DEVELOPMENT, EVALUATION AND SAFETY OF ENTOMOPATHOGENS FOR CONTROL OF ARTHROPOD PESTS

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
211	3110	1120	50%
211	3130	1120	50%

Progress 10/01/00 to 09/30/05

Outputs
The attachment and infectivity of the entomopathogenic nematode species, Steinernema carpocapsae, on soldiers and workers of the subterranean termite, Coptotermes formosanus, were evaluated. More nematodes attached to soldiers in the absence of workers compared to soldiers that were in the presence of workers. With soldiers alone, workers alone, and mixture of equal numbers of workers and soldiers, soldiers in the mixed groups had lower mortality than soldiers alone after 1 and 4 days. Exposure of small groups of termites to S. carpocapsae resulted in higher mortality of soldiers after 1- and 4-days post exposure. Thus, when soldiers alone or workers alone are exposed to nematodes, there is a differential susceptibility of soldiers and workers to nematode infection with soldiers being more susceptible than workers. Grooming behavior of the workers serve as a mechanism to reduce nematode infection of soldiers and workers as soldiers cannot groom themselves. In other studies, the glassy-winged sharpshooter is susceptible to entomopathogenic fungi, and the decorated cricket has a host-specific nematode that sexually transmitted from males to females back to males. Only male crickets are infected and the females serve as a biological vector during mating.

Impacts
During this 5 year project, the use of entomopathogens (nematodes and fungi) has been evaluated against a number of pests including the fungus gnat, white grubs, termites, the glassy winged sharpshooter, crickets, and plant-parasitic nematodes. These studies have shown the important role that these pathogens can have in biological control programs. The research on the decorated cricket provides information on the ecological and evolutionary implications of a nematode parasite that is sexually transmitted.

Publications

Luong, L. T. and Kaya, H. K. 2004. Sexually transmitted nematode affect spermatophylax production in the cricket, Gryllodes sigillatus. Behav. Ecol. 16: 153-158.
Fallon, D. J., Kaya, H. K., Gaugler, R. and Sipes, B. S. 2004. Effect of Steinernema feltiae-Xenorhabdus bovienii insect pathogen complex on Meloidogyne javanica. Nematology 61: 671-680.
Godfrey, L. D., Grafton-Cardwell, E. E., Kaya, H. K. and Chaney, W. E. 2005. Microorganisms and their byproducts, nematodes, oils and particle films have important agricultural uses. Calif. Agric. 59(1): 35-40.
Shapiro-Ilan, D. I., Fuxa, J. R., Lacey, L. A., Onstad, D. W. and Kaya, H. K. 2005. Definitions of pathogenicity and virulence in invertebrate pathology. J. Invertebr. Pathol. 88: 1-7.
Mankowski, M., Kaya, H. K., Grace, J. K. and Sipes, B. S. 2005. Differential susceptibility of subterranean termite castes to entomopathogenic nematodes. Biocontrol Sci. Technol. 15: in press.

Progress 01/01/04 to 12/31/04

Outputs
A Korean isolate of Steinernema carpocapsae was evaluated against the fungus gnat, Bradysia agrestis, in the laboratory and propagation house. In the laboratory, the infective juvenile nematodes infected third and fourth instars and pupal stage at a high rate. Second instars were infected at a low rate (was less than 35%), and the egg stage and first instars were immune to infection. Adult fungus gnats dispersed the infective juveniles from treated areas to non-treated areas. In the propagation house experiments with watermelon seedlings, S. carpocapsae significantly reduced B. agrestis larval numbers in comparison with the controls. When watermelon seed was treated with nematodes at sowing, the number of fungus gnat larvae ranged from 4 to 8 and from 5 to 8 in the nematode treated plots compared with 26 and 30 in the control plots on the 17th and 34th day post-treatment, respectively. In another project, the entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae, have been isolated from soil from organic citrus groves and were tested against glassy-winged sharpshooter adults. These isolates required high conidial concentrations to infect the sharpshooter adults.

Impacts
The use of entomopathogenic nematodes to control the fungus gnat for seedling production in propagation house will reduce the amount to chemical pesticides in the environment. Entomopathogenic fungi have the potential to control the glassy-winged sharpshooter, a devastating insect pest of grapes and other crops.

