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Wiseman: Armyworm Symposium -'94
DEDICATION OF 1994 ARMYWORM SYMPOSIUM TO
DR. ROBERT L. BURTON AND MR. E. A. HARRELL:
EXPERTS IN INSECT REARING
B. R. WISEMAN
Insect Biology & Population Management Research Laboratory
Tifton, GA 31793-0748
ABSTRACT
The 1994 Symposium on Armyworms (previously Fall Armyworm Symposium) at
the Southeastern Branch of the Entomological Society of America is dedicated to "Dr.
Robert L. Burton and Mr. E. A. Harrell: Experts in Insect Rearing." Dr. Burton, an en
tomologist (1964-1970), and Mr. E. A. Harrell, an agricultural engineer (1961-1980),
were employed by the U. S. Department of Agriculture, Agricultural Research Service
at the Southern Grains Insects Research Laboratory at Tifton, GA. The systems they
developed provided the means by which the fall armyworm, Spodoptera frugiperda (J.
E. Smith), could be reared in mass numbers on a meridic diet that resulted in quality
eggs, larvae, pupae, and adult insects.
Key Words: Fall armyworm, rearing, mechanization, diet.
RESUME
El Simposio de 1994 sobre los Gusanos Trozadores (previamente Simposio sobre
los Gusanos Trozadores de Otono) en la Rama Sureste de la Sociedad Entomoldgica de
America estuvo dedicado al tema "Dr. Robert L. Burton y Sr. E. A. Harrel: Expertos en
Cria de Insectos". El Dr. Burton, entomologo (1964-1970), y el Sr. E. A. Harrel, inge
niero agrdnomo (1961-1980), fueron empleados del Servicio de Investigacidn Agricola
del Departamento de Agricultura de los Estados Unidos, en el Laboratorio Sur de In
vestigacidn de Insectos de los Granos en Tifton, Georgia. Los sistemas que ellos desa
rrollaron posibilitaron la cria masiva del gusano trozador, Spodoptera frugiperda (J.
E. Smith), en una dieta meridica que tuvo como resultado la produccidn de huevos,
larvas, pupas e insects adults de calidad.
The 1994 "Symposium on Armyworms" (previously "Fall Armyworm Symposium")
presented at the Southeastern Branch Meeting of the Entomological Society of Amer
ica is hereby dedicated to "Dr. Robert L. Burton and Mr. E. A. Harrell: Experts in In
sect Rearing."
BIOGRAPHIES
Dr. Robert L. Burton (Fig. 1) of Stillwater, OK, was born on August 23, 1936 in Ant
lers, OK, to Charles and Sally (Holton) Burton. He married Sylvia J. Gentry Septem
ber 1, 1960 in Durant, OK. They have two sons, Robert L. Burton Jr. of Dana Point,
CA, and Brian Gentry Burton of Stillwater. Dr. Burton died February 3, 1993 in the
St. Francis Medical Center in Tulsa at the age of 56.
Dr. Burton became interested in Entomology early in his education. He attended
Eastern Oklahoma College, Southeastern State College, the University of Oklahoma,
This article is from Florida Entomologist Online, Vol. 77, No. 4 (1994).
FEO is available from the Florida Center for Library Automation gopher (sally.fcla.ufl.edu)
and is identical to Florida Entomologist (An International Journal for the Americas).
FEO is prepared by E. O. Painter Printing Co., P.O. Box 877, DeLeon Springs, FL. 32130.
Florida Entomologist 77(4)
Fig. 1. Dr. Robert L. Burton, USDA, ARS Supervisory Entomologist (1936-1993).
and Oklahoma State University. Dr. Burton received his B. S. and M. S. degrees in en
tomology from Oklahoma State University in 1963 and 1964, respectively. He was
first employed as an entomologist in 1961 with Standford-Vaddar Entomology Service
of Plainview, TX, and then as a Research Assistant with Oklahoma State in 1963. Dr.
Burton joined the U. S. Department of Agriculture, Agricultural Research Service in
1964 with his first assignment at the Southern Grain Insects Research Laboratory in
Tifton, GA. He quickly assumed a leadership role as the entomologist in charge of in
sect rearing. In 1970, Dr. Burton was transferred to Stillwater where he continued
both his work and studies. He completed his Ph. D. degree in 1974. Dr. Burton contain
ued his work at Stillwater until his death, at which time he had attained the position
of Supervisory Entomologist, Research Leader and Director of the USDA-ARS Plant
Science and Water Conservation Laboratory as well as adjunct Professor of Entomol
ogy at Oklahoma State University.
Dr. Burton authored and co-authored 126 scientific publications during his 28
years of dedicated service to agriculture. He also presented more than 114 scientific
presentations during his tenure with ARS. Dr. Burton was recognized as a world au
thority in the areas of insect diets and the laboratory production of insects.
Mr. Edsel A. Harrell (Fig. 2) began his life on a little farm in South Georgia about
four miles north of Whigham. He was born on October 17, 1924, the son of C. Braxton
and Mabel (Moore) Harrell. Edsel believed that there was a better life somewhere
December, 1994
Wiseman: Armyworm Symposium -'94
Fig. 2. Mr. Edsel A. Harrell, USDA, ARS Agricultural Engineer (1924).
other than shaking peanuts and picking cotton by hand. Upon graduation from high
school in Whigham, he left the farm for Alexandria, VA, where he began an appren
ticeship as a machinist in a torpedo plant. During World War II, Edsel served his
country honorably in the Army Signal Corps on isolated islands in the Pacific. His spe
cific assignment was cryptography. He was discharged in January of 1946.
Edsel then enrolled in Abraham Baldwin Agricultural College in Tifton, GA, to
pursue a degree in Agricultural Engineering. He obtained his BSAE in 1950 and his
MSAE in 1951 from the University of Georgia. (An interesting note: Edsel taught
eighth and ninth grade math and coached the boys and girls basketball teams at
Whigham high school while he was obtaining his BS degree). During this time he met
and married Martha E. Elkins. They have three children: Edsel Jr. of Dallas, TX, Deb
bie of Nashville, TN, and Karen of Watkinsville, GA, and five grandchildren.
Mr. Harrell began his research career as an Agricultural Engineer with the U. S.
Department of Agriculture at the U. S. Cotton Ginning Laboratory at Stoneville, MS,
in 1951. He transferred in 1961 to the Southern Grain Insects Research Laboratory
(SGIRL) in Tifton, GA, where he was in charge of the Pest Control Research Project
until his retirement in 1980. It was during this period of time that Edsel and Dr. Bur
ton teamed up to solve some of the most difficult problems encountered in the mass
rearing of Helicoverpa zea (Boddie) and Spodoptera frugiperda (J. E. Smith).
Mr. Harrell authored or co-authored more than 60 scientific publications during
his 30 years of productive service and he presented more than 40 scientific present
Florida Entomologist 77(4)
tions during his tenure with ARS. Mr. Harrell is the senior scientist on six separate
patents. Mr. Harrell is recognized as an expert in the mechanization of insect rearing
and insect control.
RESEARCH ACHIEVEMENTS
The fall armyworm has been reared in the laboratory with a variety of techniques.
The first cultures were maintained on foliage of corn, millet, bean and bean pods. Be
cause of the demands for larger numbers of insects it was inevitable that meridic diets
and mass-production rearing equipment be developed. Dr. Burton (Burton 1967) de
veloped an artificial diet for fall armyworm and was probably among the first to rear
it continuously on a meridic diet. Dr. Burton also developed a detailed description of
the rearing procedures that included diet preparations, egg incubation, diet dispens
ing and manipulation of the larvae as well as some of the first estimates of mass rear
ing costs. About this same time Burton and Harrell began to develop original devices
(Burton et al. 1966) for speeding up the procedures of mass rearing. The first two de
vices developed were the diet-dispensing and larvae-isolating systems. Then came the
development of an automated packaging system (Burton & Cox 1966). The machine
dispensed 1-oz plastic cups, each filled with a selected amount of artificial diet, dis
pensed larvae onto the diet and then, in one continuous process, capped the cup. Bur
ton & Harrell (1966) then modified the larval dispensing machine to provide more
stability, thus providing a much smoother operation. In 1968, Mr. Harrell and co
workers (Harrell et al. 1968) developed equipment and a mechanized system of col
electing pupae of the fall armyworm from rearing containers. This entire system of
rearing the fall armyworm, and various modifications thereof (Burton & Perkins
1989), has been used at the Southern Grain Insects Research Laboratory, which is
now the Insect Biology and Population Management Research (IBPMRL) since about
1966.
Mr. Harrell was instrumental in the erection of a 40 x 100 ft building which now
houses the rearing section of at IBPMRL. The building was originally built for the
purpose of housing a mass rearing system for the boll weevil (Harrell & Griffin 1981).
A side note to this is that Mr. Harrell developed equipment for use on a form-fill-seal
machine that was used in the mass production of insects. Harrell et al. (1973) devel
oped an insect diet filler to be used on the form-fill-seal machine which could fill 32
cavities with diet in less than 2 sec. Mr. Harrell and co-workers (1974a) also built
equipment that could mix and sterilize economically large amounts (up to 68 gallons
per hour) of insect diet. Then, Mr. Harrell developed equipment for use on the form
fill-seal machine (Harrell et al. 1974b) to infest cavities (cells) with insect eggs at rates
up to 544 cavities per minute. Mr. Harrell later built two environmental rooms within
the building to study environmental effects on growth of insects (Harrell et al. 1979).
The rooms had separate air-distribution systems designed to maintain a uniform and
constant temperature within +1.1 C.
HONORARIUM
The scientists that have spent time in research at the IBPMRL, and others that
have used the fall armyworm reared there, are deeply indebted to Dr. Robert L. Bur
ton and Mr. E. A. Harrell for their tireless efforts in the development of a complete
rearing system that has provided adequate numbers of quality fall armyworm eggs,
larvae, pupae and adults.
December, 1994
Wiseman: Armyworm Symposium -'94
Therefore, it is with high regard and great pleasure that we dedicate this Army
worm Symposium to Dr. Robert L. Burton and Mr. E. A. Harrell in honor of their con
tributions to insect rearing.
LITERATURE CITED
BURTON, R. L. 1967. Mass rearing the fall armyworm in the laboratory. U. S. Depart
ment of Agriculture. Agricultural Research Service. ARS 33-117. 12 pp.
BURTON, R. L., AND H. C. Cox. 1966. An automated packaging machine for lepidopter
ous larvae. J. Econ. Entomol. 59: 907-909.
BURTON, R. L., AND E. A. HARRELL. 1966. Modification of a lepidopterous larva dis
penser for a packaging machine. J. Econ. Entomol. 59: 1544-1545.
BURTON, R. L., E. A. HARRELL, H. C. COX, AND W. W. HARE. 1966. Devices to facilitate
rearing of lepidopterous larvae. J. Econ. Entomol. 59: 594-596.
BURTON, R. L., AND W. D. PERKINS. 1972. WSB, a new laboratory diet for the corn ear
worm and the fall armyworm. J. Econ. Entomol. 65: 385-386.
BURTON, R. L., AND W. D. PERKINS. 1989. Rearing the corn earworm and the fall ar
myworm for maize resistance studies, pp. 37-45 in Toward insect resistant
maize for the third world: Proc. International Symposium on Methodologies for
Developing Host Plant Resistance to Maize Insects. CIMMYT.
HARRELL, E. A., AND J. G. GRIFFIN. 1981. Facility for mass rearing of boll weevils: En
gineering aspects. U. S. Department of Agriculture. Science and Education Ad
ministration. Advances in Agricultural Technology. AAT S-19. 77 pp.
HARRELL, E. A., W. W. HARE, AND R. L. BURTON. 1968. Collecting pupae of the fall ar
myworm from rearing containers. J. Econ. Entomol. 61: 873-876.
HARRELL, E. A., W. D. PERKINS, AND B. G. MULLINIX, JR. 1979. Environmental rooms
for insect rearing. Trans, ASAE. 1979: 922-925.
HARRELL, E. A., A. N. SPARKS, W. W. HARE, AND W. D. PERKINS. 1974a. Processing di
ets for mass rearing of insects. U. S. Department of Agriculture. Agricultural
Research Service. ARS-S-44. 4 pp.
HARRELL, E. A., A. N. SPARKS, W. D. PERKINS, AND W. W. HARE. 1973. An insect diet
filler for an in line form-fill-seal machine. J. Econ. Entomol. 66:1340 1341.
HARRELL, E. A., A. N. SPARKS, W. D. PERKINS, AND W. W. HARE. 1974b. Equipment to
place insect eggs in cells on a form-fill-seal machine. U. S. Department of Agri
culture. Agricultural Research Service. ARS-S-42. 4 pp.
Florida Entomologist 77(4)
REPRODUCTIVE POTENTIAL OF ONCE-MATED MOTHS OF
THE FALL ARMYWORM (LEPIDOPTERA: NOCTUIDAE)
C. E. ROGERS AND O. G. MARTI, JR.
Insect Biology and Population Management Research Laboratory
Agricultural Research Service, U. S. Department of Agriculture
Tifton, GA 31793-0748
ABSTRACT
A laboratory study of the effects of age at a single mating on the reproductive po
tential of the fall armyworm, Spodoptera frugiperda (J. E. Smith), revealed that of
389 pairs of moths tested, 106, 281, and 2 pairs transferred 0, 1, or 2 spermatophores,
respectively. Pairs that did not transfer a spermatophore mated when males and fe
males averaged 7.0 and 8.8 days of age, respectively. Pairs transferring a single sper
matophore mated when males and females averaged 5.9 and 6.3 days of age,
respectively. The pairs transferring two spermatophores during one-night's pairing
averaged 8 and 9 days of age at mating for males and females, respectively. The age
of females at a single mating significantly affected their fecundity (r = 0.92; P<0.01),
fertility (r -0.61; P<0.01), and longevity (r = 0.83; P<0.01). Male age at a single mat
ing significantly influenced only the fertility of eggs laid by their respective female
partner (r -0.92; P<0.01). Two days post-emergence was the optimum age for mating
by both male and female moths for maximum fecundity and fertility. Delaying mating
by females significantly lengthened their survival.
Key Words: Spodoptera frugiperda, fecundity, fertility, longevity
RESUME
Un studio de laboratorio acerca de los efectos de la edad en el moment del primer
apareo sobre el potential reproductive del gusano trozador, Spodoptera frugiperda (J.
E. Smith), revel6 que de 389 parejas de polillas, 106, 281, y 2 parejas transfirieron 0,
1, y 2 espermat6foros, respectivamente. Las parejas que no transfirieron ningun es
permat6foro se aparearon cuando los machos y hembras tenian una edad promedio de
7.0 y 8.8 dias, respectivamente. Las parejas que transfirieron un solo espermat6foro
se aparearon cuando los machos y las hembras tenian un promedio de 5.9 y 6.3 dias
edad, respectivamente. Las parejas que transfirieron dos espermat6foros durante un
apareamiento de una noche tuvieron un promedio de 8 y 9 dias de edad en los machos
y hembras, respectivamente. La edad de las hembras en el moment del aparea
miento afect6 significativamente su fecundidad (r = 0.61; P <0.01), fertilidad (r =
0.83; P <0.01), y longevidad (r = 0.83; P< 0.01). La edad del macho en el moment del
apareamiento influy6 solamente en la fertilidad de los huevos puestos por su respect
tiva pareja (r = 0.60; P = 0.01). La edad 6ptima para el apareo fue de dos dias despues
de la emergencia, tanto para el macho como para la hembra, y a esta edad se obtuvie
ron fecundidad y fertilidad maximas. El retardo en el apareo de las hembras alarg6
significativamnete su sobrevivencia.
The reproductive potential, behavior, fecundity, and fertility of the fall armyworm,
Spodoptera frugiperda (J. E. Smith), have been studied under a variety of natural and
controlled environmental conditions (Luginbill 1928, Barfield & Ashley 1987, Sim
This article is from Florida Entomologist Online, Vol. 77, No. 4 (1994).
FEO is available from the Florida Center for Library Automation gopher (sally.fcla.ufl.edu)
and is identical to Florida Entomologist (An International Journal for the Americas).
FEO is prepared by E. O. Painter Printing Co., P.O. Box 877, DeLeon Springs, FL. 32130.
December, 1994
Rogers and Marti: Armyworm Symposium -'94
mons & Lynch 1990, Simmons & Marti 1992, Simmons & Rogers 1994). Due to its pe
rennial pest status in the southeastern United States, numerous strategies for
managing the fall armyworm have been proposed, including the combination of two or
more into regional management schemes (Knipling 1980). To accurately evaluate the
efficacy of these strategies, it often is necessary to standardize one or more biological
parameters of the fall armyworm in a controlled environment. We recently reported
that the age of female moths at their first mating significantly affected their fecundity,
fertility, and longevity (Rogers & Marti 1994). Here we report the effects of moth age
at a single mating on the reproductive potential of the fall armyworm.
MATERIALS AND METHODS
Experimental insects were from an established laboratory colony of the fall army
worm that had been collected from corn and maintained on a pinto bean-based diet
(Burton 1967, Perkins 1979). As moths emerged, they were placed individually in a
0.6-liter cardboard container, provided a 10% honey solution for nourishment, and
maintained at 27'C and 70-75% RH in a 14:10 (L:D) cycle. To determine the effect of
age at a single mating on fecundity and fertility of the fall armyworm, pairs of differ
ent male/female age combinations were established. The age of males and females at
pairing ranged from 1-11 days and 1-14 days post-emergence, respectively. Tests en
compassed 18 independent trials, each of which contained from 15 to 24 mating pairs.
Mating pairs were maintained overnight in the conditions mentioned above in 0.6-li
ter cardboard cages with their tops and bottoms covered with mesh netting. Cages
were lined with waxed paper to facilitate removal and counting of eggs. Males were
discarded the morning after pairing. Females were maintained in their respective
cages until they died. Cages were examined daily to record data on moth mortality/
longevity and the number of eggs laid. Dead females were dissected to determine the
number of spermatophores they received from males while copulating. The number of
unhatched eggs and viable larvae was used to compute daily fecundity and fertility for
each mating pair.
All data were subjected to an analysis of variance by the General Linear Model
Procedure, and significantly different means were separated by the least significant
difference (LSD) test (SAS Institute 1989).
RESULTS AND DISCUSSION
Significant differences (F = 4.97; df= 17, 386; P<0.01) occurred across trials for all
parameters studied, indicating that the age of males and females at mating inter
acted to affect the reproductive potential of the fall armyworm (Fig. 1). Pairs com
posed of both young males and young females produced eggs having the highest
fertility. When either sex was aged, fertility of the eggs was reduced. However, the age
of females at mating had a greater influence on egg fertility than the age of males.
Of the 389 pairs, 106 females received no spermatophores, 281 females received
one spermatophore and two females received two spermatophores during a single
night of pairing. Spermatophore transfer during moth mating may have been affected
by female age (r = 0.71; P<0.01) but not by male age (r = 0.30; P<0.01) nor by the com
bination of male-female ages (Pearson correlation coefficient). Pairings resulting in
the transfer of a single spermatophore involved males and females averaging 5.9 and
6.3 days of age, respectively. For pairs where no spermatophore was transferred, male
and female age at mating averaged 7.0 and 8.8 days, respectively. Survival of females
averaged 16.3 to 16.9 days, regardless of whether 0, 1, or 2 spermatophores were re
Florida Entomologist 77(4)
-0 o0
IR 60
40
S50
01
2 0 ,T
*
Figure 1. Interaction of male and female age at mating on egg fertility in once
mated fall armyworm moths. Data points represent means within trials.
ceived. The fertility (P<0.05) of eggs from a single mating averaged 0, 20.4, and 45.5%
for females receiving 0, 1, or 2 spermatophores, respectively. Total fecundity averaged
226.5, 1,134.7, and 1,026.5 eggs for females receiving 0, 1, or 2 spermatophores, re
spectively. Since this study concerns the reproductive potential for females restricted
to a single opportunity for mating, analyses are reported for females which received
only a single spermatophore.
The age of females at a single mating significantly affected the number of eggs
they laid (F = 8.21; d.f. = 10, 280; P<0.01), fertility of the eggs (F = 9.14; d.f. = 10, 280;
P<0.01), and longevity of mated females (F = 10.24; d.f. = 10, 281; P<0.01) (Table 1).
Females which mated at the age of 1-5 days laid more eggs than females which mated
at an older age. Also, females which mated at 11-14 days of age laid the fewest eggs
(about 50% as many as females that mated from 1 to 5 days post-emergence) (Fig. 2).
The mean fertility of eggs laid by females mated at 2 days of age was significantly
greater than it was for eggs laid by younger or older females (Table 1). The lowest fer
utility occurred in eggs laid by females whose mating was delayed until 7 days and 10
13 days post-emergence. Seven-day-old females mated with 9 and 11 day-old males.
December, 1994
Rogers and Marti: Armyworm Symposium -'94
TABLE 1. EFFECTS OF FEMALE AGE AT MATING ON FECUNDITY, FERTILITY, AND LONGEV
ITY OF FALL ARMYWORM (ONCE-MATED MOTHS).
Female
Age Total No. Eggs Laid % Eggs Hatching No. Days 9 Lived
(Days) N' ( S.E.)b,' (X S.E.)b,d' ( S.E.)b,e
1 49 1,387 79a 28 + 4b 15 lc
2 23 1,569 115a 67 + 6a 12+ ld
3 12 1,402 159a 29 + 8b 14+ lcd
4 37 1,269 91ab 14 5bc 15 lc
5 20 1,294 123a 23 + 7b 15 lc
7 39 1,150 88b 9+ 5c 17+ lb
8 21 1,002 120bc 25 + 6b 15+ lc
10 24 847 + 113cd 6 6c 21 + la
11 14 603 + 147d 5 + 8c 17+ lbc
13 32 639 + 98d 5 + 5c 20+ la
14 10 768 + 174d 15 + 9bc 19 + lab
Number of females per respective age across trials.
bMeans within a column followed by different letters are significantly different (P.
test.
Least significant difference = 341; r = 0.92 (P<0.01)
SLeast significant difference = 18; r 0.61 (P<0.01)
Least significant difference = 3; r = 0.83 (P<0.01)
0.05) by the SAS LSD
Ten-day-old females mated with 1 and 10-day-old males. Eleven-day-old females
mated with 8-day-old males, while 13-day-old females mated with 4 and 10-day-old
males. Surprisingly, females that mated one day post-emergence laid eggs that were
()
0 1,600- Y=1,555-67.02*X
E r=-0.92 p<0.01
Q)
S1,400-
0)1,200-
O 1,000-
0 800-
S600-4
I
I I I i 1 I I
0 1 2 3 4 5 6
Age of Female
8 9 10 11 12 13 14
Mating (Days)
Figure 2. Correlation between egg production and age at mating by once-mated fe
males of the fall armyworm. Data points represent means within trials.
Florida Entomologist 77(4)
December, 1994
less fertile than eggs laid by females mated 2 days post-emergence. However, 1-day
old females mated with 1-, 5-, and 11-day-old males, while 2-day-old females mated
only with 2-day-old males.
Fertility of eggs from a single mating remained relatively high (>80-97%) for about
7 days for pairs composed of 2-day-old males and females (Fig. 3). Fertility of eggs
from pairs mated at 1 day of age declined to about 35% by day 3 post-mating. Fertility
from 3-day-old pairs was below 50% and declined to about 20% by day 7 post-mating.
Mating between 1-day-old females and 10-day-old males resulted in eggs with 96.99%
fertility that remained >90% fertile from 2 through 8 days. The preceding data indi
cate that female age at mating is more important in determining fertility than male
age. This is further indicated by a significant negative correlation between mean per
cent fertility and age of females at mating (Fig. 4), while the effects of male age on per
cent fertility is relatively benign (r = 0.32; P>0.10). The sum of male and female age
at mating also significantly affected fertility of eggs on the second day post-mating
(Fig. 5). As the sum of ages of mating males and females advanced beyond 4 days, the
fertility of eggs declined as the combined ages of the pairs increased.
Both the fecundity and fertility of fall armyworm females receiving a single sper
matophore were less in this study than has been reported elsewhere (Vickery 1929,
Simmons & Lynch 1990, Rogers & Marti 1994); however, our females were restricted
to a single mating at a specific age. In considering only females which laid fertile eggs,
both fecundity (x = 1,702.22 + 111.7 no. eggs per 9) and fertility (x = 73.6 6.8% eggs
hatching) were higher for females mated at 2 days of age than they were for all fe
males mated at the same age. Simmons & Marti (1992) reported that fall armyworm
females mate an average of 3.7 times, and that two matings in a single night are com
mon. Simmons & Rogers (1994) reported that females of the fall armyworm mate in
as few as 11.5 hours after emergence, but that such matings result in eggs with a low
fertility.
100-
80-
1 60-
C
LJ 40-
S20-
0-- _- ----
0 2 4 6 8 10 12 14 16 18
Day after Mating
Figure 3. Sustained fertility of eggs from pairs composed of once-mated, two-day
old fall armyworm males and females. Data points represent means within trials.
Rogers and Marti: Armyworm Symposium '94
80-
. OF r=-0.85 p
- o
40-
S00~
20- -
W 00
0
0 2 4 6 8 10 12 14
Age at Mating (Days)
Figure 4. Effects of age of moths at mating on egg fertility two days post- mating in
once- mated fall armyworm moths. Data points represent means within trials.
Fertility of eggs laid by females which had mated with 2-day-old males was signif
icantly (F 8.75; d.f. 10, 280; P<0.01) greater than the fertility of eggs laid by fe-
males which had mated with either younger or older males (Table 2). Fertility of eggs
laid by females which had mated with males 8 days of age or older was extremely low
100- 0 Y=97.04-4.08X
-; 0 0 r=-0.70 p<0.01
- 80-
LL
-. 60-
( 40-
C 0
S20-
0- e e e
4 6 8
of Male and
10 12
Female
14
Ages
16 18 20 22 24
at Mating (Days)
Figure 5. Effects of summed age of mating pairs on fertility in once mated fall ar
mvworm moths. Data points represent means within trials.
Sum
0 2
Sum
Florida Entomologist 77(4)
TABLE 2. EFFECTS OF MALE AGE AT MATING ON FECUNDITY AND FERTILITY IN THE FALL
ARMYWORM (ONCE-MATED MOTHS).
Male Age Total No. Eggs Laid % Eggs Hatching
(Days) N'- (x S.E.)b,c/ (x +S.E.)b,d
1 40 1,251 94ab 24 5b
2 23 1,569 124a 67 6a
3 12 1,402 172a 29 8b
4 36 982 99bc 17 5bc
5 17 1,183 145b 25 7b
6 21 1,002 130b 25 + 6b
7 28 1,131 113b 22 + 6b
8 14 603+ 159c 5 + 8c
9 15 1,099 154b 0 + 8c
10 66 1,066 73b 9 + 4c
11 9 1,117+ 199b 0+ 10c
Number of males per respective age across trials.
Means within a column followed by different letters are significantly different (P<0.05) by the SAS LSD test.
'Least significant difference = 383; r -0.30 (P>0.10)
"Least significant difference = 19; r -0.92 (P<0.01)
(<9%). The age of females mating with 8 to 11-day-old males ranged from 1-13 days
post-emergence. Although the effects of male age at mating on fall armyworm repro
ductive potential beyond the second day post-emergence were difficult to assess, the
interaction of male and female ages appeared to contribute to egg fertility (Fig. 5). For
example, combined age of 4 days for males and females at mating resulted in signifi
cantly higher fecundity (F = 5.6; d.f. 10, 280; P<0.01) in mated females and signif
icantly higher (>2x) egg fertility (F 7.44; d.f. 10, 280; P<0.01). Age combinations
greater than 16-17 days resulted in pairs producing fewer eggs with a lower fertility
than pairs of younger males and females.
The longevity of fall armyworm females was significantly affected by the age at
which they mated (Table 1). Females that were denied mating until 10, 13, and 14
days of age lived significantly longer ( = 20.6 + 1.8 days) than females which mated
during the first 8 days post-emergence ( = 14.7 1.1 days). The association of female
longevity with age at mating is expressed as a highly significant correlation. This re
lationship gives credence to an oogenesis-flight syndrome in the fall armyworm that
commonly is found in other migratory species of insects (Rankin & Burchsted 1992),
in which early flight and reproduction are physiologically antagonistic. Such a phys
iologically antagonistic relationship has enabled the evolution of migration in the life
history of some species, e.g., S. exempta (Walker) (Gatehouse 1986).
Although the effects of male age at mating on the reproductive potential of the fall
armyworm were less dramatic than the effects of female age, the age of males at mat
ing nevertheless affected both fecundity of mated females, and the fertility of their
eggs (Table 2). Females of varying age that were mated with 2 to 3-day-old males laid
significantly (F = 3.17: d.f. =10, 280; P<0.01) more eggs than females mating with
older males. Male age at mating beyond three days post-emergence was less impor
tant as a contributor toward mated female fecundity. How young males may have con
tribute to the fecundity of their mates is unclear. However, Rankin & Burchsted
December, 1994
Rogers and Marti: Armyworm Symposium '94
(1992) reported that males of a migratory grasshopper, Melanoplus sanguinipes (Fab
ricius), appear to transfer key proteins to females while mating that promote oogen
esis and oviposition. Snow & Carlysle (1967) reported that unmated males of the fall
armyworm incorporate a brownish-black pigment in the ductus ejaculatorius simplex
that is transferred to females with a spermatophore on their first mating. Perhaps the
brownish-black pigmented material transferred with a male's spermatophore contrib
utes to the reproductive potential of mated females. If this pigmented material trans
ferred from young males contributes to female fecundity, our data indicates that its
importance diminishes in males which mate after day three post-emergence.
