accessible for monitoring with the
AED and treatment with spinosad. The sensors for the AED must directly contact the
insect-infested wood to detect the acoustic emissions (AE). Infested wood completely
covered by drywall, plaster, stucco, or other structural elements could not be moni-
tored using the AED and was not included in the trial. Each DWT infestation evalu-
ated in the study was required to have AE readings exceeding 5 counts for 30 sec at
one or more monitoring locations.
Delineating and Documenting Active DWT Infestations
First, the PCO inspected properties for visible signs of DWT infestation such as
pellets, ejection holes, wood damage, buckled surfaces, live termites, or alate wings.
When suspected DWT infestations were located in exposed wood, the PCO used the
AED to confirm the presence of live termites as indicated by AE counts, locate the area
of greatest AE counts, and delineate the extent of the active infestation (Fig. 1).
After delineating the infestation, the PCO selected monitoring locations using a
30-sec monitoring period. Peripheral monitoring locations marked the outer boundary
of the DWT infestation in each wood member and were selected where AE counts di-
minished to about >5 AE counts/30 sec. The PCO also marked where AE counts were
highest per 30 sec reading for each infestation.
Each monitoring location was marked, using ink pen or removable labels, and se-
quentially numbered for identification. AE readings were taken at the identical loca-
tion during a follow-up inspection at all infestations. The number of monitoring
locations varied depending on the extent of the infestation. In the example in Fig. 2,
5 monitoring locations, with AE counts of >5/30 sec, would be marked for future mon-
itoring. At every test site, background AE counts were taken for 30 sec with AED sen-
sors not attached to surfaces to measure background AE.
Thoms:A Novel Local Treatment for Drywood Termites
Fig. 1. Pest control operator using the acoustic emissions detector on wood trim in
a boat to detect drywood termites.
Application of Spinosad
Per the EUP label, PCOs drilled treatment holes (2 mm diameter) with a battery-
powered drill adjacent to monitoring locations and through DWT ejection holes and
wood damage within the infested area delineated by AED readings (Fig. 2). Holes
were drilled to intersect DWT galleries up to 3/4 through the depth of the infested wood
member. Holes accidentally drilled completely through the wood were not treated and
were sealed using 2.4 mm diameter wood dowels or wax sticks (Touch Up Stiks, Dar-
worth Co., Simsbury, CT). Laboratory trials have verified that wax sticks were not re-
pellent or toxic to DWT (R. H. Scheffrahn, Univ. of Florida, unpublished data). Drill
holes were often clustered in areas with insect activity; spacing between clusters of
drill holes generally did not exceed 60 cm.
Spinosad was provided in 1 ml volumes of suspension concentrate formulation
(NAF-85, 44.2% a.i.) in dual chamber bottles containing 99 ml of water resulting in a
0.5% dilution of spinosad when mixed. After mixing, the dual chamber bottle was con-
nected to the hand-held, low pressure automatic dosing syringe (Felton Medical Inc.,
Lenexa, KS) for application.
For vertical or diagonal wood members, the PCO injected at the highest elevation
first, moving down towards ground level. Up to 50 ml of spinosad was injected into
each drill hole. If the solution began to seep from other drill holes or the wood, injec-
tion was stopped, and the injection hole and all other drill holes with seepage were
plugged as previously described.
If a gallery was not intersected while drilling, as indicated by less than 0.5 ml of di-
lution being accepted into the drill hole, or the wood member was completely penetrated,
the PCO plugged the drill hole and drilled another hole if necessary. After treatment, all
pellets, wings, or other signs of active infestation were removed if possible using a bat-
tery operated, hand-held vacuum cleaner (The BossR, Eureka Co., Bloomington, IL).
42
Florida Entomologist 83(1)
March, 2000
.ffS e - , -. ,- -
. ..^.~ w ^ f s.. ^ a : v ^--:-- i. Ti
7.. .-..c .,-- ,
',-- ^3 "' 0-: 0 .c .^^"^'
I
Key
.......... hollowed, blistered wood
......' too damaged to inject into
: kick-out/emergence holes
drill and injection locations
_.:- pellet piles
0 no AE counts
C) number of AE comuntsO0 sec.
-- --Q t;^-, .. : __.----I
L- 'iCT inlakick-out holes
drill until gallery is
intersected
Fig. 2. Example of termite damage, pellets, AE monitoring locations, and drill and
injection locations for spinosad in typical drywood termite infestation in a door. Five
monitoring locations, containing AE counts of >5/30 sec, would be marked for future
monitoring.
All active, accessible DWT infestations were treated with spinosad. Property own-
ers were unwilling to have active infestations remain untreated as controls for these
commercial trials. In addition, 84% of the structures only had 1 infestation to treat
(See Results and Discussion below).
Post-treatment Inspection
One to 2 months after spinosad application, study sites were reinspected by the
PCO and contractor. This reinspection interval was selected based on time observed
to obtain significant reduction in DWT activity following application of spinosad in
previous field trials (Scheffrahn et al. 1997, Scheffrahn and Thoms 1999). AE readings
were taken by the PCO for 30 sec at all monitoring locations. Background AE counts
were taken as previously described. At this time, additional application of spinosad
was at the discretion of the PCO based on AE readings or other signs of DWT activity.
Retreated sites were reinspected 3 months following retreatment.
Thoms: A Novel Local Treatment for Drywood Termites 69
Data Recording
All contiguous monitoring locations with AE activity were designated as 1 infesta-
tion site. Data recorded included; infestation location and accessibility, time at site,
background AE counts, AE counts for monitoring locations, time for monitoring and
treating the infestation, number of drill holes, ml spinosad injected, and presence of
damage, pellets, or wings, removal of pellets or wings, and dimensions of wood mem-
ber(s) treated. Treated infestations were photographed, with each monitoring location
marked by fluorescent 1.5 cm diameter circular sticker, and graphed.
Statistical Analyses
AE counts before and after treatment and time measurements were log trans-
formed and compared by t-test (Minitab 1998).
RESULTS AND DISCUSSION
Study Sites
A total of 37 structures were treated. Treated structures included residential prop-
erties (19 single family homes, 3 garages, 1 apartment, 1 fence), commercial proper-
ties (4 offices, 1 motel, 1 marina, 1 store, 1 manufacturing facility, 1 church), the wood
frame of a 1929 Buick automobile, and 3 boats.
Delineation of DWT Infestations
A total of 44 DWT infestations were delineated using the AED. The majority (84%)
of structures had only 1 DWT infestation treated, 13% (n = 6) had 2 infestations, and
3% (n = 1) had 3 infestations.
Over half (57%) of the wood members infested and treated were doors (n = 9), door
frames (8), and window frames (8). Other wood members treated included trim (n = 3),
rafters and beams (3), floors (3), studs (3), baseboards (2), cabinets (2), a fence, a boat
hatch, plywood sheathing, a pillar base, and wall paneling.
One or more visual signs of DWT activity; damage (including DWT ejection holes),
pellets, or alate wings, occurred at every DWT infestation. The AED can detect DWT
feeding up to about 60 cm along the grain of the wood and 6 cm across the grain of the
wood from where the sensor is placed (Scheffrahn et al. 1993). Because the AED can-
not be used efficiently to test every accessible wood member in a structure, signs of
DWT infestation were necessary to determine where to take AE readings. The most
common indicator of DWT activity was pellets, found at 93% of the infestations
treated. Damage was found at 64% of the infestations treated. Wings were found at
only 16% of the infestations treated, probably because trials were initiated in Septem-
ber after DWT termite peak swarming in May-July (Scheffrahn et al. 1988).
The number of monitoring locations per DWT infestation was 4.2 3.0 (mean +
SD) and ranged from 1 to 15. The more extensive the DWT infestation, the greater the
number of monitoring locations. The majority of the infestations treated were interior
(68%) and were completely accessible (86%), probably because these infestations were
more readily observed by building occupants and by PCOs during inspection. In addi-
tion, DWT pellets would be more easily observed indoors than outdoors, where they
are dispersed by wind and rainfall.
Florida Entomologist 83(1)
March, 2000
Application of spinosad
A mean + SD of 10 + 5 holes (range 2-19) were drilled per DWT infestation and 4.3
+ 3.1 holes (range 1-17) were injected with spinosad, resulting in 43% of the drill holes
injected with spinosad. A mean + SD of 60.7 + 35.2 ml of spinosad (range 10-160 ml)
was injected per DWT infestation. The mean amount of spinosad injected per DWT in-
festation in the 1997 FL EUP trial was similar to the amount (56 ml) applied in the
1994 FL field trial (Scheffrahn et al. 1997). Qualitatively, PCOs observed no staining
of structural surfaces or detectable odor when applying spinosad.
The EUP label for spinosad indicated best results would be achieved when spacing
between injection holes does not exceed 60 cm. This spacing recommendation was
based on previous field research (Scheffrahn et al. 1997, Scheffrahn and Thoms 1999).
The spacing between drill holes was 60 cm or less at all infestations, with the excep-
tion of two infestations in which the maximum spacing was 118 cm and 175 cm. These
sites had 81% and 100% reduction in AE counts, respectively, following application of
spinosad, indicating that satisfactory results can be obtained in certain circum-
stances with wider hole spacing.
AE Monitoring and Post-treatment Inspection
Post-treatment inspections occurred a mean + SD of 44 + 15 days (range 21-74) af-
ter initial treatment. The post-treatment AE counts (1.5 + 5.6, range 0-40) were sig-
nificantly lower (paired t-test on log transformed data; P < 0.0001) than the
pretreatment AE counts (23.9 + 27.5; range 1-240).
Application of spinosad resulted in mean 94% reduction in termite activity as in-
dicated by AE counts. Ninety percent or greater reduction in DWT activity was ob-
tained at 89% (n = 40) of the infestations. In fact, DWT activity as determined by AE
counts was eliminated at 61% (n = 27) of the treated infestations.
Five untreated drywood termite infestations were monitored in southeast Florida
(Scheffrahn and Thoms 1999) during the Fall of 1997, concurrent with this trial.
These infestations had a slight reduction (9% decrease) in AE counts during the eval-
uation period. These results indicate any significant reduction in DWT activity follow-
ing application of spinosad could reasonably be attributed to spinosad.
The overall 94% reduction in AE counts obtained by PCOs applying spinosad was
equivalent or better than that obtained by researchers applying spinosad in previous
field trials. Researchers demonstrated reduction in DWT activity after application of
spinosad by 88% 2 months post-treatment (Scheffrahn et al. 1997) and by 92% (Schef-
frahn and Thoms 1999).
Retreatment was attempted by one PCO at 3 DWT infestations. Two of these 3 in-
festations had the lowest reduction in trial post-treatment AE counts, 57% and 43%,
and 60 ml and 40 ml, respectively, of spinosad was injected into 2 drill holes in each
infestation. Retreatment further reduced AE activity by an additional 32-34% at
these 2 infestations. The third infestation had a 91% reduction in AE counts; retreat-
ment was attempted due to the large number of new pellets observed on the post-
treatment inspection but no spinosad could be injected. No new pellets were observed
at this infestation on subsequent reinspection. A lower percentage, 24%, of the drill
holes were injected during retreatment than the 43% injected during initial treat-
ment. These results indicate that intersecting the active galleries in some DWT infes-
tations can be difficult.
In 30 of 41 DWT infestations with pellets, pellets were removed by vacuuming dur-
ing the first inspection. Eight (23%) of these infestations had pellet piles present
Thoms: A Novel Local Treatment for Drywood Termites 71
again during the post-treatment inspection. These infestations had a mean reduction
of 97% (range 91-100%) in AE counts/30 sec during the post-treatment inspection.
These results suggest that time for termites to contact a lethal dose of spinosad varies,
resulting in pellets being ejected from some infestations after initial application of
spinosad.
Time Efficiency
The time per site visit was significantly greater (paired t-test on log transformed
data; P < 0.0001) for the first visit (58.6 + 24.3 min; range 20-125 min) than that of the
second visit (13.1 + 6.5 min; range 5-35 min). The increased time for the first visit was
due to identifying, delineating, and treating infestations, which was not repeated dur-
ing the second visit with the exception of 3 sites where retreatment was attempted.