Publications

Hazir, S., Kaya, H. K., Stock, S. P. and Keskin, N. 2003. Entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) for biological control of soil pests. Turkish J. Biol. 27: 181-202.
Kim, H. H., Choo, H. Y., Kaya, H. K., Lee, D. W., Lee, S. M. and Jeon, H. Y. 2004. Steinernema carpocapsae (Rhabditida: Steinernematidae) as a biological control agent against the fungus gnat Bradysia agrestis (Diptera: Sciaridae) in propagation houses. Biocontrol Sci. Technol. 14: 171-183.

Progress 01/01/03 to 12/31/03

Outputs
An extensive survey was conducted for entomopathogenic nematode throughout Turkey with 1080 soil samples taken producing 22 positive sites. The isolated nematodes included Heterorhabditis bacteriophora, Steinernema feltiae, S. affine, and a new Steinernema species. The most common species was S. feltiae which was isolated from 10 sites in 6 regions, followed by H. bacteriophora from 7 sites in 5 regions, S. affine from 4 sites and 2 regions, and the Steinernema sp. from 1 site. The soils of the positive nematode sites were classified as sandy, sandy loam or loam (68.2 percent) and sandy-clay-loam or clay loam (31.8 percent). The habitats from which the entomopathogenic nematodes were isolated were broadly classified as disturbed (59.1 percent) which included agricultural fields and poplar planted for lumber or wind breaks, and undisturbed (40.9 percent) which included pine forests, grassland, and marsh and reed locations. In another study, the entomopathogenic fungus, Beauveria bassiana, is being evaluated against glassy-winged sharpshooter adults. Thus far, fungal mortality has been recorded only at high conidial concentrations.

Impacts
The survey in Turkey has provided new isolates of genetic and biological control material for use against soil insect pests. The evaluation of entomopathogenic fungi against the glassy-winged sharpshooter may lead to a biological control program against this devastating insect pest of grapes and other crops.

Publications

Hazir, S., Keskin, N., Stock, S. P., Kaya, H. K. and Ozcan, S. 2003. Diversity and distribution of entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae) in Turkey. Biodiversity Conserv. 12:375-386.
Kaya, H. K., Bonner, T. and McGuire, M. 2003. Entomopathogenic fungi for biological control of the glassy-winged sharpshooter, Homalodisca coagulata. Sym. Proc. 2003 Pierces Dis. Res. Symp., Calif. Food Agri. Pp. 263-264.

Progress 01/01/02 to 12/31/02

Outputs
Larval and adult activity of the oriental beetle (Exomala orientalis), an important pest of turfgrass in Korea and the USA, was investigated. Adult emergence was first observed on the greens in late May with peak adult emergence occurring two weeks later. Surveys of turfgrass at golf courses showed that oriental beetle grub densities varied from course to course with more grubs on the tees and fairways than on the greens. As the greens cannot tolerate grub damage, this part of the course became the focal point of the study. A common denominator was that beetle grub densities were always higher at greens with Japanese chestnut trees around them. Emergence holes left by the adults and the presence of chestnut trees appear to be good indicators of high grub densities on the greens for infestations in the following year. In another study, female crickets served as a means for mechanical transmission of the nematode Mehdinema alii to male crickets. This nematode only develops and reproduces in the gut of adult male crickets and is sexually transmitted from infected males to females back to males. The female cricket is promiscuous and will mate multiple times with different male crickets over her lifetime. Immature male crickets are not infected by the nematode.

Impacts
By understanding the spatial distribution of the oriental beetle grub, a control strategy can be developed. Sampling for beetle grubs can take place where they are most likely to occur and control tactics can be implemented. The research with the cricket-nematode system will provide insights on host behavior and fitness and into the ecological and evolutionary implications of a sexually transmitted parasite.

Publications

Choo, H. Y., Lee, D. W., Park, J. W., Kaya, H. K., Smitley, D. R., Lee, S. M. and Choo, Y. M. 2002. Life history and spatial distribution of the oriental beetle (Coleoptera: Scarabaeidae) in golf courses in Korea. J. Econ. Entomol. 95:72-80.
Choo, H. Y., Kaya, H. K., Huh, J., Lee, D. W., Kim, H. H., Lee, S. M. and Choo, Y. M. 2002. Entomopathogenic nematode (Steinernema spp. and Heterorhabditis bacteriophora) and a fungus Beauveria brongniartii for biological control of the white grubs, Ectinohoplia rufipes and Exomala orientalis, in Korean golf courses. BioControl 47: 177-192.
Luong, L. T. and Kaya, H. K. 2002. Infection dynamics of a sexually transmitted nematode (Mehdinema alii) in the decorated cricket (Gryllodes sigillatus). Can. J. Zool. 80:1145-1148.