Many factors (e.g., plant resistance, irradiation, chemosterilants, biological
agents, number of matings, colony age, host strain, diet, pheromones, toxic chemicals,
cultural strategies, etc.) are known to adversely affect the reproductive potential of
the fall armyworm (Young et al. 1968, Lynch et al. 1980, Hamm & Hare 1982, Car
penter et al. 1986, Gross & Pair 1986, Silvain 1986, Simmons & Lynch 1990, Sen
Seong et al. 1985, Chandler & Sumner 1991, Quisenberry 1991, Pashley et al. 1992,
and Rogers & Marti 1994). Knowledge of the individual and collective effects of these
factors on the reproductive potential of the fall armyworm is critical for the imple
mentation of an effective regional management strategy (Knipling 1980). Of equal im
portance is a knowledge of the effects of age at mating on the reproductive potential
of the fall armyworm if efficacious propagation, treatment, and augmentation of in
sects are to be realized to support regional suppression of fall armyworm populations.
The age of fall armyworm moths at mating when only a single opportunity for mat
ing exists is critical for the sustainability of reproducing populations. Female age at
a single mating is more important than male age for maintenance of a high reproduc
tive potential. However, two days post-emergence for both males and females is the
optimum age for mating for enhanced reproductive potential in the fall armyworm.
REFERENCES CITED
BARFIELD, C. S., AND T. R. ASHLEY. 1987. Effects of corn phenology and temperature
on the life cycle of the fall armyworm Spodoptera frugiperda (Lepidoptera: Noc
tuidae). Florida Entomol. 70: 110-116.
BURTON, R. L. 1967. Mass rearing the fall armyworm in the laboratory. USDA, ARS
33-177, Gov Print. Office, Wash., DC.
CARPENTER, J. E., J. R. YOUNG, AND A. N. SPARKS. 1986. Fall armyworm (Lepidoptera:
Noctuidae): Comparison of inherited deleterious effects in progeny from irradi
ated males and females. J. Econ. Entomol. 79: 46-49.
CHANDLER, L. D., AND H. R. SUMNER. 1991. Effect of various chemigation methodolo
gies on suppression of the fall armyworm (Lepidoptera: Noctuidae) in corn.
Florida Entomol. 74: 270-279.
GATEHOUSE, A. G. 1986. Migration in the African armyworm, Spodoptera exempta, pp.
128-144 in Danthanarayana, W. [ed.]. Insect flight: dispersal and migration.
Berlin/Heidelberg: Springer-Verlag, 289 pp.
GROSS, H. R., AND S. D. PAIR. 1986. The fall armyworm: status and expectations of bi
logical control with parasitoids and predators. Florida Entomol. 69: 502-515.
HAMM, J. J., AND W. W. HARE. 1982. Application of entomopathogens in irrigation wa
ter for control of fall armyworms and corn earworms (Lepidoptera: Noctuidae)
on corn. J. Econ. Entomol. 75: 1074-1079.
KNIPLING, E. F. 1980. Regional management of the fall armyworm -a realistic ap
proach. Florida Entomol. 63: 468-480.
LUGINBILL, P. 1928. The fall armyworm. U. S. Dept. Agric. Tech. Bull. 34. Gov Print.
Office, Wash., DC.
Florida Entomologist 77(4)
LYNCH, R. E., P. B. MARTIN, AND J. W. GARDNER. 1980. Cultural manipulation of
coastal bermudagrass to avoid losses from the fall armyworm. Florida Ento
mol. 63: 411-419.
PASHLEY, D. P., A. M. HAMMOND, AND T. N. HARDY. 1992. Reproductive isolating mech
anisms in fall armyworm host strains (Lepidoptera: Noctuidae). Ann. Entomol.
Soc. America 85: 400-405.
PERKINS, W. D. 1979. Laboratory rearing of the fall armyworm. Florida Entomol. 62:
87-91.
QUISENBERRY, S. S. 1991. Fall armyworm (Lepidoptera: Noctuidae) host strain repro
ductive compatibility. The Florida Entomol. 74: 194-199.
RANKIN, M. A, AND J. C. A. BURCHSTED. 1992. The cost of migration. Annu. Rev. En
tomol. 37: 533-559.
ROGERS, C. E., AND O. G. MARTI, JR. 1994. Effects of age at first mating on the repro
ductive potential of the fall armyworm (Lepidoptera: Noctuidae). Environ. En
tomol. 23: 322-325.
SAS INSTITUTE. 1989. SAS/STAT User's guide, version 6, 4th ed., vol. 1 and vol. 2. SAS
Institute, Cary, NC.
SEN-SEONG, N. G., F. M. DAVIS, AND W. P. WILLIAMS. 1985. Survival, growth, and re
production of the fall armyworm (Lepidoptera: Noctuidae) as affected by resis
tant genotypes. J. Econ. Entomol. 78: 967-971.
SILVAIN, J. F. 1986. Use of pheromone traps as a warning system against attacks of
Spodoptera frugiperda larvae in French Guiana. Florida Entomol. 69: 139-147.
SIMMONS, A. M., AND R. E. LYNCH. 1990. Egg production and adult longevity of
Spodoptera frugiperda, Helicoverpa zea (Lepidoptera: Noctuidae), and Elasmo
palpus lignosellus (Lepidoptera: Pyralidae) on selected adult diets. Florida En
tomol. 73: 665-671.
SIMMONS, A. M., AND O. G. MARTI, JR. 1992. Mating by the fall armyworm (Lepi
doptera: Noctuidae): frequency, duration, and effect of temperature. Environ.
Entomol. 21: 371-375.
SIMMONS, A. M., AND C. E. ROGERS. 1994. Fall armyworm (Lepidoptera: Noctuidae)
mating: effects of age and scotophase on pre-mating time, mating incidence,
and fertility. J. Entomol. Science 29: 201-208.
SNOW, J. W., AND T C. CARLYSLE. 1967. A characteristic indicating the mating status
of male fall armyworm moths. Ann. Entomol. Soc. America 60: 1071-1074.
VICKERY, R. A. 1929. Studies on the fall armyworm in the Gulf Coast of Texas. U. S.
Dept. Agric. Tech. Bull. 138. Gov. Print. Office, Wash., DC.
YOUNG, J. R., J. W. SNOW, AND A. N. SPARKS. 1968. Mating of untreated and tepa
chemosterilized fall armyworm moths. J. Econ. Entomol. 61: 657-661.
December, 1994
Chandler: Armyworm Symposium -'94
EVALUATION OF INSECT GROWTH REGULATOR-FEEDING
STIMULANT COMBINATIONS FOR MANAGEMENT OF FALL
ARMYWORM (LEPIDOPTERA: NOCTUIDAE)
L. D. CHANDLER'
Insect Biology and Population Management Research Laboratory
Agricultural Research Service, U. S. Department of Agriculture
Tifton, GA 31793-0748
'Current address: USDA-ARS, R.R. 3, Brookings, SD 57006.
ABSTRACT
Application of RH-5992 2F, a neural agonist insect growth regulator, to foliage of
corn (Zea mays [L.]) and southern pea (Vigna unguiculata [L.]), resulted in significant
levels of fall armyworm (Spodoptera frugiperda [J. E. Smith]) larval control. The ad
edition of a cottonseed flour-based feeding stimulant, Konsume, at 10% of total spray
volume to the insect growth regulator reduced the length of time needed for larval
mortality to occur compared to the insect growth regulator alone. Additionally, feed
ing damage and percentage of corn plants infested by fall armyworm was significantly
reduced using RH-5992 2F + Konsume. Residual activity of RH-5992 remained high
(> 84% larval mortality at the highest evaluated rate of RH-5992) on southern pea
throughout the two-week test period.
Key Words: Spodoptera frugiperda, insect management, insecticide additives
RESUME
La aplicaci6n de RH-5992 2F, un agonista neural regulador del crecimiento de los
insects, al follaje del maiz (Zea mays [L.]) y del guisante sureno (Vigna unguiculata
[L.]), produjo niveles significativos de control larval del gusano trozador (Spodoptera
frugiperda [J.E.Smith]). La adici6n al regulador de crecimiento de un estimulante de
la alimentaci6n a base de harina de algod6n, Kosume, al 10% del volume total de as
persi6n, redujo el tiempo requerido para matar las larvas en comparaci6n con el regu
lador de crecimiento solo. Adicionalmente, el dano por alimentaci6n de las larvas y el
porcentaje de plants de maiz infestadas por el gusano trozador fueron significativa
mente reducidos usando RH-5992 2F + Kosume. La actividad residual del RH-5992
permaneci6 alta (>84% de mortalidad larval en la concentraci6n mas alta de RH
5992) en el guisante sureno durante las dos semanas de prueba.
Use of phagostimulants to enhance activity of insect growth regulators against fall
armyworm (FAW), Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), in
the laboratory has been reported (Chandler 1993). The mortality rate of FAW larvae
increased significantly when they fed on leaves of southern pea, Vigna unguiculata
(L.), that had been treated with either of two insect growth regulators (RH-5992 or di
flubenzuron), in combination with KonsumeR, a cottonseed flour-based insect feeding
stimulant. Larval mortality was increased 2 and 3 days after treatment when Kon
sume (10% of total solution) and RH-5992 were applied in combination (Chandler
1993). This increase in mortality was more notable than that observed with difluben
zuron/Konsume combinations. The increased mortality during the first three days fol
lowing treatment with RH-5992 is important because it can reduce FAW related
This article is from Florida Entomologist Online, Vol. 77, No. 4 (1994).
FEO is available from the Florida Center for Library Automation gopher (sally.fcla.ufl.edu)
and is identical to Florida Entomologist (An International Journal for the Americas).
FEO is prepared by E. O. Painter Printing Co., P.O. Box 877, DeLeon Springs, FL. 32130.
Florida Entomologist 77(4)
damage sooner following treatment, which may aid acceptance of this particular type
of insect growth regulator by growers. RH-5992 interferes with the normal molting
process of lepidopterous larvae by acting as an agonist of insect molting hormone
(Rohm and Haas Co. 1989). It has been shown to have high (> 90%) levels of activity
against FAW larvae at concentrations of 0.001 to 1.0% active ingredient [AI] (Chan
dler et al. 1992).
The studies reported here were designed to evaluate the use of RH-5992/Konsume
combinations under simulated and actual field conditions for management of FAW.
Studies were conducted to evaluate the residual effectiveness and control potential of
RH-5992, with and without the addition of the feeding stimulant, and to compare the
effectiveness of RH-5992 with thiodicarb, a standard chemical insecticide used for
control of FAW larvae.
MATERIALS AND METHODS
Spray Table Study
RH-5992 2F (Rohm and Haas Co., Philadelphia, Pa.) was formulated in water at
the rates of 11.0 and 22.0 gm AI/ha. Both of these formulations were sprayed on south
ern peas, with and without the addition of Konsume (Fermone Inc., Phoenix, AZ) (10%
of total volume) to the mixture. In addition, peas were treated with a Konsume (10%
of total volume)-water mixture and with water alone. The peas were planted in 25 x
61 x 5 cm rectangular plastic trays filled with potting media, and these were held in
a greenhouse (24-30 C and 50-100% relative humidity [RH]). In the greenhouse the
plants were allowed to reach the 2 leaf stage (approximately 2 weeks old) prior to
treatment. On 17 May, 1993, 24 trays of peas per treatment (6 total treatments) were
sprayed with the above mixtures. The trays were placed on a conveyor-driven spray
table calibrated to apply 38.2 liter per ha at 59 kg/cm2 with a single TX-6 cone nozzle
fixed 46 cm above the crop. The table was set to convey the plants at a speed of 15.2
m per min, and the spray nozzle was powered by compressed air. Following treat
ment, the trays of peas were returned to the greenhouse.
Leaves were collected from the treated plants 2 h and 1, 3, 7, 10, and 14 days after
treatment. Four trays of cowpeas were used on each collection date for each treat
ment. Each tray was designated as a separate replicate. Neonate FAW larvae were ob
stained from laboratory cultures at the Insect Biology and Population Management
Research Laboratory in Tifton, GA. These larvae were reared as described by Perkins
(1979). The larvae were held on pinto bean diet at 24 + 1 C for 3 days before being ex
posed to treated leaf surfaces thus allowing all insects to reach a uniform age and size.
On each leaf collection date, 30 leaves per replicate (4 replicates total per collection
date) per treatment were placed in 30 ml plastic cups. Single 3-day-old larvae were
placed on each leaf and the cup was capped. Cups containing larvae were held in en
vironmental cabinets in the laboratory at 24 1 C, a photoperiod of 12:12 (L:D), and
50 + 5% RH. After 48 h, cups were opened and the number of living versus dead larvae
was recorded. Surviving larvae were then placed in 30 ml cups containing 10 ml of
bean diet and the number of living versus dead larvae recorded following an addi
tional 3 days (120 h after application mortality). Larvae were then disposed of.
Field Study
Field corn (Zea mays [L.]) was planted in August 1993 at the USDA-ARS Belflower
Farm in Tift Co., GA. Nine treatments, including an untreated control, were arranged
December, 1994
Chandler: Armyworm Symposium '94
in a randomized block design with four replications. Plots were 3 rows (91 cm per row)
wide by 7.6 m long. Treatments consisted of RH-5992 2F applied at rates of 22.0, 45.9
and 91.8 gm AI/ha with and without the addition of Konsume at 10% of the total vol
ume. A 10% solution of Konsume alone and thiodicarb (Larvin 3.2) at 45.9 gm AI/ha
were also evaluated. Three treatments were made to whorl stage corn beginning 23
August and continued every 10 days (final treatment on 13 September). Insecticide
applications were made with a CO2 backpack sprayer calibrated to apply 30.6 liter per
ha at 79 kg per cm2 using a TX-6 nozzle and traveling at 3.2 km/hr. Prior to and every
3-5 days after initial treatment through the test period, the number of damaged
plants (15 plants examined per plot) were counted. Counts were terminated on 1 Oc
tober. Damaged plants were defined as those where fresh larval feeding damage and
frass were found. The number of plants damaged per plot were converted to percent
ages for data analysis. Additionally, damage ratings were taken beginning on the sec
ond count date following treatment. Ratings consisted of examining the entire plot for
FAW feeding damage on a scale of 0-5, in which 0 = no damage, 1 = 120% damage, 2
21-40% damage, 3 41 60% damage, 4 61 80% damage, and 5 81100% damage.
Data Analyses
Means and standard deviations were calculated for percent mortality, percentage
of plants damaged, and damage ratings, both by date and as combined averages (after
initial treatment) over the length of the experiments. Analyses of variance (PROC
GLM, SAS 1985) were conducted for all data sets. For the spray table study, set least
square means were used to compare all possible treatment combinations. Contrasts
were made between individual rates of RH-5992 with and without Konsume, between
RH-5992 treatments combined with and without Konsume, between the untreated
control and Konsume only, and between the untreated control and all other treat
ments for 48 and 120 h mortality data. For the field study, orthogonal contrasts were
made to determine whether the tested rates of RH-5992, with or without Konsume,
resulted in either a linear or quadratic response in the number of damaged plants and
damage ratings per treatment. Comparisons were also made between RH-5992 with
and without the addition of Konsume, Konsume alone vs the untreated control, RH
5992 vs thiodicarb, and RH-5992 vs Konsume alone.
RESULTS AND DISCUSSION
Spray Table Study
High levels of fall armyworm larval mortality were observed following application of
RH-5992 2F with and without the addition of Konsume to the mix (Tables 1 and 2).
Mortality ranged from 5.9 to 67.5 % and from 62.5 to 98.4 %, depending upon the date
and rate of active ingredient, 48 and 120 hours after leaf collection of treated leaves,
respectively. Over the entire 14-day leaf collection period, no trend in loss of RH-5992
residual activity could be discerned (Tables 1 and 2). Some mortality of fall army
worm larvae was noted following feeding on foliage treated with Konsume alone.
However, the highest Konsume related mortality rates (17.5 %), compared to other
treatments, were not considered to be of great importance in inflicting death to the in
sect (Table 2).
Florida Entomologist 77(4)
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December, 1994
Chandler: Armyworm Symposium '94 415
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Florida Entomologist 77(4)
Analysis of variance for 48 h after leaf collection mortality indicated a significant
interaction between date and treatment (F = 7.74, df = 25, P 0.0001). Similar results
were obtained following analysis of variance for 120 hour after leaf collection mortal
ity (F = 3.56, df = 25, P = 0.0001). These interactions indicated that treatments re
sponded differently on each leaf collection date. Therefore, comparisons among
treatments (least square means) were made on individual leaf collection dates. Con
trasts were then conducted on seasonal average data to determine overall effects of
the insect growth regulator/feeding stimulant mixture on fall armyworm mortality.
Least square means resulted in significant differences in treatment comparisons
based on time of mortality observations and length of time after treatment (Tables 3
and 4). In most instances mortality from the untreated control and 10% Konsume
alone treatments was significantly less than all other treatments for both 48 and 120
h mortality on each leaf collection date (Tables 3 and 4). Significant increases in mor
tality caused by RH-5992 + Konsume and RH-5992 alone treatments were most often
noted within 7 days of treatment and primarily with 48 h mortality data. Data indi
cated that 48 h readings showed an increase in mortality within the first 7 days fol
lowing treatment when Konsume was added to the insect growth regulator. Mortality
observed after 120 h was similar among most insect growth regulator treatments. Af
ter 7 days, no increase in mortality could be attributed to Konsume in the formula
tions, but mortality rates remained high (Tables 3 and 4). RH-5992 (11.0 gms AI/ha)
+ Konsume resulted in significantly less mortality 14 days after application (120 h
mortality) than was noted with other RH-5992 treatments.
Contrasts conducted for 48 and 120 h after leaf collection summary data indicated
that increasing rates of RH-5992, with and without Konsume, significantly affected
fall armyworm larval mortality. RH-5992 resulted in higher mortality at the 22.0 gm
AI/ha rate than at the 11.0 gm AI/ha rate on both leaf mortality observation dates (Ta
bles 5 and 6). Also, the addition of Konsume to RH-5992 resulted in higher levels of
fall armyworm larval mortality, both 48 and 120 h after leaf collection, than that
achieved with RH-5992 alone, regardless of insect growth regulator active ingredient
rate (Tables 5 and 6). Konsume alone resulted in significantly higher levels of mortal
ity than the untreated control, and the untreated control had significantly less larval
mortality than all of the other treatments combined 48 and 120 h after leaf collection.
Field Study
Percentage of corn plants damaged by fall armyworm prior to initial insect growth
regulator treatment (23 Aug.) ranged from 3 22% per treatment (Table 7), but no sig
nificant differences in damaged plants were observed on this date although the data
are quite variable. Damage increased in the untreated plots through 13 Sept. (Tables
7 and 8). Populations of fall armyworm then decreased as indicated by the reduced
percentage of plants damaged. Damage again increased from 17 Sept. until 1 Oct. (Ta
bles 7 and 8). Fewer plants were damaged in the plots treated with RH-5992 2F at
91.8 gm AI/ha mixed with 10% Konsume; percentage of plants damaged ranged from
2 to 32%.
There were no significant interactions between date and treatment for percentage
of plants damaged and damage ratings (F 0.87, df=88, P = 0.7728 and F 0.52, df=72,
P = 0.9994, respectively). All dates were combined for orthogonal contrasts.
Increasing rates of RH-5992, both with and without the addition of Konsume,
resulted in a linear response for both reduction of percentage of plants damaged and
plant damage ratings caused by fall armyworm larval feeding (Tables 9 and 10). A
quadratic relationship was not indicated. The addition of Konsume to RH-5992 re
December, 1994
Chandler: Armyworm Symposium '94
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Chandler: Armyworm Symposium -'94 419
TABLE 5. ANALYSIS OF VARIANCE TABLE FOR 48 HOUR AFTER LEAF COLLECTION FALL AR
MYWORM LARVAE MORTALITY.
Sum of Mean
DF Squares Square
Model
Error
Corrected Total
Date
Rep (Date)
1) RH-5992 22.0 vs. 11.0
Gm Ai/Ha
2) RH-5992 + Konsume 22.0
vs. 11.0 Gm Ai/Ha
3) RH-5992 + Konsume vs.
RH-5992
4) Konsume vs. Untreated
5) All Treatments vs.
Untreated
1) Interacted with Date
2) Interacted with Date
3) Interacted with Date
4) Interacted with Date
5) Interacted with Date
F Value Pr > F
53 48757.842 919.959 19.94 0.0001
90 4151.283 46.125
143 52909.125
Type II
Sum of Mean
DF Squares Square F Value Pr > F
5 156.732 31.346 0.68 0.6400
18 845.290 46.961 1.02 0.4481
1 521.401 521.401 11.30 0.0011
1 1982.755 1982.755 42.99 0.0001
1 1834.876 1834.876 39.78 0.0001
1 14175.567 14175.567 307.33 0.0001
24231.177
783.937
779.919
1658.931
3269.530
5690.151
24231.177
156.787
155.984
331.786
693.906
1138.030
525.33
3.40
3.38
7.19
14.18
24.67
0.0001
0.0074
0.0076
0.0001
0.0001
0.0001
suited in significantly less feeding damage than when RH-5992 was used alone (Ta
bles 9 and 10). No differences in percentages of plants damaged or damage ratings
were observed comparing RH-5992 with thiodicarb (Larvin 3.2) (Tables 9 and 10). Dif
ferences were observed when comparing plants treated with all rates of RH-5992 and
those treated with Konsume alone or with untreated plants. RH-5992 treated plants
had significantly less damage than did plants treated with Konsume alone. Plants
treated with Konsume resulted in a significant reduction in damage compared to the
untreated control. However, plants treated with Konsume alone did not provide
needed levels of economic fall armyworm control. These findings are similar to those
observed with the spray table test.
In conclusion, use of RH-5992 2F resulted in significant levels of fall armyworm
larval control on both southern pea and field corn. Addition of Konsume (at 10% of to
tal volume) to the insect growth regulator provided significantly greater fall army
worm mortality in a shorter period of time and significantly reduced fall armyworm
feeding damage compared to use of the insect growth regulator alone. These results
further confirmed the laboratory findings of Chandler (1993) which indicated that the
use of a cottonseed flour-based insect feeding stimulant enhanced the activity of RH
Florida Entomologist 77(4)
TABLE 6. ANALYSIS OF VARIANCE TABLE FOR 120 HOUR AFTER LEAF COLLECTION FALL
ARMYWORM LARVAE MORTALITY.
Sum of Mean
DF Squares Square
Model
Error
Corrected Total
Date
Rep (Date)
1) RH-5992 22.0 vs. 11.0
Gm Ai/Ha
2) RH-5992 + Konsume 22.0
vs. 11.0 Gm Ai/Ha
3) RH-5992 + Konsume vs.
RH-5992
4) Konsume vs. Untreated
5) All Treatments vs.
Untreated
1) Interacted with Date
2) Interacted with Date
3) Interacted with Date
4) Interacted with Date
5) Interacted with Date
F Value Pr > F
53 220142.655 4153.635 88.81 0.0001
90 4209.078 46.768
143 224351.733
Type II
Sum of Mean
DF Squares Square F Value Pr > F
625.084
1000.820
125.017 2.67 0.0267
55.601 1.19 0.2873
1 1102.083 1102.083 23.57 0.0001
1 980.117 980.117 20.96 0.0001
425.463 425.463 9.10
120032.688 120032.688 2566.58
210735.730
430.734
429.367
1526.069
1039.311
1239.215
210735.730
86.147
85.873
305.214
207.862
247.843
4506.03
1.84
1.84
6.53
5.30
5.30
0.0033
0.0001
0.0001
0.1126
0.1137
0.0001
0.0012
0.0003
5992 and decreased time of larval mortality. Furthermore, spray table tests indicated
that the residual activity of RH-5992 in a controlled environment remained relatively
high throughout a two-week period. These positive results demonstrated the useful
ness of insect growth regulator/feeding stimulant combinations for use in field set
tings. Further study is needed to refine insect growth regulator rates and to
determine the economic feasibility of adding feeding stimulants to insect growth reg-
ulator mixtures.
ACKNOWLEDGMENTS
The author wishes to thank Lenny Atkins, Steve Hooks, Laura Abbott, Larry
Walker, Wendy Tyson, and Matt Wauchope for their technical assistance in conduct
ing these studies. Richard Layton is thanked for his help in conducting the statistical
analyses of the data. Proprietary names are necessary to report factually on available
December, 1994
Chandler: Armyworm Symposium '94
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December, 1994
Chandler: Armyworm Symposium -'94 423
TABLE 9. ANALYSIS OF VARIANCE TABLE FOR PERCENTAGE OF PLANTS DAMAGED BY FALL
ARMYWORM LARVAE, ORTHOGONAL CONTRASTS.
Sum of Mean F
DF Squares Square Value Pr > F
Model
Error
Corrected Total
143 148613.169 1039.253 3.58 0.0001
288 83671.605 290.526
431 232284.774
Type II
Sum of Mean F
DF Squares Square Value Pr > F
Date 11 65647.737 5967.976 20.54 0.0001
Rep (Date) 36 35683.951 991.221 3.41 0.0001
1) RH-5992-Linear 1 2467.130 2467.130 8.49 0.0038
2) RH-5992-Quad. 1 259.414 259.414 0.89 0.3455
3) RH-5992 + Konsume-Linear 1 8816.667 8816.667 30.35 0.0001
4) RH-5992 + Konsume-Quad. 1 326.543 326.543 1.12 0.2900
5) RH-5992 vs. RH-5992 +
Konsume 1 3200.000 3200.000 11.01 0.0010
6) Konsume vs. Untreated 1 6373.663 6373.663 21.94 0.0001
7) RH-5992 vs. Larvin 1 28.408 28.408 0.10 0.7547
8) RH-5992 vs. Konsume 1 8779.020 8779.020 30.22 0.0001
1) Interacted with Date 11 793.981 72.180 0.25 0.9935
2) Interacted with Date 11 3101.698 281.973 0.97 0.4734
3) Interacted with Date 11 750.000 68.182 0.23 0.9949
4) Interacted with Date 11 1899.383 172.671 0.59 0.8331
5) Interacted with Date 11 4729.630 429.966 1.48 0.1381
6) Interacted with Date 11 4102.263 372.933 1.28 0.2331
7) Interacted with Date 11 2743.351 249.396 0.86 0.5818
8) Interacted with Date 11 6784.208 616.746 2.12 0.0189
TABLE 10. ANALYSIS OF VARIANCE TABLE FOR DAMAGE RATINGS RESULTING FROM
FEEDING BY FALL ARMYWORM LARVAE, ORTHOGONAL CONTRASTS.
Sum of Mean F
DF Squares Square Value Pr > F
Model 119 214.822 1.805 2.54 0.0001
Error 240 170.778 0.712
Corrected Total 359 385.600
424 Florida Entomologist 77(4) December, 1994
TABLE 10. (CONTINUED) ANALYSIS OF VARIANCE TABLE FOR DAMAGE RATINGS RESULT
ING FROM FEEDING BY FALL ARMYWORM LARVAE, ORTHOGONAL CONTRASTS.
Type II
Sum of Mean F
DF Squares Square Value Pr > F
Date 9 45.656 5.073 7.13 0.0001
Rep (Date) 30 95.722 3.191 4.48 0.0001
1) RH-5992-Linear 1 4.513 4.513 6.34 0.0124
2) RH-5992-Quad. 1 0.104 0.104 0.15 0.7023
3) RH-5992 + Konsume-Linear 1 12.013 12.013 16.88 0.0001
4) RH-5992 + Konsume-Quad. 1 0.704 0.704 0.99 0.3208
5) RH-5992 vs. RH-5992 +
Konsume 1 5.400 5.400 7.59 0.0063
6) Konsume vs. Untreated 1 15.313 15.313 21.52 0.0001
7) RH-5992 vs. Larvin 1 0.078 0.078 0.11 0.7407
8) RH-5992 vs. Konsume 1 22.802 22.802 32.04 0.0001
1) Interacted with Date 9 2.363 0.263 0.37 0.9490
2) Interacted with Date 9 2.854 0.317 0.45 0.9091
3) Interacted with Date 9 1.863 0.207 0.29 0.9768
4) Interacted with Date 9 1.421 0.158 0.22 0.9912
5) Interacted with Date 9 5.517 0.613 0.86 0.5605
6) Interacted with Date 9 3.007 0.334 0.47 0.8942
7) Interacted with Date 9 4.648 0.516 0.73 0.6851
8) Interacted with Date 9 5.375 0.597 0.84 0.5806
data; however, the USDA neither guarantees nor warrants the product, and the use
of the name by USDA implies no approval of the product to the exclusion of others
that may be suitable. U.S. Department of Agriculture, Agricultural Research Service,
Northern Plains Area, is an equal opportunity/affirmative action employer and all
agency services are available without discrimination
REFERENCES CITED
CHANDLER, L.D. 1993. Use of feeding stimulants to enhance insect growth regulator
induced mortality of fall armyworm (Lepidoptera: Noctuidae) larvae. Florida
Entomol. 76: 316-326.