The time for the first visit varied depending on the number of infestations per trial
site (Fig. 3). The more DWT infestations, the longer the initial visit. For all infestation
sizes, the post-treatment inspection took less time than the first visit, because the in-
festations were already delineated and treated as previously discussed.
The time to monitor an infestation using the AED was significantly greater (paired
t-test; P < 0.0001) on the first visit (23.4 + 11.9 min; range 9-60 min) than that on the
second visit (6.3 + 2.9 min; 2-14 min). For all infestations, the time to monitor during
the post-treatment inspection was always less, generally by at least 50%, than that of
the pretreatment inspection because the monitoring locations were previously marked.
The time to drill, inject spinosad, and plug treatment holes during the first visit
was 13.7 + 5.7 min (range 5-30 min) per infestation. The time to treat an infestation
was dependent on its size, which was indicated by the number of monitoring locations
(Table 1). Photographs and graphs of treated infestations document the minimum
mean distance between monitoring locations was ca. 30 cm. The average size of an in-
festation, with a mean of 4 monitoring locations, was equivalent to treating a 90-cm
length of a 10 cm x 4 cm wood member.
140
100 J -- -
S 80 -t-. -g -- 1st visit
S 60 I@ 2nd visit
4 0 1
o 20
1 2 3
No. Infestations/Site
Fig. 3. Mean (_ SD) total time (min) for first and second visit to trial sites in FL,
1997.
Florida Entomologist 83(1)
March, 2000
TABLE 1. ESTIMATED TIME (MIN) TO TREAT GIVEN LENGTHS OF WOOD SECTIONS (10 CM
WIDE x 4 CM IN DEPTH) USING VARIOUS LOCAL DRYWOOD TERMITE TREATMENT
METHODS
Estimated time in min to treat given lengths (cm)
of wood sections 10 cm wide x 4 cm in depth"
Treatment One section Three sections Fourteen sections
method (30 cm) (90 cm) (420 cm)
Spinosad Injectedb 11 12 30
Microwave' 8 24 112
Electro-Gund 15 45 210
'One, 3, and 14 sections equivalent to the smallest area (1-2 monitoring locations = 30 cm in length), mean
area (4 monitoring locations = 90 cm in length), and largest area (15 monitoring locations = 420 cm in length)
treated, respectively, for 1997 PCO trial.
Does not include AED monitoring time.
Time estimates derived from Lewis and Haverty (1996) did not include time for equipment set-up and re-
moval.
Time estimates derived from Creffield et al. (1997) did not include time for equipment set-up and wood prep-
aration using the "drill-and-pin" method.
Currently available localized treatments for DWT include microwaves and the
Electro-Gun" (Etex Ltd, Las Vegas, NV). The Electro-Gun emits high frequency elec-
tricity (60,000 HZ), high voltage (100,000+ volts), and low current (below 0.5 amp) to
exposed wood to kill termites (Creffield et al. 1997). The mean time to treat small in-
festations (wood members 30 cm long, Table 1) using spinosad was similar to that doc-
umented for microwaves (Lewis and Haverty 1996) and the Electro-Gun (Creffield et
al. 1997). The efficiency of the spinosad treatment times increased, compared to other
localized treatments, as the infestation size increased. The mean time to treat medium
infestations (wood members 90 cm long) using spinosad was 50% and 73% faster than
that documented for microwaves and the Electro-Gun (Table 1), respectively. The time
to treat the largest infestation (wood member 420 cm long) using spinosad was even
faster, 73% and 86%, than that of microwaves and the Electro-Gun, respectively.
The apparent increase in efficiency for spinosad treatments, compared to micro-
waves and the Electro-Gun, as the infestation size increased can be explained by actual
size of the treatment zone. Spinosad is applied as point injections, while for the latter
two methods, the entire wood member is exposed to microwave energy or electrical cur-
rent, respectively. Termites do not need to be directly contacted by spinosad during ap-
plication for them to acquire a lethal dose by later contact with treated substrates.
Choice bioassays in which only 10% of the gallery was pretreated with spinosad yielded
98-100% termite mortality through 2 years of aging (Scheffrahn et al. 1997, Scheffrahn
and Thoms 1999). Conversely, microwave and Electro-Gun treatments are non-resid-
ual; the entire infestation must be contacted by the microwave energy or electrical cur-
rent, respectively, to insure killing significant numbers of termites.
Other non-fumigation treatments for control of DWT include freezing and heating
infested wood members. Freezing requires injecting liquid nitrogen (N2) into wall
voids to reduce structural lumber temperatures within the void to -20C, the lethal
temperature required to kill DWT (Rust et al. 1997). Rust et al. (1997) documented
the mean time to reach this temperature when injecting N2 was 7 min, which varied
from 1-28 min depending on the injection rate of N2 and the relative location of the
wood member and the N2 injection point. Heating involves enclosing infested areas
Thoms: A Novel Local Treatment for Drywood Termites 73
with thermal confinement barriers and applying heat using propane gas blowers to
heat infested wood to 49C for 30 min (Woodrow and Grace 1998). Woodrow and Grace
(1998) documented the mean time to achieve this temperature accumulation was 128
min, which varied from 45-330 min depending on the location of the wood member. It
is difficult, however, to compare the time efficiency of spinosad treatments to temper-
ature modification techniques, which are used to treat compartmentalized areas and
not individual wood members. In fact, exposed, isolated wood members may be diffi-
cult to treat with liquid N2. Additionally, both methods require heavy, expensive
equipment and offer no residual efficacy.
The time estimates in Table 1 for spinosad are the entire treatment time, including
time to drill and plug holes. By comparison, the time estimates for microwaves, the
Electro-Gun, heat and freeze treatments were conservative and do not account for the
total time required to conduct the treatments. Only the time to apply the lethal dos-
age was documented for these treatments: previous reports did not include time for
drilling and pinning holes for the Electro-Gun (Creffield et al. 1997), or time to pre-
pare structures or install and remove microwave equipment (Lewis and Haverty
1996) or temperature modification equipment (Rust et al. 1997, Woodrow and Grace
1998). These additional procedures could significantly increase the time required to
apply these treatments. PCOs select treatment protocols based on labor requirements
as well as efficacy. Therefore, it is important for researchers to document total time re-
quired to conduct efficacious treatments.
CONCLUSIONS
The quantitative and qualitative results of the 1997 EUP trials in FL demon-
strated that the combination of the AED, spinosad, and injector provide efficient con-
trol of localized, accessible DWT infestations. The AED provided a simple method to
nondestructively delineate DWT infestations before treatment and monitor efficacy of
treatments. The active ingredient, spinosad, had no detectable odor, did not stain, was
simple and fast to apply, and did not require complete coverage of the drywood termite
galleries to be effective.
The new technology does have limitations. The AED sensors must have direct con-
tact with infested wood to detect DWT. The active galleries must be at least partially
accessible and intersected by drilling to inject spinosad. In spite of these limitations,
the EUP field trial indicated many localized infestations of DWT in FL can be effec-
tively and efficiently treated using this new technology.
ACKNOWLEDGMENTS
The author wishes to thank the participating PCOs for contributing their time and
input into this project and the contractors, A. Leasure and T. Beehler, who ensured
complete documentation of PCO activities during the trials. P. Scherer provided sta-
tistical analyses.
REFERENCES CITED
ANONYMOUS. 1996. Spinosad Technical Guide. DowElanco, Indianapolis, IN, 25 pp.
CREFFIELD, J. W., J. R. J. FRENCH, AND N. CHEW. 1997. A Laboratory Assessment on
the Effectiveness of the Electro-Gun in Eradicating Adults of the Indigenous
Australian Drywood Termite, Cryptotermes primus (Isoptera: Kalotermitidae).
CSIRO Client Report No. 163. 6 pp.
Florida Entomologist 83(1)
March, 2000
LEWIS, V. R., AND M. I. HAVERTY. 1996. Evaluations of Six Techniques for Control of
the Western Drywood Termite (Isoptera: Kalotermitidae) in Structures.
J. Econ. Entomol. 89: 922-934.
MINITAB. 1998. Release 11 and 12. Minitab, Inc. State College, PA.
RUST, M. K., E. 0. PAINE, AND D. A. REIERSON. 1997. Evaluation of Freezing to Con-
trol Wood-Destroying Insects (Isoptera, Coleoptera). J. Econ. Entomol. 90:
1215-1221.
SCHEFFRAHN, R. H., J. R. MANGOLD, AND N.-Y. Su. 1988. A survey of structure-infest-
ing termites of peninsular Florida. Fla. Entomol. 71: 615-630.
SCHEFFRAHN, R. H., W. P. ROBBINS, P. BUSEY, N.-Y. SU, AND R. K. MUELLER. 1993.
Evaluation of a novel, hand-held, acoustic emissions detector to monitor ter-
mites (Isoptera: Kalotermitidae, Rhinotermitidae) in wood. J. Econ. Entomol.
86: 1720-1729.
SCHEFFRAHN, R. H., N.-Y. SU, AND P. BUSEY. 1997. Laboratory and Field Evaluations
of Selected Chemical treatments for Control of Drywood Termites (Isoptera:
Kalotermitidae). J. Econ. Entomol. 90: 492-502.
SCHEFFRAHN, R. H., N.-Y. Su, J. KRECEK, A. VAN LIEMPT, B. MAHARAJH, AND G. S.
WHEELER. 1998. Prevention of Colony Foundation by Cryptotermes brevis and
Remedial Control of Drywood Termites (Isoptera: Kalotermitidae) with Se-
lected Chemical Treatments. J. Econ. Entomol. 91: 1387-1396.
SCHEFFRAHN, R. H., AND E. M. THOMS. 1999. A Novel, Localized Treatment Using Spi-
nosad to Control Structural Infestations of Drywood Termites. Down To Earth
54(1): 24-31.
Su, N.-Y., AND R. H. SCHEFFRAHN. 1990. Economically important termites in the
United States and their control. Sociobiology 17: 77-94.
WOODROW, R. J., AND J. K. GRACE. 1998. Field Studies on the use of High Tempera-
tures to Control Cryptotermes brevis (Isoptera: Kalotermitidae). Sociobiology
32: 27-49.
Florida Entomologist 83(1)
March, 2000
AN IMPROVED AND QUANTIFIED TECHNIQUE FOR MARKING
INDIVIDUAL FIRE ANTS (HYMENOPTERA: FORMICIDAE)
DANIEL P. WOJCIK,1 RICHARD J. BURGES,2 CHANTAL M. BLANTON2 AND DANA A. FOCKS1
1Center for Medical, Agricultural and Veterinary Entomology, USDA, ARS
P.O. Box 14565, Gainesville, FL 32604 U.S.A., dwojcik@gainesville.usda.ufl.edu
2Department of Entomology and Nematology, University of Florida
Gainesville, FL 32611 U.S.A.
ABSTRACT
Individual fire ants, Solenopsis invicta Buren, were marked with dots of Markal
brand Ball Point Paint Markers. Marked ants were returned to the colony while the
paint was still wet. The marks were slowly lost over a 100-day period, with one mark
lasting 119 days. No mortality could be attributed to the paint. The proportion of ants
retaining marks over time can be expressed as a simple exponential decay model: pro-
portion with marks = 0.7665 exp (-0.0175 time in days). The technique will be use-
ful in assessing basic behavioral characteristics, such as polygyne versus monogyne
interactions, nestmate discrimination, foraging profiles, and in assessing impact of
candidate biological control organisms on behavior and survivorship of fire ants.
Key Words: Solenopsis invicta, methods, model, paint, longevity, non-linear regression
Wojcik et al.: Marking Ants
RESUME
Hormigas coloradas (fire ants) Solenopsis invicta Buren fueron marcadas con bo-
ligrafos Markal y devueltas a su colonia cuando la pintura aun estaba fresca. Las
marcas desaparecieron lentamente en un period de 100 dias (una marca dur6 119
dias). La pintura no caus6 la muerte a las hormigas. Se desarroll6 un modelo expo-
nencial simple para predecir la proporci6n de hormigas que retienen la marca de pin-
tura al paso del tiempo. Esta tecnica permitird evaluar el comportamiento de las
hormigas, por ejemplo, las interacciones poliginas vs. mon6ginas, la discriminaci6n
dentro del nido y los habitos alimenticios de esta especie. Tambien sera possible eva-
luar el impact de organismos con potential de control biol6gico en el comportamiento
y supervivencia de estas hormigas.