Progress 01/01/01 to 12/31/01

Outputs
White grubs are serious pests of turfgrass on golf courses, parks, and home lawns. Six Korean entomopathogenic nematode isolates Steinernema carpocapsae Pocheon, S. glaseri Dongrae, S. glaseri Mungyeong, S. longicaudum Gongju, S. longicaudum Nonsan, and Heterorhabditis sp. Gyeongsan were tested against larvae of the oriental beetle. In addition, the organophosphate insecticide, chlorpyrifos-methyl, was combined with Heterorhabditis sp. to determine if a synergistic effect upon larval mortality could be obtained. Both laboratory and field tests were conducted. Laboratory results showed that when 300 infective nematode juveniles in 30 cc of soil was applied, Heterorhabditis sp. caused 100 percent mortality of the second instars four weeks posttreatment, followed by S. longicaudum Nonsan and S. longicaudum Gongju. S. carpocapsae Pocheon and S. glaseri Dongrae were the least effective species. When nematodes were applied at the same rate as the second instars to overwintering third instars, the efficacy was low with Heterorhabditis sp. causing the highest mortality at 39 percent four weeks posttreatment. The combination of half the recommended rates of Heterorhabditis sp. (500 million nematodes/ha) and chlorpyrifos-methyl (9.4 liters active ingredient/ha) was more effective than Heterorhabditis sp. or chlorpyrifos-methyl alone at half rate. In the field, Heterorhabditis sp. was the most effective representing 70 percent mortality, but there were no differences in mortality among the Steinernema spp. Combination of Heterorhabditis sp. with chlorpyrifos-methyl resulted in a synergistic effect representing 91 percent mortality compared with 69 percent in the nematode or 22 percent in insecticide alone treatments.

Impacts
Different species/isolates of entomopathogenic nematodes cause differential mortality in white grub populations. It is important to select the right nematode species to control the target pests. Combinations of entomopathogenic nematodes and chemical pesticides can act synergistically resulting in economic control of a pest species.

Publications

Baur, M. E. and Kaya, H. K. 2001. Persistence of entomopathogenic nematodes. Bulletin from Regional Project S-265.
Hattingly, J. L. and Kaya, H. K. 2001. Entomopathogenic nematodes: prospects for biological control in South Africa. Proc.13th Entomol. Congr., Entomol. Soc. Southern Africa. pp. 28-29.
Koppenhofer, A.M. and Kaya, H. K. 2001. Entomopathogenic nematodes and insect pest management, in: Microbial Biopesticides, Koul, O. and Dhaliwal, G. S., eds. Taylor & Francis, New York, pp. 277-305.

Progress 01/01/00 to 12/31/00

Outputs
Entomopathogenic nematodes and the chloronicotinyl insecticide, imidacloprid, interacted synergistically on the mortality of third-instar white grubs. The degree of interaction varied with nematode species, being synergistic for Steinernema glaseri and Heterorhabditis bacteriophora, but only additive for S. kushidai. The major factor responsible for synergistic interactions between imidacloprid and entomopathogenic nematodes appears to be the general disruption of normal nerve function due to imidacloprid resulting in drastically reduced activity of the grubs. This sluggishness facilitates host attachment by the infective nematodes. The nematode, S. carpocapsae, was compatible with Diglyphus begini, an ectoparasitoid of a dipterous leafminer species. Adult parasitoids were not susceptible to nematode infection, leafminer larvae parasitized by D. begini were less susceptible to nematode infection, and adult parasitoids detected and tended to avoid ovipositing on nematode-infected leafminer larvae.

Impacts
Combinations of entomopathogenic nematodes and environmentally friendly chemical pesticides can act synergistically. A biological control agent by itself may not be effective, but in combination with other agents, the nematode and chemical agent may work together to provide economic control of a pest species. The combination of nematodes and a parasitoid may be an effective approach to biologically control leafminers.