CHANDLER, L.D., S.D. PAIR, AND W.E. HARRISON. 1992. RH-5992: Anew insect growth
regulator active against corn earworm and fall armyworm (Lepidoptera: Noc
tuidae). J. Econ. Entomol. 85: 1099-1103.
PERKINS, W.D. 1979. Laboratory rearing of the fall armyworm. Florida Entomol. 62:
87-91.
ROHM AND HAAS CO. 1989. RH-5992 insect growth regulator. Technical Information
Bulletin AG-2255. 6pp.
SAS INSTITUTE. 1985. SAS/STAT User's Guide. SAS Institute, Cary, NC.
Hamm et al.: Armyworm Symposium '94
FIELD TESTS WITH A FLUORESCENT BRIGHTENER TO
ENHANCE INFECTIVITY OF FALL ARMYWORM
(LEPIDOPTERA: NOCTUIDAE)
NUCLEAR POLYHEDROSIS VIRUS
J. J. HAMM, L. D. CHANDLER AND H. R. SUMNER
Insect Biology and Population Management Research Laboratory
U.S. Department of Agriculture, Agricultural Research Service
Tifton, GA 31793-0748
ABSTRACT
The nuclear polyhedrosis virus (NPV) of fall armyworm, Spodoptera frugiperda (J.
E. Smith), was applied in combination with Fluorescent Brightener 28 (Calcofluor
White M2R, Tinopal LPW) to whorl-stage corn. Concentrations of NPV ranged from 5
larval equivalents (1 LE = 6 x 109 polyhedral occlusion bodies) to 1235 LE per ha. Con
centrations of fluorescent brightener ranged from 0.1 to 5% by weight in water and
the water volume ranged from 234 to 926 liters per ha. Two days after treatment, fall
armyworm larvae were collected from the treated plants and held on bean diet to ob
serve mortality due to NPV, parasitoids, and ascovirus. The fluorescent brightener in
teracted significantly with virus concentration and with water volume to increase
larval mortality. There was no increase in mortality due to NPV as the percent fluo
recent brightener increased beyond 1%. In the higher volumes of water, 0.25% fluo
recent brightener resulted in the highest percent mortality due to NPV Cotesia
marginiventris was the most abundant parasitoid recovered from fall armyworm in
these tests, and as the percent mortality due to NPV increased, the percent mortality
due to parasitoids and ascovirus decreased. Thus, the total mortality was not affected
as greatly as the percent mortality due to NPV by changes in water volume or fluo
recent brightener concentration. The reduction in mortality due to parasitoids did
not appear to be a direct effect of the fluorescent brightener on the parasitoids. How
ever, increased infectivity of the NPV and earlier mortality from NPV associated with
the fluorescent brightener resulted in more host larvae dying of NPV before the par
asitoids could complete development.
Key Words: Spodoptera frugiperda, nuclear polyhedrosis virus, fluorescent bright
ener, biocontrol, corn, Cotesia marginiventris
RESUME
El virus de la polihedrosis nuclear (VPN) del gusano trozador, Spodoptera frugi
perda (J. E. Smith), fue aplicado en combinaci6n con Fluorescent Brightener 28 (Cal
cofluor White M2R, Tinopal LPW) a plants de maiz en estado vegetative. Las
concentraciones del VPN estuvieron en el rango de los 5 a 1235 equivalentes larvales
(EL) por ha (1 EL 6 x 109 cuerpos polihedrales de oclusi6n). Las concentraciones de
Fluorescent Brightener estuvieron en el rango de 0.1 a 5% por peso en agua y el volu
men del agua en el rango de 234 a 926 litros por hectarea. Dos dias despues del tra
tamiento las larvas del gusano trozador fueron colectadas de las plants tratadas y
mantenidas en dieta de frijoles para observer la mortalidad debida al VPN, parasitoi
des, y ascovirus. Fluorescent Brightener interactud significativamente con la concern
traci6n del virus y con el volume del agua para aumentar la mortalidad larval. No
hubo aumento de la mortalidad debido al VPN cuando el porcentaje de Fluorescent
Brightener aumento a mas del 1%. En los volumenes mas altos de agua, el 0.25% de
Fluorescent Brightener produjo el porcentaje de mortalidad mas alto. Cotesia margi
niventris fue el parasitoide mas abundantemente recobrado del gusano trozador en
This article is from Florida Entomologist Online, Vol. 77, No. 4 (1994).
FEO is available from the Florida Center for Library Automation gopher (sally.fcla.ufl.edu)
and is identical to Florida Entomologist (An International Journal for the Americas).
FEO is prepare y. E. O. Painter Printing Co., P.O.Box877, DeLeon Springs, FL. 32130.
'-------Thi doumLLntL wasi created wVIth FrmIac 4.0.2------ ',
Florida Entomologist 77(4)
estas pruebas y en la media en que aument6 el porcentaje de mortalidad debido al
VPN, el producido por los parasitoides y ascovirus disminuy6. De esta manera, la mor
talidad total no fue afectada tanto como el porcentaje de mortalidad debido al VPN por
los volumenes de agua o la concentraci6n de Fluorescent Brightener. La reducci6n en
la mortalidad producida por los parasitoides no pareci6 deberse al efecto del marcador
en los mismos. Sin embargo, el incremento de la infectividad del VPN y la mortalidad
temprana debidos al virus asociado con el Fluorescent Brightener provocaron que mas
larvas murieran por el VPN antes que los parasitoides pudieran completar su desa
rrollo.
The nuclear polyhedrosis virus (SfNPV) is a naturally occurring pathogen of fall
armyworm, Spodoptera frugiperda (J. E. Smith), (Gardner & Fuxa 1980, Fuxa 1982).
However, field tests with SfNPV have resulted in rather low levels of control of fall ar
myworm larvae (Hamm & Young 1971, Hamm & Hare 1982). In these earlier tests,
the virus was not formulated with adjuvants to protect the virus from sunlight or to
otherwise enhance its infectivity Recently, however, Shapiro (1992) demonstrated
that UV protection was possible using a series of optical or fluorescent brighteners
(FB). More importantly, five of the optical brighteners, including Tinopal LPW, en
hanced the infectivity of an NPV that infects gypsy moth larvae, even when the virus
was not exposed to UV irradiation (Shapiro & Robertson 1992). Later, Hamm & Sha
piro (1992) demonstrated significant enhancement of the SfNPV by Tinopal LPW in
laboratory bioassays. Because of this unique enhancement of viral infectivity for lep
idopterous larvae, a patent for the use of fluorescent brighteners in biological control
was awarded 23 June 1992 (Shapiro et al. 1992).
The field tests reported here were conducted to determine if adding FB to the
SfNPV would increase the level of control of fall armyworm larvae in whorl-stage
corn. Because parasitoids (Ashley 1986) and ascovirus (Hamm et al. 1986) contribute
to the natural control of fall armyworm, the effects of SfNPV and FB on parasitoids
and ascovirus were studied also. Control of fall armyworm on corn is difficult, even
with insecticides, because the larvae feed down into the whorl. Therefore, the insecti
cides are generally applied in the maximum amount of water that can be applied eco
nomically with ground equipment (94-468 liters per ha). Consequently, the
relationship between water volume, SfNPV, and FB was also evaluated.
MATERIALS AND METHODS
Materials
The SfNPV was produced in the laboratory in fall armyworm larvae. The polyhe
dral occlusion bodies (POB) were partially purified by slow and high speed centrifu
gation and suspended in 0.1 m phosphate buffer (pH 7) containing 100 gg/ml
garamycin and stored at 6'C. The virus was quantified by counting POB with a
Petroff-Houser bacterial counter. Concentrations were expressed as Larval Equiva
lents (LE), the approximate number of POB produced per larva, based on 6 X 109 POB
per LE. Fluorescent Brightener 28 (Calcofluor white M2R, Tinopal LPW) was ob
stained from Sigma Chemical Co. No other UV screens, wetting agents, or feeding
stimulants were used.
December, 1994
Hamm et al.: Armyworm Symposium -'94
General Procedures
Tests were conducted in whorl-stage corn in Tift Co. GA. Plots were single rows 6
to 7.6 m long separated by 6 m of untreated corn on the ends and five rows of un
treated corn (4.6 m) on the sides. There were five replications of each treatment ar
ranged in randomized complete blocks. Corn plants were artificially infested in early
season tests conducted in May and June of 1989 and 1991. Newly hatched fall army
worm larvae from the Insect Biology and Population Management Research Labora
tory colony in Tifton, GA, were mixed with corncob grits to the desired concentration
(Wiseman & Widstrom 1980) and applied to the whorl-stage corn with a pushcart ap
plicator (Sumner et al. 1992). Corn plots were sprayed 3 days after being artificially
infested, except for May 1991 when (due to cool weather) treatments were applied 5
days after infestation. Late season tests in August and September of 1993 were nat
urally infested.
All viruses were applied using a Ford 4000 hi-clearance tractor equipped with a
single row spray boom with a single agricultural spray nozzle and tanks pressurized
with compressed air. Spray nozzles were changed, pressure adjusted, and tractor ve
locity set to accommodate the amounts of material applied per ha for each test. Two
days after treatment, plants were cut and brought into the laboratory. Up to 30 larvae
per plot were collected from these plants and placed individually in 30-ml plastic cups
containing bean diet. Larvae were held for observation for 8 days.
Larvae that died the first day after collection were considered to have died from in
jury during collection and were subtracted from the number collected. After the first
day, mortality was attributed to either parasitoids, SfNPV, or ascovirus. Parasitoids
were observed to emerge from the larvae and spin cocoons. Almost all parasitoids re
covered were Cotesia marginiventris (Hymenoptera: Braconidae). SfNPV was indi
TABLE 1. MEAN PERCENT MORTALITY AND STANDARD DEVIATION DUE TO NPV, PARASI
TOIDS, ASCOVIRUS, AND TOTAL MORTALITY OF FALL ARMYWORM LARVAE
TREATED ON WHORL-STAGE CORN WITH SFNPV AND FB IN 246 LITERS PER
HA OF WATER, 15 MAY 1989.
NPV Parasitoids Ascovirus Total
NPV in LE %
per ha FB Mean SD Mean SD Mean SD Mean SD
0 0 0 0 35.9 8.7 8.7 8.0 46.8 9.1
0 0.1 0 0 35.5 14.1 6.1 4.5 41.6 17.4
0 1 0 0 27.9 10.5 9.5 9.8 38.9 10.5
5 0 6.3 4.7 35.9 7.5 9.6 7.1 51.8 10.7
5 0.1 17.4 8.8 33.2 8.8 2.1 3.2 52.7 9.4
5 1 15.1 9.9 38.8 11.5 5.5 5.1 60.0 9.4
50 0 25.9 6.8 21.4 14.2 2.8 3.0 50.1 10.7
50 0.1 25.8 9.9 26.3 14.1 4.0 5.4 56.8 15.0
50 1 36.6 13.3 17.6 12.3 5.0 1.9 60.0 10.9
500 0 58.9 12.0 15.1 12.0 1.5 3.4 75.5 5.2
500 0.1 48.4 10.0 23.0 7.1 2.1 2.0 74.3 12.2
500 1 72.4 14.7 6.8 4.2 2.0 2.0 81.2 14.2
Florida Entomologist 77(4)
PAR
t 60-
0 N$ ON 1 N
Fig. 1. Mean percent mortality of fall armyworm larvae on whorl-stage corn
caused by NPV, parasitoids (PAR), and ascovirus (AV); treated 15 May 1989 with 4
levels of NPV in 3 levels of fluorescent brightener in 246 liters per ha of water.
cated when the larvae melted and/or contained POB typical of NPV Ascovirus was
indicated when the larvae remained small and contained the vesicles typical of ascovi-
rus
Percent mortality was determined by dividing the number that died from each
cause by the number of larvae collected (minus the number that died the first day af
ter collection). Total percent mortality was computed by adding the mortality factors
TABLE 2. MEAN PERCENT MORTALITY AND STANDARD DEVIATION DUE TO NPV, PARASI-
TOIDS, ASCOVIRUS, AND TOTAL MORTALITY OF FALL ARMYWORM LARVAE
TREATED ON WHORL-STAGE CORN WITH NPV AND FB IN 486 LITERS PER HA
OF WATER, 12 JUNE 1989.
NPV Parasitoids Ascovirus Total
NPV in LE %
per ha FB Mean SD Mean SD Mean SD Mean SD
0 0 0 0 2.4 2.4 0 0 2.4 2.4
50 0 44.6 10.3 0 0 1.0 2.1 45.6 9.1
50 0.1 46.1 19.0 0 0 0 0 46.1 19.0
50 1 68.4 19.8 0 0 0 0 68.4 19.8
50 5 379 12.3 0 9.0 419 7.3
50 5 37.9 12.3 0 0 4.0 9.0 41.9 7.3
December, 1994
Hamm et al.: Armyworm Symposium -'94
0 0 4b 0
SV-V
C<: 4P'
Fig. 2. Mean percent mortality of fall armyworm larvae on whorl-stage corn
caused by NPV, parasitoids (PAR), and ascovirus (AV); treated 12 June 1989 with 50
LE per ha of NPV in 0, 0.1, 1, and 5% fluorescent brightener in 486 liters per ha of wa
ter plus an untreated control.
together. Means and standard deviations were calculated for each morality variable.
A GLM procedure (SAS 1985) was conducted for each data set using both the percent
mortality and the arcsin of the square root of the percent. Percentages are shown in
the tables, but the interactions are based on the analyses of the transformed percent
ages. Regression analyses were conducted to determine linear and quadratic effects.
Rates of Virus, Fluorescent Brightener, and Water Applied
The first test, in May 1989, consisted of 12 treatments: 0, 5, 50 and 500 LE per ha
of SfNPV, each applied in 0, 0.1%, and 1% FB in 246 liters per ha of water.
In the second test, June 1989, the amount of water was increased to 486 liters per
ha and a single level of SfNPV, 50 LE per ha, was applied in 4 levels of FB, 0, 0.1, 1,
and 5 percent.
In 1991, two tests were conducted in which there was an untreated control; in all
other treatments a constant amount of SfNPV in varying amounts of water and FB.
SfNPV at 618 LE per ha was applied in 234 liters per ha water containing 0, 0.25, 0.5,
1, and 2% FB, or in 468 liters per ha water containing 0, 0.25, 0.5, and 1% FB, or in
936 liters per ha water containing 0, 0.25, or 0.5% FB. The amount of FB applied was
585, 1,169, 2,338, and 4,677 g per ha. The whorl-stage corn was infested 17 May, but
due to cool, rainy weather it was not treated until 22 May, 5 days after infestation
rather than 3 days as in other tests. When the test was repeated, the corn was in
fested 31 May and treated 3 June.
Florida Entomologist 77(4)
In 1993, 2 tests were conducted using naturally-infested whorl-stage corn. Treat
ments were applied 27 August and 27 September with 936 liters per ha water contain
ing 0 virus and 0 FB, 124 LE in 0 FB, 124 LE in 0.25% FB, 1,235 LE in 0 FB, or 1,235
LE in 0.25% FB. Thus all treatments receiving FB received 2,340 g per ha of the ad
juvant.
RESULTS AND DISCUSSION
The 1989 treatment means and standard deviations for the first test are shown in
Table 1 and the mean percent mortality due to NPV, parasitoids, and ascovirus are
presented graphically in Fig. 1. GLM analysis showed an interaction between linear
effects of NPV concentration and linear effects of FB concentration on percent mortal
ity due to NPV. Percent mortality due to parasitoids, ascovirus, and percent total mor
tality showed only linear effects of NPV concentration. The greatest percent mortality
due to NPV, 72.4%, occurred in the 500 LE per ha treatment with 1% FB. The greatest
mortality due to NPV in a 50 LE per ha treatment was also in 1% FB. There was a
general increase in percent mortality attributable to NPV with increasing NPV con
centration and with increasing FB concentration. However, there was a general de
crease in the percent mortality caused by parasitoids and ascovirus as the percent
mortality due to NPV increased.
Treatment means and standard deviations for test 2 in 1989 are shown in Table
2. The mean percent mortality due to NPV, parasitoids, and ascovirus is presented
TABLE 3. MEAN PERCENT MORTALITY AND STANDARD DEVIATION DUE TO NPV, PARASI
TOIDS, AND TOTAL MORTALITY OF FALL ARMYWORM LARVAE TREATED ON
WHORL-STAGE CORN WITH 618 LE PER HA OF NPV IN VARIOUS VOLUMES OF
WATER AND CONCENTRATIONS OF FB, 22 MAY 1991.
Treatments
Water FB NPV Parasitoids Total
Liters
per ha % g per ha Mean SD Mean SD Mean SD
Untreated Control 0.7 1.5 53.4 9.1 54.1 9.8
234 0 0 36.9 11.7 43.0 8.7 79.9 14.7
468 0 0 21.3 6.8 55.4 10.4 76.7 6.8
936 0 0 36.9 5.0 41.7 9.9 78.5 7.2
234 .25 585 34.7 8.7 48.0 8.0 82.7 6.8
468 .25 1170 34.8 11.1 39.2 7.6 74.0 10.0
936 .25 2340 29.2 13.9 58.7 17.6 87.9 9.5
234 .5 1170 31.5 5.7 43.1 16.8 74.6 18.3
468 .5 2340 39.2 8.3 43.3 7.8 82.5 6.2
936 .5 4680 51.3 6.2 33.8 7.1 85.1 1.9
234 1 2340 39.5 12.1 48.4 9.4 87.9 5.1
468 1 4680 42.0 7.3 40.7 9.2 82.7 2.9
234 2 4680 33.8 13.6 52.5 8.6 86.3 6.4
December, 1994
Hamm et al.: Armyworm Symposium -'94
TABLE 4. MEAN PERCENT MORTALITY AND STANDARD DEVIATION DUE TO NPV, PARASI
TOIDS, AND TOTAL MORTALITY OF FALL ARMYWORM LARVAE TREATED ON
WHORL STAGE CORN WITH 618 LE PER HA OF NPV IN VARIOUS VOLUMES OF
WATER AND CONCENTRATIONS OF FB, 3 JUNE 1991.
Treatments
Water FB NPV Parasitoids Total
Liters
per ha % g per ha Mean SD Mean SD Mean SD
Untreated Control 4.1 4.5 19.7 4.4 23.8 6.4
234 0 0 28.5 16.2 20.3 5.3 48.8 12.7
468 0 0 27.0 13.7 14.7 7.6 41.7 14.9
936 0 0 33.7 10.7 15.0 11.6 48.7 10.7
234 .25 585 22.7 13.1 16.8 4.1 39.5 13.4
468 .25 1170 39.3 7.2 8.0 5.5 47.3 9.5
936 .25 2340 61.7 16.7 9.5 4.5 71.3 14.8
234 .5 1170 9.5 7.5 17.4 6.4 26.9 10.1
468 .5 2340 39.9 7.5 10.1 5.7 50.0 3.2
936 .5 4680 46.6 14.0 12.3 8.1 58.9 8.8
234 1 2340 40.4 10.5 10.1 7.0 50.5 14.5
468 1 4680 33.5 10.6 16.2 10.1 49.7 1.8
234 2 4680 27.1 9.4 17.0 5.6 44.0 11.5
graphically in Fig. 2. Because all treatments (except the untreated control) contained
the same concentration of virus, the untreated control was omitted from the GLM
analysis so that virus concentration would not be a factor. Thus, the effect of FB con
centration at the given level of virus could be clearly demonstrated. GLM analysis
showed a quadratic effect of FB on percent mortality due to NPV and percent total
mortality, but no significant effect on percent mortality due to ascovirus. There was no
mortality due to parasitoids in any of the virus treatments and much less mortality
due to parasitoids in the control for this test than in the first test. An increase in the
FB from 1% (4,860 g per ha) to 5% (24,300 g per ha) resulted in a decrease in percent
mortality due to NPV
The 1991 tests were designed to test both the effects of water volume and concern
tration, or amount, of FB on mortality due to NPV Thus, the virus level remained con
stant except for the untreated control which was omitted from the analysis so that
virus concentration would not be a factor. The treatment means and standard devia
tions are shown in Tables 3 and 4. No mortality due to ascovirus was detected in the
1991 tests. Mortality due to parasitoids was much higher (53.4% in the untreated con
trol) in the 22 May test, which was treated 5 days after infestation, than in the 3 June
test (19.7% in the untreated control) which was treated 3 days after infestation.
In the 22 May test, with the higher rate of parasitoids, the interactions between
water and FB were similar when FB was expressed as either percent or as g per
ha (Fig. 3). There were interactions between quadratic effects of water and quadratic
effects of FB for both percent mortality due to NPV and percent mortality due
to parasitoids; again, as the mean percent mortality due to NPV increased the
Florida Entomologist 77(4)
I/ha
3 936
2 468
1 ~234
I I 1 I I I I I 1
0 585 1,170 2,340 4,680
Grams Fluorescent Brightener per ha
Figure 3. Mean percent mortality of fall armyworm larvae on whorl-stage corn
caused by NPV following treatment on 22 May 1991 with 618 LE per ha of NPV in 5
levels of fluorescent brightener in 3 volumes of water.
mean percent mortality due to parasitoids decreased. However, percent total mor
tality showed only a linear effect of FB (Fig. 4).
In the 3 June test, lower rates of parasitism interfered less with the effects of wa
ter and FB on mortality due to NPV; thus, the interactions between water and FB
were different when FB was expressed as percent than when it was expressed as g per
ha. When FB was expressed as percent (Fig, 5), there was an interaction between the
linear effects of water and the quadratic effects of FB on both percent mortality due
to NPV and total mortality. However, there was no significant effect of water or FB on
percent mortality caused by parasitoids. When FB was expressed in g per ha, there
was a quadratic effect of FB on both percent mortality attributable to NPV (Fig. 6)
and percent mortality due to parasitoids. Again, a decrease in mortality due to para
sitoids was associated with the increase in mortality due to NPV There was an inter
I/ ha
100
60
40
20
0 585 1,170 2,340 4,680
Grams Fluorescent Brightener per ha
Fig. 4. Mean percent total mortality (NPV and parasitoids) of fall armyworm lar
vae on whorl-stage corn, treated 22 May 1991 with 618 LE per ha of NPV in 5 levels
of fluorescent brightener in 3 volumes of water.
December, 1994
(I
Ame-
as
Hamm et al.: Armyworm Symposium '94 433
I/ha
60
40 m 234
30
20
10
0
0 .25 .5 1 2
Percent Fluorescent Brightener
Fig. 5. Mean percent mortality of fall armyworm larvae on whorl-stage corn
caused by NPV following treatment on 3 June 1991with 618 LE per ha of NPV in 5
levels of fluorescent brightener expressed as percent of 3 volumes of water.
action between the linear effects of water and the quadratic effects of FB on total
mortality (Fig. 7).
In the 1993 tests, a high volume of water, 936 liters per ha, was used to compare
effects of 0.25% FB vs 0 FB at 3 levels of virus. The treatment means and standard de
viations are shown in Tables 5 and 6. The percent mortality due to NPV, parasitoids,
and ascovirus are shown graphically in Figs. 8 and 9. The 27 August test showed an
interaction between the quadratic effects of virus and the linear effects of FB on per
cent mortality due to NPV, but only the quadratic effect of virus was noted for total
mortality. There were no significant effects on percent mortality due to parasitoids
and no mortality due to ascovirus. The 27 September tests showed quadratic effects
of virus on percent mortality due to NPV, ascovirus, and total mortality. There was a
0
2 70
+ 60
Q) so
0 50
L 40
30
20
10
0
1/ha
K3 936
S468
g 234
0 585 1,170 2,340 4,680
Grams Fluorescent Brightener per ha
Fig. 6. Mean percent mortality of fall armyworm larvae on whorl-stage corn
caused by NPV following treatment on 3 June 1991 with 618 LE per ha of NPV in 5
levels of fluorescent brightener in 3 volumes of water.
A
Florida Entomologist 77(4)
585 1,170 2.340 4,680
Grams Fluorescent Brightener per ha
Fig. 7. Mean percent total mortality (NPV and parasitoids) of fall armyworm lar
vae on whorl-stage corn treated 3 June 1991 with 618 LE per ha of NPV in 5 levels of
fluorescent brightener in 3 volumes of water.
significant interaction between the linear effects of virus and linear effects of FB on
percent mortality due to parasitoids.
SUMMARY
Many factors are important to the successful control of fall armyworm with the
SfNPV. First the virus must be placed where the larvae are feeding and in a concern
tration sufficient for the larvae to ingest a lethal dose. In these tests, mortality due to
SfNPV increased with increasing virus concentration up to the highest rate tested,
1235 LE per ha. It is apparent from these tests that increasing the volume of water,
up to 936 liters per ha, helped to deliver the virus deep into the whorl of the corn plant
TABLE 5. MEAN PERCENT MORTALITY AND STANDARD DEVIATION DUE TO NPV, PARASI
TOIDS, AND TOTAL MORTALITY OF FALL ARMYWORM LARVAE TREATED ON
WHORL-STAGE CORN WITH NPV AND FB IN 936 LITERS PER HA OF WATER, 27
AUGUST 1993.
Treatments
NPV Parasitoids Total
NPV in LE
per ha % FB Mean SD Mean SD Mean SD
0 0 0.8 1.9 7.3 6.2 8.1 6.7
0 .25 0 0 10.3 4.9 10.3 4.9
124 0 11.8 7.9 8.5 4.7 20.5 11.4
124 .25 28.7 13.3 8.0 7.0 36.7 8.0
1235 0 40.7 12.1 8.7 7.2 49.4 11.6
1235 .25 52.6 9.8 4.9 5.1 57.5 9.2
December, 1994
Hamm et al.: Armyworm Symposium -'94
TABLE 6. MEAN PERCENT MORTALITY AND STANDARD DEVIATION DUE TO NPV, PARASI
TOIDS, ASCOVIRUS, AND TOTAL MORTALITY OF FALL ARMYWORM LARVAE
TREATED ON WHORL-STAGE CORN WITH NPV AND FB IN 936 LITERS PER HA
OF WATER, 27 SEPTEMBER 1993.
NPV Parasitoids Ascovirus Total
NPV in
LE per
ha % FB Mean SD Mean SD Mean SD Mean SD
0 0 .7 1.5 7.9 6.7 8.4 5.5 20.0 6.1
0 .25 0 0 16.5 4.3 4.2 6.1 22.9 9.1
124 0 36.3 12.0 12.1 7.0 0.7 1.5 49.3 8.5
124 .25 47.3 4.8 9.1 6.5 0.7 1.6 58.1 10.8
1235 0 69.3 8.4 10.8 4.4 1.4 3.2 82.9 6.0
1235 .25 84.6 4.9 0.7 1.5 0.7 1.5 86.5 5.6
where the larvae were feeding. The FB interacted significantly with virus concentra
tion and water volume to increase mortality caused by NPV However, there was no
increase in mortality due to NPV as the percent FB increased beyond 1%. In higher
volumes of water (468 and 936 liters per ha) 0.5 and 0.25% FB resulted in the highest
percent mortality due to NPV Of the FB rates, expressed as weight, 2,340 g per ha in
Fig. 8. Mean percent mortality of fall armyworm larvae on whorl-stage corn due to
NPV and parasitoids (PAR), following treatment on 27 August 1993 with 3 levels of
NPV in 2 levels of fluorescent brightener in 936 liters per ha of water.
Florida Entomologist 77(4)
Fig. 9. Mean percent mortality of fall armyworm larvae on whorl-stage corn due to
NPV, parasitoids (PAR), and ascovirus (AV), treated 27 September 1993 with 3 levels
of NPV in 2 levels of fluorescent brightener in 936 liters per ha of water.
936 liters per ha resulted in the highest percent mortality due to NPV. In general, as
the percent mortality due to NPV increased the percent mortality due to parasitoids
and ascovirus decreased. This did not appear to be a direct effect of FB on the parasi
toids. The increased infectivity of the NPV and earlier mortality of larvae due to NPV
associated with the FB resulted in death of host larvae attributable to NPV before the
parasitoids could complete development. Thus, the total mortality was not affected as
greatly as the percent mortality due to NPV by changes in water volume or FB con
centration.
ACKNOWLEDGMENTS
The authors wish to thank JoAnne Denham and Lenny Atkins for their technical
assistance in conducting these studies. Richard Layton is thanked for his help in con
ducting the statistical analyses of the data. Proprietary names are necessary to report
factually on available data; however, the USDA neither guarantees nor warrants the
product, and the use of the name by USDA implies no approval of the product to the
exclusion of others that may be suitable.
REFERENCES CITED
ASHLEY, T R. 1986. Geographical distributions and parasitization levels for parasi
toids of the fall armyworm, Spodoptera frugiperda. Florida Entomol. 69: 516
524.
FUXA, J. R. 1982. Prevalence of viral infections in populations of fall armyworm,
Spodoptera frugiperda, in southeastern Louisiana. Environ. Entomol. 11: 239
242.
December, 1994
Hamm et al.: Armyworm Symposium -'94
GARDNER, W. A., AND J. R. FUXA. 1980. Pathogens for the suppression of the fall ar
myworm. Florida Entomol. 63: 439-447.