Marking insects is important in research in biology, ecology, and behavior (South-
wood 1978). However, the nature of the insect cuticle presents problems with adhe-
sion and durability of marks, especially for insects with very smooth cuticle (Walker
& Wineriter 1981). Mass marking of red imported fire ants (Solenopsis invicta Buren)
for population studies using spray paints has been documented (Bhatkar et al. 1991),
but this method can cause ant mortality and cannot be used to mark a particular in-
dividual chosen for study. Other methods used for marking individual ants, can be in-
appropriate, cumbersome, or unsuitable, particularly for small fire ant workers (Kruk
de Bruin et al. 1977, Mirenda & Vinson 1979, Verron & Barreau 1974, Porter & Jor-
gensen 1980, Stuart 1986, Showler et al. 1989, 1990, Porter 1991). Longevity of marks
is often inadequate when used in long term studies in fire ant colonies because of the
chemical constituents of fire ant cuticle (Lok et al. 1975 and their intense grooming
behavior (Wilson 1962) removes paint marks. Since fire ant workers can live 60 to 90
days (Vinson 1997), a marking system was needed which would last for a large portion
of the ants life-span. The purpose of this study was to develop a method of marking in-
dividual fire ants which lasted for most of the ants life span.
MATERIALS AND METHODS
Red imported fire ant colonies were collected in Gainesville, FL, separated from
the soil, and maintained in the laboratory using standard procedures (Banks et al.
1981). In preliminary screening, over 150 dyes, stains, or paints were tested for 1) lack
of mortality, 2) ease of use and 3) longevity of marks. Only Markal ball point paint
markers (Markal Co., 1201 Pratt Blvd, Elk Grove Village, IL 60007) met these criteria
and were studied further to determine the longevity of the marks on worker ants. This
paint was initially chosen for testing because it is designed for marking on oily sur-
faces and freshly cut wood, particularly pine. Preliminary studies indicated that if
ants were returned to their colonies when the paint had dried, these paint marks
would only last a few days. For the marks to last longer, the ants had to be returned
to their home colony while the paint was still wet. The ants were grasped with forceps
and the top of the gaster touched into a drop of paint. Dots of blue, red, white, yellow,
orange, or green paint were placed on seven individual workers for each color (one
color per ant). Forty-two ants were marked in each of 6 queen-right colonies (each col-
ony contained one queen) for a total of 252 marked ants. The marked ants were re-
turned to the colony while the paint was still wet. No attempt was made to mark
newly-eclosed workers. The colonies were checked daily for marked ants for three
days, then twice weekly until less than one percent of the marked ants were recovered
in two consecutive examinations.
Florida Entomologist 83(1)
March, 2000
We desired to develop an equation that could be used to predict the expected pro-
portion of ants retaining their marks as a function of time since application. Because
the proportion retaining marks appeared on visual inspection to be constant over
time, we fitted a simple exponential decay model using the combined data set of all
replicates using a standard statistical package (Jandels SigmaStat, ver. 2.0; Jandel
Corporation, P. 0. Box 7005, San Rafael, CA 94912-7005).
RESULTS AND DISCUSSION
The marks were slowly lost over a 100-day period, with one mark lasting 119 days
(Fig. 1). No mortality was attributed to the paint. Large chips of paint were rarely
found (three times). Dead marked ants were found for 9% of the marked ants (23 out
of 252 workers). No differences were found in the longevity of any one color. In three
instances, unmarked ants acquired paint marks; presumably they came into contact
with the marked ants before the paint dried. Returning marked ants to the colony
while the paint was still wet, possibly allowed the paint to acquire the colony odor,
thereby making it less objectionable to other worker ants. Fire ant workers that have
been isolated from the colony are intensely scrutinized upon return to the colony tray.
Normally any foreign material is vigorously removed by the examining workers
0 20 40 60
80 100 120
80 100 120
Time (Days Lapsed)
Fig. 1. Survivorship of marks on Solenopsis invicta workers made with Markal
paints. Observed and predicted proportion of ants retaining marks over time. The dots
indicate observed proportions and the line represents the exponential decay function
developed with non-linear regression using all replicates. See Table 1 for statistics on
fit and coefficients.
Wojcik et al.: Marking Ants
(Mirenda & Vinson 1979). This is the critical period for paint marks on the ants. If the
marked workers can reenter the colony and the marks survive the initial period of
scrutiny, the marks have an enhanced survival rate.
The proportion of ants retaining marks over time can be estimated with the follow-
ing expression:
Proportion with marks = 0.7665 exp(-0.0175 time)
where time indicates the elapsed number of days since the marks were applied (Fig. 1).
The proportion of the variability in Proportion with marks that could be explained by
reference to time (i.e., the coefficient of determination, R2) was 0.62. Table 1 provides
the full accounting of the analysis. Glancey & Lofgren (1988), using this technique, re-
covered marked fire ant queens 9-months after marking and releasing into a polygyne
field colony. This technique will be useful in various aspects of fire ant and other ant re-
search in a variety of studies including: polygyne versus monogyne colonies, nestmate
discrimination, foraging, and impact of biological control organisms.
INTERPRETIVE SUMMARY
Fire ants occur in parts of 11 southern states, and cause hundreds of millions of
dollars of damage to domestic animals, wildlife, and the infrastructure (roads, electri-
cal systems, equipment). Additionally, several deaths of humans occur each year. Un-
derstanding the biology and behavior of fire ants is critical to developing new
management strategies. Researchers at the ARS Center for Medical, Agricultural and
Veterinary Entomology in Gainesville, Fl, developed a simple system to mark individ-
ual ants with a small dot of special paint so that their foraging profiles and interac-
tions with other nestmates could be studied and characterized. If the paint was still
fresh when the ants were reintroduced into the colony, nestmates were less likely to
try and remove it than if it was dry at the time of reintroduction. Consequently, in the
absence of active grooming, marks lasted up to 119 days and did not appear to cause
mortality. This technique will be useful in learning how fire ants interact with their
TABLE 1. STATISTICS FOR THE NON-LINEAR REGRESSION OF "PROPORTION RETAINING
MARKS" AS A FUNCTION OF TIME SINCE APPLICATION.
Statistics for coefficients:
Coefficient Std. Error t P
0.7665 0.0301 25.4847 <0.0001
0.0175 0.0017 10.3777 <0.0001
Analysis of Variance:
DF SS MS F P
Regression 1 5.9422 5.9422 195.1055 <0.0001
Residual 122 3.7157 0.0305
Total 123 9.6579 0.0785
Florida Entomologist 83(1)
March, 2000
nestmates and ants of other nests. This is expected to provide insight into how colo-
nies function, and more importantly, how we may be able to disrupt critical interac-
tions so that colonies do not survive.
ACKNOWLEDGMENTS
This article reports the results of research only. Mention of a proprietary product
does not constitute an endorsement or a recommendation for its use by the U.S. De-
partment of Agriculture. Current Address for R. J. Burges is Alachua County Envi-
ronmental Protection Department, 226 S. Main St., Gainesville, FL 32653. Current
Address for C. M. Blanton is Rt 1 Box 3112C, Havana, FL 32333. We thank M.
Romero, CMAVE, for providing the Spanish abstract.
REFERENCES CITED
BANKS, W. A., C. S. LOFGREN, D. P. JOUVENAZ, C. E. STRINGER, P. M. BISHOP, D. F.
WILLIAMS, D. P. WOJCIK, AND B. M. GLANCEY. 1981. Techniques for collecting,
rearing, and handling imported fire ants. USDA, SEA, AATS-S-21, 9 p.
BHATKAR, A. P., S. B. VINSON, AND H. SITTERTZ-BHATKAR. 1991. Mass-marking and
recognition of marked workers in Solenopsis invicta Buren (Hymenoptera: For-
micidae). Folia Entomol. Mexicana 82: 139-159.
GLANCEY, B. M., AND C. S. LOFGREN. 1988. Adoption of newly-mated queens: a mech-
anism for proliferation and perpetuation of polygynous red imported fire ants,
Solenopsis invicta Buren. Florida Entomol. 71: 581-587.
LOK, J. B., E. W. CUPP, AND G. J. BLOMQUIST. 1975. Cuticular lipids of the imported
fire ants, Solenopsis invicta and richteri. Insect Biochem. 5: 821-829.
KRUK DE BRUIN, M., L. C. M. ROST, AND F. G. A. M. DRAISMA. 1977. Estimates of the
number of foraging ants with the Lincoln-index method in relation to the col-
ony size of Formica polyctena. J. Anim. Ecol. 46: 457-470.
MIRENDA, J. T., AND S. B. VINSON. 1979. A marking technique for adults of the red im-
ported fire ant (Hymenoptera: Formicidae). Florida Entomol. 62: 279-281.
PORTER, S. D. 1991. Origins of new queens in polygyne red imported fire ant colonies
(Hymenoptera: Formicidae). J. Entomol. Sci. 26: 474-478
PORTER, S. D., AND C. D. JORGENSEN. 1980. Recapture studies of the harvester ant,
Pogonomyrmex owyheei Cole, using a fluorescent marking technique. Ecol. En-
tomol. 5: 263-269.
SHOWLER, A. T., R. M., KNAUS, AND T. E. REAGAN. 1989. Foraging territoriality of the
imported fire ant, Solenopsis invicta Buren, in sugarcane as determined by
neutron activation analysis. Insect. Soc. 36: 235-239.
SHOWLER, A. T., R. M., KNAUS, AND T. E. REAGAN. 1990. Studies of the territorial dy-
namics of the red imported fire ant (Solenopsis invicta Buren, Hymenoptera:
Formicidae). Agric. Ecosyst. Environ. 30: 97-105
SOUTHWOOD, T. R. E. 1978. Ecological methods: with particular reference to the study
of insect populations. Chapman and Hall, London, 2nd Ed. 524 p.
STUART, R. J. 1986. Use of polyester fibers to mark small leptothoracine ants (Hy-
menoptera: Formicidae). J. Kansas Entomol. Soc. 59: 566-568.
VERRON, H., AND S. BARREAU. 1974. Une technique de marquage des insects de pe-
tite taille. Bull. Biol. 108: 259-262.
VINSON, S. B. 1997. Invasion of the red imported fire ant (Hymenoptera: Formicidae):
Spread, biology, and impact. Am. Entomol. 43: 23-39.
WALKER, T. J., AND S. A. WINERITER. 1981. Marking techniques for recognizing indi-
vidual insects. Florida Entomol. 64: 18-29.
WILSON, E. 0. 1962. Chemical communication among workers of the fire ant Solenop-
sis saevissima (Fr. Smith). 3. The experimental induction of social responses.
Anim. Behav. 10: 159-164.
Halbert et al.:Aphids New to the Southeastern States
NEWLY ESTABLISHED AND RARELY COLLECTED APHIDS
(HOMOPTERA: APHIDIDAE) IN FLORIDA AND THE
SOUTHEASTERN UNITED STATES
SUSAN E. HALBERT,' GEORGES REMAUDIERE2 AND SUSAN E. WEBB3
'Division of Plant Industry, Florida Department of Agriculture and Consumer
Services, P.O. Box 147100, Gainesville, Florida 32614-7100
2Museum National D'Histoire Naturelle, 45, Rue de Buffon, F-75005, Paris, France
3University of Florida, Department of Entomology and Nematology, P.O. Box 110620,
Gainesville, FL 32611-0620
ABSTRACT
Several aphid species are reported as newly established in Florida and/or the
southeastern United States, includingAcyrthosiphon kondoi Shinji,Aphis amaranthi
Holman, Brachycaudus helichrysi (Kaltenbach), Coloradoa achilleae Hille Ris Lam-
bers, Hyadaphis coriandri (Das), Hyperomyzus carduellinus (Theobald), Melanaphis
sp., Schizaphis rotundiventris (Signoret), Shivaphis celti Das, Takecallis arundicolens
(Clarke), and Toxoptera citricida (Kirkaldy). Further establishment records are re-
ported for Trichosiphonaphis polygoni (van der Goot) that was previously reported
from a few counties in Florida and Georgia. Recent Florida finds are reported for three
native species, includingAphis minima Tissot, Kaltenbachiella ulmifusa (Walsh & Ri-
ley), and Uroleucon elephantopicola Robinson. Identification information is provided
for newly introduced exotic species.
Key Words: Aphididae, aphid, exotic pest, Florida, Southeastern USA
RESUME
Se ha reportado que varias species de afidos se han establecido recientemente en
Florida y/o el Sureste de los Estados Unidos. Entre 6stas se encuentranAcyrthosiphon
kondoi Shinji,Aphis amaranthi Holman, Brachycaudus helicrysi (Kaltenbach), Colo-
radoa achilleae Hille Ris Lambers, Hyadaphis coriandri (Das), Hyperomyzus cardue-
llinus (Theobald), Melanaphis sp., Schizaphis rotundriventris (Signoret), Shivaphis
celti Das, Takecallis arundicolens (Clarke) y Toxoptera citricida (Kirkaldy). Tambien
se report el establecimiento de Trichosiphonaphis polygoni (van der Goot), cuya pre-
sencia se habia reportado en algunos condados de los estados de Florida y Georgia. En
Florida se report el reciente hallazgo de tres species nativas,Aphis minima Tissot,
Kaltenbachiella ulmifusa (Walsh y Riley) y Uroleucon elephantopicola Robinson. Se
provee informaci6n para la identificaci6n de lases species ex6ticas introducidas recien-
temente.
In the past two years, several aphid species have been collected in Florida and
other southeastern states that represent new records, range extensions, or re-collec-
tions of rare species. This paper lists these species and provides notes and identifica-
tion information. Reference specimens are deposited at the Florida State Collection of
Arthropods (FSCA), Gainesville, FL.
Florida Entomologist 83(1)
March, 2000
Acyrthosiphon kondoi Shinji
Acyrthosiphon kondoi was found in Florida for the first time in pan traps sampled
as part of a study of temporal and spatial dynamics of cucurbit potyviruses in Lees-
burg, Lake County, FL (14 April 1993, 30 April 1993, 8 April 1994; Susan E. Webb)
(Mora-Aguilera 1995). Reproducing colonies were found on Trifolium pratense L. (red
clover) in a University of Florida greenhouse in Gainesville, Alachua County (17 May
1995; David E. Moon).Acyrthosiphon kondoi is a native of Asia, where it occurs from
India to Japan. It was introduced into California in the mid 1970's (Blackman & Eas-
top 1984) and since has colonized much of the United States. It also is established in
Australia and New Zealand, South Africa, the Middle East and Mexico and also has
spread into many Central and South American countries (Blackman & Eastop 1984).
Acyrthosiphon kondoi can be a major pest of alfalfa, Medicago sativa L.; however, it is
not likely to be a major problem in Florida because alfalfa production is very limited.
Damage to Florida clover is unknown but unlikely. Acyrthosiphon kondoi is reported
as a vector of bean yellow mosaic virus, a potyvirus (Chan et al. 1991). It may also vec-
tor other non-persistently transmitted plant viruses, but it does not seem to be a sig-
nificant vector pest species.
Two species of Acyrthosiphon occur on alfalfa in the United States:Acyrthosiphon
pisum (Harris) has dark antennal joints, andA. kondoi does not. Macrosiphum creelii
Davis, a rare species with a similar overall appearance, also is reported on alfalfa in
the United States. Macrosiphum creelii can be distinguished from the Acyrthosiphon
spp. by the presence of several rows of polygonal reticulation at the distal ends of its
siphunculi.
Aphis amaranthi Holman
A severe infestation of Aphis amaranthi was found on Amaranthus spinosus L.
(spiny pigweed) in Gainesville, Alachua County, FL (25 April 1997; Michael C. Tho-
mas) in a laboratory culture of Conotrachelus cervinus Hustache established using
plants obtained from the University of Florida Tropical Research and Extension Cen-
ter, Homestead, Dade County, FL. The identification ofA. amaranthi was confirmed
by Dr. Jaroslav Holman, Czech Republic.Aphis amaranthi was described from Cuba
and also has been found in Brazil on Amaranthus deflexus L. (largefruit amaranth)
(Remaudibre 1994). It has not been reported formally in the USA, although it is in-
cluded in Smith et al. (1992) key to alatae from North Carolina. We think it is likely
that the plants on whichA. amaranthi was found in Gainesville were infested origi-
nally in Homestead, because infestations on A. spinosus could not be found in the
Gainesville area. Specimens identified as Aphis fabae Scopoli from Miami, Dade
County, FL (David Storch and Willio L. Francillon; 8 March 1990) are actuallyA. am-
aranthi suggesting that this species has been in Miami for several years.
Four Aphis spp. have been reported previously from Amaranthus in Florida ac-
cording to Florida Department of Agriculture and Consumer Services, Division of
Plant Industry (DPI) records:Aphis craccivora Koch,A. fabae,Aphis gossypii Glover,
and Aphis spiraecola Patch. All are polyphagous worldwide pest species. Aphis fabae
has been recorded onAmaranthus in Florida twice, but in each case, specimens were
misidentified; thus, it is doubtful thatA. fabae colonizes Amaranthus in Florida. A key
to the remaining fourAphis on Florida Amaranthus follows:
la. Abdominal dorsum of apterous adults heavily sclerotized and shiny in
life; alate forms with dorsal abdominal banding, especially on posterior
segments; antennal segment III of alate form with about 7 somewhat
Halbert et al.:Aphids New to the Southeastern States 81
tuberculate rhinaria that vary in size so the segment looks lumpy in
profile; cauda as dark as siphunculi, somewhat pointed at the tip and
with 6-7 stiff curved setae (Fig. 1).................................... A. craccivora
lb. Abdominal dorsum of alate and adult apterous forms at most with lat-
eral sclerites and bands on segments VII and VIII and not shiny in live
specimens; number of rhinaria variable, but if varying much in size
then more than 7 rhinaria and antennal segment III not lumpy in pro-
file; cauda variable but not pointed.............................. ................... 2
2a. Cauda distinctly paler than the siphunculi, with 4-7 stiff curled setae
........................................................................................... ....... A g ossyp ii
2b. Cauda as dark as the siphunculi, usually with more than 7 setae; if
cauda is paler than siphunculi, then it has at least 8 setae ................ 3
3a. Length of dorsal setae on hind femur equal to or less than the diameter
of antennal segment III at the base; lateral abdominal tubercle on seg-
ment VII about twice the diameter of the spiracle; antennal segment
III of alatae with 8-22 rhinaria, not in a row; cauda not constricted; ul-
timate rostral segment often with 3-4 accessory setae; aphids dingy
colored and rotund........................................A. amaranthi
3b. Length of dorsal setae of hind femora two to three times the diameter
of antennal segment III at the base; lateral abdominal tubercle on seg-
ment VII about the same diameter as the spiracle; antennal segment
III of alatae with 6-12 rhinaria, usually in a row, except in late fall and
early spring specimens; cauda constricted; ultimate rostral segment
A B C D
Fig. 1. Cauda shape and setae for A: Aphis craccivora Koch, B. Aphis gossypii
Glover, C. Aphis amaranthi Holman, and D. Aphis spiraecola Patch.
Florida Entomologist 83(1)
March, 2000
with two accessory setae; aphids bright yellow or yellow-green and not
particularly rotund....................................... A. spiraecola
Aphis minima Tissot
A severe infestation was found on Prunus serotina Ehrh. (wild black cherry) in a
natural area in Gainesville, Alachua County, FL (25 April 1997; Robert P. Esser). This
aphid causes severe leaf curling on its host. Although the aphid was described from
Florida, it has been collected rarely. There are no DPI records for this species since
1938.Aphis minima, as its name suggests, is tiny. It can be identified easily using the
key to aphids on Prunus in Blackman & Eastop (1994).
Brachycaudus helichrysi (Kaltenbach)
Brachycaudus helichrysi was found on two Erechtites hieraciifolia (L.) Raf. ex DC.
(American burnweed) plants in Melbourne, Brevard County, FL (21 April 1997; Karen
L. Garrett-Kraus). Another infestation on the same plant species was found in Vero
Beach, Indian River County, FL (9 May 1997; Kenneth L. Hibbard). This aphid species
is a cosmopolitan pest on Prunus spp. (winter hosts) and various Compositae (sum-
mer hosts), especially Dendranthema x grandiflora (Ramat.) Kitam (chrysanthe-
mum), on which it can be a major pest (Blackman and Eastop 1984). Apparently, this
is the first Florida record for an established population of this species in spite of a
large chrysanthemum industry in the state. Brachycaudus helichrysi has been col-
lected in pan traps in the past by plant virus epidemiologists in Leesburg, Lake
County, FL (Webb et al. 1994). On the positive side, in separate host transfer attempts
by DPI inspectors Kenneth L. Hibbard and Karen L. Garrett-Kraus, the eastern Flor-
ida population from Erechtites failed to establish colonies on chrysanthemum.
Coloradoa achilleae Hille Ris Lambers
Several specimens of C. achilleae were found on a wild Achillea millefolium L.
(common yarrow) plant at the B.H. Corpening North Carolina Forest Service Training
Facility, Crossnore, NC (22 October 1996; Susan E. Halbert). Apparently, this is a new
record for the Western Hemisphere for this Eurasian species.
Coloradoa achilleae can be separated easily from most other aphids on Achillea.
Most other aphid species infesting this host in North America include species of Uro-
leucon and Macrosiphoniella, which are relatively large, conspicuous aphids with
dark siphunculi. Coloradoa achilleae is small, pale and cryptic. Species reported from
Achillea that might be confused with C. achilleae include B. helichrysi, which lacks
the capitate setae and acute ultimate rostral segment of C. achilleae, and several Ple-
otrichophorus spp. The latter species have the processus terminalis at least 3 3/4
times the base of antennal segment VI, which clearly separates them from C. achil-
leae. SeveralAchillea species have become popular ornamental plants, so it is likely
that these inconspicuous aphids will be distributed widely in the near future. It is un-
known if C. achilleae will be damaging to plants grown under cultivated conditions.
Coloradoa is a Eurasian genus with 31 currently accepted species (Remaudiere
and Remaudibre 1997). There are now six species of Coloradoa reported in North
America, all of them introduced. Coloradoa achilleae can be recognized by its associ-
ation with Achillea and by its short processus terminalis, which is just barely longer
than the base of antennal segment VI. Hille Ris Lambers (1939) has the original de-
scription of C. achilleae and a key that includes five of the six North American species.
Halbert et al.:Aphids New to the Southeastern States
Some specimens of Coloradoa angelicae (del Guercio), the sixth species, may come out
to, C. achilleae using Hille Ris Lambers key; however, the two species can be sepa-
rated easily because C. angelicae has swollen siphunculi and C. achilleae has straight
ones. Heie (1992) has a key to European species that includes all the North American
species. Coloradoa angelicae is included under its junior synonym Coloradoa absin-
thiella Ossiannilsson (Ossiannilsson 1962).
Several Coloradoa spp. have been in North America for many years, but Coloradoa
tanacetina (Walker), which is specific to Tanacetum spp., was first found in North
America in Rhode Island in 1974. By 1977, it could be found in New York and Maine
(Smith and Parron 1978). In 1992, the senior author collected it in northern Minne-
sota. It is a mystery how Eurasian Coloradoa spp., which are host specific to various
weeds, keep getting introduced into North America.
Hyadaphis coriandri (Das)
Colonies of H. coriandri were found on fennel (Foeniculum vulgare Mill.) at Or-
ange County, FL residences in Apopka (11 September 1997;Anthony N. Capitano) and
Orlando (29 September 1997; Anthony N. Capitano and Barbara J. Wilder). In Decem-
ber, 1998, an infestation was found at a residence in Tampa, Hillsborough County (27
December 1998; Anthony N. Capitano). No commercial operations that raise or sell
plants are known to be infested. Hyadaphis coriandri probably is native to Central
Asia, where it is holocyclic and heteroicious, migrating from Lonicera nummulariifo-
lia Jaub. & Spach. and other Lonicera spp. to various Umbelliferae (Remaudibre and
Halbert, unpublished data). Its current distribution includes southern Europe, Cen-
tral Asia and the whole of Africa, where it lives anholocyclically on Umbelliferae. Hy-
adaphis coriandri is a serious pest of coriander (Coriandrum sativum L.) and fennel.