HAMM, J. J., AND W. W. HARE. 1982. Application of entomopathogens in irrigation wa
ter for control of fall armyworms and corn earworms (Lepidoptera: Noctuidae)
on corn. J. Econ. Entomol. 75: 1074-1079.
HAMM, J JJ., S. D. PAIR, AND O. G. MARTI, JR 1986. Incidence and host range of a new
ascovirus form fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctu
idae). Florida Entomol. 69: 524-531.
HAMM, J. J., AND M. SHAPIRO. 1992. Infectivity of fall armyworm (Lepidoptera: Noc
tuidae) nuclear polyhedrosis virus enhanced by a fluorescent brightener. J.
Econ. Entomol. 85: 2149-2152.
HAMM, J. J., AND J. R. YOUNG. 1971. Value of virus presilk treatment for corn ear
worm and fall armyworm control in sweet corn. J. Econ. Entomol. 64: 144-146.
SAS INSTITUTE. 1985. SAS/STAT User's Guide. SAS Institute, Cary, NC.
SHAPIRO, M. 1992. Use of optical brighteners as radiation protectants for gypsy moth
(Lepidoptera: Lymantriidae) nuclear polyhedrosis virus. J. Econ. Entomol. 85:
1682-1686.
SHAPIRO, M., E. M. DOUGHERTY, AND J. J. HAMM. 1992. Compositions and methods for
biocontrol using fluorescent brighteners. U.S. Patent no. 5,124,149.
SHAPIRO, M., AND J. L. ROBERTSON. 1992. Enhancement of gypsy moth (Lepidoptera:
Lymantriidae) baculovirus activity by optical brighteners. J. Econ. Entomol.
85: 1120-1124.
SUMNER, H. R., H. R. GROSS, AND B. R. WISEMAN. 1992. Pushcart mounted rotary ap
plicator for infesting plants with the larvae of Spodoptera frugiperda (Lepi
doptera: Noctuidae). J. Econ. Entomol. 85: 276-280.
WISEMAN, B. R., AND N. W. WIDSTROM. 1980. Comparison of methods of infesting
whorl-stage corn with fall armyworm. J. Econ. Entomol. 73: 440-442.
YOUNG, J. R. 1980. Suppression of fall armyworm populations by incorporation of in
secticides into irrigation water. Florida Entomol. 63: 447-450.
4444444444444444444444444444444444444444444444444444
A GENETICALLY-MODIFIED BACILLUS THURINGIENSIS
PRODUCT EFFECTIVE FOR CONTROL OF THE FALL
ARMYWORM (LEPIDOPTERA: NOCTUIDAE) ON CORN
J. N. ALL', J. D. STANCIL', T. B. JOHNSON2, AND R. GOUGER2
'Department of Entomology
University of Georgia, Athens, GA 30602
2Ecogen Inc., Langhorne, PA 19047
ABSTRACT
ECX9399, a variant of strain EG2348 (the active ingredient of the bioinsecticide
Condor") of Bacillus thuringiensis (Berliner) (Bt) subspecies kurstaki was developed
by recombinant DNA technology by Ecogen Inc. This strain showed greater control of
fall armyworm, Spodoptera frugiperda (J. E. Smith), infestations in whorl stage corn,
Zea mays L., than other Bt products in field tests conducted in Georgia, Mississippi
and Florida during 1993. Control by EC9399 was greatest in Mississippi, where a 4
day spray interval (total of 3 sprays) was used and least in Georgia, where a 7-day
schedule (total of 3 sprays) was maintained. The new genetically-modified Bt product
This article is from Florida Entomologist Online, Vol. 77, No. 4 (1994).
FEO is available from the Florida Center for Library Automation gopher (sally.fcla.ufl.edu)
and is identical to Florida Entomologist (An International Journal for the Americas).
FEO is prepared by E. O. Painter Printing Co., P.O. Box 877, DeLeon Springs, FL. 32130.
Florida Entomologist 77(4)
had comparable efficacy (decrease in larval number on plants and reduced defoliation)
to methomyl, which was used at commercial rates as a conventional insecticide stan
dard at the 3 locations.
Key Words: Corn, Bacillus thuringiensis, Spodoptera frugiperda
RESUME
El ECX9399, unavariante de la cepa EG2348 ingrediente active del bioinsecticida
Condor*) de Bacillus thuringiensis (Berliner) (Bt) subespecie kurstaki, fue desarro
llado por Ecogen Inc. mediante la tecnologia de la recombinaci6n del DNA. Esta cepa
demostr6 mayor control de las infestaciones del gusano trozador, Spodoptera frugi
perda (J. E. Smith), en el maiz, Zea mays L., en estado vegetative que otros products
de Bt en pruebas de campo llevadas a cabo en Georgia, Mississippi y Florida durante
1993. El control con EC9399 fue mayor en Mississippi, donde fue utilizado un inter
valo de aspersiones de cuatro dias (3 aspersiones en total) y menor en Georgia, donde
fue mantenido un program de siete dias (tres aspersiones en total). El nuevo pro
ducto de Bt gen6ticamente modificado tuvo una eficacia (disminuci6n del numero de
larvas por plant y de la defoliaci6n) comparable a la del methomyl, que fue empleado
en concentraciones comerciales como un insecticide conventional estandar en los tres
lugares.
Bacillus thuringiensis (Berliner) (Bt) subspecies kurstaki products have generally
exhibited moderate to low effectiveness for controlling the fall armyworm (FAW),
Spodoptera frugiperda (J. E. Smith) (Gardner & Fuxa 1980; Krieg & Langenbruch
1981; Teague 1993). Recently, products derived from new Bt strains have been com
mercialized, including the EG2348 strain of Bt subspecies kurstaki, the active ingre
dient in the bioinsecticide Condor". These products have shown improved toxicity for
certain insects (Gawron-Burke & Baum 1991). EG2348 was developed by Ecogen Inc.,
(Langhorne, PA 19047) utilizing natural processes for transfer of plasmids with genes
encoding for production of specified insecticidal crystal proteins (Gawron-Burke &
Baum 1991). Recombinant DNA (rDNA) technology has made it possible to improve
Bt strains (Carlton & Gawron-Burke 1993), and recently Ecogen produced a rDNA
modified variant (ECX9399) of EG2348 that was more toxic to FAW in laboratory tests
(T. Johnson, Ecogen, Inc., Langhorne PA, unpublished data). This study reports re
sults of 1993 field trials in 3 locations with an oil flowable formulation of ECX9399 for
FAW control in corn, Zea mays L.
MATERIALS AND METHODS
Field experiments were conducted near Athens, GA, and Oktibbeha, MS, in Au
gust and near Groveland, FL, in November. A field corn cultivar (DeKalb 689) was
used in GA, Pioneer Tropical corn was planted in MS, and Silverqueen sweetcorn was
employed in FL. Plots at the 3 locations varied from 1 to 4 rows 6 to 12 m long. A ran
domized complete block experimental design was used with 4 or 5 replications.
Spray applications were made with CO2 sprayers mounted with full-cone spray
tips and calibrated at the rate of 80 to 120 liters per ha. Three applications were made
in the GA (7-day intervals) and MS (4-day intervals) tests and 4 applications (4 to 6
day intervals) were made at the FL site. In each experiment, sprays were applied dur
ing the mid-whorl stage of plant development when moderate FAW infestations were
December, 1994
All et al.: Armyworm Symposium -'94
present in the fields (50% or more plants infested with small larvae). Test materials
included Cutlass" WP (Bt subspecies kurstaki, strain EG2371), Condor OF (Bt sub
species kurstaki, strain 2348, in an oil flowable formulation), ECX9399 OF (oil flow
able formulation), and methomyl (Lannate" LV) (see Table 1 for rates).
Efficacy was determined at selected intervals during and following the spray ap
plications by examining the plants in each plot for defoliation. In MS a visual estimate
of defoliation was made, whereas, in GA and FL a 0 to 8 (GA) or 0 to 10 (FL) rating of
defoliation and whorl injury was made, progressing from 0 to destruction of plants.
Additionally, between 5 and 10 plants in each plot were examined for larvae at se
elected intervals during and after the spray period. They were categorized as small (<8
mm), intermediate (>8-12 mm) and large (>12 mm). To compare the data between lo
cations, the defoliation estimates and larval counts were converted to percent control
by determining the ratio of plant injury or larval counts in the treatment versus the
untreated checks. Analysis of variance and Duncan's new multiple range test were
conducted using a computer based statistical analysis system (SAS User's Guide: Sta
tistics 1985).
RESULTS
The FAW infestations at the 3 locations were moderate to heavy. The data in Table
1 demonstrate that the formulation of the genetically-modified Bt strain ECX9399
produced control comparable to the conventional standard methomyl. Control with Bt
was best in MS, where a 4-day spray interval was used, and least in GA, which had a
7-day schedule. Larval numbers also were significantly reduced on corn treated with
ECX9399, but were statistically different from methomyl and Condor" in GA. In the
MS trial, larval populations were similar in ECX9399 and Condor" plots, and both
were significantly less than in the methomyl treatment. In FL, larval populations
were significantly less in ECX9399 than in Cutlass", but not the methomyl treatment.
TABLE 1. EFFICACY OF SELECTED BTINSECTICIDAL PRODUCTS FOR FAW ON MID-WHORL
STAGE CORN IN 3 LOCATIONS DURING 1993.
% Control'
GA3 MS3 FL3
Insecticide Rate2 Damage Larvae Damage Larvae Damage Larvae
ECX9399 OF 1.6 61.1a 32a 94.8a 79.3a 79.1a 82.9a
Condor" OF 1.6-1.07 32.8bc Oa 92.0a 77.8a
Cutlass WP 1.13 44.9b 27.1b
Methomyl 1.13-0.5 55.6ab Oa 89.5a 27.4b 88.4a 98.1a
'Means followed by the same letter within a column are not significantly different in Duncan's new multiple
range analysis (P < 0.05).
2Rates of ECX9399 OF and Condor OF are presented as volume (in liters) of formulated product per ha, Cut
lass WP as weight (in kg) of formulated product per ha and methomyl (Lannate LV) as weight (in kg) of active
ingredient per ha. Condor was used at a rate of 1.6 liter per ha in GA and 1.07 liter per ha in MS; methomyl
was used at 1.13 kg per ha rate in FL and 0.5 kg per ha at GA and MS.
'Applications in GA were made on a 7-day schedule for 3 sprays, MS was every 4 days for 3 sprays and FL
was every 4 or 6 days for 4 sprays.
Florida Entomologist 77(4)
The FL results were similar to those reported by Teague (1993) for Cutlass" and meth
omyl for FAW control on sweetcorn.
The results show that recombinant DNA technology can be used to improve the
toxicity and specificity of Btto insects such as the FAW. ECX9399 was superior to its
parent strain, EG2348 (Condor"), in controlling FAW populations and damage in
three locations. The fact that ECX9399 produced similar control as methomyl (one of
the most efficacious materials available for FAW (All et al. 1986)) in the experiments
accentuates the potential of genetically-improved Bt strains for insect management.
REFERENCES CITED
ALL, J. N., A. JAVID, AND P. GUILLEBEAU. 1986. Control of fall armyworm with insec
ticides in north Georgia sweetcorn. Florida Entomol. 69: 598-602.
CARLTON, B. C., AND C. GAWRON-BURKE. 1993. Genetic improvement of Bacillus thu
ringiensis for bioinsecticide development, pp. 43 61 in L. Kim [ed.], Advanced
engineered pesticides. Marcel Dekker, Inc., New York.
GARDNER, W. A., AND J. R. FUXA. 1980. Pathogens for the suppression of the fall ar
myworm. Florida Entomol. 63: 439-447.
GAWRON-BURKE, C., AND J. A. BAUM. 1991. Genetic manipulation of Bacillus thuring
iensis insecticidal crystal protein genes in bacteria, pp. 237-263 in J. K. Setlow
[ed.], Genetic engineering. Plenum Press, New York.
KRIEG, A., AND G. A. LANGENBRUCH. 1981. Susceptibility of arthropod species to Ba
cillus thuringiensis, pp. 837-896 in H. D. Burges [ed.], Microbial control of pests
and plant diseases 1970-1980. Academic, New York.
SAS USER'S GUIDE: STATISTICS. 1985. SAS Inst., Cary, NC. 957 pp.
TEAGUE, T G. 1993. Control of fall armyworm in sweet corn with Bacillus thuringien
sis, 1991. Insecticide & Acaricide Tests 18: 127-128.
December, 1994
Florida Entomologist 77(4)
MANAGEMENT OF THE BEET ARMYWORM (LEPIDOPTERA:
NOCTUIDAE) IN COTTON: ROLE OF NATURAL ENEMIES
JOHN R. RUBERSON'3, GARY A. HERZOGz, WILLIAM R. LAMBERT AND W. JOE LEWIS'
'Insect Biology and Population Management Research Laboratory United States
Department of Agriculture, Agricultural Research Service Tifton, GA 31793
Dept. of Entomology, University of Georgia, Tifton, GA 31793
3Current address: Dept. of Entomology, University of Georgia,
P.O. Box 748, Tifton, GA 31793
ABSTRACT
The beet armyworm, Spodoptera exigua (Hubner), has recently become a persis
tent and explosive pest of cotton in the southeastern United States. It is, however, at
tacked by a large and diverse complex of beneficial arthropods and pathogens that
appear capable of maintaining beet armyworm populations below economically-dam
aging levels. Disruption of this complex contributes to outbreaks of S. exigua. It can
This article is from Florida Entomologist Online, Vol. 77, No. 4 (1994).
FEO is available from the Florida Center for Library Automation gopher (sally.fcla.ufl.edu)
and is identical to Florida Entomologist (An International Journal for the Americas).
FEO is prepared by E. O. Painter Printing Co., P.O. Box 877, DeLeon Springs, FL. 32130.
December, 1994
Ruberson et al.: Armyworm Symposium -'94
also exacerbate problems with other pests because the complex of beneficial organ
isms attacking the beet armyworm is comprised of generalist species that also sup
press other pests in the cotton production system. Management of the beet armyworm
through conservation of its natural enemies, therefore, provides multiple benefits to
growers by managing other pests as well.
Key Words: Beet armyworm, cotton, biological control, Spodoptera exigua, parasitoid,
predator
RESUME
El gusano trozador de la remolacha, Spodoptera exigua, recientemente se ha con
vertido en una plaga persistent y explosive del algod6n en el sureste de los Estados
Unidos; sin embargo, es atacado por un complejo grande y divers de artr6podos tiles
y pat6genos que parece ser capaz de mantener las poblaciones del gusano de la remo
lacha por debajo de los niveles de dano econ6mico. La alteraci6n de este complejo fa
vorece la aparici6n de brotes del gusano trozador, pero tambien puede aumentar los
problems con otras plagas porque el complejo de los organismos tiles que atacan el
gusano de la remolacha esta compuesto de species generalistas que tambien pueden
suprimir otras plagas en el sistema de producci6n del algod6n. Por lo tanto, el manejo
del gusano de la remolacha mediante la conservaci6n de sus enemigos naturales tam
bien ofrece beneficios multiples a los granjeros en el manejo de otras plagas.
The beet armyworm, Spodoptera exigua (Hiibner), is an introduced pest of number
ous crops in the United States. It appears to be a native of southern Asia, although its
origin is presently unclear. It was first reported in the United States with the collec
tion of specimens in Oregon and California in 1876 (Harvey 1876). The insect dis
persed across the country and was established in Florida by the late 1920s, where it
was recorded feeding only on asparagus fern, gladiolus, and grasses (Wilson 1932). In
the years since its introduction, the beet armyworm has become progressively more
pestiferous in the United States on an increasingly wide range of crop plants (see
Pearson 1982). Its current recorded host range in North America exceeds 90 plant
species, including numerous important crop species such as corn, cotton, soybeans,
peanuts, cabbage, tomatoes, and peppers (Pearson 1982). The bases for this apparent
host range expansion are presently unclear; the changes suggest that this insect has
considerable phenotypic plasticity in its host range [and likely genotypic, as is the
case with the fall armyworm, Spodoptera frugiperda (Pashley, pers. comm.)] and thus
it may become an increasingly widespread pest in the future.
In addition to its broad host range, there are several facets of S. exiguas biology
that may predispose it to being an explosive pest. First, S. exigua has a relatively brief
developmental time under field conditions (Ali & Gaylor 1991), permitting rapid cy
cling of generations. Second, it has a high reproductive capacity, with average calcu
lated fecundities ranging from 604.7 to 1724.7 eggs per female (Wilson 1934, Hogg &
Gutierrez 1980, Chu & Wu 1992). A simple calculation illustrates this point. Assum
ing a population sex ratio of 1 female to 1 male, a realized field fecundity of 200 eggs
(approx. 2 egg masses) per female, and restricted emigration and immigration, 99%
mortality within a generation would be necessary to simply maintain the population
at a constant size. Thus, suppression of this pest requires high levels of mortality to
counterbalance its high fecundity. Third, these insects are highly mobile and are thus
capable of colonizing wide-ranging areas (French 1969, Mitchell 1979). Finally, insec
Florida Entomologist 77(4)
ticides typically provide less than adequate control (e.g., Cobb & Bass 1975, Meinke
& Ware 1978, Brewer & Trumble 1989, Wolfenbarger & Brewer 1993). This is due, at
least in part, to the insect's innate tolerance of many insecticidal materials at recom-
mended field rates. But the beet armyworm's ovipositional and feeding biology also in
fluences insecticide efficacy. Females oviposit eggs in masses of 46 to 230 eggs (x+ SD
S99.4 40.6; n = 75 field-collected egg masses; J.R.R. unpubl.), typically on the un
dersurface of leaves in the lower plant canopy Insecticide coverage is often inade
quate in these areas, particularly after the canopy has expanded. Further, beet
armyworm larvae feed in groups through the first and second instars, then disperse
as third instars (Poe et al. 1973). This feeding behavior concentrates a large proper
tion of the population into a relatively small area during the period when the larvae
are most susceptible to insecticides. Thus, to kill a sufficient number of larvae to at
tain control, the material must contact a relatively small proportion of the plant can
opy in the plant region most difficult to cover -a very difficult proposition when the
plants are large and the canopy is closed.
Despite its pestiferous potential, the beet armyworm has been historically a spo
radic and minor pest of cotton in the southeastern United States (Smith 1989). In re
cent years, however, it has become a persistent and serious cotton pest in the
southeastern and mid-southern United States, especially in regions conducting the
Boll Weevil Eradication Program (e.g., Fig. 1). However, the current ubiquity and con
sistency of the outbreaks, both inside and outside of active eradication zones, suggest
that this pest has become a more widespread and serious cotton pest for reasons in
dependent of the Boll Weevil Eradication Program. However, this program likely pro
vides a ready opportunity for the beet armyworm to escape natural controls.
5
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a.
0 -
1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
Year
Fig. 1. Number of specific beet armyworm insecticide treatments applied per acre
of cotton production in the state of Georgia from 1980 to 1992. "BWEP", demarcated
by the vertical dashed lines, indicates the period when the Boll Weevil Eradication
Program was in its active phase in the state.
December, 1994
Ruberson et al.: Armyworm Symposium '94
Regardless of the cause, it is critical at this juncture to devise efficacious, biorational
pest management approaches.
Natural enemies appear to be a key element in the management of the beet army
worm. In 1973, Eveleens et al. demonstrated that beet armyworm outbreaks could be
induced by applications of organophosphate insecticides in cotton. Cotton can support
a large and diverse complex of beneficial arthropods (Whitcomb & Bell 1964, van den
Bosch & Hagen 1966) and in production systems receiving multiple treatments of
highly toxic materials, such as organophosphates and pyrethroids, these complexes
can be seriously disrupted for the remainder of the growing season. Subsequently, in
the absence of the beneficial arthropods, production of an acceptable crop will require
continued, repeated use of insecticides. The Boll Weevil Eradication Program relies on
widespread, repetitive applications of organophosphates to suppress and eventually
eliminate boll weevil populations (USDA-APHIS 1991).These treatments have a pro
found detrimental impact that releases beet armyworm populations from their natu
ral biological control agents (e.g., Wilkinson et al. 1979).
NATURAL ENEMIES OF THE BEET ARMYWORM
The large number of predators and parasitoids that have been found associated
with beet armyworm eggs and larvae are listed in Tables 1 and 2. This complex of nat
ural enemies differs among various geographic regions; however, there are common
linkages. Several parasitoid species, for example, have been found across the cotton
belt, including the braconids Cotesia marginiventris, Meteorus autographae, Chelo
nus insularis, the ichneumonid Temelucha sp., and the tachinid Lespesia archip
pivora (Table 2). Their relative abundance and efficacy, however, vary among regions.
Similarly, several genera of predators are shared across the cotton belt. It is notewor
thy that the most commonly encountered natural enemies of the beet armyworm in all
regions are generalists that attack a variety of hosts in multiple habitats. Given that
the beet armyworm is an introduced pest, such a pattern is to be expected in the ab
sence of specific imported biological control agents.
In addition to predators and parasitoids, several pathogens have also been recov
ered from the beet armyworm. A nuclear polyhedrosis virus has been widely reported
(Oatman & Platner 1972, Eveleens et al.1973, Pearson 1982, Kolodny-Hirsch et al.
1993). Fungal pathogens, however, can also be important. Wilson (1933) reported that
a fungus, described at the time as Spicaria prasina (probably Nomuraea rileyi), deci
mated populations of beet armyworm larvae during wet weather. In our studies in
Georgia, we have observed larvae infected with the fungi Erynia sp. nr. pieris (identi
fled by Dr. Donald Steinkraus, Univ. of Arkansas) and N rileyi. Of these two species,
Erynia was the most commonly encountered.
Despite the large number of natural enemies cataloged to date, there are few data
to demonstrate their impact on beet armyworm populations. Eveleens et al. (1973)
demonstrated in California that beet armyworm outbreaks could be induced by appli
cations of organophosphate insecticides, which presumably disrupt the natural en
emy complex. They suggested that predators were the most important mortality
agents for the beet armyworm populations in their study, and that the greatest loss
occurred in the egg and early larval stages. Hogg & Gutierrez (1980) also observed
high rates of loss for eggs and small larvae of the beet armyworm in cotton in Califor
nia and also attributed much of this loss to predators.
De Clercq & Degheele (1994) recently demonstrated in the laboratory that the na
tive predaceous pentatomid Podisus maculiventris can consume large numbers of all
stages of beet armyworm. It is, however, particularly destructive to eggs (ranging
from 53.5 eggs consumed during the second instar to 111.6 eggs consumed per day by
Florida Entomologist 77(4)
TABLE 1. PREDATORS OBSERVED IN ASSOCIATION WITH BEET ARMYWORM EGGS OR
YOUNG LARVAE IN THE UNITED STATES.
State
Taxon/Species Association' Location References
Dermaptera
Labidura riparia
Heteroptera
Orius insidiosus
Orius tristicolor
Geocoris pallens
Geocoris punctipes
Geocoris uliginosus
Podisus maculiventris
Nabis roseipennis
Nabis americoferus
Zelus sp.
Sinea sp.
Neuroptera
Chrysoperla carnea
Chrusoperla refilabris
Hemerobius sp.
Coleoptera
Collops
Notoxus calcaratus
Coccinella septempunctata
Hymenoptera
Polistes fuscatus
Solenopsis invicta
Arachnida
Unidentified (3 species)
Unidentified
E, L Georgia Ruberson et al. 1994
E, L Georgia Ruberson et al. 1994
E, L California Eveleens et al. 1973; Hogg
and Gutierrez 1980
E, L California Eveleens et al. 1973; Hogg
and Gutierrez 1980
E, L Georgia Ruberson et al. 1994
E, L Georgia Ruberson et al. 1994
L Florida Wilson 1933;
Georgia Ruberson et al. 1994
L Georgia Ruberson et al. 1994
E. L California Eveleens et al. 1973
E, L Georgia
California
E, L California
Ruberson et al.
Eveleens et al.
Eveleens et al.
E, L California Eveleens et al. 1973; Hogg
and Gutierrez 1980
E, L Georgia Ruberson et al. 1994
E, L Georgia Ruberson et al. 1994
E, L California
E, L California
E Georgia
Eveleens et al. 1973
Eveleens et al. 1973
Ruberson et al. 1994
L Florida Wilson 1933
E, L Georgia Ruberson et al. 1994
L Georgia Ruberson et al. 1994
California Eveleens et al. 1973
1Stage association indicates with which stages of beet armyworm the predators were found; E = eggs and L =
larvae.
adult female predators) and small larvae. Also, most life stages of beet armyworm are
reportedly suitable prey for predator development. These data provide a glimpse into
the possible impact of predators on beet armyworms, although P maculiventris ap
pears to be only a small, and inconsistent, part of the total natural enemy complex in
the field. The overall impact of natural enemies in the field, however, is poorly delin
December, 1994
Ruberson et al.: Armyworm Symposium -'94
TABLE 2. PARASITOIDS OF BEET ARMYWORM EGG AND LARVAE RECORDED IN THE
UNITED STATES.
Stages
Taxon/Species Attacked' Location References
Diptera: Tachinidae
Lespesia archippivora
Eucelatoria armigera
Eucelatoria rubentis
Eucelatoria sp. nr. armigera
Winthemia rufopicta
Archytas californiae
Archytas apicifer
Archytas marmoratus
Voria ruralis
Chaetogodia monticola
Gonia crassicornis
Hymenoptera: Braconidae
Cotesia marginiventris
Cotesia laeviceps
Cotesia militaris
Meteorus autographae
Meteorus leviventris
Meteorus rubens
Meteorus laphygmae
L1 L5 California van den Bosch & Hagen
1966; Henneberry et al.
1991; Eveleen et al. 1973
Texas Harding 1976
Oklahoma Soteres et al. 1984
Georgia Ruberson et al. 1993
California van den Bosch & Hagen
1966; Henneberry et al.
1991
Florida Wilson 1933; Tingle et al.
1978
California
Florida
California
California
Georgia
California
Hawaii
Florida
Henneberry et al. 1991
Tingle et al. 1978
Eveleens et al. 1973
Henneberry et al. 1991
Ruberson et al. 1994
Eveleens et al. 1973
Swezey 1935
Wilson 1933
L1 L4 California van den Bosch & Hagen
1966; Pearson 1982;
Henneberry et al. 1991
Oklahoma Soteres et al. 1984
Florida Wilson 1933; Tingle et al.
1978
Georgia Ruberson et al. 1993
U.S. Krombein et al. 1979
No. America Krombein et al. 1979
L1 L4 Florida Wilson 1933; Tingle et al.
1978
Georgia Ruberson et al. 1993
Texas Harding 1976
Texas van den Bosch & Hagen
1966; Harding 1976
California Henneberry et al. 1991
Krombein et al. 1979
,Stages attacked" signifies larval instars (L1-L5) and eggs (E) susceptible to parasitization by the respective
parasitoids.
2Oviposits in eggs and emerges from the late larval stages.
Florida Entomologist 77(4)
TABLE 2.(CONTINUED) PARASITOIDS OF BEET ARMYWORM EGG AND LARVAE RECORDED
IN THE UNITED STATES.
Stages
Taxon/Species Attacked' Location References
Chelonus insularis E L52 California van den Bosch & Haeen
Texas
Oklahoma
Florida
Aleiodes laphygmae
Cremnops haemotodes
Zele melea
Hymenoptera: Ichneumonidae
Hyposoter exiguae
Hyposoter annulipes
Pristomerus spinator
Campoletis argentifrons
Campoletis flavicincta
Campoletis sonorensis
Temelucha sp.
Nepiera fuscifemora
Ophion sp.
Therion longipes
Rubicundiella perpturbatrix
Sinophorus caradrinae (?)
Georgia
L1-L3 Georgia
California
Oklahoma
1966; Eveleens et al.
1973; Pearson 1982;
Henneberry et al. 1991
Harding 1976
Soteres et al. 1984
Wilson 1933; Tingle et al
1978
Ruberson et al. 1993
Ruberson et al. 1993
Henneberry et al. 1991
Soteres et al. 1984
L1 L3 California van den Bosch & Hagen
1966; Eveleens et al.
1973; Pearson 1982;
Henneberry et al. 1991
U.S. Krombein et al. 1979
L1-L3 California Eveleens et al. 1973;
Pearson 1982; Hen
neberry et al. 1991
Oklahoma Soteres et al. 1984
U.S. van den Bosch & Hagen
1966
L1 L3 Georgia Ruberson et al. 1993
L1 L3 U.S. Krombein et al. 1979
Oklahoma Soteres et al. 1984
California Pearson 1982; Hen
neberry et al. 1991
Florida Tingle et al. 1978
West U.S. Krombein et al. 1979
Georgia Ruberson et al. 1993
California van den Bosch & Hagen
1966; Eveleens et al. 1973
West U.S. van den Bosch & Hagen
1966; Krombein et al. 1979
Colorado Krombein et al. 1979
"Stages attacked" signifies larval instars (L1-L5) and eggs (E) susceptible to parasitization by the respective
parasitoids.
2Oviposits in eggs and emerges from the late larval stages.
December, 1994
Ruberson et al.: Armyworm Symposium '94
TABLE 2.(CONTINUED) PARASITOIDS OF BEET ARMYWORM EGG AND LARVAE RECORDED
IN THE UNITED STATES.