It is not known how it was introduced into Florida, but a possible source would be im-
ported fresh herbs.
Two more other species of Hyadaphis occur in North America: Hyadaphis tatari-
cae (Aizenberg) (formerly suspected to be a synonym of H. coriandri (Hille Ris Lam-
bers 1966)), and Hyadaphis foeniculi (Passerini). The first one is strictly monoecious
on Lonicera spp. and is a serious pest. It was introduced into North America in the
mid 1970s (Voegtlin 1984). In about 10 years, it could be found as far west as western
Idaho (Voegtlin and Stoetzel 1988). The second one, H. foeniculi, is heteroecious, like
H. coriandri, and it has been in North America for many years. Voegtlin (1984) has ex-
cellent drawings, photos and other taxonomic and morphological information on H.
tataricae and H. foeniculi. The three species can be separated by the following key:
la. Siphunculi dark and 3.5-5 times as long as wide (Fig. 2) and markedly
swollen on the distal half; on Lonicera and various Umbelliferae
................................................................................................ H foen icu li
lb. Siphunculi pale or lightly pigmented and about 3 times as long as wide
and slightly swollen; host variable............................... ................... 2
2a. Ultimate rostral segment 0.067-0.093 mm long; setae on abdominal
segment VIII about 0.02-0.044 mm; siphunculi of apterae pale and con-
stricted at the base; rhinaria on antennal segment III of alatae tuber-
culate; inside folded leaves of Lonicera in northern states, causing
severe distortion and "witches' broom" deformation of infested termi-
nals .................................................................................... H tataricae
Florida Entomologist 83(1)
March, 2000
/ ^^ -^-,/ / ^-r-- -'
A B C
Fig. 2. Siphunculi of A. Hyadaphis foeniculi (Passerini), B. Hyadaphis coriandri
(Das), and C. Hyadaphis tataricae (Aizenberg).
2b. Ultimate rostral segment 0.10-0.126 mm long; setae on abdominal seg-
ment VIII about 0.008-0.016 (0.027) mm long; siphunculi of apterae
lightly pigmented and not constricted at the base; rhinaria on antennal
segment III of alatae not tuberculate; on umbelliferous herbs
(Anethum, Coriandrum, Foeniculum, etc.), celery (Apium graveolens L.
var. dulce (Miller) DC.) carrots (Daucus carota L. var. sativus Hoffm.)
and possibly blond psyllium (Plantago ovata Forssk.) (Blackman and
Eastop 1984; Kumar and Sagar 1994)............................. H. coriandri
Hyperomyzus carduellinus (Theobald)
Single specimens of H. carduellinus were collected in Florida suction traps in Ken-
dall, Dade County, FL (14-21 March 1997), Fort Pierce, St. Lucie County, FL (14-21
March 1997) and Quincy, Gadsden County, FL (28 March-4 April 1997). These collec-
tions represent a new North American record for this species. Hyperomyzus carduel-
linus is an Asian species that is found from Afghanistan to Korea and Taiwan. It also
has been collected in Argentina (Nieto Nafria et al. 1994), Bolivia (Remaudiere,
Weemaels and Nicolas 1992), Australia, and Africa. Infestations of H. carduellinus
were found on Sonchus oleraceus L. (common sowthistle) weeds in Homestead, Dade
County, FL (3 April 1997; Edward T. Putland), Fort Pierce, St. Lucie County, FL (4
April 1997; Kenneth L. Hibbard), Apopka, Orange County, FL (7 April 1997; Leslie J.
Wilber) and Winter Haven, Polk County (7 April 1997; Susan E. Halbert and Martha
Halbert et al.:Aphids New to the Southeastern States
A. 'Ginger' Simpson). The aphid is specific to Sonchus and related plants and is not
likely to become a pest. The colony in Winter Haven was a mixed infestation with Hy-
peromyzus lactucae (L.), which has been in North America for a long time. Hyper-
omyzus is a large genus, but most of the species that occur in North America are in the
New World subgenus H. (Neonasonovia). Hyperomyzus (Neonasonovia) spp. can be
separated from H. sensu strict most easily using alate forms. Alatae of H. sensu
strict have well-defined dorsal abdominal patches, whereas those of H. (Neona-
sonovia) do not. Only three Hyperomyzus sensu strict, all occurring on Sonchus, are
found in North America. Hyperomyzus lactucae (L.) and Hyperomyzus pallidus Hille
Ris Lambers migrate to Ribes as a winter host in northern climates. Hyperomyzus
pallidus appears to be restricted to northern states (Smith & Parron 1978). They can
be separated using the following key:
la. Siphunculi of apterae swollen only to 1.1-1.3 times their minimum di-
ameter; siphunculi of alatae swollen to 1.2-1.6 times their minimum
diameter; setae on the dorsum of abdominal segment VIII of apterae
and alatae less than 0.02 mm; patch on abdominal dorsum of alate
form pale and usually restricted to segments IV-V....... H. carduellinus
lb. Siphunculi of apterae swollen to 1.5-1.9 times their minimum diame-
ter; siphunculi of alatae swollen to 1.5-2.2 times their minimum diam-
eter; setae on dorsum of abdominal segment VIII more than 0.02 mm
in length; patch on abdominal dorsum of alate form darker and extend-
ing to abdominal segm ent III ....................................... ................... 2
2a. Setae on antennal segment III about 1/2 the basal diameter of the seg-
ment; rhinaria on antennal segment III of apterous form clustered to-
ward the base of the segment; alatae with patch on abdominal dorsum
broken into bars, especially anteriorly; siphunculi of alate form dusky
................................................................................................. H. lactucae
2b. Setae on antennal segment III about v4 the basal diameter of the seg-
ment; rhinaria on antennal segment III of apterous form more or less
distributed the length of the segment; alatae with patch on abdominal
dorsum dark and dense, with no broken bar on abdominal segment III;
siphunculi of alate form dark.................. .................... H. pallidus
Kaltenbachiella ulmifusa (Walsh & Riley)
An infestation of this native species was found on its winter host, Ulmus rubra
Muhl. (slippery elm), in Florida Caverns State Park north of Marianna, Jackson
County, FL (6 May 1997; Paul E. Skelley). The summer hosts are roots of Labiatae
(Blackman and Eastop 1994). This find in the Florida panhandle represents a major
range extension for this species, which was previously known only as far south as
North Carolina (Smith and Parron 1978).
Melanaphis sp.
A species of Melanaphis was found on Miscanthus (Gramineae) plants at an
amusement park in Orange County, FL (19 December 1996; Barbara J. Wilder). The
plants had been obtained recently from a nursery in California. The aphid is an East
Florida Entomologist 83(1)
March, 2000
Asian species that is apparently specific to Miscanthus. A host choice experiment in
DPI quarantine confirmed that the aphids on Miscanthus were not Melanaphis sac-
chari (Zehntner), the sugarcane aphid, because the aphids from Miscanthus avoided
the sugarcane (Saccharum officinarum L.), but heavily colonized the Miscanthus. The
species name for this Melanaphis sp. has not been determined due to sketchy descrip-
tions of Asian species and missing type material, but this find is certainly a new
record for the Western Hemisphere. The status of the North American Melanaphis
spp. will be the subject of another paper.
An attempt was made to eradicate the Florida population by eliminating the en-
tire infested shipment. At the time of this writing, no more infestations have been
found in Orange County, FL; however, another infestation was found in Alachua, Ala-
chua County, FL (16 March 1998; Teresa Estok) that was traced to a nursery near
Pensacola, Santa Rosa County FL (26 March 1998; Steven B. Matthews).
Schizaphis rotundiventris (Signoret)
Schizaphis rotundiventris, an aphid native to the Old World tropics and subtrop-
ics, was identified positively for the first time in the Western Hemisphere when a se-
vere infestation was found on Cyperus papyrus L. (papyrus) in a wetlands experiment
at a University of Florida greenhouse in Gainesville, Alachua County, FL (Mark Otto;
February, 1996). Two aphids collected in Tampa, Hillsborough County in 1988 (27
April 1988; Howard L. Wallace and E. Ray Simmons), also from Cyperus papyrus and
found among FSCA unknowns, are also this species, indicating that S. rotundiventris
has been in Florida for at least 10 years. B6rner and Heinze (1957, p. 104) stated that
Schizaphis cyperi van der Goot (Ainslie), has some importance as a vector of sugar-
cane mosaic virus in the USA; however, there is no citation for this information, and
we could not find its source. The record may be the result of confusion of S. cyperi van
der Goot, a junior synonym of S. rotundiventris, with Carolinaia cyperi Ainslie, which
is common on Cyperus in Florida. B6rner and Heinze list (Ainslie) after van der Goot
as the describer, evidently synonymizing the two species. This mistaken synonymy
easily explains the apparent Florida record. According to DPI records, although other
species of aphids were collected from Cyperus in Florida prior to 1988, there were no
S. rotundiventris, and no unknowns that are likely to be S. rotundiventris. Thus, the
Florida records listed above comprise the first positive report for S. rotundiventris in
the Western Hemisphere. A single specimen of S. rotundiventris was found in a sam-
ple collected in a green tile water pan trap in Leesburg, Lake County, FL (23 Septem-
ber 1992; Susan E. Webb). In 1996 and 1997, the same species was found in suction
trap samples from Fort Pierce, Immokalee (Collier County), Kendall, Quincy, and
Winter Haven. Specimens were collected in 1997 in a suction trap in Belle Glade,
Palm Beach County, FL (Gregg S. Nuessly). Collections were most frequent in the fall.
A single S. rotundiventris was collected in a suction trap in Key West, Monroe County,
FL in September 1998. Schizaphis rotundiventris also was collected in suction trap
samples from Blackville, South Carolina on numerous occasions (1994 and 1995; Jay
W. Chapin).
Schizaphis rotundiventris can be identified using the key by Eastop (1961), in
which it comes out to S. cyperi. All of the North American species are included in Eas-
top's key except Schizaphis gracilis Richards, which has been collected only in the Ca-
nadian Arctic. Schizaphis rotundiventris is distinctive because of its long black
siphunculi and dark cauda. Schizaphis viridirubra (Gillette & Palmer) also has long
black siphunculi, but the cauda is usually quite pale, and setae are much longer and
more numerous than those of S. rotundiventris. Setae on antennal segment III of S.
Halbert et al.:Aphids New to the Southeastern States
viridirubra are at least as long as the diameter of the segment at the base; whereas
those on antennal segment III of S. rotundiventris are less than half as long as the di-
ameter of the segment at the base. Alatae in trap samples can be separated from
Aphis spp. by the once-branched media on the fore wing and short ultimate rostral
segment that is characteristic of Schizaphis.
Schizaphis rotundiventris is normally host specific to several species of Cyperus,
including yellow nutsedge (Cyperus esculentus L.) and purple nutsedge (C. rotundus
L.), but it has been reported from a few other plants (Cyperaceae: Fimbristylis, Kyl-
lingia, Mariscus; and Palmae: Cocos nucifera L., coconut palm and Elaeis guineensis
Jacq., oil palm) (Blackman and Eastop 1984). It is not likely to become a pest in North
America.
Shivaphis celti Das
Shivaphis celti was found for the first time in Florida in Jacksonville, Duval
County, on Celtis laevigata Willd., sugarberry (13 August 1997; Flewellyn W. Podris).
Shivaphis celti is an Asian species that colonizes leaves of Celtis spp. Shivaphis celti is
conspicuous because it secretes copious quantities of bluish white wax. Additional lo-
cations where S. celti was found in Florida include Lake Jem, Lake County, FL (28 Au-
gust 1997; Christine M. Murphy), Gainesville, Alachua County, FL (9 September 1997;
Robert P. Esser), and Scottsmoor, Brevard County, FL (17 September 1998; Gregory A.
Brown). Shivaphis celti was found in suction trap samples from Winter Haven, Polk
County, FL (5 September 1997) and Quincy, Gadsden county (3 October 1997). In 1998,
S. celti was collected in suction traps in Belle Glade (10 September 1998; Gregg S.
Nuessly) and Kendall. A specimen was found in a fruit fly detection trap in Palmetto,
Manatee County, FL (4 September 1998; Elmer Goodroad). Shivaphis celti is easy to
identify because it is the only waxy aphid on Celtis in North America. Sexuales of S.
celti were found on 10 October 1997 in Gainesville. In late summer of 1998, S. celti be-
came a conspicuous pest in north Florida on Celtis used in urban landscape situations.
Although this is the first published report, S. celti has been in North America for
at least a year. Dr. John Graham, Evans, Georgia, found S. celti in Aiken County,
South Carolina on Celtis laevigata on 17 November 1996, and then in Columbia
County, Georgia on Celtis occidentalis L. (beaverwood) on 23 November 1996 about a
year prior to its discovery in Florida, which explains the aphid's sudden and extensive
distribution throughout northern Florida in the fall of 1997. Shivaphis celti was also
collected by Jim Soloman in Stoneville, Washington County, Mississippi on 31 July
1998 (data courtesy of Dr. Andrew S. Jensen, USNM).
In recent years, a number of Asian aphids that are specific to trees, particularly
Ulmus, have been introduced into Europe and North America (Remaudibre et al.
1988; Halbert & Pike 1990). Prior (1974) has shown how bonsai Ulmus are responsi-
ble for spreading East Asian aphids in Britain. Celtis, like the small-leaved Ulmus
spp., is a popular plant for bonsai. Georgia has a major bonsai importing business, so
it is possible that S. celti was introduced into Georgia on imported Asian bonsai Celtis
and has since extended its range into Florida.
Takecallis arundicolens (Clarke)
Small colonies of T arundicolens were found on Arundinaria gigantea (Walter)
Muhl. (cane) in Torreya State Park in Bristol, Liberty County, FL (6 January 1997;
Susan E. Halbert and Letitia C. Croom). Another collection was made on the same
host at a botanical park in Gainesville, Alachua County, FL (25 March 1997; Su-
Florida Entomologist 83(1)
March, 2000
san E. Halbert, Nancy C. Coile and Norma McGinn). This Asian aphid was previously
known in the USA only from California (Smith & Parron 1978) and Oregon (Andrew
Jensen, personal communication).
Takecallis spp., which colonize only bamboo and related plants, can be recognized
by a tubercle on the clypeus that characterizes the genus. The three species in North
America, all of which probably occur in the southeastern states, can be separated by
the following key:
la. Aphid pale except for antennal joints. Cauda and siphunculi may be
dusky.................................... ...................... T taiwanus (Takahashi)
lb. Aphid with black markings other than on antennal joints .................. 2
2a. Elongate black spots on abdominal dorsum; cauda dusky; antennal
segment III dark near the base...................... T arundinariae (Essig)
2b. No spots on the abdominal dorsum; cauda jet black; antennal segment
III pale near the base but with a dark portion distally around the rhi-
naria ................ ...................... T arundicolens
Toxoptera citricida (Kirkaldy)
Toxoptera citricida (Kirkaldy), brown citrus aphid, was discovered in Florida in
early November, 1995 (Halbert & Brown 1996). It is one of the world's most damaging
pests of citrus, primarily because it is an efficient vector of citrus tristeza virus (CTV).
A delimiting survey was initiated immediately that involved both state and USDA
personnel. The metropolitan areas of Miami, Dade County, FL and Ft. Lauderdale,
Broward County, FL were found to be infested, with the highest density in Miami. The
initial distribution implicated introduction on illegally imported citrus plants rather
than natural spread from the Caribbean Basin. By late June of 1996, infestations had
been found in the southeastern Florida urban areas from Islamorada, Monroe County,
in the Florida Keys to Palm Beach, Palm Beach County. There was also a single find
in a trailer park in Naples, Collier County (19 June 1996; Floyd E. Crim) on the south-
west coast. Two commercial lime groves and three commercial lime nurseries in
southern Dade County had slight infestations. The remainder of the finds were in doo-
ryards, ornamental nurseries and small abandoned citrus groves in urban areas.
During the next year (July 1996-June 1997), T citricida colonized the citrus belt
of Florida. Infestations were widespread but low in density in the Gulf Citrus and In-
dian River citrus production areas in July/August 1996. By late spring of 1997, colo-
nies could be found in the Central Florida Ridge area. Infestations became heavy,
particularly in the Immokalee, Collier County, area in the fall of 1996, and localized
outbreaks involving up to 20 acres occurred in commercial groves in the late spring of
1997. Several registered scion groves became infested. The impact of the aphid popu-
lations on spread of CTV is not known at this time.
Toxoptera citricida is native to East Asia, but it has now colonized virtually all of
the world's citrus production areas except the Mediterranean region and the remain-
ing citrus producing states in the USA. Toxoptera citricida was introduced into South
America in the 1930s (Carver 1978) and gradually moved north. It was first reported
in Central America by Voegtlin & Villalobos (1992) and spread quickly throughout the
Caribbean Basin thereafter (Stoetzel 1994).
The Division of Plant Industry was instrumental in organizing a Task Force on T
citricida and CTV two years before T citricida was discovered in Florida. Thus, the
mechanism was in place to assess risk and plan rational strategy. Although T citri-
Halbert et al.:Aphids New to the Southeastern States
cida was detected very early after its initial establishment (we estimate about 4
months), it was not possible to eradicate it. Regular nursery inspections in infested
areas, combined with compliance agreements, ensured that nurseries did not spread
T citricida to uninfested locations by moving infested citrus plants. In fact, T citri-
cida did not colonize Florida any faster than would be expected by natural spread
(Wellings 1994; Halbert et al. 1998).
Toxoptera citricida is easy to identify. The long setae on antennal segment III (about
as long as the diameter of the segment) will separate even small T citricida nymphs
from all the other aphid species on North American citrus. A recent key to common
North American aphids on citrus (Halbert & Brown 1996) is designed for use in the field
with the aid of a good hand lens. Stoetzel (1994) treats the world citrus aphid fauna.
Trichosiphonaphis polygoni (van der Goot)
Trichosiphonaphis polygoni was reported in Florida and Georgia by Smith and Den-
mark (1982) and has since become abundant enough in Florida to be collected in 1996
and 1997 in suction traps in Immokalee, Fort Pierce, Winter Haven, and Quincy, and in
1997 in Belle Glade (Gregg S. Nuessly). Most collections occurred in the fall. Tricho-
siphonaphis polygoni was also collected in a green tile water pan trap in Leesburg, Lake
County (5 April 1994; Susan E. Webb). It was also collected in traps in Blackville, South
Carolina (1994 and 1995; Jay W. Chapin) and in Guntersville, Alabama (October-No-
vember 1996; Kathy L. Flanders). Trichosiphonaphis polygoni is an East Asian species
that occurs in India, China and Japan. It has become established in Africa (Burundi and
Kenya) (Remaudiere et al. 1994) and in Panama (Remaudiere, Serain, Trouvbe and De-
meester 1992). Trichosiphonaphis polygoni may have been introduced into Florida on
contaminated Polygonum with shipments of aquarium plants (Polhemus 1997).
Trichosiphonaphis polygoni is specific to Polygonum and is easy to recognize. Fron-
tal tubercles are well developed similar to those of Ovatus. There is a tendency for the
hind wing of T polygoni to have only one oblique vein. Siphunculi are relatively close
together and dark with a slight, but rather abrupt swelling near the distal end, and
the siphuncular opening is slightly oblique, with no flange. Several minute setae are
present laterally on the siphunculi near the proximal end. The only North American
aphid with similar siphuncular setae is Glendenningia philadelphi MacGillivray, but
it has much more swollen siphunculi and a dense patch on the abdominal dorsum of
the alate form and occurs only in Idaho, Montana, Washington and British Columbia.
Uroleucon elephantopicola Robinson
Uroleucon elephantopicola, a native species specific to Elephantopus spp., was
found in Gainesville by DPI nematologist Dr. Robert P. Esser in July, 1995. His collec-
tion nearly doubled the total number of these aphids that have ever been collected and
extended its range from Illinois to Florida. Uroleucon elephantopicola can be found on
the undersides of leaves until the plant produces a flower stalk, after which the
aphids are on the stalk and under the inflorescence. Uroleucon elephantopicola is
dark in color and can be recognized by its long ultimate rostral segment and its asso-
ciation with the host plant. Robinson (1985) described the species and provided an ex-
cellent key that includes it.
ACKNOWLEDGMENTS
We thank Paul E. Skelley, Gay Donaldson-Fortier, and Gayle van de Kerckhove for
making slides, Jaroslav Holman for confirmation of Aphis amaranthi, F. W. Quednau
for confirmation of Shivaphis celti, Victor Eastop, British Museum of Natural History,
Florida Entomologist 83(1)
March, 2000
for solving the confusion about the previous status of Schizaphis rotundiventris in the
USA, Randi W. Eckel for loan of Coloradoa spp., David J. Voegtlin for help with pro-
curing literature, Gregg S. Nuessly, University of Florida, Everglades Research & Ex-
tension Center, Belle Glade, for supplying sugarcane plants, and David J. Voegtlin,
Illinois Natural History Survey, Andrew S. Jensen, U.S. National Museum, and Nancy
C. Coile, Wayne N. Dixon, Gregory A. Evans, John B. Heppner and Gary J. Steck (all
DPI) for reviewing the manuscript. The cooperators who help with the Florida suction
trap survey include Robert C. Bullock, University of Florida Indian River Research &
Extension Center, Ft. Pierce; Richard K. Sprenkel, University of Florida North Flor-
ida Research & Extension Center, Quincy; Philip A. Stansly and Mark A. Pomerinke,
University of Florida Southwest Florida Research & Extension Center, Immokalee;
John MacKean, USDA/APHIS/PPQ, Key West; Michael C. Kesinger, Division of Plant
Industry, Florida Department of Agriculture and Consumer Services (DPI), Winter
Haven; and Debra S. Chalot and Gwen Myres, DPI, Kendall. Many DPI and USDA in-
spectors helped with the survey for T citricida.
LITERATURE CITED
BLACKMAN, R. L., AND V. F. EASTOP. 1984. Aphids on the world's crops. J. Wiley and
Sons, Chichester.
BLACKMAN, R. L., AND V. F. EASTOP. 1994. Aphids on the world's trees. CAB Interna-
tional, Wallingford, UK.
BORNER, C., AND K. HEINZE. 1957. Aphidina-Aphidoidea. pp. 1-402. In H. Blunck, Ed.
Teirische Schadlinge an Nutzpflanzen. 2. Teil. 4. Lieferung. P. Parey, Berlin.
CARVER, M. 1978. The black citrus aphids, Toxoptera citricidus (Kirkaldy) and T au-
rantii (Boyer de Fonscolombe) (Homoptera: Aphididae). Journal of the Austra-
lian Entomol. Soc. 17: 263-270.
CHAN, C. K., A. R. FORBES, AND D. A. RAWORTH. 1991. Aphid-transmitted viruses and
their vectors of the world. Agriculture Canada, British Columbia Technical
Bulletin 1991-3E. Vancouver. 216 pp.
EASTOP, V. F. 1961. A key for the determination of Schizaphis Borner. Entomologist
94: 241-246.
HALBERT, S. E., AND L. G. BROWN. 1996. Toxoptera citricida (Kirkaldy), Brown citrus
aphid-identification, biology and management strategies. Florida Depart-
ment of Agriculture and Consumer Services, Division of Plant Industry,
Gainesville. Entomol. Cir. No. 374. 6p.
HALBERT, S. E., G. A. EVANS, AND D. C. CLINTON. 1998. Establishment of Toxoptera
citricida in Florida. pp. 547-554. In J. M.Nieto Nafria and A. F. G. Dixon (eds.),
Aphids in natural and managed ecosystems. Universidad de Leon, Leon, Spain.
HALBERT, S. E., AND K. S. PIKE. 1990. An Asian elm aphid (Homoptera: Aphididae)
new to North America. Proc. Entomol. Soc. Wash. 92: 672-674.
HEIE, 0. E. 1992. The Aphidoidea (Hemiptera) of Fennoscandia and Denmark. IV.