Stages
Taxon/Species Attacked' Location References
Hymenoptera: Eulophidae
Euplectrus plathypenae L3-L5 Florida Wilson 1933
Hymenoptera:
Trichogrammatidae
Trichogramma spp. E California van den Bosch & Hagen
1966
"Stages attacked" signifies larval instars (L1-L5) and eggs (E) susceptible to parasitization by the respective
parasitoids.
2Oviposits in eggs and emerges from the late larval stages.
eated and/or entirely unknown in the southeastern U.S. where beet armyworm prob
lems have recently been most severe.
IMPACT OF NATURAL ENEMIES ON BEET ARMYWORM POPULATIONS IN GEORGIA
We have undertaken various field studies in Georgia in an effort to characterize
mortality factors and levels for beet armyworm populations.These studies have fo
caused on two areas: 1) characterization and quantification of beet armyworm parasi
toids and pathogens, and 2) determination of their impact on survival of eggs, small
larvae, and pupae.
Larval Mortality: Impact of Parasitoids and Pathogens
Beet armyworm larvae of all ages were sampled from commercial cotton fields in
Georgia in 1992 and 1993 (see Ruberson et al. 1993 for details). Collections were made
on various dates from 15 July to 16 September in 1992 and from 24 May to 12 October
in 1993. Totals of 7,545 and 7,072 larvae were collected in 1992 and 1993, respectively
The parasitoids reared from these larvae (in relation to instar collected) are presented
in Table 3, with rates of parasitism by each species. The parasitism rates for the two
years, pooled across larval instars and collection locales, were 46.8% and 40.2% in
1992 and 1993, respectively. The majority of parasitism, and resultant larval mortal
ity, occurred in the early instars. In both years, C. marginiventris was the predomi
nant species, and it accounted for more of the parasitism in 1993 than it did in 1992,
particularly in the second and third instars (Table 3). This contrasts with results from
California indicating that the tachinid L. archippivora and the braconid C. insularis
were the most important parasitoids in cotton and alfalfa, respectively (Henneberry
et al. 1991, and Pearson 1982, respectively). Soteres et al. (1984) also found C. insu
laris to be the most common parasitoid attacking beet armyworms in alfalfa in Okla
homa. C. marginiventris, however, is the dominant parasitoid of beet armyworm
larvae from pigweed in Florida (Tingle at al. 1978). Thus, C. marginiventris appears
to be the more dominant species in the eastern half of the United States, whereas C.
insularis is more dominant in the west.
Cotesia marginiventris is highly attracted to plants damaged by beet armyworm
feeding (e.g., Turlings et al. 1991), and this response is intensified by the clumped
Florida Entomologist 77(4)
TABLE 3. PARASITISM RATES (%) IN POPULATIONS OF BEET ARMYWORM LARVAE COL
ELECTED IN GEORGIA COTTON IN 1992 AND 1993. LARVAE WERE COLLECTED
FROM BARTOW, BEN HILL, DECATUR, DOOLY, LAURENS, MILLER, SEMI
NOLE, AND TIFT COUNTIES.
% Parasitism of Beet Armyworm Larval Instar'
Parasitoid 1 2 3 4 5
1992
Cotesia marginiventris 37.0 37.5 37.0 3.4 1.5
Aleiodes laphygmae 0.06 0.6 0.3 0.0 0.0
Meteorus autographae 4.7 10.6 7.6 3.4 0.0
Chelonus insularis 0.6 0.9 0.9 2.0 0.0
Lespesia archippivora 0.07 0.8 2.2 4.1 3.3
Ichneumonidae2 1.0 0.4 1.3 0.3 8.2
Unknown parasites 0.2 0.5 1.3 1.0 0.0
Total % parasitism 43.6 51.2 50.6 14.2 13.0
No. larvae collected 2977.0 2701.0 1512.0 294.0 61.0
1993
Cotesia marginiventris 35.8 58.5 63.4 2.9 0.2
Aleiodes laphygmae 0.0 0.8 0.0 0.0 0.0
Meteorus autographae 0.0 0.1 0.7 0.1 0.0
Cardiochiles nigriceps 0.0 0.0 0.1 0.0 0.0
Pristomerus spinator 0.0 0.3 0.9 0.8 0.0
Lespesia archippivora 0.02 0.3 0.8 0.6 2.2
Archytas marmoratus 0.0 0.0 0.03 0.5 0.5
Unknown parasites 0.02 0.1 1.1 0.4 0.8
Total % parasitism 35.8 60.1 67.0 5.3 3.7
No. larvae collected 2914.0 1542.0 1207.0 768.0 641.0
Instar of larvae at time of collection.
Includes Campoletis sonorensis, Pristomerus spinator, and Ophion sp.
feeding behavior of the beet armyworm larvae on cotton plants [A. Datema (Wagenin
gen, The Netherlands), J.R.R., and W.J.L., unpubl.]. This parasitoid, therefore, is
highly-attuned to locating clusters of beet armyworm larvae. It is, however, suscepti
ble to several organophosphate and pyrethroid insecticides (Wilkinson et al. 1979, Ru
berson et al. 1993), which could limit its efficacy in conventional, chemical-intensive
cotton production.
Several pathogens were also recovered from larvae collected in the field, although
disease did not appear to be a substantial mortality factor. The most commonly-en
countered pathogen was the fungus Erynia sp. nr. pieris (determined by Dr. Donald
Steinkraus, Univ. of Arkansas), which killed 6.2% of the larvae collected in 1992, but
only 0.3% of those collected in 1993 (there was exceptionally little rain that year). A
few specimens collected in 1992 were infected with N. rileyi, but no N. rileyi was ob
served in 1993. A nuclear polyhedrosis virus was found in 1.8% of the larvae collected
December, 1994
Ruberson et al.: Armyworm Symposium -'94
in 1992 and in 0.1% of the larvae in 1993. In addition, a single larva infected with an
ascovirus (determined by Dr. John J. Hamm, USDA-ARS, Tifton GA) was collected in
1992. The senior author and J.J. Hamm (USDA-ARS, Tifton, GA) found this virus to
be a poor pathogen of beet armyworm larvae in laboratory tests.
Overall parasitoid and pathogen-related mortality from our collections ranged
from approximately 40 to 50%. These overall rates were generally higher than those
observed in the California studies noted above (Pearson 1982, Henneberry et al.
1991). However, Pearson (1982) did observe comparable parasitism levels for larvae
on alfalfa in the late summer and early fall in Imperial Valley. This level of mortality
comprises a relatively high level of loss in the population, but is well below the 99%
needed to maintain or suppress the pest population.
Impact of Predation on Eggs, Larvae, and Pupae.
Two studies were undertaken to examine loss of beet armyworms in the field. The
first examined the rate of loss for eggs and small larvae to assess loss prior to, and in
the initial periods of susceptibility to parasitization. The second study addressed the
loss of beet armyworm pupae in the soil.
Egg/Larvae Predation. The study to determine egg/larval losses was conducted
from 16 to 27 August, 1993, in cotton plots in Tift County, Georgia. Beet armyworm
egg masses (approximately 100 eggs each), laid on wax paper, were attached to the
undersides of leaves in each of four 0.5 acre plots. Two of the plots received weekly ap
plications of conventional insecticide (the pyrethroid 1-cyhalothrin) beginning the first
week in July, whereas the other plots were untreated. Insecticide was applied in the
treated plots immediately prior to, and twice during, the experiment. Twenty-four egg
masses were placed in each plot (approximately 1 per 1000 plants; action threshold is
2-3 per 100 plants). Egg masses were observed daily for hatching and for indications
of predation. After hatching, the wax paper was removed, surviving larvae were ob
served and counted 2, 4, 6, and 8 days post-hatch, and the presence and identity of
predators on the leaves near the larval groups were recorded.
High rates of loss were noted for egg masses exposed to predators in both the
treated and untreated cotton, although loss was faster in the absence of insecticides
(Table 5). Twice as many egg masses were entirely destroyed in the untreated cotton,
however, as in the treated cotton. Most of the loss occurred in the egg and early-larval
stages, as was suggested by Eveleens et al. (1973) and Hogg & Gutierrez (1980). We
attribute this loss to predator activity. Thus, survival of beet armyworms was en
hanced in the insecticide-treated plots.
More predators were observed in association with the beet armyworm eggs and
larvae in the untreated cotton than in the treated cotton (Table 4). For example, only
larvae of the green lacewing, Chrysoperla rufilabris were found associated with beet
armyworm eggs in the treated plots, compared with 11 different predators in the un
treated plots. Thus, insecticide treatments disrupted a major portion of the beneficial
arthropod complex.
Two constraints limit the general applicability of these data concerning predation
of beet armyworms. First, the plots were small, and widespread recolonization of
treated plots by predators from adjacent untreated areas would be more rapid in
these plots than would be the case for large cotton fields. Second, the density of beet
armyworm egg masses placed in the plots was very low, which provided an excellent
opportunity for the resident beneficial populations to eliminate them.However, this
second point has some positive ramifications. Our data suggest that a conserved pred
ator complex is capable of greatly reducing, and perhaps eliminating, low populations
of the beet armyworm. Thus, the predator complex may be invaluable for eliminating
Florida Entomologist 77(4)
TABLE 4. PREDATORS, AND THEIR FREQUENCY, FOUND IN ASSOCIATION WITH BEET AR
MYWORM EGGS AND LARVAE IN TREATED (PYRETHROID INSECTICIDE) AND
UNTREATED COTTON (16-27 AUGUST 1993; TIFT. CO., GEORGIA).'
Predator Taxon/Species Untreated Cotton Treated Cotton
Heteroptera
Orius insidiosus E (5, 8) L (2, 3) E (0, 0) L (3, 3)
Geocoris punctipes E (2, 3) L (3, 3) E (0, 0) L (0, 0)
Geocoris uliginosus E (1, 1) L (1, 1) E (0, 0) L (0, 0)
Nabis roseipennis E (1, 1) L (2, 3) E (0, 0) L (0, 0)
Zelus sp. E (1, 2) L (1, 1) E (0, 0) L (0, 0)
Posisus maculiventris E (1, 1) L (1, 1) E (0, 0) L (0, 0)
Dermaptera
Labidura riparia E (1, 1) L (2, 4) E (0, 0) L (0, 0)
Coleoptera
Coccinella 7punctata E (0, 0) L (1, 1) E (0, 0) L (1, 1)
Neuroptera
Chrysoperla rufilabris E (2, 2) L (5, 7) E (2, 2) L (0, 0)
Hemerobius sp. E (1, 1) L (0, 0) E (0, 0) L (1, 2)
Diptera
Syrphid E (0, 0) L (1, 1) E (0, 0) L (0, 0)
Hymenoptera
Solenopsis invicta E (3, 24) L (3, 16) E (0, 0) L (3, 21)
Araneida
Spiders E (1, 1) L (1, 1) E (0, 0) L (0, 0)
Totals E (19, 45) L (23, 42) E (2, 2) L (8, 27)
E = egg masses, L = larval clutches. The numbers in parenthesis after each letter are, respectively, 1) the
number of egg masses or larval clutches on which the predator was found, and 2) the total number of the pred
ator taxon observed in association with beet armyworm eggs or larvae.
incipient beet armyworm populations, at least until sufficient egg and larval popular
tions are present in the field to outstrip the predators' capacity to consume a substan
tial majority of the eggs and larvae.
Pupal Mortality. We examined loss in the pupal stage by placing ultimate-instar
beet armyworm larvae under a styrofoam cup, with an opened, 30-ml diet cup con
training artificial diet and a larva on the soil surface. Larvae were placed in two plots
(100 per plot) of each of two treatments, insecticide-treated and unsprayed. A styro
foam collar (9 cm diam) into which the covering cup fit snugly was forced into the
ground until its rim was level with the soil surface (about 6 cm). This prevented es
cape of the larvae because beet armyworms pupate in the upper 2-3 cm of soil. The
opened diet cup with larva was then placed inside the collar and a styrofoam cup,
which fit snugly into the collar, was placed over the cup with the insect. After the lar
vae had entered the soil and pupated, the covering cups were removed to expose the
pupation sites to biotic and abiotic conditions in the field. Twenty additional cups and
larvae were set up, with the covering cups left in place to trap the adult moths at
emergence. These sentinel larvae were observed every day for adult emergence. When
December, 1994
Ruberson et al.: Armyworm Symposium '94
TABLE 5. LOSS OF BEET ARMYWORM EGG MASSES, EGGS AND LARVAE IN TREATED AND
UNTREATED COTTON (MEAN SD; 16-27 AUGUST, 1993.)
No. Egg Masses Remaining No. Larvae Remaining/Egg Mass
Days of
Exposure Treated Untreated Treated Untreated
0 24 +0.0 24 +0.0 97.0 + 9.07 100.5 +9.01
H'+2 23.0+ 1.4 15.0 +4.2 18.6 +18.1 18.2+ 13.4
H+4 17.0 +0.0 10.0 +2.8 15.1 + 14.6 13.7+ 11.7
H+6 9.0+ 1.4 4.5 +0.7 11.3+ 15.5 6.0 +3.8
H+8 4.0+ 1.4 0.5 +0.7 3.5 + 2.8 1.0+0.0
"H" refers to hatch. Thus "H+2" means 2 days after egg hatch.
adult emergence was complete in the sentinel cups, all pupation sites were excavated,
and the status of the pupal remains determined.
Loss of pupae was surprisingly high in both treatments. Only 42.3% + 2.12 (SD) of
the pupae produced adult moths in the treated plots, compared with 21.0% + 0.28 pu
pae surviving to adult emergence in the untreated plots. Thus, loss in the untreated
plots was twice that observed in the insecticide-treated plots, although both treat
ments sustained fairly high mortality.
Much of the loss observed in the experiment may be attributable to activity of im
ported fire ants, Solenopsis invicta. Fire ants were abundant in both fields, although
they appeared to be more common in the untreated cotton than in the treated plots.
Fire ants were observed removing pupal parts from pupation sites during the expert
iment; such sites afterward yielded no signs of pupal remains when excavated.
CONCLUSIONS
Although some of the results reported above are preliminary, summing up all of
the mortality factors and their impacts yields a mortality rate in excess of 99% in un
treated cotton. This suggests that the natural enemy complex functioning in cotton
has the capacity to suppress beet armyworm populations. This conclusion, suggested
by the California research reviewed above, points to the necessity of conserving the
natural enemies for effective suppression of the beet armyworm. The completion of
the active phase of the Boll Weevil Eradication Program in most of Georgia has pro
vided the cotton production system an enormous opportunity to utilize natural ene
mies. In the absence of early-season applications of organophosphate insecticides to
control the boll weevil, the natural enemy populations are able to increase in the cot
ton crop, and use of selective insecticides on a strictly as-needed basis will permit
growers to realize the full benefits of these natural enemies. Under this system, the
beet armyworm should not be a serious pest, except in cases where other pest control
approaches disrupt the complex of resident beneficial organisms. Growers will reap
benefits, however, beyond the natural control of beet armyworm populations. The
complex of natural enemies that attacks the beet armyworm is comprised of general
ists that will also provide some level of suppression of other arthropod pests in the
system, as well, and benefit the overall cotton insect management program.
Florida Entomologist 77(4)
ACKNOWLEDGMENTS
We appreciate the assistance of Eddie McGriff (Decatur Co.), Mark Mitchell (Sem-
inole and Miller Cos.), Jack Wall (Dooly Co.), and Mark Crosby (Laurens Co.) in locat
ing fields for larval collections. Ray Wilson, Daniel West, Elizabeth Cravey, Wes
Shiver, and Russ Ottens helped collect larvae and assisted with various aspects of the
experiments. We greatly appreciate the determinations of the parasitoid species by
Drs. R. W. Carlson (Ichneumonids), E. E. Grissell (Chalcididae), P M. Marsh (Bra
conids), and N. E. Woodley (Tachinids). The comments of Drs. Robert M. McPherson
(Univ. of Georgia) and Robert Lynch (USDA-ARS) on the manuscript are also appre
ciated.
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CHU, Y., AND H. WU. 1992. The studies on emergence, copulation and oviposition of
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Florida Entomologist 77(4)
BEET ARMYWORMS (LEPIDOPTERA: NOCTUIDAE) IN
NORTHEAST LOUISIANA: OBSERVATIONS ON AN
UNCOMMON INSECT PEST
E. BURRIS, J.B. GRAVES, B.R. LEONARD, AND C.A. WHITE
Louisiana State University Agricultural Center, Baton Rouge, Louisiana
ABSTRACT
Outbreaks of beet armyworm, Spodoptera exigua (Hubner), in cotton in Louisiana
occurred in 1983, 1988, 1992 and 1993. The outbreaks generally followed historic pat
terns observed in other locations, i.e., (1) local endemic populations developed rapidly
for one or two generations when climatic conditions were favorable and (2) biological
control organisms were suppressed by pesticides. Outbreaks of beet armyworm in
Louisiana usually are less severe than in other southeastern states, because popular
tions are usually lower and they occur in the latter part of the growing season. In
1993, beet armyworms infested more ha and caused higher levels of economic damage
in Louisiana than in prior years. Insecticide screening tests conducted in 1993 indi
cated that Pirate (AC 303630) was more efficacious compared to all other insecticides.
Beet armyworm larvae (2nd-3rd instar) were confined to Monsanto transgenic Bacil
lus thuringiensis (Bt) cotton (line 1076) and untreated Coker 312 in the laboratory. No
significant (P<0.05) differences in leaf area consumed, mortality or pupal weights
were detected.
Key Words: Beet armyworm, Spodoptera exigua, cotton, insecticides
RESUME
Brotes del gusano trozador de la remolacha, Spodoptera exigua (Hubner),
ocurrieron en el algoddn de Louisiana en 1983, 1988, 1992 y 1993. Los brotes
generalmente siguieron los patrons histdricos observados en otras localidades, o sea,
que (1) las poblaciones locales end6micas se desarrollaron rapidamente en una o dos
generaciones cuando las condiciones climaticas fueron favorables y (2) los enemigos
naturales fueron eliminados por los pesticides. Los brotes del gusano trozador de la
remolacha en Louisiana usualmente son menos severos que en otros estados del
sureste, porque sus poblaciones son menores y aparecen al final de la estacidn. En
1993, los gusasnos trozadores de la remolacha infestaron mas hectareas y causaron
mas dano econ6mico en Louisiana que en los anos anteriores. Las pruebas de tamizaje
de insecticides llevadas a cabo en 1993 indicaron que Pirate (AC 303630) fue mas
eficaz en comparaci6n con otros insecticides. En el laboratorio fueron confinadas
larvas del gusano trozador de la remolacha (2 y 3" instar) con algod6n Monsanto
transg6nico de Bacillus thuringiensis (Bt) (linea 1076) y Cocker 312 sin tratar. No
fueron detectadas diferencias significativas (P<0.05) en el area de hojas consumida,
mortalidad o peso pupal.
Beet armyworms, Spodoptera exigua (Hubner), were introduced into the western
U.S. in the late 19th century (Chittenden 1902). They dispersed rapidly across the
U.S. and, by the late 1920's, they were recognized as a sporadic pest of cotton in the
Southeastern U.S. (Wilson 1932).
The earliest preserved beet armyworm specimens from Louisiana in the LSU De
apartment of Entomology museum were collected in Baton Rouge. One specimen was
collected from broadbean on 6 January 1932 and another from turnip on 29 Septem
ber 1937 (Joan B. Chapin, Dept. of Entomology, LSU Agricultural Center, Baton
Rouge, personal communication). Light trap collections of noctuids in Baton Rouge
This article is from Florida Entomologist Online, Vol. 77, No. 4 (1994).
FEO is available from the Florida Center for Library Automation gopher (sally.fcla.ufl.edu)
and is identical to Florida Entomologist (An International Journal for the Americas).
FEO is prepared by E. O. Painter Printing Co., P.O. Box 877, DeLeon Springs, FL. 32130.
December, 1994
Burris et al: Armyworm Symposium -'94
from the years 1957 through 1960 revealed that beet armyworm moths were captured
from 27 March through 6 December (Chapin & Callahan 1967). Beet armyworm lar
vae were collected from cole crops (Brassicae) in mid-December (date unknown) in Ba
ton Rouge (Oliver & Chapin 1981).
Outbreaks of beet armyworm are reported to be sporadic, occurring roughly every
2-5 years (Rabb & Kennedy 1979). These outbreaks typically occur one or two gener
nations after favorable climatic conditions are accompanied by suppression of biologi
cal control agents by pesticides used for control of other pests.
In Florida, no evidence of hibernation has been observed, and all stages of the in
sect are found throughout the year (Smith 1993). The ability of beet armyworms to
overwinter is limited by frost kills of host plants and by temperatures below 10C
(Butler et al. 1976). Whether or not the beet armyworm hibernates and/or overwin
ters in Louisiana is unknown. Average daily minimum temperatures (1931-1980) for
the Northeast Research Station at St. Joseph for January, February, March, are re
spectively 3.0, 4.2 and 7.8'C (Thompson et al. 1983). Therefore, during most years,
cold temperatures in Northeastern Louisiana may cause high mortality of beet army
worms.
Other deterrents to population growth of beet armyworms in Louisiana may exist.
For example, they are polyphagous feeders that damage vegetable crops, ornamentals
and field crops, and commercial production of ornamentals and vegetable crops within
the major cotton production regions in Louisiana is limited.
Several private agricultural consultants have annually reported problems with
beet armyworms in isolated fields in Northeast Louisiana. This suggests a need for
studies of migration and/or overwintering biology of beet armyworm in this area.
Their scouting records show armyworm egg masses (fall armyworm, Spodoptera fru
giperda (J.E. Smith) or beet armyworm) were found in August of 1980, 1983 and 1985,
and in July of 1988 and 1990. The 1988 beet armyworm outbreaks in Louisiana oc
curred within two days of severe outbreaks in Alabama (Ed Jones Consulting Service,
Rayville Louisiana, personal communication). In 1993, the first beet armyworm egg
masses were observed in June (Ray Young, Young Consulting Service, Wisner, Louisi
ana, personal communication).
Beet armyworm outbreaks in Louisiana have generally followed the patterns ob
served in other major cotton producing states in the Southeastern U.S [Alabama
(Smith 1985, 1989a, 1989b, 1993, 1994), Georgia and Mississippi], except that the
percent of the total cotton ha infested is usually lower (Head 1989 1992). An exception
occurred in 1993 in Louisiana, when 242,820 of the 354,113 ha harvested (69%) were
infested and economic injury occurred on about 80,940 ha (23% of harvested ha, Wil
liams, 1994). Reports from Alabama indicated 73% of the ha planted to cotton were in
fested with beet armyworm in 1993 with 26% of harvested ha suffering economic
damage (Williams 1994). Williams (1994) also reported that 82% of the cotton
(546,345 ha) in Mississippi was infested with beet armyworms in 1993 and 69% re
ceived one or more insecticide applications for beet armyworm control.
The outbreaks of beet armyworm in 1983 and 1992 in Louisiana provided an op
portunity to evaluate the efficacy of several insecticides. In 1983, the pyrethroids
cypermethrin (0.0670.112 kg AI/ha), flucythrinate (0.09 kg AI/ha) and tralomethrin
(0.021 kg AI/ha) failed to provide satisfactory control of the pest. However, maximum
labeled rates of sulprofos (1.68 kg AI/ha) and profenofos (1.12 kg AI/ha) as well as
methomyl (0.5 kg AI/ha) and thiodicarb (0.67 kg AI/ha) provided satisfactory control
(Burris 1983). In 1992, sulprofos (1.68 kg AI/ha), methomyl (0.51 kg AI/ha), thiodicarb
(1.0 kg AI/ha) and Pirate (AC 303630) (0.23-0.39 kg AI/ha) were the only insecticides
that significantly reduced numbers of beet armyworm larvae (Graves 1993a, 1993b,
1993c). However, Pirate was the only insecticide that provided >90% control. Mix
Florida Entomologist 77(4)
tures of fenvalerate (0.17 kg AI/ha) + profenofos (0.56 kg AI/ha) and fenvalerate (0.17
kg AI/ha) + amitraz (0.28 kg AI/ha) also significantly reduced beet armyworm larval
densities, but control by these treatments was only about 70%.
The widespread beet armyworm infestations and numerous field control failures
that occurred in 1993 in Louisiana prompted research to re-evaluate the efficacy of se
elected insecticides and to determine the effectiveness of transgenic cotton containing
the Bt toxin on development of this pest.
MATERIALS AND METHODS
Insecticide Screening Tests.
Northeast Research Station. Cotton (DPL 51) was planted on 8 May with plots con
sisting of four 19.8m rows with 102 cm centers. Treatments (see Table 1) were ar
ranged in a randomized complete block design and replicated four times. Applications
were made with a high clearance sprayer calibrated to deliver 93.5 liters total spray
per ha through Teejet X-12 hollow cone nozzles (two per row) at 3.9 kg/cm2. For Test
1, insecticide treatments were applied 29 July and 2 and 16 August. On 14 August, vi
sual ratings were used to estimate the level of foliage feeding by the beet armyworm.
TABLE 1. EVALUATION OF SELECTED INSECTICIDES AGAINST BEET ARMYWORM ON THE
NORTHEAST RESEARCH STATION 1993.
Percent2
Treatment Rate/ha (kg AI) Visual' Ratings Control
Test 1
UTC 3.0a 0
AC 303630 0.17 0.5c 83
AC 303630 0.22 0.Od 100
AC 303630 0.28 0.5c 83
-1cyhalothrin 0.045 3.0a 0
Thiodicarb 0.31 1.0b 67
Thiodicarb 1.01 0.5c 83
AC 303630 + Icyhalothrin 0.28 + 0.031 0.5c 83
AC 303630 + amitraz 0.28 + 0.28 0.5c 83
Test 2
UTC 3.0a 0
1-cyhalothrin 0.03 2.4ab 20
Profenofos 1.12 1.9ab 37
Profenofos + thiodicarb 0.75+ 0.30 1.3ab 57
Profenofos + Icyhalothrin 0.45 + 0.028 2.5a 17
Profenofos + Bt (Design 100 WP) 0.45 + 0.833 2.4ab 20
Profenofos + methomyl 0.56+ 0.17 0.6b 80
'Means followed by same letter do not significantly differ (P<0.05; Duncans MRT). For visual ratings: 0 (no
feeding damage), 1 (feeding damage within the lower 1/3 of the plant), 2 (feeding damage in the lower 1/3 and
middle 1/3 of the plant) or 3 (feeding damage throughout the plant).
2Compared to UTC.
'Formulated product.
December, 1994
Burris et al.: Armyworm Symposium -'94
For Test 2, treatments were applied on 19, 23, 27 July and 2, 6 and 17 August. Visual
ratings of beet armyworm damage to foliage were made on 19 August. A visual defo
liation rating for each plot was scored as follows: 0 (no feeding damage), 1 (feeding
damage within the lower 1/3 of the plant), 2 (feeding damage in the lower 1/3 and mid
dle 1/3 of the plant), or 3 (feeding damage throughout the plant).
Macon Ridge Branch. Cotton (Stoneville 887) was planted on 2 June with plots
consisting of four 15.2m rows with 102 cm centers. Treatments (see Table 2) were ar
ranged in a randomized complete block design and replicated four times. Applications
were made with a high clearance sprayer through Teejet X-8 hollow cone nozzles (2
per row) at 3.2 kg/cm2.
For Test 1, insecticide treatments were made on 4, 9, 20 and 31 August with 56.1
liters total spray per ha. Visual ratings of beet armyworm damage to all plots were
made on 8 September using the rating system previously described. For Test 2, insec
ticide treatments were made on 30 August with 93.5 liters total spray per ha. The
plots were sampled 7 days after treatment using a shake cloth. Two samples were
taken between the two center rows in each plot (total of 1.8 meters per plot). Plants
were vigorously shaken on both rows to dislodge all larvae, which were then counted.
Effects of Transgenic Bt Cotton on Beet Armyworm.
A randomized block experimental design with four replications was used to com
pare the development of beet armyworms on cotton plants expressing the Bacillus
thuringiensis (Bt) toxin (Monsanto line 1076) or the nontransgenic parent (Coker
TABLE 2. EVALUATION OF SELECTED INSECTICIDES AGAINST BEET ARMYWORM ON THE
MACON RIDGE BRANCH OF THE NORTHEAST RESEARCH STATION 1993.
Efficiency Percent2
Treatment Rate/ha (kg AI) Rating Control
Test 1 Visual Rating'
UTC 3.0a 0
AC 303630 0.22 0.1c 97
AC 303630 0.34 0.3c 90
AC 303630 0.45 O.Oc 100
AC 303630 + methomyl 0.22 + 0.14 O.Oc 100
-1cyhalothrin 0.03 2.3b 23
Profenofos 1.12 2.6ab 13
Test 2 Larvae/1.8m
UTC 9.5a 0
AC 303630 0.28 1.2b 87
Bt (Javelin 100WG) 1.683 5.0ab 47
Thiodicarb 0.45 7.6a 20
Thiodicarb 0.90 5.6ab 18
Methomyl 0.67 7.8a 18
Chlorpyrifos 1.12 5.9ab 38
'Means followed by same letter do not significantly differ (P<0.05; Duncans MRT). For visual ratings: 0 (no
feeding damage), 1 (feeding damage within the lower 1/3 of the plant), 2 (feeding damage in the lower 1/3 and
middle 1/3 of the plant) or 3 (feeding damage throughout the plant).