Family Aphididae: Part 1 of tribe Macrosiphini of subfamily Aphidinae. Fauna
Entomologica Scandinavica 25. E. J. Brill/Scandinavian Science Press Ltd.,
Leiden, New York, Kobenhavn, Koln.
HILLE RIS LAMBERS, D. 1939. On some western European aphids. Zoologische Med-
edeelingen 22: 79-119.
HILLE RIS LAMBERS, D. 1966. New and little known aphids from Pakistan (Ho-
moptera: Aphididae). Tijdschrift voor Entomologie 109: 193-220.
KUMAR, N., AND P. SAGAR. 1994. Seasonal history and host range of the coriander
aphid, Hyadaphis coriandri (Das). Journal of Research, Punjab Agricultural
University 31: 283-284.
MORA-AGUILARA, G. 1995. Aphid vector dynamics and temporal and spatial charac-
teristics of watermelon virus epidemics. Ph.D. dissertation, University of Flor-
ida, Gainesville.
Halbert et al.:Aphids New to the Southeastern States
NIETO NAFRIA, J. M., M. A. DELFINO, AND M. P. MIER DURANTE. 1994. La afidofauna
de la Argentina en 1992. Universidad de Le6n, Le6n, Spain.
OSSIANNILSSON, F. 1962. Coloradoa absinthiella, n. sp., a new Swedish aphid (Hem.,
Horn., Aphidoidea). Opuscula Entomologica 27: 115-116.
POLHEMUS J. T., AND R. P. RUTTER. 1997. Synaptonecta issa (Heteroptera: Corixidae),
first new world record of an Asian water bug in Florida. Entomol. News 108:
300-304.
PRIOR, R. N. B. 1974. Three Japanese aphids introduced in Britain on imported
'bonzai' trees. Plant Pathol. 23: 48.
REMAUDIERE, G. 1994. Revue et cle des especes sud-americaines d'Aphidina et de-
scription d'unAphis nouveau sur le continent africain. Revue franchise d'Ento-
mologie (N.S.) 14(2): 49-58.
REMAUDIERE, G., A. AUTRIQUE, AND L. NTAHIMPERA. 1994. Trichosiphonaphispolygoni
(van der Goot), Homoptera, Aphididae nouveau sur le continent africain. Revue
franchise d'Entomologie (N.S.) 16(1): 36.
REMAUDIERE, G., F. W. QUEDNAU, AND 0. E. HEIE. 1988. Un nouveau Tinocallis sur
Ulmus, originaire d'Asie Centrale et semblable a T saltans (Nevsky) (Ho-
moptera: Aphididae). Can. Entomol. 120: 211-219.
REMAUDIERE, G., AND M. REMAUDIERE. 1997. Catalogue des Aphididae du Monde.
INRA. 478 pp. Versailles.
REMAUDIERE, G., M. SERAIN, C. TROUVBE, AND S. DEMEESTER. 1992. Donnees nouv-
elles sur le genre Trichosiphonaphis Takahashi, 1922: cycles, hotes, synony-
mies et distribution geographique (Homoptera, Aphididae). Revue franchise
d'Entomologie (N.S.) 14(2): 19-46.
REMAUDIERE, G., N. WEEMAELS, AND J. NICOLAS. (1991) 1992. Contribution al la con-
naissance de la faune aphidienne de la Bolivie (Homoptera: Aphididae). Para-
sitica (Gembloux) 47(1): 19-46.
ROBINSON, A. G. 1985. Annotated list of Uroleucon (Uroleucon, Uromelan, Satula)
(Homoptera: Aphididae) of America north of Mexico, with keys and descriptions
of new species. Can. Entomol. 117: 1029-1054.
SMITH, C. F., R. W. ECKEL, AND E. LAMPERT. 1992. A key to many of the common alate
aphids of North Carolina (Aphididae: Homoptera). North Carolina State Uni-
versity Technical Bulletin 299. North Carolina State University, Raleigh.
SMITH, C. F., AND H. A. DENMARK. 1982. Trichosiphonaphis polygoni (van der Goot)
Homoptera: Aphididae), a genus and species new to the United states. Florida
Entomol. 65: 381-382.
SMITH, C. F., AND C. S. PARRON. 1978. An annotated list of the Aphididae (Homoptera)
of North America. North Carolina Agricultural Experiment Station, Raleigh.
STOETZEL, M. B. 1994. Aphids (Homoptera: Aphididae) of potential importance on Cit-
rus in the United States with illustrated keys to species. Proceedings of the En-
tomological Society of Washington 96: 74-90.
VOEGTLIN, D. J. 1984.Notes on Hyadaphis foeniculi and redescription of Hyadaphis
tataricae (Homoptera: Aphididae). Great Lakes Entomol. 17: 55-67.
VOEGTLIN, D. J., AND M. B. STOETZEL. 1988. Hyadaphis tataricae (Homoptera: Aphi-
didae): 10 years after its introduction into North America. Proc. Entomol. Soc.
Wash. 90: 256-257.
VOEGTLIN, D. J., AND W. VILLALOBOS M. 1992. Confirmation of the brown citrus aphid
Toxoptera citricidus, in Costa Rica. Florida Entomol. 75: 161-162.
WEBB, S. E., M. L. KOK-YOKOMI, AND D. J. VOEGTLIN. 1994. Effects of trap color on
species composition of alate aphids (Homoptera: Aphididae) caught over water-
melon plants. Florida Entomol. 77: 146-154.
WELLINGS, P. A. 1994. How variable are rates of colonization? European J. of Entomol.
91: 121-125.
Florida Entomologist 83(1)
March, 2000
FIRST REPORT OF INCISITERMES MINOR (ISOPTERA:
KALOTERMITIDAE) IN LOUISIANA
MATTHEW T. MESSENGER', RUDOLF H. SCHEFFRAHN2 AND NAN-YAO SU2
1City of New Orleans Mosquito and Termite Control Board
6601 South Shore Harbor Boulevard, New Orleans, LA 70126
2Ft. Lauderdale Research and Education Center, University of Florida
Institute of Food & Agricultural Sciences, 3205 College Avenue
Ft. Lauderdale, FL 33314
On 9 June 1998, drywood termite alates, soldiers, and pseudergates were collected
from inside a dead limb of a living Arizona ash, Fraxinus velutina Torr., tree inside 31-
acre Louis Armstrong Park, which is located immediately northwest of the French
Quarter in New Orleans, Louisiana. Subsequent inspection of Perseverance Hall in
the park revealed an extensive drywood termite infestation on the first and second
floors. Perseverance Hall is located in the southeast portion of the park approximately
25 meters from the ash tree. On 22 July 1999, a drywood soldier was collected from in-
side Perseverance Hall. Previously, only a few pseudergates and dark-colored wings
had been recovered. The alates and soldiers collected from the ash tree and the soldier
and wings recovered in Perseverance Hall were identified as the western drywood ter-
mite, Incisitermes minor (Hagen) (Isoptera: Kalotermitidae) using termite keys devel-
oped by Banks & Snyder (1920), Snyder (1954), Weesner (1965), and Scheffrahn & Su
(1994). Incisitermes minor alates were also collected during the last week of May until
the last week of June from 20.7 cm x 10.2 cm glue traps (TRAPPERLTD, Bell Labo-
ratories, Inc., Madison, WI.) placed near lights inside the park and on the perimeter
fence surrounding the park. Two I. minor alates were recovered from 19 traps in 1998
and 28 alates were recovered from 70 traps in 1999. These glue traps were originally
placed in the park to monitor flight activity of the Formosan subterranean termite,
Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). This is the first record
of I. minor in Louisiana and the first infestation in non-structural wood noted for this
species in Louisiana. Voucher specimens were deposited at the University of Florida
termite collection in Ft. Lauderdale and at the City of New Orleans Mosquito and Ter-
mite Control Board termite collection in New Orleans.
Incisitermes minor is considered one of the five most economically important and
destructive termites in the United States (Su & Scheffrahn 1990). However, the main
distribution of I. minor is primarily found in the southwestern U.S. and northwestern
Mexico (Light 1934). Non-native drywood termite species are generally introduced
into new areas after infested furniture and lumber is shipped from one state to an-
other. The first introduction of I. minor in Florida was reported after alates swarmed
from an infested chair that was shipped from California (Scheffrahn et al. 1988). Sny-
der (1954) reported the introduction of I. minor into a church in Cleveland, Ohio, in
wood boxes shipped from Mexico and into a house in Niagara Falls, New York, from
grape boxes shipped from California. Incisitermes minor was also introduced to a
building in Toronto, Canada (Grace et al. 1991). Other reports of I. minor introduc-
tions in structural wood include Ohio, Oklahoma, Arkansas, Maryland, and Iowa (Gay
1967). Howell et al. (1987) reported I. minor from furniture in Texas.
The source of the I. minor infestation in New Orleans is unclear. It is not known
whether the ash was infested with I. minor before being planted near Perseverance
Hall 15-18 years ago. Some reports suggest Perseverance Hall has had a drywood in-
Scientific Notes
festation for at least 5-10 years. The introduction may have occurred when infested
furniture was shipped from California, Arizona, or northwestern Mexico and placed
inside Perseverance Hall or one of the other three adjacent buildings.
In August, 1999 Perseverance hall and adjacent buildings were leased to the Na-
tional Park Service. Planned control measures for Perseverance Hall and adjacent
buildings include fumigation and removal of the infested Arizona ash limb.
SUMMARY
A well-established infestation of the western drywood termite, Incisitermes minor
(Hagen) (Isoptera: Kalotermitidae), was discovered in Louis Armstrong Park in New
Orleans, Louisiana. Colonies are present inside historical Perseverance Hall and in a
dead limb of a nearby live Arizona ash tree. This is the first report of this species in
Louisiana and the first report of a non-endemic drywood termite species infesting
non-structural wood.
We are grateful to E. S. Bordes and M. K. Carroll, City of New Orleans Mosquito
and Termite Control Board, for reviewing the manuscript. Partial funding for this
project was provided by USDA-ARS under the grant agreement No. 58-6435-8-108.
This article is Florida Agricultural Experiment Station Journal Series No. R-06970.
REFERENCES CITED
BANKS, N., AND T. E. SNYDER. 1920. A revision of Nearctic termites with notes on bi-
ology and geographic distribution. Bull. Smithsonian Mus. 108: 1-228.
GAY, F. J. 1967. A world review of introduced species of termites. Bull. Commonwealth
Sci. Industrial Res. Organ. 286: 1-88.
GRACE, J. K., G. M. CUTTEN, R. H. SCHEFFRAHN, AND D. K. M. KEVAN. 1991. First in-
festation by Incisitermes minor of a Canadian building (Isoptera: Kalotermiti-
dae). Sociobiology 18: 299-304.
HOWELL, H. N., P. J. HAMAN, AND T. A. GRANOVSKY. 1987. The geographical distribu-
tion of the termite genera Reticulitermes, Coptotermes, and Incisitermes in
Texas. Southwest. Entomol. 12: 119-125.
LIGHT, S. F. 1934. The distribution and biology of the common dry-wood termite, Kal-
otermes minor, pp. 210-216 in C. A. Kofoid, S. F. Light, A. C. Horner, M. Randall,
W. B. Herms, and E. E. Bowe [eds.] Termites and termite control. 2nd ed. Uni-
versity of California Press, Berkeley, California. 795 pp.
SCHEFFRAHN, R. H., AND N.-Y. SU. 1994. Keys to soldier and winged adult termites
(Isoptera) of Florida. Florida Entomol. 77: 460-474.
SCHEFFRAHN, R. H., J. R. MANGOLD, AND N.-Y. SU. 1988. A survey of structure-infest-
ing termites of peninsular Florida. Florida Entomol. 71: 615-630.
SNYDER, T. E. 1954. Order Isoptera. The termites of the United States and Canada.
Natl. Pest Contr. Assn., New York, New York. 64 pp.
Su, N.-Y., AND R. H. SCHEFFRAHN. 1990. Economically important termites in the
United States and their control. Sociobiology 17: 77-94.
WEESNER, F. M. 1965. Termites of the United States, a handbook. Natl. Pest Contr.
Assn., Elizabeth, New Jersey. 70 pp.
Florida Entomologist 83(1)
March, 2000
SEASONAL FLIGHT OF PLECIA NEARCTICA
(DIPTERA:BIBIONIDAE) IN SOUTHERN FLORIDA
RON CHERRY AND RICHARD RAID
Everglades Research and Education Center, P.O. Box 8003, Belle Glade, FL 33430
The lovebug, Plecia nearctica Hardy, is a serious nuisance to motorists traveling in
southern states. The insects are smashed against windshields obscuring vision and
cars may overheat when radiators become clogged. The smashed insects also damage
car paint if the body fluids are not removed soon after contact (Callahan and Denmark
1973). The insect was first described by Hardy (1940) from Galveston, Texas, who re-
ported it to be widely spread, but more common in Texas and Louisiana than other
Gulf Coast states. It has now progressed to all states bordering on the Gulf of Mexico,
as well as Georgia, South Carolina, and parts of Central America. It was first collected
in Florida in 1949 and today is found throughout Florida (Denmark and Mead 1992).
Adult flights of lovebugs have been reported to occur primarily during May and
September in different areas of the insect's range (Hetrick 1970; Callahan and Den-
mark 1973; Buschman 1976; Thornhill 1976; Callahan 1985). However, in spite of
these previous reports, no data have ever been presented actually showing seasonal
flights of the lovebugs. Our objective was to determine seasonal flight patterns of
P. nearctica in southern Florida. Additional data on temporal sychronony of flights at
different locations are also presented.
Yellow sticky traps (Pherocon AM, no bait) made by Trece Inc., Salinas, California
and baited with anethole (Cherry 1998) were used to monitor adult flights of lovebugs.
Sampling was conducted by putting out 15 new sticky traps each month at approxi-
mately mid-month. These 15 traps were located at three different locations (5 traps/
location) to provide data on temporal synchrony between locations. One location was
the Everglades Research and Education Center (location one), University of Florida,
located near Belle Glade, Florida. The other two locations were located approximately
24 km southwest of the research center (location two) and 31 km east of the research
center (location three). All three locations were located within Palm Beach County,
Florida, and surrounded by agricultural lands (sugarcane, rice, vegetables). Traps at
each location were placed 250 m apart in a straight line (i.e. a one km transect) adja-
cent roads. Each trap was hung one m above the ground on a metal rod and had a
sponge (3 x 3 x 3 cm) containing 5 ml of anethole wedged into it. All 15 traps were
hung and baited on the same day and collected seven days later. The seven day expo-
sure period was used to avoid short term inclement weather factors such as rain, ex-
treme winds, etc. that might greatly reduce adult catches within a shorter trap
exposure time. Traps were collected by wrapping each trap in clear cellophane in the
field. Lovebugs on each trap were counted by microscopic identification in a labora-
tory. A sample of lovebug adults collected on the traps during different major flight pe-
riods (May, September, December) was sent to Dr. Gary Steck, Division of Plant
Industry, Gainesville, Florida who corroborated that the insects were P. nearctica.
Statistical analysis was conducted by SAS (1996). Temporal synchrony of adult
flights between locations was determined by multiple correlation using the total num-
ber of adults caught each month at each location. Differences in mean numbers of
adults caught at each location during different months were determined by using
Tukey's test. A figure to visually show the overall seasonal flight pattern of the love-
bugs is also presented.
Although different numbers of lovebugs were observed between locations (Table
1), there was temporal synchrony in flight between locations. Multiple correlation of
Scientific Notes
TABLE 1. MEAN NUMBER OF ADULT LOVEBUGS CAUGHT PER TRAP IN DIFFERENT MONTHS
AT THREE DIFFERENT LOCATIONS IN PALM BEACH COUNTY, FLORIDA.
Location
1 2 3
April 1998 64.4 a 206.8 a 543.2 a
May 57.4 a 39.0 bc 213.4 c
June 1.4 a 1.8 c 12.8 e
July 23.4 a 11.8 c 53.8 de
Aug. 59.8 a 75.2 b 390.8 b
Sep. 99.0 a 149.2 a 566.0 a
Oct. 0.0 a 0.0 c 0.0 e
Nov. 0.0 a 0.4 c 0.0 e
Dec. 17.2 a 10.2 c 160.0 cd
Jan. 1999 28.0 a 28.6 bc 72.4 de
Feb. 12.0 a 6.8 c 89.4 cde
Mar. 2.0 a 4.0 c 25.2 e
aMeans in a column followed by the same letter are not significantly different (alpha = 0.05) using Tukey's test
(SAS 1996).
'Location one is the Everglades Research and Education Center (EREC) located at Belle Glade, Florida. Lo-
cations two and three are 24 km southwest and 31 km east of the EREC, respectively.
the total number of adults on traps between locations each month gave Pearson cor-
relation coefficients of 0.83, 0.93, and 0.94 between locations one and two, locations
one and three, and locations two and three respectively, all of which are highly signif-
icant (P < 0.001). Local differences in adult emergence schedules have been reported
in other insects such as the oriental beetle, Exomala orientalis (Waterhouse), in a New
York golf course (Facundo et al. 1999).
At all three locations, major flight activity took place during April-May and Au-
gust-September, plummeted during October-November and then rose again in De-
cember (Table 1). The total number of lovebugs caught at all locations each month is
shown in Figure 1, which gives a visual summary of the lovebug flight throughout the
year. As noted earlier, several studies have reported that lovebug major flight periods
were in May and September. Our data are in general agreement with the reported
May and September flight activity. However, our data showed more flight activity in
April than May and also large numbers of adults flying in August. Moreover, we ob-
served a minor flight peak in December that has not previously been reported. Our
data indicating three lovebug flight peaks per year in southern Florida do not neces-
sarily contradict observations from earlier studies of two flight peaks which may be
the actual pattern for more northern populations. Additional research is needed to de-
termine exactly when lovebugs fly in different parts of their range.
This report is Florida Agricultural Experiment Station Journal Series Number R-
07052.
SUMMARY
Temporal synchrony was observed in flights of adult lovebugs between three loca-
tions. Flight peaks occurred in April, September, and December.
96 Florida Entomologist 83(1) March, 2000
5000,
4500 -
4000 /
S 3500 / '
> 3000 \ /
S2500 -\ /
W 2000 /
S1500 -/
1000 -
500 \
0 -- I II
Apr98' Jun Aug Oct Dec Feb 99'
MONTH
Fig. 1. Total number of lovebugs caught on 15 sticky traps over a seven day period
each month.
REFERENCES CITED
BUSCHMAN, L. L. 1976. Invasion of Florida by the "lovebug" Plecia nearctica (Diptera:
Bibionidae). Florida Entomol. 59: 191-194.
CALLAHAN, P. S. 1985. Dielectric waveguide modeling at 3.0 cm of the antenna sensilla
of the lovebug, Plecia nearctica Hardy. Applied optics. 24: 1094-1097.
CALLAHAN, P. S., AND H. A. DENMARK. 1973. Attraction of the "lovebug", Plecia nearc-
tica (Diptera: Bibionidae), to UV irradiated automobile exhaust fumes. Florida
Entomol. 56: 113-119.
CALLAHAN, P. S., T. C. CARLYSE, AND H. A. DENMARK. 1985. Mechanism of attraction
of the lovebug, Plecia nearctica, to southern highways: further evidence for the
IR-dielectic waveguide theory of insect olfaction. Applied Optics 24: 1088-1093.
CHERRY, R. 1998. Attraction of the lovebug, Plecia nearctica (Diptera: Bibionidae) to
anethole. Florida Entomol. 81: 559-562.
DENMARK, H. A., AND F. W. MEAD. 1992. Lovebug, Plecia nearctica Hardy (Diptera:
Bibionidae). Fla. Dept. Agric. Consumer. Serv. Entomol. Circ. No. 350.
FACUNDO, H. T., M. G. VILLANI, C. E. LINN JR., AND W. L. ROELOFS. 1999. Temporal
and spatial distribution of the oriental beetle (Coleoptera: Scarabaeidae) in a
golf course environment. Environ. Entomol. 28:14-21.
HARDY, D. E. 1940. Studies in New World Plecia (Bibionidae: Diptera). Part 1. Kansas
Entomol. Soc. 13(1): 15-27.
HETRICK, L. A. 1970. Biology of the "love-bug", Plecia nearctica (Diptera: Bibionidae).
Florida Entomol. 53: 23-26.
SAS INSTITUTE. 1996. SAS Systems for Windows. Version 6.12 SAS Institute, Cary,
NC.
THORNHILL, R. 1976. Dispersal of Plecia nearctica (Diptera: Bibionidae). Florida En-
tomol. 59: 45-53.
Scientific Notes
CURRENT STATUS OF PINK HIBISCUS MEALYBUG IN
PUERTO RICO INCLUDING A KEY TO PARASITOID SPECIES
J. P. MICHAUD1 AND G. A. EVANS2
1Citrus Research and Education Center
700 Experiment Station Road, Lake Alfred, FL 33850
2Division of Plant Industry/Entomology, P.O. Box 147100, Gainesville, FL 32614-7100
The first report in the western hemisphere of the pink hibiscus mealybug, Ma-
conellicoccus hirsutus (Green), was from Grenada in 1993 (Persad 1995). Trinidad
was infested in August of 1995 (Jones 1995) and St. Kitts in October of the same year
(Thomas & Thomas 1996). Sixteen islands in the Lesser Antilles were infested by Au-
gust of 1997 (Meyerdirk 1997). PHMB was first reported on the Island ofVieques, Pu-
erto Rico in the summer of 1997 and in the Ceiba and Fajardo districts in the
southeastern corner of the main island in October of the same year (USDA, APHIS,
PPQ personal communication). In contrast to the dramatic impact this pest has had
on agricultural production in other islands of the East Indies, damage in Puerto Rico
has apparently been limited to hibiscus species in urban settings. One possible expla-
nation is establishment of the parasitoid Anagyrus kamali Moursi (Encyrtidae), a
parasitoid that has provided excellent control of PHMB in other countries (Mani
1989). Both A kamali and Gyranusoidea indica Shafee, Alam, and Agarwal (En-
cyrtidae) were released by agents of USDA, APHIS, PPQ in Puerto Rico shortly after
discovery of PHMB on the mainland of Puerto Rico (L. Wiscovitch, personal commu-
nication). We surveyed PHMB in southeastern Puerto Rico in early February, 1999
with the following objectives: (1) to determine the extent of westward spread of
PHMB; (2) to monitor plant damage and record plant species affected and; (3) to iden-
tify parasitoids and predators attacking the pest.
We first surveyed PHMB on Feb. 2 in the region of the original infestation (Ceiba
and Fajardo). We evaluated damage and PHMB populations on hibiscus, examined
other susceptible host plants, and retained samples for subsequent parasitoid emer-
gence. On Feb. 4, in the company of USDA, APHIS, PPQ inspectors E. Rodriguez and
M. Rosado, we followed the southern coast along highways No. 1 and 3 from Ponce
eastward examining roadside hibiscus shrubbery. The most western infestation we
discovered was in the neighborhood of La Pica, district ofYabucoa at km. 100 on high-
way No. 3, about 45 km east of the original infestation in Ceiba. Damage to the hedge
indicated that PHMB had probably been present for a period of 2-3 weeks. Descending
into the valley of Yabucoa, we observed larger, established infestations on the prop-
erty of the R. J. Reynolds Tobacco Co. at the intersection of highways No. 3 and 908.
More damaged hibiscus was evident on highway 3 east to Humacoa, where we con-
cluded our search.
We categorized hibiscus shrubs according to level of damage (low, moderate or
high) and whether or not PHMB colonies were still alive on the shrub. In many cases,
attempts had been made to prune out damaged branches on heavily infested shrubs
and this may have affected our damage estimates. Table 1 summarizes our observa-
tions on damage and PHMB populations at the four sites sampled.
We observed and collected the following coccinellid species preying on PHMB in
Puerto Rico: Cycloneda sanguinea limbifer Casey (adults and larvae), Coelophora
inaequalis (F.) (adults), Diomus sp. (adults), Cryptolaemus montrouzieri Mulsant
(adults and larvae), Scymnus sp. (adults), Zilus eleutherae (Casey) (adults). We col-
lected a total of 24 samples of PHMB by clipping infested hibiscus twigs into venti-
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