2Compared to UTC.
'Formulated product.
Florida Entomologist 77(4)
312). Seed for both genotypes was supplied by Monsanto Company (Agricultural
Products, 800 North Lindbergh Boulevard, St. Louis, MO 63167) and planted 17 May
in plots four 9.2m rows with 102 cm centers. All plots received an in-furrow treatment
of PCNB plus etridiazole (1.40 kg AI/ha) plus acephate (0.84 kg AI/ha) at planting. Vi
sual rating of defoliation were made on 2 August using the system previously de
scribed.
A laboratory experiment was conducted to further examine the effects of trans
genic Bt cotton on beet armyworm. Newly hatched aggregates of beet armyworm lar
vae were collected from several fields at the Northeast Research Station on 13 August
and transported to the laboratory. Ten leaves per plot were randomly collected from
the second and third position below the terminal from transgenic Bt cotton and Coker
312 cotton plants. Each leaf was placed in a petri dish and five beet armyworm larvae
(50 per plot) were placed in each dish. The petri dishes were covered and larvae were
allowed to feed for 72 h. Leaf area was determined for each leaf at the beginning and
end of the experiment using a LiCor", (Li-3100) Area Meter (Lincoln, Nebraska). Sur
viving larvae were transferred to a petri dish containing fresh leaves collected from
the same plots as previously described. The experiment was terminated when larvae
pupated. Percent pupation and pupal weights were determined.
RESULTS AND DISCUSSION
Insecticide Screening Tests.
Pirate (AC303630) was the only insecticide among those evaluated that consis
tently provided satisfactory control of beet armyworm larvae. Applications of Pirate
at rates of 0.17-0.45 kg AI/ha resulted in 83-100% control (Tables 1 and 2) at both lo
cations of the Northeast Research Station. Similar control was observed at the same
application rate (0.28 kg AI/ha) using two different efficacy ratings (83% control using
visual ratings, Test 1, Table 1 versus 87% control using shake cloth, Test 2, Table 2).
In all tests and at every rate tested Pirate, either alone or in combination with other
insecticides, significantly (P<0.05) decreased defoliation. Also, significantly (P<0.05)
fewer live larvae were observed than in the untreated plots or the plots treated with
1-cyhalothrin, profenofos, methomyl or thiodicarb at low rates (0.31 and 0.45 kg AI/
ha). Thiodicarb at high rates (0.9 and 1.01 kg AI/ha) resulted in 41 and 83% control,
respectively (Tables 1 and 2). Chlorpyrifos at 1.12 kg AI/ha only provided 38% control
(Table 2).
Transgenic Cotton Evaluations.
Natural infestations of beet armyworm were present in all field plots. The visual
observations of damaged leaves on 2 August indicated no significant (P<0.05) differ
TABLE 3. EVALUATION OF TRANSGENIC BT COTTON FOR BEET ARMYWORM CONTROL ON
THE NORTHEAST RESEARCH STATION 1993.
Percent Pupal Weight Leaf area
Treatment Pupating (g) (% Consumed) Visual Ratings'
Bt Line 1076 18a 0.05718a 49.35a 2.2a
Coker 312 31a 0.05458a 49.35a 2.4a
'Means followed by same letter do not significantly differ (P<05; Duncan's MRT). For visual ratings: 0 (no
feeding damage), 1 (feeding damage within the lower 1/3 of the plant), 2 (feeding damage in the lower 1/3 and
middle 1/3 of the plant) or 3 (feeding damage throughout the plant).
December, 1994
Burris et al.: Armyworm Symposium -'94
ences for beet armyworm damage between nontransgenic cotton and transgenic cot
ton plants (Table 3). However, leaf area measurements were significantly (P<0.05)
higher for Bt line 1076 than for Coker 312 parent line on 16 August (data not pre
sented). When beet armyworm larvae were confined to Bt line 1076 and Coker 312
parent line leaves in the laboratory, there was no significant (P<0.05) difference in leaf
consumption, mortality (% pupating) and pupal weights (Table 3). The Bt endotoxin
present in line 1076 appeared to have little or no effect on beet armyworm develop
ment.
REFERENCES CITED
BUTLER, G. D., JR., S. L. POE, G. L. CRANE, C. NELLINGER, AND D. CLARK. 1976. Acom
puter model to evaluate chemical control of beet armyworms in chrysanthe
mum ranges in Florida. Florida Entomol. 59:93-100.
BURRIS, E. 1983. Evaluation of cotton insecticides in Louisiana. Proceedings Missis
sippi Entomological association. Vol. 3:14
CHAPIN, J. B., AND P. S. CALLAHAN. 1967. A List of the Noctuidae (Lepidoptera, In
secta) collected in the vicinity of Baton Rouge, Louisiana. The Proceedings of
the Louisiana Academy of Sciences, Vol. 30:39-48.
CHITTENDEN, F. H. 1902. Some insects injurious to vegetable crops. USDA Div. of En
tomol. Bull. 33 N.S. pp. 37-46.
GRAVES, J. B., B. R. LEONARD, AND P. A. CLAY. 1993a. Evaluation of selected insecti
cide mixtures against late season populations of bollworm, tobacco budworm
and beet armyworm. Insecticide and Acaricide Tests 18:223.
GRAVES, J. B., B. R. LEONARD, AND P. A. CLAY. 1993b. Evaluation of selected insecti
cide mixtures against late season populations of bollworm, tobacco budworm
and beet armyworm. Insecticide and Acaricide Tests 18:223.
GRAVES, J. B., B. R. LEONARD, AND P. A. CLAY. 1993c. Evaluation of Pirate against late
season populations of bollworm, tobacco budworm and beet armyworm. Insec
ticide and Acaricide Tests 18:224.
HEAD, R. B. 1989-1992. Cotton insect losses, in Proceedings, Beltwide Cotton Prod.
Res. Conf., National Cotton Council, Memphis, Tenn.
OLIVER, A. D., AND J. B. CHAPIN. 1981. Biology and illustrated key for the identifica
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RABB, R. L., AND G. G. KENNEDY. 1979. Movement of highly mobile insects: concepts
and methodology in research, pp. 386-393 in Proceedings of a Conference,
"Movement of Selected Species of Lepidoptera in the Southeastern United
States," Raleigh, North Carolina.
SMITH, R.H. 1985. Fall and beet armyworm control in Proc. Beltwide Cotton Prod.
Res. Conf., National Cotton Council, Memphis, TN.
SMITH, R. H. 1989a. Experiences with beet armyworm control in cotton in 1988, pp.
273-275 in Proceedings Beltwide Cotton Prod. Res. Conf., National Cotton
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SMITH, R. H. 1989b. Beet armyworms on cotton. Alabama Cooperative Extension Ser
vice, Auburn University, Alabama, Circular Anr-538.
SMITH, R. H. 1993. Managing cotton to avoid beet armyworms. Auburn University, Al
abama, Newsletter 5, pp. May 6, 1993.
SMITH, R. H. 1994. Beet Armyworm: A costly caterpillar. Proceedings Beltwide Cotton
Prod. Res. Conf., National Cotton Council, Memphis, Tenn. (In Press)
THOMPSON, R. C., R. A. MULLER, AND S. H. CRAWFORD. 1983. Climate at the North
east Research Station, St. Joseph, Louisiana, 1931-80. Louisiana Agric. Expt.
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WILLIAMS, M.R. 1994. Cotton insect losses estimates, 1993. Proc. Beltwide Cotton
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Florida Entomologist 77(4)
KEYS TO SOLDIER AND WINGED ADULT TERMITES
(ISOPTERA) OF FLORIDA
RUDOLF H. SCHEFFRAHN AND NAN-YAO SU
Ft. Lauderdale Research and Education Center
University of Florida, Institute of Food & Agric. Sciences
3205 College Avenue, Ft. Lauderdale, FL 33314
ABSTRACT
Illustrated identification keys are presented for soldiers and winged adults of the
following 17 termite species known from Florida: Calcaritermes nearcticus Snyder,
Neotermes castaneus (Burmeister), N. jouteli (Banks), N. luykxi Nickle and Collins,
Kalotermes approximatus Snyder, Incisitermes miller (Emerson), I. minor (Hagen), I.
schwarzi (Banks), I. snyderi (Light), Cryptotermes brevis (Walker), and C. cavifrons
Banks, Family Kalotermitidae; Coptotermes formosanus Shiraki, Reticulitermes fla
vipes (Kollar), R. hageni Banks, R. virginicus (Banks), and Prorhinotermes simplex
(Hagen), Family Rhinotermitidae; and Amitermes floridensis Scheffrahn, Mangold, &
Su, Family Termitidae.
Key Words: Identification, Kalotermitidae, Rhinotermitidae, Termitidae
RESUME
Se presentan claves ilustradas de identification para los soldados y los adults con
alas de las 17 species de terms conocidas de la Florida, U.S.A.: Calcaritermes near
ticus (Snyder), Neotermes castaneus (Burmeister), N.jouteli (Banks), N. luykxi Nickle
y Collins, Kalotermes approximatus Snyder, Incisitermes miller (Emerson), I. minor
(Hagen), I. schwarzi (Banks), I. snyderi (Light), Cryptotermes brevis (Walker), y C. ca
vifrons Banks, Familia Kalotermitidae; Coptotermes formosanus Shiraki, Reticuliter
mes flavipes (Kollar), R. hageni Banks, R. virginicus (Banks), y Prorhinotermes
simplex (Hagen), Familia Rhinotermitidae; y Amitermes floridensis Scheffrahn, Man
gold, y Su, Familia Termitidae.
A number of identification keys have been published for the termites of the United
States (Banks & Snyder 1920; Light 1934a,b; Snyder 1954; Weesner 1965), including
four for the termites of Florida and the southeastern states (Emerson & Miller 1943,
Miller 1949, Weesner 1965, Gleason & Koehler 1980). Additionally, Nickle & Collins
(1989) have published a key to drywood termites (Kalotermitidae) of the eastern U.S.,
all of which occur in Florida. In fact, the only eastern Nearctic termite species not
found in Florida are Reticulitermes arenincola Goellner known from Indiana and the
Boston, Massachusetts, area (Dobson 1918, Snyder 1949) and R. tibialis Banks which
extends its eastern range into Illinois and Indiana (Snyder 1954).
Unclear or sparse illustrations, illustrations not drawn to scale or lacking a scale,
heavy reliance on morphometrics, use of obsolete names, and typographical errors
have, in some earlier termite keys, led to confusion and incorrect identifications, es
pecially by nonspecialists. The recent addition of three species to Florida's termite
fauna, Incisitermes minor (Hagen) (Scheffrahn et al. 1988), Amitermes floridensis
Scheffrahn et al. (1989), and Neotermes luykxi Nickle & Collins (1989), has further
rendered previous keys obsolete.
This article is from Florida Entomologist Online, Vol. 77, No. 4 (1994).
FEO is available from the Florida Center for Library Automation gopher (sally.fcla.ufl.edu)
and is identical to Florida Entomologist (An International Journal for the Americas).
FEO is prepared by E. O. Painter Printing Co., PO. Box 877, DeLeon Springs, FL. 32130.
TI-Ths dLlu.menLt was ud4d wtll F0,iM; .mF 4.0.231
December, 1994
Scheffrahn and Su: Florida Termite Keys
The condition of a specimen will greatly affect the probability of a correct identify
cation. Desiccated specimens are the most difficult to identify because of the resultant
shrinkage, color change (usually darkening), and fragile nature resulting in lost or
broken appendages. Usually only the wings and mandibles of dry specimens tend to
remain relatively unaltered. Termites are best kept alive after collection and then
killed by freezing just before being keyed. If specimens cannot be kept alive, they
should be immersed in aqueous ethanol or isopropanol of at least 40% (i.e., 80-proof
liquor or rubbing alcohol). For long-term museum storage, 85% ethanol has proven to
be the best preservative (M.S. Collins, pers. comm.). The mandibles of dead soldiers
are usually crossed and the labrum may be retracted or folded. Alate wings, especially
in the critical costal region, may curl ventrally Wings alone are often collected follow
ing a dispersal flight and can yield at least a generic identification using the adult key.
Wings must be completely flat in order to see the costal venation in proper perspec
tive. This can be accomplished by immersing the wing in a reservoir of water or alco
hol, sliding it onto a microscope slide or other clear flat surface, covering it with
another slide, and allowing it to dry. Alternatively, a dried wing can be flattened by
laying the dorsal surface on a drop of water. Wing membrane texture can best be ob
served when dry. Because the winged adult key uses the forewing, several wings
should be examined and keyed if detached from the body. Alates collected before dis
persal flights may be incompletely sclerotized causing cuticle, wing membrane, and
veins to be lighter in color than when fully mature for flight.
From a practical standpoint, correct identification is especially critical for pest
taxa, such as termites, which may require very different control methods depending
upon the target species. Although the morphological diversity among the termites of
Florida is moderately broad, some species are not easily distinguished. Fortunately,
the tentative identification of the soldier caste can be confirmed or refuted by inde
pendent identification of the winged adult alatee), and vice versa. Alates, however, are
seasonal, may be difficult to find, and occur only in a mature colony.
In the following keys, we attempt to separate species by parsimonious use of the
most recognizable and consistent characters even if resultant groupings are not tax
onomically related (e.g., grouping by presence or absence of wing membrane pigmen
station Simple measurements are used to supplement couplets or when dimension
provides a clear separation of a group or species. This reduces the confusion resulting
from the presence of long and short-headed soldier forms in some kalotermitid spe
cies (Nickle & Collins 1989) or size variations among conspecific soldiers due to colony
size, age, or nutritional status. Adult measurements are less variable than those of
soldiers. To further help in identification, we have incorporated the known Florida
distribution, pest status, and dispersal flight data based on a previous survey (Schef
frahn et al. 1988) and unpublished records. These are given only as general guidelines
and exceptions may occur (i.e. autumn flights by Incisitermes snyderi (Light) and Reti
culitermes spp.). When available, generally accepted common names (Snyder 1954,
R.H.S. unpublished) or accepted common names (ESA 1989) are also provided.
Several taxonomic issues must be addressed with respect to this work. The first
and most troublesome, is the character overlap between Neotermesjouteli (Banks)
and Neotermes luykxi. All measurements and characters provided in the description
of N. luykxi soldiers and adults (Nickle & Collins 1989) fall within the range of those
designated as N. jouteli in our reference collection. Apparently, the only diagnostic
characters separating the two are their respective chromosome numbers and alloz
yme patterns (Luykx et al. 1990) neither of which can be obtained from preserved
specimens. Chromosome number has been shown to vary within single insect species
(Emmel et al. 1973) although it appears to be stable within species of Kalotermitidae
Florida Entomologist 77(4)
(Luykx 1990). Therefore, we cannot differentiate between these two Neotermes spe
cies in either key. Secondly, Prorhinotermes simplex (Hagen), the Florida "dampwood"
termite, shares its habit of nesting in moist, decaying wood with the true dampwood
termites (Neotermes spp.), although the former is actually a subterranean termite
(Family Rhinotermitidae) which we have observed tunneling in soil. Thirdly, separate
ing soldiers of Reticulitermes species is difficult. Although head and pronotum mea
surements and mandibular characters are useful, precise micromeasurements are
required and some interspecific overlap may occasionally surface. In subsequent
studys (Hostettler et al. 1995), labrum shape, although also subtle, has been found to
be an effective additional character for separating soldiers of all three Reticulitermes
species. Finally, an ongoing revision of Nearctic Reticulitermes suggests that an un
described or erroneously synonymized species may occur in Florida's panhandle (T.
Myles pers. comm.).
MATERIALS AND METHODS
Line drawings of specimens were prepared at 20-80x magnification with the aid of
a camera lucida attached to an Olympus SZH light microscope. Measurements were
made with an ocular micrometer. Scanning electron micrographs were made with a
Hitachi S-4000 field emission microscope (6-8 kV). Specimens were dehydrated in ab
solute ethanol and 1,1,1,3,3,3 hexamethyldisilazane (Nation 1983) prior to sputter
coating with gold.
Material examined for this key is from the authors' reference collection containing
about 1,200 colony samples taken in Florida between 1985 and 1994 including 785
samples collected from structures in peninsular Florida (Scheffrahn et al. 1988), the
Florida State Collection of Arthropods (Fla. Dept. Agric. Cons. Serv, Division of Plant
Industry, Gainesville, Florida) and the E.M. Miller collection from the University of
Miami on loan from P. Luykx containing 111 samples taken in Florida between 1930
and 1968.
KEY To TERMITE SOLDIERS OF FLORIDA
1 Pronotum (Fig. 8a) as wide or wider than width of head viewed from
above (Figs. 1-20 dorsal views); for species with prominent mandibles,
inner margin of left mandible (Fig. 8e) with two or more marginal teeth
(Figs. 8-20 dorsal views). (Drywood and dampwood termites) Family
K a lo term itid a e ................................................................... .................. 2
Pronotum width narrower than width of head viewed from above; each
mandible with no exposed teeth or only one tooth visible on inner margin
(Figs. 22-32 dorsal views). (Subterranean termites) Families Rhinoter
m itid ae an d Term itid ae ........................................................................... 11
2 Frons nearly vertical with deep furrow or rimmed above by a ridge; head
plug-like; mandibles not prominent; head color deep reddish brown to
black; (Figs. 1,2,4-7). (Powderpost drywood termites)............................. 3
Frons (Fig. 8c) slopes more or less gradually from plane of vertex (Fig.
8b), surface smooth; head flattened, quadrate or elongate; mandibles
project prominently; head color orange to reddish brown; (Figs. 8-21).
(Drywood and dam pwood term ites) ......................................................... 5
3 Frons with deep furrow (Figs. 1,2); foretibia with one prominent spur at
right angle to tibial axis and two small apical spurs (Fig. 3). (Rare in
structures, known from Clay Co. to Sebring.) .........................................
.............. ........ . ................................... .. Calcariterm es nearcticus
December, 1994
Scheffrahn and Su: Florida Termite Keys
3
1 2
aa
4 6
9
Figs. 1-9. Dorsal and lateral views of heads and pronota of termite soldiers from
Florida: Calcaritermes nearcticus, Figs. 1 2 1.i I. Fig. 3; bar = 3.2 mm); Cryptoter
mes cavifrons, Figs. 4-5; Cryptotermes brevis, Figs. 6-7; Neotermesjouteli, Figs. 8-9
(pronotum 8a, vertex 8b, frons 8c, antenna 8d, mandible 8e, labrum 8f, eyespot Fig.
9a). Bar = 2 mm.
Florida Entomologist 77(4)
Ridge surrounding frons forming "bowl" (Figs. 5,7); foretibia lacking a
prom in en t apical spu r ......................................... ................................. 4
4 Vertex smooth (Figs. 4,5); smaller species. (Uncommon structural pest
(moderate moisture requirement), known from St. Johns Co. south) .......
.............................................................................. Cryp toterm es cavifrons
Vertex rough, wrinkled, often concave (Figs. 6,7); larger species. (Intro
duced species; common pest of structures and furniture statewide; never
found in non-structural wood -West Indian powderpost termite.) ..........
.......................................................................... .......... Cryptoterm es brevis
5 Eyespot (Fig. 9a) black; antennae with up to 19 segments; third anten
nal segment about as long as fourth and fifth combined; soldiers usually
large (Figs. 8,9). (Occasionalpest in moisture-exposed wood, known from
Ft. Pierce south).......................................................... Neoterm esjoutelfb
Eyespot hyaline or indistinct; number and size of antennal segments
variable, soldier size variable .................................................................. 6
6 Third antennal segment greatly enlarged and club-like, as long or longer
than fourth through sixth combined, and about twice as wide as fourth
(Figs. 10,11,S1); larger species. (Regularly introduced into Florida as a
structural pest, may be permanently established in some areas -western
drywood termite) ....................................................... Incisitermes minor
Third antennal segment shorter than fourth through sixth combined
and less than tw ice as w ide as fourth ...................................................... 7
7 Anterior margin of pronotum weakly and evenly concave; length of third
antennal segment less than fourth and fifth combined (Figs. 12-15) .... 8
Anterior margin of pronotum incised (Figs. 16,18,20); length of third an
tennal segment about equal to or greater than fourth and fifth combined
(F ig s S 3 ,S 5 ) ........................................... .................. ...... .................. 9
8 Pronotum more than twice as wide as long, collar-like, posterior margin
with rounded corners; third antennal segment equal to or slightly longer
than second or fourth; lateral margins of mandibles widen near bases
but do not constitute "humps"; large species (Figs. 12,13). (Occasional
pest in moisture-exposed wood and living trees, known from Lake Co.
south.) .................................. ............ .................. N eoterm es castaneus'
Pronotum more square, less than twice as wide as long, posterior margin
nearly straight with square corners; third antennal segment longer than
second but shorter than fourth and fifth combined; lateral margins of
mandibles with distinct "humps" near bases; medium-small species
(Figs. 14,15). (Uncommon structural pest, known from Sarasota north.)
..................................................................Kalotermes approximatus
9 Small species; antennae with 10-11 segments; pronotum about 1 mm
wide, posterior margin rather evenly convex (Figs. 16,17). (Known only
from Florida Keys, pest status unknown) ............... Incisitermes miller
Medium species; antennae with 11-16 segments; pronotum 1.3-1.9 mm
wide, posterior margin more straight or slightly concave in middle, cor
ners roun ded (F igs. 18,20) ...................................................................... 10
10 Tip of labrum bluntly pointed (Fig. S2); third antennal segment as long
as fourth and fifth combined (Fig. S3); antennae with 11-14 segments
(Figs. 18,19). (Common in structural wood statewide -southeastern dry
wood termite)........................................................... Incisitermessnyderi
Tip of labrum truncate (Fig. S4); third antennal segment longer than
fourth and fifth combined (Fig. S5); antennae with up to 16 segments
(Figs. 20,21). (Rare structural pest, known mostly from coastal south)...
December, 1994
Scheffrahn and Su: Florida Termite Keys
10
15 '1 7 -
Figs. 10 17. Dorsal and lateral views of heads and pronota of termite soldiers from
Florida: Incisitermes minor, Figs. 10 11; Neotermes castaneus, Figs. 12 13; Kalotermes
approximatus, Figs. 14-15; Incisitermes miller, Figs. 16-17. Bar = 2 mm.
................................................................................. In cisiterm es schw arz
11 Teeth on inner margin of mandibles reduced to serrations at base and so
usually hidden from view by labrum; head capsule not elliptical when
viewed laterally (Figs. 24-33). Family Rhinotermitidae ....................... 12
11
^I
Florida Entomologist 77(4)
Figs. S 1 -S7. Scanning electron micrographs of Incisitermes minor soldier antenna,
Fig. Sl; I. snyderi soldier labrum, Fig. S2, and antenna, Fig. S3; I. schwarzi soldier la
brum, Fig. S4 (mandible tips broken), and antenna, Fig. S5; Reticulitermes virginicus
soldier mandibles, Fig. S6; R. hageni soldier mandibles, Fig. S7.
December, 1994
Scheffrahn and Su: Florida Termite Keys
One prominent triangular tooth on inner margin of each sickle-shaped
mandible, head capsule elliptical when viewed laterally (Figs. 22,23);
smallest soldier caste in Florida. Family Termitidae. (Occasionally asso
ciated with structural lumber, known from west central Florida -Florida
dark-winged subterranean termite) ..................... Amitermes floridensis'
12 Head outline rectangular from above, sides of head parallel (Figs.
24,26,28). (R eticuliterm es spp)................................................................ 13
Head outline oval or egg-shaped from above, narrowing in front, sides of
head convex (F igs. 30,32) ................................. .............. ................... 15
13 Pronotum width usually greater than 0.90 mm; head length with man
dibles equal to or greater than 2.8 mm; points of mandibles, especially
left, curved inward about 70-90 (Figs. 24,25). (Widespread pest through
out state -eastern subterranean termite.) ............ Reticulitermes flavipes
Pronotum width usually less than 0.85 mm; head length with mandibles
less than or equal to 2.7 mm; curvature of mandible points 45-90 ..... 14
14 Larger species (Figs. 26,27), pronotum width greater than 0.70 mm;
points of mandibles, especially left, curved inward about 70-90 points
of mandibles broader (Fig. S6) than following species; basal serrations of
left mandible, when exposed for viewing, more prominent (Fig. S6); dis
tinct and gradual inward curvature of blade of right mandible (Fig. S6).
(Widespread pest throughout state -dark southern subterranean ter
m ite) .............. .............................................Reticuliterm es virginicus
Smaller species (Figs. 28,29), pronotum width less than or equal to 0.70
mm; points of mandibles, especially left, curved inward about 45 points
more slender (Fig. S7) than above species; basal serrations of left man
dible, when exposed for viewing, less prominent (Fig. S7); blade of right
mandible more straight before point (Fig. S7). (Less common in struck
tures statewide -light southern subterranean termite)..............................
................................................................................ R eticuliterm es hagenf
15 Fontanelle consisting of a prominent, oval, anterior-facing opening aris
ing from a mound on vertex and frons (Figs. 30,31a). (Introduced species
common in or near structures in certain areas of Broward, Dade, Hills
borough, and Orange Cos., and coastal panhandle -Formosan subterra
nean termite.)................................................... Coptotermesformosanus
Fontanelle consisting of a minute, circular, dorsal-facing opening on sur
face of vertex (Figs. 32a, 33). (Occasionally in structures in Broward and
Dade Cos. Florida "dampwood" term ite)..................................................
.......................................................... ......... Prorhinotermes simpler
KEY To WINGED ADULT TERMITES OF FLORIDA
1 With wing unfolded and flattened between glass plates, three or more
sclerotized veins in costal field costall margin, subcosta, radius, radial
sector, and, in some, median, e.g., Fig. 37a,c-e and Fig. 45a-c) at about
one-third wing length from wing suture; in most species, numerous di
agonal cross veins connecting two or more remaining veins in costal field
along remaining length of wing (Figs. 34,35-37, 39,41 45). (Drywood and
true dam p w ood term ites)........................................................................... 2
Two sclerotized veins in costal field costall margin and radial sector, e.g.,
Fig. 46a-b) in foremargin of wings visible along entire length of wing
Florida Entomologist 77(4)
and, in most species, connected by short vertical cross veins in distal
third of wing (Figs. 46-48,50,52,54). (Subterranean termites).............. 10
2 When viewed over white background or with several wings overlapping
as when folded over the abdomen, entire wing membrane translucently
pigmented blackish; veins in costal field darker than membrane ......... 3
0 j
19 21
18 20
22 23 25 26 27
24
a
28 29 30 31
32 33
Figs 18-33. Dorsal and lateral views of heads and pronota of termite soldiers from
Florida: Incisitermes snyderi, Figs. 18 19; I. schwarzi, Figs. 20-21; Amitermes
floridensis, Figs. 22-23; Reticulitermes flavipes, Figs. 24-25; R. virginicus, Figs. 26-27;
R. hageni, Figs. 28-29; Coptotermes formosanus, Figs. 30-31 fontanellee 31a); Prorhi
notermes simplex, Figs. 32-33 fontanellee 32a). Bar = 2 mm.
December, 1994
Scheffrahn and Su: Florida Termite Keys
Wing membrane unpigmented or very faintly yellow-brown, veins in cos
tal field white to medium brown when viewed as above ......................... 5
3 In forewing, median vein is sclerotized and runs near veins in costal field
(Fig. 34a), no diagonal cross veins connecting veins in costal field; wing
membrane with distinct papillae or bumps; length with wings 7 mm.
(Rare in structures, known from Clay Co. to Sebring, midday flights
March to May.)................................................ Calcaritermes nearcticus'
In forewing, median vein is unsclerotized and runs midway between
veins in costal field above, and cubitus below; diagonal cross veins be
tween sclerotized veins in costal field (Figs. 35,36) ................................. 4
4 Head and pronotum orange-brown, abdomen dark brown; stout-bodied,
medium-large species, length with wings 11-12.5 mm; hairs on head
shorter than diameter of eye; arolium absent between tarsal claws; in
forewing, few diagonal cross veins branching forward from radial sector
(Fig. 35). (Regularly introduced into Florida as a structural pest, may be
permanently established in some areas, ....'..' .. .' .. September to No
member -western drywood termite.) .......................... Incisitermesminor
Head, thorax, and abdominal tergites (plates) reddish brown;
medium-small species, length with wings 8.5-10 mm; hairs on head
longer than diameter of eye; arolium present between tarsal claws; in
forewing, few cross veins branching forward from median vein (Fig.
36a). (Uncommon in structures, from Sarasota north, daytime flights
September to November)................................. Kalotermes approximatus
5 In forewing, four sclerotized veins in costal field costall margin, radius,
radial sector, and median, e.g., Fig. 37a, c-e, respectively) at about
one-third wing length from body; sclerotized media running close to ra
dial sector (Figs. 37,39); large, stout-bodied species. ................................
(D am p w ood term ites) .................................................... ....................... 6
In forewing, three sclerotized veins in costal field costall margin, radius,
and radial sector, e.g., Fig. 45a-c, respectively) at about one-third wing
length from body, media (Fig. 45d) not sclerotized and running midway
between radial sector and cubitus (Figs. 41-45); size variable................
(Powderpost and drywood termites) ................................. 7
6 Head, body, and veins in costal field chestnut brown; long erect hairs on
head and pronotum (Fig. 38); largest alate caste in Florida, length with
wings about 15-16 mm (forewing, Fig. 37). (Occasional pest in
moisture-exposed wood and living trees, known from Lake Co. south,
evening flights peak in October and November) .......................................
.... .............. ....................................................... N eoter es castaneu '
Head, body, and veins in costal field light yellowish-brown to
reddish-brown; very short hairs on pronotum (Fig. 40); wing membrane
very faintly yellow-brown; length with wings 12-15 mm (forewing, Fig.
39). (Occasional pest in moisture-exposed wood, known from Vero Beach
south, evening flights Spring or Fall.) .........................Neotermesjoutelfb
7 In forewing, unsclerotized media curving near mid-wing to join veins in
costal field (Figs. 41a,42a; note variations in C. brevis forewing veination
in Scheffrahn et al. (1988, Fig. 2.); head and body brown....................... 8
In forewing, unsclerotized media running to near tip of wing even if
branched along its course (Figs. 43a,44a,45d) ........................................ 9
8 Small dull-brown species, length with wings 8-9 mm, wing membrane
weakly tuberculate (pimply); head width (through eyes) 0.85-0.97 mm;
Florida Entomologist 77(4)
35 2
I I~--
3940
aa
41
42
43
44
Figs. 34-44. Right forewing of termite adults from Florida: Calcaritermes nearcti
cus, Fig. 34 (median vein 34a); Incisitermes minor, Fig. 35 (median vein 35a); Kaloter
mes approximatus, Fig. 36 (median vein 36a); Neotermes castaneus, Fig. 37 costall
margin 37a, subcostal vein 37b, radius 37c, radial sector 37d, and media 37e); and
dorsal view of pronotum, Fig. 38; N.jouteli, Fig. 39, and dorsal view of pronotum, Fig.
40; Cryptotermes cavifrons, Fig. 41 (median vein 41a); C. brevis, Fig. 42 (median vein
42a); Incisitermes miller, Fig. 43 (median vein 43a); I. snyderi, Fig. 44 (median vein
44a). Bar = 4 mm for forewings, 2.4 mm for pronota.
December, 1994
Scheffrahn and Su: Florida Termite Keys
antennae with 13-16 segments (forewing, Fig. 41). (Uncommon
structural pest (moderate moisture requirement), known from St. Johns
Co. south, evening flights year round.) ............... Cryptotermes cavifrons'
Medium dull-brown species, length with wings 10-11 mm; head width
1.05-1.15 mm; antennae with 14-18 segments (forewing, Fig. 42).
(Introduced species, common pest of structures and furniture statewide,
never found in non-structural wood, evening and night flights April to
July -West Indian powderpost termite) ..................... Cryptotermesbrevis
9 Head, thorax, and body dark brown; veins in costal field brown, wing
membrane tuberculate; head width 'ii ., -1. ,. i about 0.9 mm; ocellus
more elliptical; small species, length with wings 7-8 mm; (forewing, Fig.
43). (Known only from Florida Keys, pest status unknown, daytime
flights April to July) .............................................. Incisitermesmiller
Head and body color pale yellow-brown to pale reddish brown; veins in
costal field pale yellow-brown in distal half of wing; head width 1.20 1.35
mm; ocellus more round; medium species, length with wings 11-12 mm
(forewing, Fig. 44). (Common in structures statewide, evening flights
May to August -southeastern drywood termite.) .......................................
.................................................................... ......... In cisiterm es sn y d eri
Head and body color medium brown; veins in costal field brown along en
tire length of wing; head width 1.40-1.52 mm; ocellus more elliptical;
medium-large species, length with wings 13-15 mm (forewing, Fig. 45).
(Rare structural pest, known mostly from coastal south, small evening or
night flights except during winter peaking in April and May) .................
................................................................................. In cisiterm es schw arz
10 Wing membrane smooth between veins; wing surface and margin
adorned w ith fine hairs (Figs. 46,47) ..................................................... 11
Wing membrane net-like reticulatee) between veins, no hairs on wing
surface or m argin (Figs. 48,50,52,54) .................................................... 12
11 Head and pronotum yellow-brown; wing membrane unpigmented; veins
in costal field (Fig. 46a,b) yellowish brown at base to almost white at tip;
large species, length with wings about 14 mm (forewing, Fig. 46). (Intro
duced species common in or near structures in certain areas ofBroward,
Dade, Hillsborough, and Orange Cos., and coastal panhandle, late after
noon and evening flights April to July Formosan subterranean termite)
................................... ......................... Coptoterm es form osanus
Head and pronotum dark brown; wing membrane dark with black
interior veins (Fig. 47); small species with wings long in proportion to
body length; length with wings about 9 mm. (Occasional structural and
outdoor nuisance (large swarms), known from west central Florida,
daytime flights following rain June to September -Florida dark-winged
subterranean termite (Fam ily Termitidae)) ................................................
................................................................................. A m term es oridensis
12 Body color pale brown to light reddish brown ....................................... 13
B ody color dark brow n to black ............................................................. 14
13 Forewing not broad in middle, costal margin not convex, median vein
runs uninterrupted below veins in costal field (Fig. 48a); thorax and ab
domen narrow (Fig. 49); small species, length with wings 7-8 mm. (Less
common in structures statewide, ....'..' .. .'.. in sunshine December to
April -light southern subterranean termite.) .............................................
................................................ ................. ......... R eticuliterm es hageni
Florida Entomologist 77(4)
49
S51
53 _
52
Figs. 45-55. Right forewing of termite adults from Florida: I. schwarzi, Fig. 45 (cos
tal margin 45a, radius 45b, radial sector 45c, and media 45d); Coptotermes formosa
nus, Fig. 46 costall margin 46a and radial sector 46b); Amitermes floridensis, Fig. 47;
Reticulitermes hageni, Fig. 48 (median vein 48a), and dorsal view of body, Fig. 49; Pro
rhinotermes simplex, Fig. 50 (median vein 50a), and dorsal view of body, Fig. 51; R. fla
vipes. Fig. 52, lateral view of head, Fig. 53; R. virginicus. Fig. 54, lateral view of head,
Fig. 55. Bar = 4 mm for forewings, 2.4 mm for heads and bodies.
Forewing broad in middle, costal margin covex, median vein disjointed,
indistinct (Fig. 50a); thorax and abdomen broader than above (Fig. 51);
medium-small species, length with wings 9-10 mm. (Occasionally in
structures in Broward and Dade Cos., evening and night flights October
to January Florida "dampwood" term ite.) ..............................................
.............. ............................................................ Prorhinoterm es sim pler
December, 1994
54
p 55
48
Scheffrahn and Su: Florida Termite Keys
14 Medium-small species, length with wings 8.5-10.5 mm; ocellus about one
time its diameter or more from compound eye (Fig. 53); veins in costal
field of wing light brown, membrane faintly yellow-brown (forewing, Fig.
52). (Widespread pest throughout state, midday flights in sunshine
January to April -eastern subterranean termite) ......................................
....................................................... ..........Reticulitermes lavipes
Small species, length with wings 7.0-9.5 mm, usually 7.08.0 mm; ocellus
less than its diameter from compound eye (Fig. 55); veins in costal field
of wing whitish or hyaline except near base, membrane hyaline (forew
ing, Fig. 54). (Widespread pest throughout state, midday flights in sun
shine March to May -dark southern subterranean termite.) ...................
...................................................... ...... .........Reticuliterm es virginicus
FOOTNOTES FOR KEYS
SIn the United States, known only from Florida.
bIndistinguishable from Neotermes luykxi. See introduction.
For additional characters see Hostettler et al. (1995).
ACKNOWLEDGMENTS
We thank D.S. Williams of the ICBR Electron Microscope Core Facility at the Uni
versity of Florida, Gainesville, for technical assistance with electron microscopy; and
M. S. Collins, F W. Howard, S. Jones, J. Krecek, P. Luykx, T Myles, J. Peters, and J.
Tsai for reviewing and improving various stages of this contribution no. R-03258 of
the Florida Agricultural Experiment Stations Journal Series.
REFERENCES CITED
BANKS, N. AND T.E. SNYDER 1920. A revision of the Nearctic termites with notes on
biology and geographic distribution. U.S. Natl. Mus. Bull. 108, 228 pp.
DOBSON, R.J. 1918. AEuropean termite Reticulotermes [sic!] lucifugusRossi in the vi
cinity of Boston. Psyche 25: 99 101.
EMERSON, A.E., AND E.M. MILLER. 1943. A key to the termites of Florida Entomol.
News 54: 184-187.
EMMEL, T.C., H.R. TREW, AND O. SHIELDS. 1973. Chromosomal variability in a Nearc
tic lycaenid butterfly, Philotes sonorensis (Lepidoptera: Lycaenidae).
Pan-Pacific Entomol. 49: 74-80.
ENTOMOLOGICAL SOCIETY OF AMERICA. 1989. Common names of insects and related
organisms. Lanham, MD. 199 pp.
GLEASON, R.W., AND P.G. KOEHLER. 1980. Termites of the eastern and southeastern
United States: pictorial keys to soldiers and winged reproductive. Flor. Coop.
Ext. Serv, Inst. Food Agric Sci., Univ. Florida Bull. 192.
HOSTETTLER, N.C., D.W. HALL, AND R.H. SCHEFFRAHN. 1995. Morphometric variation
and labral shape in Florida Reticulitermes (Isoptera: Rhinotermitidae): signif
icance for identification. Florida Entomol. (in press).
LIGHT, S.F. 1934a. The desert termites of the Genus Amitermes, pp. 199-205 in C. A.
Kofoid [ed.]. Termites and termite control. University of California Press, Ber
keley, Calif. 795 pp.
LIGHT, S.F. 1934b. Dry-wood termites, their classification and distribution, ibid. pp.
206-209.
LUYKX, P. 1990. A cytogenetic survey of 25 species of lower termites from Australia.
Genome 33: 8088.
Florida Entomologist 77(4)
December, 1994
LUYKX, P., D.A. NICKLE, AND B.I. CROTHER 1990. A morphological, allozymic, and
karyotypic assessment of the phylogeny of some lower termites (Isoptera: Kal
otermitidae). Proc. Entomol. Soc. Washington 92: 385-399.
MILLER, E.M. 1949. A handbook on Florida termites. Tech. Ser., Univ. Miami Press,
Coral Gables, FL, 30 pp.
NATION, J.A. 1983. A new method using hexamethyldisilazane for the preparation of
soft insect tissue for scanning electron microscopy. Stain Technol. 55: 347-352.
NICKLE, D.A., AND M.S. COLLINS. 1989. Key to the Kalotermitidae of eastern United
States with a new Neotermes from Florida (Isoptera). Proc. Entomol. Soc.
Washington 91: 269-285.
SCHEFFRAHN, R.H., J.R. MANGOLD, AND N.-Y. Su. 1988. A survey of
structure-infesting termites of peninsular Florida. Florida Entomol. 71:
615-630.
SCHEFFRAHN, R.H., N.-Y. Su, AND J.R. MANGOLD. 1989. Amitermes floridensis, a new
species and first record of a higher termite in the eastern United States
(Isoptera: Termitidae: Termitinae). Florida Entomol. 72: 618-625.
SNYDER, T.E. 1949. Catalog of the termites (Isoptera) of the world. Smithsonian Misc.
Coll. No. 3953, 112: 1490.
SNYDER, T.E. 1954. Order Isoptera. The termites of the United States and Canada.
Natl. Pest Contr. Assn., New York, NY, 64 pp.
WEESNER, F.M. 1965. Termites of the United States, A handbook. Natl. Pest Contr.
Assn., Elizabeth, New Jersey, 70 pp.
4444444444444444444444444444444444444444444444444444
Florida Entomologist 77(4)
ODONTOTAENIUS FLORIDANUS NEW SPECIES
(COLEOPTERA: PASSALIDAE): A SECOND U.S. PASSALID
BEETLE
JACK C. SCHUSTER
Systematic Entomology Laboratory
Universidad del Valle de Guatemala
Aptdo. 82
Guatemala City, GUATEMALA
ABSTRACT
Larvae and adults of Odontotaenius floridanus New Species are described from
the southern end of the Lake Wales Ridge in Highland Co., FL. This species may have
evolved as a population isolated during times of higher sea level from the mainland
species 0. disjunctus (Illiger) or a close common ancestor. It differs notably from O.
disjunctus in having much wider front tibiae and a less pedunculate horn. A key is
given to the species of the genus.
Key Words: Florida, endemism, Lake Wales
RESUME
Son descritas las larvas y adults de Odontotaenius floridanus Nueva Especie
del extreme sur de Lake Wales Ridge, en Highland Co., Florida. Esta especie pudo ha
ber evolucionado, como una poblaci6n aislada en 6pocas en que el nivel del mar era
This article is from Florida Entomologist Online, Vol. 77, No. 4 (1994).
FEO is available from the Florida Center for Library Automation gopher (sally.fcla.ufl.edu)
and is identical to Florida Entomologist (An International Journal for the Americas).
FEO is prepared by E. O. Painter Printing Co., P.O. Box 877, DeLeon Springs, FL. 32130.
December, 1994
Schuster: Odontotaenius floridanus, A New U.S. Passalid 475
mas alto, a partir de 0. disjunctus (Illiger) o de otro ancestro comun cercano. Difiere
notablemente de 0. disjunctus en tener las tibias delanteras mas anchas y el cuerno
menos pedunculado. Se ofrece una clave para las species del g6nero.
Only one species of Passalidae, Odontotaenius disjunctus (Illiger), is known to oc
cur in the U.S. at present, though two other species may have occurred in Arizona at
the turn of the century (Schuster 1983).
Recently, while examining 0. disjunctus in the Florida State Collection of Arthro
pods in Gainesville, I noted two specimens with a somewhat different morphology. On
examining the labels, I noticed that the collector, L. L. Lampert, had also remarked on
their uniqueness. Both came from the same area of south-central Florida in High
lands Co. Later, I had an opportunity to examine the collection of the Archbold Bio
logical Station and encountered three more similar specimens. Subsequently, with
the aid of four other Florida entomologists, I conducted a search for this elusive insect
at the Archbold site. One of the collaborators, Paul Skelley, managed to find an oak log
with a pair of adults and four larvae. All seven adult specimens fit the description be
low.
The genus Odontotaenius was revalidated by Reyes-Castillo (1970) and includes
eight species (Reyes-Castillo 1970, Castillo et al. 1988). Three of these species, known
only from the types, are probably synonyms of either 0. striatopunctatus (Percheron)
or 0. zodiacus (Truqui). The types need to be examined to make further synonymies.
Odontotaenius is characterized by a marked fronto-clypeal suture, thick anterior
clypeal border, median frontal structure of "striatopunctatus" type, posterior half of
supraorbital ridges bifurcate, and short antennal lamellae with the distal margins
rounded (Reyes-Castillo 1970).
Odontotaenius floridanus Schuster New Species
DESCRIPTION. Head: Anterior border of labrum deeply concave. Clypeus greatly
swollen in middle. Median frontal structure ("horn") of "striatopunctatus" type
(Reyes-Castillo 1970) (Fig. 1). Supraorbital ridge bifurcated posteriorly. Canthus ex
tends laterally same distance as eye margin, anterior corner with right angle. Eyes
small, ratio of dorsal eye width to head width 1:11.4. Lateral circular scars of mentum
indistinct or absent.
Thorax: Lateral fossa of pronotum with 1 4 light punctations. Mesosternum bare,
without lateral depressions, with wide (0.7 mm) matt bands along anterior borders.
Mesepisternum pubescent. Metasternum with 10-18 punctations delimiting each lat
ero-posterior side of disk, anterior angles pubescent, lateral fossae narrow and pubes
cent.
Elytra: Anterior profile convex, anterior face of elytra sloping. Striae 7 and 8
united anteriorly.
Wing: Normal size, not reduced.
Legs: Tibia I very wide (Fig. 2), tibia ratio (see Fig. 3) 0.264-0.333, x = 0.312, n = 7.
Dimensions (mm): Total length, mandible tip to elytral tip 36-42, x = 40.2; elytral
length 18.5-21, x = 20.2, elytral width 12-15, x = 13.6, pronotal width 11.5-14.5, x
13.5.
LARVA. The larva has only 12-14 AR setae and 7-8 internal coxal setae. Other
wise, the basic setal pattern is the same as in 0. disjunctus. Larval head widths: in
star III 6.0, instar II = 4.1-4.3.
Florida Entomologist 77(4)
1
Fig. 1. Lateral view of heads of 0. disjunctus (left) and 0. floridanus (right) show
ing "horn" (median frontal structure) shapes.
DIAGNOSIS. The adult is most similar to 0. disjunctus. The latter species differs
from 0. floridanus in having a rounded canthus which projects beyond the eye mar
gin, larger eyes (dorsal eye width to head width ratio 1:9.5 -1:10), mentum with dis
Fig. 2. Dorsal view of front tibiae of 0. disjunctus (left) and 0. floridanus (right)
showing size difference.
December, 1994
Schuster: Odontotaenius floridanus, A New U.S. Passalid 477
Fig. 3. Passalid tibia, ventral view, showing parameters of tibia ratio. The ratio is
the width at the widest point divided by the length shown.
tinct lateral circular scars, usually no punctations in lateral prothoracic fossae,
mesosternum with narrow (0.3 mm) matt bands along anterior borders, metasternum
without punctations delimiting latero-posterior sides of disk, flatter anterior profile of
elytra, anterior face of elytra vertical, elytral striae 7 and 8 not united anteriorly, and
narrow tibia I (ratio 0.185-0.239, x = 0.216, n = 8 Florida specimens). The aedeagi of
the two species are very similar. The "horn" on the head of 0. floridanus is not as pe
dunculate as in 0. disjunctus or 0. striatopunctatus (Fig. 1).
The larva is similar to that of 0. disjunctus (Schuster & Reyes-Castillo 1981). It
has fewer AR setae and usually more internal coxal setae than larvae of the latter spe
cies.
MATERIAL EXAMINED. Seven adults and four larvae.
TYPE MATERIAL. Holotype male, Florida, Highlands Co., Archbold Biological
Station near Lake Placid, 18 I 93, P. Skelley, in a hardwood log. Allotype female, same
data as holotype, together with four larvae.
Paratypes: Four specimens collected at Archbold Biological Station: 28 III 1973,
L.L. Lampert, in pitfall trap; VIII 1970, J. Douglas; 20 IX 1992, U.G. Mueller; 23 IV
1983, M. Deyrup, ground. Another specimen was collected at Sebring, Highlands Co.,
Flamingo Villas Scrub by P. Martin, 11 IX 1987.
Types will be deposited in the Florida State Collection of Arthropods and the col
election of the Universidad del Valle de Guatemala.
ETYMOLOGY. The trivial name floridanuss" refers to the state where this species
is apparently endemic.
Florida Entomologist 77(4)
DISCUSSION
This species is obviously derived from Odontotaenius disjunctus or a close common
ancestor. It differs most notably in the "horn", or median frontal structure, and the en
large front tibiae. This latter characteristic is found in passalids which burrow in the
ground under logs, as in Taeniocerus spp. (Kon & Araya 1992, Kon & Johki 1987), in
leaf cutter ant detritus as in Ptichopus angulatus (Percheron) or in passalids in other
detritus-like habitats (Johki & Kon 1987). Almost nothing is known concerning the
habits of 0. floridanus.
0. floridanus is known only from the southern terminus of the Lake Wales Ridge
of Highlands Co., Florida. A high concentration of endemic Florida scrub biota is rec
ognized from this area (Deyrup 1989, 1990).
The history of Odontotaenius in North America may be proposed as follows: at
some point during the Cenozoic when mesic forest (Quercus, Liquidambar, Acer, etc.),
similar to that of the southeastern U.S. at present, extended relatively unbroken as
far as Honduras, the ancestor of the U.S. species migrated into the U.S. from eastern
Mexico. Subsequently, a dry barrier formed in southern Texas and Tamaulipas, iso
lating the U.S. populations. At various times since the Miocene, the ridges of Florida,
especially the Lake Wales ridge, may have been isolated from the rest of the mainland
by marine transgressions (Deyrup 1989). The ridges, then islands in the "Florida Ar
chipelago", may have given rise to various endemic species, including 0. floridanus;
however, if one considers the fact that many endemic species of the Florida ridges ap
pear to be relict species which had wider distributions at one time (Deyrup 1990), 0.
floridanus may have originated elsewhere and migrated into Florida, only now being
restricted in its range. Of particular interest now is whether 0. floridanus is re
stricted to the Lake Wales ridge (as are various other taxa (Deyrup 1989)), or whether
it or other endemic passalid species occur on other Florida ridges. Although its wings
appear normal, 0. floridanus has not been found in other than Highlands Co., despite
the fact that I have examined hundreds of passalid specimens from Florida. 0. dis
junctus is found throughout much of Florida north of Lake Okeechobee (Schuster
1983), including the Archbold Biological Station, where it is sympatric with 0. flori
danus.
Other interesting questions concern the degree of ecological overlap between these
two Florida species. Does habitat sympatry occur, i.e., do they occur in the same forest
types? I suspect this may be the case, considering that 0. disjunctus inhabits a wide
variety of broadleaf forests in North America, including the relatively dry turkey-oak
sandhills of north central Florida (Schuster 1978). Does microhabitat sympatry occur,
i.e., do they occur in the same kind (species, degree of decomposition) of logs, or even
the same log? This would not be surprising, considering that Luederwaldt (1931)
found 10 species in a single log in Brazil, and frequently three or four species are
found in the same log in the tropics. Further collecting in Florida should answer some
of these questions.
The following key is based on that of Castillo et al. (1988):
KEY TO THE SPECIES OF ODONTOTAENIUS
1. Frontal fossae glabrous, clypeus swollen or with triangular projection in
m id d le ..................................................................................................... 3
1' Frontal fossae pubescent, clypeus uniform width throughout or nar
row er in m middle ........................... ............ 2
December, 1994
Schuster: Odontotaenius floridanus, A New U.S. Passalid 479
2. Metasternal disc delimited by punctations, eyes reduced; Mexico, Si
erra M adre Oriental.......................................................... zodiacus
2' Metasternal disc not delimited by punctations, eyes normal; Mexico,
Jalisco, Sierra de M anantlan............ ......... ......................... 0. cerastes
3. Clypeus with triangular projection in middle, body length <35mm; Mex-
ico to Colombia ........................ ...... ....... ... 0.. striatopunctatus
3' Clypeus gently sw ollen in m iddle ............................................................. 4
4. Body length >35m m ; U .S.A., Canada...................... ........................ 5
4' Body length 25-26mm; Ecuador ....................................... 0. striatulus
5. Prothoracic tibiae narrow, horn pedunculate (Figs. 1,2); eastern U.S.A.,
southeastern Canada........................ ............. ............ 0. disjunctus
5' Prothoracic tibiae wide, horn extends forward without marked peduncle
(Figs. 1,2); south-central Florida ....................................... 0. floridanus
ACKNOWLEDGMENTS
Special thanks to Michael Thomas and Mark Deyrup for facilitating the expedition
to Highlands Co., Paul Skelley for finding the beasts with larvae in the field, and
Mark Deyrup and the F.S.C.A. for providing other specimens. Mark Deyrup, Pedro
Reyes-Castillo, Gary Steck and an anonymous reviewer provided cogent criticism of
the manuscript. The Universidad del Valle de Guatemala provided support.
REFERENCES CITED
CASTILLO, C., L.E. RIVERA-CERVANTES, AND P. REYES-CASTILLO. 1988. Estudio sobre
los Passalidae (Coleoptera: Lamellicornia) de la Sierra de Manantlan, Jalisco.
Acta Zool. Mexicana (n.s.) 30: 120.
DEYRUP, M. 1989. Arthropods endemic to Florida scrub. Florida Scientist 52(4): 254
270.
DEYRUP, M. 1990. Arthropod footprints in the sands of time. Florida Entomol. 73: 529
538.
JOHKI, Y. AND, M. KON. 1987. Morpho-ecological analysis on the relationship between
habitat and body shape in adult passalid beetles (Coleoptera: Passalidae).
Mem. Fac. Sci., Kyoto Univ., (Ser. Biol.), 2: 119-128.
KON, M., AND K. ARAYA. 1992. On the microhabitat of the Bornean passalid beetle,
Taeniocerus platypus (Coleoptera, Passalidae). Elytra, Tokyo, 20(1): 129-130.
KON, M., AND Y. JOHKI. 1987. A new type of microhabitat, the interface between the
log and the ground, observed in the passalid beetle of Borneo Taeniocerus bi
canthatus (Coleoptera: Passalidae). J. Ethology 5(2): 197 198.
LUEDERWALDT, H. 1931. Monographia dos passalideos do Brasil (Col.). Rev. Mus.
Paul., 17 (1st parte).
REYES-CASTILLO, P. 1970. Coleoptera, Passalidae: Morfologia y division en grandes
grupos; g6neros americanos. Folia Entomol. Mexicana 20-22: 1240.
SCHUSTER, J. 1978. Biogeographical and ecological limits of New World Passalidae
(Coleoptera). Coleopterists Bulletin 32(1): 21-28.
SCHUSTER, J. 1983. The Passalidae of the United States. Coleopterists Bulletin 37(4):
302-305.
SCHUSTER, J., AND P. REYES-CASTILLO. 1981. New World genera of Passalidae (Co
leoptera): a revision of larvae. An. Esc. nac. Cienc. Bio., Mexico. 25: 79-116.
Florida Entomologist 77(4)
FEEDING BY BA GOUS AFFINIS (COLEOPTERA:
CURCULIONIDAE) INHIBITS GERMINATION OF HYDRILLA
TUBERS
K.E. GODFREY AND L.W.J. ANDERSON
USDA, ARS, Aquatic Weed Control Research Laboratory
University of California
Davis, CA 95616
ABSTRACT
Bagous affinis Hustache (Coleoptera: Curculionidae) larvae feed inside subterra
nean turions or tubers of hydrilla (Hydrilla verticillata (L.f.) Royle, Hydrocharita
ceae) during low water conditions. This results in reduced germination of the tubers.
To determine the number of B. affinis required to reduce tuber germination, dioecious
hydrilla tubers were exposed to various B. affinis egg to tuber ratios. The tubers were
then held for germination. The number of adults produced and the number of tubers
germinating for each treatment and damage category were recorded. In all treat
ments, tuber germination was significantly reduced compared with the controls. The
proportion of tubers germinating tended to decrease with an increase in the number
of eggs initially placed in the treatment. This reduction in germination resulted from
an increase in feeding damage. The results of this study suggest that B. affinis should
be released in the field with an egg to tuber ratio of 2:1 or greater.
Key Words: Biological control, aquatic weed control, hydrilla tuber weevil, insect feed
ing damage
RESUME
Las larvas de Bagous affinis Hustache (Coleoptera: Curculionidae) se alimentan
de los tallos subterraneos (tub6rculos) de la elodea de la Florida (Hydrilla verticillata
[L.f.] Royle, Hydrocharitaceae) cuando el agua es poco profunda, lo que reduce su ger
minaci6n. Para determinar el ndmero de B. affinis requerido para reducir la germi
naci6n de los tallos subterraneos de la elodea, fueron expuestos tub6rculos di6icos a
varias densidades de huevos del insecto y se esper6 a que germinaran. El numero de
adults producido, el numero de tub6rculos que germinaron y la categoria de los danos
fueron registrados en cada tratamiento. En todas las variantes la germinaci6n de los
tub6rculos fue significativamente reducida con respect a los testigos. La proporci6n
de los tub6rculos germinados tendi6 a disminuir con el aumento del ndmero de huevos
inicialmente colocados en cada tratamiento. Esta reducci6n de la germinaci6n fue el
resultado del aumento del dano producido por los insects al alimentarse de los tallos.
Los resultados de este studio sugieren que B. affinis debe liberarse en el campo a una
proporci6n de huevos por tub6rculo de 2:1 o mayor.
Bagous affinis Hustache (Coleoptera: Curculionidae), the hydrilla tuber weevil, is
a biological control agent for hydrilla (Hydrilla verticillata (L.f.) Royle; Hydrocharita
ceae), a submersed aquatic weed. The life cycle of this weevil is geared to a wet-dry
seasonal climate. In the dry season, the weevils feed upon the above-ground portions
of the hydrilla plant that are exposed as water recedes from an aquatic site (Baloch
et al. 1980, Buckingham 1988). Female weevils oviposit in moist organic matter found
This article is from Florida Entomologist Online, Vol. 77, No. 4 (1994).
FEO is available from the Florida Center for Library Automation gopher (sally.fcla.ufl.edu)
and is identical to Florida Entomologist (An International Journal for the Americas).
FEO is prepared by E. O. Painter Printing Co., P.O. Box 877, DeLeon Springs, FL. 32130.
December, 1994
Godfrey & Anderson: B. affinis & Hydrilla Tubers
in and among the stranded hydrilla plants (Baloch et al. 1980, Buckingham 1988).
Upon egg hatch, the larvae burrow through the soil seeking subterranean turions (tu
bers) of hydrilla. The larvae complete three instars while feeding inside the tubers
and then pupate either within the tuber or in the soil (Bennett & Buckingham 1991).
The feeding activity of the larvae destroys the tubers by consuming the meristems, or
by providing an entryway for other organisms such as fungi or bacteria. Destruction
of populations of hydrilla tubers, known as tuber banks, is important in controlling
hydrilla because the tubers are a source of new infestations for up to 4 years after for
mation of the tubers (Van & Steward 1990, L. W J. A., unpublished data).
Hydrilla is classified as a Category A pest in California and, as such, must be man
aged with eradication as the objective. In a cooperative program with the California
Department of Food and Agriculture, we investigated the use of the hydrilla tuber
weevil in an inundative release program to reduce and possibly eliminate tuber banks
at selected sites in California. The hydrilla tuber weevil was selected for use in this
program because in its native range it infested almost 100% of hydrilla tubers at a site
during the dry season. In the following wet season, there was little or no regrowth of
the hydrilla at this site (Baloch et al. 1980). In California, some of the water systems
infested with hydrilla undergo a seasonal drawdown, thereby potentially exposing hy
drilla tubers to attack by B. affinis. To estimate the number of weevils to be released
at an infested site, the number of weevils and the amount of feeding damage required
to cause a reduction in germination of a population of tubers must be determined. In
this study, the relationship between B. affinis density and reduction in tuber germi
nation was investigated by measuring the amount of germination by dioecious hyd
rilla tubers after exposure to different numbers of B. affinis larvae. This study was
conducted in the laboratory because the Category A pest designation of hydrilla would
not allow the establishment of field plots.
MATERIALS AND METHODS
The ratio of B. affinis to hydrilla tubers required to reduce tuber germination was
investigated in experiments that were conducted at the USDA Aquatic Weed Control
Research Laboratory, Davis, California, from 16 December 1992 to 20 May 1994. The
insects used in these experiments had been in laboratory culture for 8 to 10 genera
tions. The weevils used to originate this colony were collected outside Bangalore, In
dia in April 1991. They were cultured in quarantine at the Florida Biological Control
Laboratory, Gainesville, Florida, for 1 generation before shipment to California in the
summer of 1991. The dioecious hydrilla tubers were obtained from the USDAAquatic
Plant Management Laboratory, Ft. Lauderdale, Florida. Known numbers of hydrilla
tubers were exposed to different numbers of B. affinis larvae. Eggs were used to ini
tiate the experiments because placing eggs on the soil surface more closely reflects ac
tual field conditions in which adults are released and allowed to oviposit. Eggs are
also more amenable to transfer to experimental containers than neonate larvae. Of
the eggs used in these experiments, approximately 90% hatched (K. E. G., unpub
lished data).
Fifty replicates of each of the following egg to tuber ratio treatments were estab
lished: 1:5 (2 eggs: 10 tubers), 1:4 (2 eggs: 8 tubers), 1:2 (2 eggs: 4 tubers), 1:1 (2 eggs:
2 tubers), 2:1 (4 eggs: 2 tubers), and 5:1 (10 eggs: 2 tubers). These treatments repre
sent the following tuber densities: 10 tubers, 3,306 per m2; 8 tubers, 2,645 per m2; 4 tu
bers, 1,323 per m2; and 2 tubers, 662 per m2. The treatments describe the initial
experimental conditions. Each replicate consisted of a plastic rearing container (5.5 x
5.5 x 6 cm) filled with a sandy loam soil that had been moistened with a 1% benomyl
Florida Entomologist 77(4)
solution until damp, but friable. The benomyl solution was used to prevent the growth
of fungi (Bennett & Buckingham 1991). Hydrilla tubers were weighed individually,
and the required number buried approximately 3 cm below the soil surface. B. affinis
eggs were dissected from water-soaked wood (an oviposition media) that had been
placed in a colony cage for 24-48 h. The appropriate number of eggs was placed on
moist filter paper on the soil surface, and the container was covered with foil to main
tain soil moisture. Controls were set up exactly like the experimental containers, ex
cept that no eggs were included. Thirty-five replicates were set up as controls for each
of the four tuber densities in the six treatment ratios (i.e., tuber density of 10 for the
1:5 ratio; 8 for the 1:4 ratio; 4 for the 1:2 ratio; and 2 for the 1:1, 2:1, and 5:1 ratios).
All containers, both treatments and controls, were held at 27 C for 25 days. The con
tainers were misted 3 times per week with tap water to maintain soil moisture.
To determine germination of the tubers, all B. affinis and tubers were recovered
and counted. The tubers were then broken in half medially. The interior of each tuber
was examined and scored according to the following feeding damage scheme: 0, 1-25,
25-50, 50-75, and 75-100% of the interior damaged. The tubers were then grouped ac
cording to treatment, replicate, and feeding damage category, and placed in petri
dishes (9 cm diam). The tubers were covered with tap water and placed at 27 C with
a photoperiod of 16:8 (L:D) for 7 days. Under these conditions, any non-dormant tu
bers capable of germinating should have germinated (Spencer & Anderson 1986).
The effect of breaking the tubers in half medially on germination was investigated
by examining the germination of 100 tubers, 50 broken, and 50 left entire. The tubers
were placed in petri dishes (9 cm diam), covered with tap water, and held for 7 days
at 27 C with a photoperiod of 16:8 (L:D). The number of tubers germinating was re
corded.
Comparisons of the proportion of tubers in each feeding damage category among
ratio treatments were done using X2 analysis (Steel & Torrie 1960). The effect of tuber
size on the amount of feeding damage was investigated by assigning tubers to one of
five size classes (0.10 -0.15 gm, 0.16-0.20 gm, 0.21 0.25 gm, 0.26 0.30 gm, or 0.31
0.35 gm) and comparing the proportion of tubers in each feeding damage category
among size classes. This comparison was done using X2 analysis (Steel & Torrie 1960).
The proportion of tubers germinating among ratio treatments, between ratio treat
ments and controls, among feeding damage categories, and between broken and en
tire tubers were compared using X2 analysis (Steel & Torrie 1960).
RESULTS
The number of B. affinis adults produced increased with an increase in the egg to
tuber ratio treatment (Table 1). The treatments were set up with differing numbers
of eggs, so the proportion of adults produced were compared among treatments. Sig
nificantly lower proportions of adults were produced at the 5:1, 2:1, and 1:1 treatment
ratios than at the 1:5, 1:4, and 1:2 treatments (Table 1;X2 39.02, df=5, P<0.05). This
lower production of adults may be due to greater intraspecific competition among the
larvae. Such competition could result in greater mortality of the larvae in the higher
treatments as compared with the lower treatment ratios, even though the larvae are
not cannibalistic (Bennett & Buckingham 1991).
The proportion of tubers fed upon increased with an increase in the egg to tuber
treatment ratio (Fig. 1A; X2 91.1, df=5, P<0.01). The proportion of tubers damaged
was found to be independent of the weight of the tuber (Table 1;X2 6.1, df=4, P>0.10),
suggesting that the increase in damage was the result of an increase in the number
of larvae present. The proportions of tubers withinthe feeding damage categories dif
December, 1994
Godfrey & Anderson: B. affinis & Hydrilla Tubers
TABLE 1. THE MEAN WEIGHT + STD. ERR. OF TUBERS, THE MEAN NUMBER + STD. ERR. OF
B. AFFINIS ADULTS PRODUCED AND THE PROPORTION OF EGGS SURVIVING TO
THE ADULT STAGE IN EACH RATIO TREATMENT.
Mean Wt. of Mean No. of B. Proportion of Eggs
Ratio Treatments Tubers (gm) affinis Produced Surviving To Adult
1:5 0.21 +0.003 0.7 +0.01 0.35
1:4 0.21 +0.003 0.62 +0.01 0.31
1:2 0.22 +0.004 0.84 +0.13 0.42
1:1 0.25 +0.007 0.50 + 0.10 0.25
2:1 0.22 +0.005 0.86 +0.14 0.22
5:1 0.23 +0.007 1.76 +0.29 0.18
fered significantly among the egg to tuber treatment ratios (Fig. 1B; X2=304.6, df=20,
P<0.01). At the low treatments (1:5), more of the tubers were in the no or low (0%, 1
25%) feeding damage categories, whereas, at the higher treatments, more tubers were
found in the higher feeding damage categories (50-75%, 75-100%; Fig. 1B).
Germination of the tubers was not influenced by breaking the tubers in half medi
ally (X 2.38, df=1, P>0.10). Of the tubers that were broken in half, 64% (n 50) ger
minated. Of the tubers left entire, 78% (n = 50) germinated.
Comparisons of the proportion of tubers germinating in the treatments with those
in the controls summed over all feeding damage categories revealed significant differ
ences (Fig. 2A; 1:5: X245.39, df=l, P<0.01; 1:4: X 15.76, df=l, P<0.01; 1:2:
X2 9.91,dfl, P<0.01; 1:1: X 14.69, df=l, P<0.01; 2:1: X 14.69, df=l, P<0.01; 5:1:
X2 14.96, df=, P<0.01). In all egg to tuber treatment ratios, except the 1:2 treatment,
the proportion of tubers germinating was less in the treatments than in the controls
(Fig. 2A). This demonstrated the ability of B. affinis to reduce tuber germination. In
the 1:2 egg to tuber treatment ratio, a greater proportion of tubers germinated in the
treatment than in the control (Fig. 2A). The reason for this difference is unclear. How
ever, in this treatment, the proportion of tubers germinating in all feeding damage
categories was greater than in other treatments (Fig. 2B).
In general, there was a reduction in tuber germinationwith an increase in the den
sity of B. affinis and the amount of feeding damage (Figs. 2A, 2B, and 3). Comparison
of the proportion of tubers germinating among egg to tuber treatment ratios without
regard to feeding damage category, revealed a significant decrease in germination as
the treatment ratio increased (Fig. 2A; X2=71.0, df=5, P<0.05). The proportion of tu
bers germinating in the controls and in each feeding damage category, regardless of
ratio treatment, decreased significantly with an increase in damage category (Fig. 3;
X2=101.58, df=5, P<0.01). The proportion of tubers germinating decreased substan
tially for those tubers in the 25-50 and 50-75% feeding damage categories. No tubers
germinated in the 75 100% feeding damage category (Fig. 3).
DISCUSSION
The results suggest that for B. affinis to decimate hydrilla tuber banks, they
should be released with an egg to tuber ratio of 2:1 or greater. The objectives of the re
lease should dictate the ratio used. For example, if B. affinis was used in an inocu
lative release program where establishment of the weevil was the objective, the egg to
tuber ratio for release should be 1:1 or 2:1. These lower ratios should be used because
Florida Entomologist 77(4)
1:5 1:4 1:2 1:1 2:1 5:1
Egg to Tuber Ratio
Fig. 1. A.) The proportion of tubers that had been fed upon or not fed upon for the
1:5 (n = 500 tubers), 1:4 (n = 399 tubers), 1:2 (n = 200 tubers), 1:1 (n = 99 tubers), 2:1
(n = 99 tubers), and 5:1 (n = 100 tubers) egg to tuber ratio treatments. Please note 1
tuber was unaccounted for in the 1:4, 1:1, and 2:1 treatments. The proportion of tu
bers fed upon increased significantly (P < 0.01) with an increase in the ratio treat
ment. B.) The proportion of tubers in each feeding damage category in which feeding
damage occurred for each treatment. The proportion of tubers within feeding damage
categories differed significantly (P < 0.01) among the ratio treatments.
December, 1994
Godfrey & Anderson: B. affinis & Hydrilla Tubers
Control
Treatment
S1-25% .s-75%
6 0.4-
2 0.3-
O
0.
0.1
oil
1:5 1:4 1:2 1:1 2:1 5:1
0% 25-50% 75-100% B
S i [] 1-25% [] 50-75%
S0.8
I'-
0 0.4-
0
2 0.2-
0
1:5 1:4 1:2 1:1 2:1 5:1
Egg to Tuber Ratio
Fig. 2. A.) The proportion of tubers germinating in the controls and in each ratio
treatment. There was a significant decrease (P < 0.05) in germination with an in
crease in ratio treatment. Within each ratio treatment, the proportion of tubers ger
minating differed from that in the controls (P < 0.01). (See text for X2 values). B.) The
proportion of tubers germinating in each feeding damage category for each treatment.
Florida Entomologist 77(4)
0.7-
0.6-
0.5-
0.4
S0.3-
a.
0.2
0.1-
0
Control 0% 1-25% 25-50% 50-75% 75-100%
Feeding Damage
Fig. 3. The proportion of tubers germinating in each feeding damage category
summed over the controls and all egg to tuber ratio treatments. There was a signifi
cant (P < 0.01) decrease in germination with an increase in feeding damage category.
they resulted in proportionally more adults being produced from the eggs than the 5:1
egg to tuber ratio. However, if B. affinis was used in an inundative release program
where the objective was maximum tuber destruction, then the egg to tuber ratio for
release should be 5:1 or greater. The higher egg to tuber ratio should be used because
production of adult B. affinis would not be a priority.
The egg stage of B. affinis may not be the most convenient life stage for release in
the field. Conversion of the number of eggs to the number of adults requires knowl
edge of the mean fecundity, the sex ratio of a population of weevils, and the percent
egg eclosion. For B. affinis in the laboratory, the mean fecundity is 231.7 eggs per fe
male (Bennett & Buckingham 1991), the sex ratio is approximately 1:1 (Bennett &
Buckingham 1991), and approximately 90% of all eggs hatch (K. E. G., unpublished
data). To achieve a 2:1 egg to tuber ratio at a site would require 1 weevil for every 52
tubers, assuming that the life history attributes for B. affinis given above are repre
sentative of those in the field. For the 5:1 egg to tuber ratio, 1 weevil would be re
quired for every 21 tubers.
In hydrilla-infested aquatic sites in Florida and California, tuber densities ranged
from 0-510 and 20-1,000 tubers per m2, respectively (Bowes et al. 1979, Anderson &
Dechoretz 1982, Sutton & Portier 1985). Reduction of the tuber banks in infested sites
in Florida using B. affinis would have required the release of between 0.1 -10 weevils
per m2 to achieve the 2:1 egg to tuber ratio, and between 0.1 -25 weevils per m2 for the
5:1 ratio. In California, between 1 -20 weevils per m2 would have to be released for the
2:1 ratio, and between 1 48 weevils per m2 for the 5:1 ratio.
In practice, the number of weevils released should probably be greater than those
given above because the weevils may not be as successful in the field as they are in the
December, 1994
Godfrey & Anderson: B. affinis & Hydrilla Tubers
laboratory. In two other studies where B. affinis was released in the field, the percent
of tubers attacked was not as great as that in the laboratory. In Florida, B. affinis was
released at an egg to tuber ratio of about 1:5. In the tubers recovered from these sites,
0 16.6% had been fed upon (Buckingham et al. 1994). In California, B. affiniswas re
leased at an egg to tuber ratio of approximately 1.2:1, and 11.2% of the sentinel tubers
(tubers that were placed in the field to monitor the success of a release) were fed upon
(Godfrey et al. 1994). In this laboratory study, 37.2 and 52.5% of the tubers had been
fed upon in the 1:5 and 1:1 ratios, respectively. The lower rate of larval attack in the
field may have been due to a variety of factors such as soil temperature, soil texture,
or movement by the adults before oviposition (Buckingham et al. 1994).
The ratios of weevils to tubers required for maximum tuber destruction deter
mined in this study should be viewed as guidelines for release numbers. Many factors
influence the ability of B. affinis to destroy tubers. However, the results of this study
suggest that under favorable conditions, B. affinis has the ability to impact hydrilla
tuber banks.
ACKNOWLEDGMENTS
We acknowledge K. Steward for supplying many of the hydrilla tubers used in this
study and D. Davis for her technical assistance. We thank S. Sheldon, F. Ryan, and L.
Godfrey for reviewing an earlier draft of this manuscript. This research was sup
ported with a grant from California Department of Food and Agriculture.
Mention of a proprietary product does not constitute an endorsement or a recom-
mendation for its use by USDA.
REFERENCES CITED
ANDERSON, L.W.J., AND N. DECHORETZ. 1982. Growth, reproduction and control of
Hydrilla verticillata (L.f.) Royle in an irrigation system in the southwestern
U.S. Proc. EWRS 6th Symposium on Aquat. Weeds. pp. 54-61.
BALOCH, G.M., SANA-ULLAH, AND M.A. GHANI. 1980. Some promising insects for the
biological control of Hydrilla verticillata in Pakistan. Trop. Pest Manage. 26:
194-200.
BENNETT, C.A., AND G.R. BUCKINGHAM. 1991. Laboratory biologies of Bagous affinis
and B. laevigatus (Coleoptera: Curculionidae) attacking tubers of Hydrilla ver
ticillata (Hydrocharitaceae). Ann. Entomol. Soc. America 84: 420-428.
BOWES, G., A.S. HOLADAY, AND W.T. HALLER. 1979. Seasonal variation in the biom
ass, tuber density, and photosynthetic metabolism of hydrilla in three Florida
lakes. J. Aquat. Plant Manage. 17: 6165.
BUCKINGHAM, G.R. 1988. Reunion in Florida -hydrilla, a weevil, and a fly. Aquatics
10: 19-25.
BUCKINGHAM, G.R., C.A. BENNETT, AND E.A. OKRAH. 1994. Temporary establishment
of the hydrilla tuber weevil (Bagous affinis) during a drawdown in north-cen
tral Florida. J. Aquat. Plant Manage. 31: (in press).
GODFREY, K.E., L.W.J. ANDERSON, S.D. PERRY, AND N. DECHORETZ. 1994. Overwin
tering and establishment potential of Bagous affinis (Coleoptera: Curculion
idae) on Hydrilla verticillata (Hydrocharitaceae) in northern California.
Florida Entomol. 77: 221-230.
SPENCER, D.F., AND L.W.J. ANDERSON. 1986. Photoperiod responses in monoecious
and dioecious Hydrilla verticillata. Weed Sci. 34: 551-557.
STEEL, R.G.D., AND J.H. TORRIE. 1960. Principles and procedures of statistics.
McGraw-Hill Book Company, Inc. New York. 481pp.
488 Florida Entomologist 77(4) December, 1994
SUTTON, D.L., AND K.M. PORTIER. 1985. Density of tubers and turions of Hydrilla in
South Florida. J. Aquat. Plant Manage. 23: 6467.
VAN, T.K., AND K.K. STEWARD. 1990. Longevity of monoecious hydrilla propagules. J.
Aquat. Plant Manage. 28: 7476.
++++++++++++++++++++++++++++++++++++++++++++++++++++
Florida Entomologist 77(4)
THREE NEW SPECIES OF RHYPAROCHROMINE LYGAEIDAE
(HEMIPTERA: HETEROPTERA) FROM HISPANIOLA
JAMES A. SLATER' AND RICHARD M. BARANOWSKI2
1Dept. Ecology & Evolutionary Biology
University of Connecticut
Storrs, CT 06269
University of Florida Institute of Food and Agricultural Sciences
Tropical Research and Education Center
Homestead, FL 33031
ABSTRACT
Three new species of rhyparochromine Lygaeidae, of the tribe Myodochini, Her
aeus caliginosus New Species, Heraeus concolor New Species, and Catenes spiculus
New Species from Hispaniola are described. H. caliginosus and C. spiculus are fig
ured. Catenes Distant has previously been known only from a single Central Ameri
can species.
Key Words: West Indies, Myodochini, Heraeus, Catenes
RESUME
Se described tres nuevas species de Lygaeidae rhyparochromine, de la tribu Myo
dochini, Heraeus caliginosus Nueva Especie, Heraeus concolor Nueva Especie y
Catenes spiculus Nueva Especie colectados en Espanola. Se proven figures de H.
caliginosus y de C. spiculus. El genero Catenes Distant se conocia previamente en
base a una sola especie Centroamericana.
During the course of our ongoing study of the lygaeid fauna of the West Indies, we
have had occasion to study several interesting specimens taken in light traps in the
Dominican Republic. Several of these specimens represent undescribed species of the
tribe Myodochini that are treated below.
The genus Heraeus Stal is a complex taxon with four species previously known
from the West Indies (Slater 1964). Catenes Distant, however, has been known previ
ously only from a single Central American species, Catenes porrectus Distant (Distant
1893).
This article is from Florida Entomologist Online, Vol. 77, No. 4 (1994).
FEO is available from the Florida Center for Library Automation gopher (sally.fcla.ufl.edu)
and is identical to Florida Entomologist (An International Journal for the Americas).
FEO is prepared by E. O. Painter Printing Co., P.O. Box 877, DeLeon Springs, FL. 32130.
December, 1994
Slater & Baranowski: New Species of Lygaeidae (Hemiptera) 489
One of the striking features of these new species is that all of them show a con
trastingly dark and light color pattern. This is also true for a species of Ozophora
(tribe Ozophorini) which will be discussed in a later paper. This convergence of color
pattern in what are otherwise unrelated taxa must be an adaptation to a substrate
which will only be clarified when material can be taken in situ in the field.
All measurements are in millimeters.
Catenes spiculus Slater and Baranowski, New Species
(Fig. 1)
DESCRIPTION: Elongate, nearly parallel-sided. Head black, shining. Anterior
pronotal lobe dark chestnut brown with a black median stripe running through entire
pronotum and scutellum. Anterior pronotal collar reddish brown, concolorous with
posterior pronotal lobe. Posterior pronotal lobe reddish brown on either side of black
midline, becoming darker reddish brown laterally. Scutellum dark chocolate brown
with a median black stripe, apex white. Hemelytra nearly uniformly testaceous with
punctures strongly constrastingly dark brown; lateral corial margins pale yellow; co
rium posteriorly with an apical dark brown macula and a second macula laterally not
reaching lateral margin of corium, located at level of middle of apical corial margin.
Membrane fumose with veins contrastingly white. Thoracic pleura and sterna dark
chocolate brown, almost black. Abdomen bright reddish brown. Legs white, or pale
yellow, with distal third of meso and metafemora and distal half of forefemora
strongly contrastingly dark brown. Labium pale yellow. Antennae with first segment
chocolate brown, second segment pale yellow with extreme distal end infuscated,
third segment pale yellow on proximal two thirds, but with an extensively developed
dark brown distal third, fourth segment with base and apical third dark chocolate
brown, remainder of segment white. Dorsal surface clothed with upstanding hairs.
Pronotum and scutellum dull, strongly contrasting with shining surface of head.
Head extremely elongate and tapering, apex exceeding distal end of first antenna
segment. Eyes sessile, set midway along lateral margins of head, remote from ante
rior pronotal margin. Length head 1.36, width 0.92, interocular space 0.36. Pronotum
with a distinct anterior collar, anterior lobe much narrower than posterior, transverse
impression complete. Length pronotum 1.30, width 1.60. Scutellum lacking a promi
nent median carina, although mesal area somewhat elevated. Length scutellum 1.02,
width 0.76. Hemelytra with corium nearly parallel sided, slightly concave at level of
apex of scutellum. Length claval commissure 0.90. Midline distance apex clavus to
apex corium 1.28. Midline distance apex corium to apex abdomen 1.06. Metathoracic
scent gland auricle directed slightly postero-laterad, short, subelliptical. Evaporative
area large, occupying most of anterior lobe of metapleuron, narrowing posteriorly and
extending anteriorly onto posterior area of mesopleuron. Mesepimeron emergent.
Forefemora relatively slender, slightly incrassate, armed below distally with a simple
series of spines as follows: two major spines with three minor spines between them, a
proximally placed hair spine and a single small distal spine. Labium elongate, extend
ing onto second abdominal sternum. First labial segment extending caudad beyond
posterior margin of eye but not reaching base of head; second segment reaching be
tween forecoxae; third segment reaching or slightly exceeding metacoxae. Length la
bial segments I 1.04, II 1.24, III 1.24, IV 0.50. Antennae slender, fourth segment
narrowly fusiform. Length antennal segments I 0.56, II 1.40, III 1.20, IV 1.20. Total
body length 6.64.
HOLOTYPE. Female. Dominican Republic: Guanumo, Finca Goya, 30.V.1989
(Gustavo Anzerro) blacklightt trap). In National Museum of Natural History
(NMNH).
Florida Entomologist 77(4)
N.\
tI I
'- I
U
A.3
I.) V
Figure 1. Catenes spiculus Slater and Baranowski New Species.
ETYMOLOGY. Referring to the sharp needle-like anterior end of the head.
Distant's (1893) original description of Catenes porrectus, the only previously
known species in the genus, is very short. It was described from Guatemala and Pan
ama and is known only from these locations. Distant's (1893) color plate shows C. por
rectus differing from C. spiculus n. sp. in having a pale yellow first antenna segment,
the forefemora yellow with dark dots over the entire surface, the darkened distal third
of the meso and metafemora interrupted by a pale yellow annulus, dark distal ends
December, 1994
'"^
Slater & Baranowski: New Species of Lygaeidae (Hemiptera) 491
to all tibiae, a reddish brown head and scutellum and lacking a subapical dark macula
along the costal margin of the corium. Catanes porrectus is said to be 8 mm long.
We have examined two males from Venezuela (Miranda EST EXT. Rio Negro cr.
CAPAYA, 100 m. 17-19.VI.80) (in Universidad Central de Venezuela) which agree
with the figure and description of C. porrectus (Distant 1893) in all respects, except
that the meso and metafemoral annuli are obscure, all femora have numerous black
spots, and the hemelytra are completely and uniformly yellowish.
Heraeus caliginosus Slater and Baranowski, New Species
(Fig. 2)
DESCRIPTION. Coloration chiefly black to extremely dark brown. Head black,
strongly shining. Pronotum and scutellum dull black, with two small yellow macula
on either side of midline on posterior lobe immediately behind transverse impression.
Scutellum gray on anterior half, with a narrow black median stripe and an oblique
black macula midway between meson and lateral margin on each basal half. Heme
lytra in large part dark chocolate brown. Clavus yellow on anterior two-thirds with
contrasting dark brown punctures, extreme base and distal third dark brown. Corium
yellowish basally, area at level of claval commissure interspersed with yellowish and
dark brown. A large rectangular white macula distally on corium at level of middle of
apical corial margin, extending from costal margin nearly to apical corial margin, but
not actually attaining latter. Membrane dark brown, veins in part pale yellow, a very
conspicuous rectangular white bar mesally on apical third of membrane. Thoracic
pleura and sterna uniformly dull black. Abdomen shining reddish brown, a quadrate
yellow macula present along dorsal margin of sternum five. Entire forefemora and
distal halves of middle and hind femora dark chocolate brown, strongly contrasting
with white proximal halves of middle and hind femora. Tibiae and tarsi pale yellow,
tibiae infuscated with brown at extreme proximal and distal ends. Labium pale yel
lowish brown. First antenna segment dark red-brown, second and third segments al
most uniformly yellow, segment three becoming ochraceous distally, fourth segment
dark brown with a short, narrow, inconspicuous, poorly differentiated, pale annulus
on proximal third (figure exaggerates pale annulus). Dorsal surface with a few scat
tered upright hairs present, these more numerous and elongate on head and scutel
lum. Thoracic punctures weak, indistinct, those on clavus and corium larger and
conspicuous.
Head elongate, porrect. First antennal segment slightly exceeding apex of tylus.
Eyes placed near middle of head, area behind eyes characteristically constricted.
Length head 1.34, width 0.88, interocular space 0.42. Pronotum with anterior collar
narrow dorsally becoming strongly widened ventrally (typical for genus). A row of
deep conspicuous punctures on depression behind posterior margin of anterior collar.
Anterior pronotal lobe moderately convex but not elevated to level of posterior lobe,
transverse impression complete and punctate. Length pronotum 1.0, width 1.44.
Length scutellum 0.92, width 0.72. Lateral corial margins nearly parallel-sided,
slightly concave at level of apex of scutellum. Length claval commissure 0.56. Midline
distance apex clavus to apex corium 1.24. Midline distance apex corium to apex abdo
men 0.98. Metathoracic scent gland auricle short, slightly curving posteriorly. Evap
orative area occupying inner two thirds of metapleuron. Forefemora strongly
incrassate, armed below with at least four major spines, distally with a series of
smaller spines. Labium elongate, exceeding metacoxae, attaining middle of abdomi
nal sternum two (first visible segment), segment one almost reaching base of head,
second segment extending onto anterior portion of mesosternum. Length labial seg
Florida Entomologist 77(4)
December, 1994
-. ->i
' 3
S."~
'Asr
xi:
Figure 2. Heraeus caliginosus Slater and Baranowski New Species.
ments I 1.08, II 1.20, III 0.60, IV 0.66 (approx.). Antennae conventionally terete,
fourth segment narrowly fusiform. Length antennal segments I 0.58, II 1.16, III 1.10,
IV 1.20. Total body length 5.76.
TYPES. Holotype. Female. Dominican Republic: Pedernales Prov., 21 km. N.
Cabo Rojo, 19.VI.1976 (R. E. Woodruff) blacklightt trap). In Florida State Collection
of Arthropods. Paratype: 1 male. Dominican Republic: Barahona, 6 km. NW
Paraiso, Rio Nizao, 18-02N, 17-12W, 170 m. 25-26-VII-1990 (C. Young, J. E. Rawlins,
S. A. Thompson). In Carnegie Museum.
ETYMOLOGY. Referring to the dark coloration of the body
Heraeus caliginosus n. sp. is most closely related to Heraeus guttatus (Dallas), the
two species resembling one another closely in size and general body proportions. Her
aeus caliginosus may readily be distinguished from H guttatus by the elongate la
bium which extends well onto the second abdominal segment. In H guttatus the
labium extends, at most, only between the metacoxae. In H caliginosus the first an
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