Publications

Sher, R., Parrella, M. P., and Kaya, H. K. 2000. Biological control of the leafminer Liriomyza trifolii (Burgess): implications for intraguild predation between Diglyphus begini Ashmead and Steinernema carpocapsae (Weiser). Biol. Contr. 17:155-163.
Koppenhofer, A. M., Grewal, P. S., and Kaya, H. K. 2000. Synergism of imidacloprid and entomopathogenic nematodes against white grubs: the mechanism. Entomol. Exp. Appl. 94:283-293.
Vega, F. E., Lacey, L. A., Reid, A. P., Herard, F., Pilarska, D., Danova, E., Tomov, R., and Kaya, H. K. 2000. Infectivity of a Bulgarian and an American strain of Steinernema carpocapsae (Nematoda: Steinernematidae) against the coding moth. BioControl 45:337-343.
Gaugler, R., Grewal, P., Kaya, H. K. and Smith-Fiola, D. 2000. Quality assessment of commercially produced entomopathogenic nematodes. Biol. Contr. 17:100-109.
Koppenhofer, A. M., and Kaya, H. K. 2000. Interactions of a nucleopolyhedrovirus with azadirachtin and imidacloprid. J. Invertebr. Pathol. 75:84-86.
Koppenhofer, A. M., Wilson, M., Brown, I., Kaya, H. K., and Gaugler, R. 2000. Biological control agents for white grubs (Coleoptera: Scarabaeidae) in anticipation of the establishment of the Japanese beetle in California. Journal of Economic Entomology 93:71-87.

Progress 01/01/99 to 12/31/99

Outputs
Entomopathogenic nematodes and the bacterium, Bacillus thuringiensis subspecies japonensis, caused additive and synergistic mortality in third-instar Cyclocephala species (white grubs) when the nematodes were applied at least 7 days after the bacterium. These additive and synergistic interactions were observed in the greenhouse and field. The interaction between the nematodes and the bacterium was more synergistic in younger than in older third instar white grubs. In a field test against one population of a white grub species consisting of second and third instars, combinations of nematodes and the bacterium at economic application rates provided acceptable control levels whether the rates were applied simultaneously or with a 4-day delay between the nematodes and bacterium. In another study, the nematode Steinernema rarum was characterized ecologically. That is, the nematode's physiological host range, host-foraging behavior, thermal activity range, and soil moisture range was characterized. This nematode is well-adapted to lepidopteran hosts, infects hosts at the soil surface and deeper in the soil profile (intermediate foraging strategy), infects and develops well at 25 C and is active over a wide range of soil moistures.

Impacts
42. Combinations of biological control agents can be synergistic. One biological control agent by itself may not be effective, but in combination, both agents work together to provide economic control. The combination of nematodes and a bacterium may be an effective approach to biologically control white grub pests.

Publications

Koppenhofer, A. M, Choo, H. Y., Kaya, H. K., Lee, D. W. and Gelernter, W. D. 1999. Increased field and greenhouse efficacy against scarab grubs with a combination of an entomopathogenic nematode and Bacillus thuringiensis. Biol. Contr. 14:37-44.
Koppenhofer, A. M. and Kaya, H. K. 1999. Ecological characterization of Steinernema rarum. J. Invertebr. Pathol. 73:120-128.

Progress 01/01/98 to 12/01/98

Outputs
Ants were the most apparent invertebrate scavengers observed foraging on entomopathogenic nematode-killed insects in the field. Workers of the Argentine ant scavenged nematode-killed insects on the surface and those buried 2 cm below the soil surface. Ant workers scavenged significantly more steinernematid-killed (60-85 percent) than heterorhabditid-killed (10-20 percent) insects. More 4-day-old postinfected insects (host died within 48 hours after nematode exposure) were scavenged than 10-day-old postinfected insects. Survival of steinernematid nematodes may be significantly impacted by invertebrate scavengers, especially ants, than heterorhabditid nematodes because of the selective feeding by the scavengers. Tests conducted with insects killed by the mutualistic bacteria of heterorhabditids, PHOTORHABDUS LUMINESCENS, indicated that they were responsible for the selective feeding by the worker ants. In another study, a method for estimating entomopathogenic nematode densities in soil samples based on repeated sampling with wax moth larvae as bait hosts was developed.

Impacts
(N/A)

Publications

KOPPENHOFER, A. M., CAMPBELL, J. F., KAYA, H. K., and GAUGLER, R. Estimation of entomopathogenic nematode pollution density in soil by correlation between bait insect mortality and nematode penetration.
BAUR, M. E., KAYA, H. K., and STRONG, D. R. Foraging ants as scavengers on entomopathogenic-killed hosts. Biol. Contr. 12:
CHOO, H. Y., KIM, H. H., and KAYA, H. K. Effects of selected chemical pesticides on AGAMERMIS UNKA (Nematoda: Mermithidae), a parasite of the brown plant hopper, NILAPARVATA LUGENS. Biocontr. Sci. Technol.

Progress 01/01/97 to 12/01/97

Outputs
The emergence of infective juveniles of entomopathogenic nematodes from nematode-killed insects was influenced by moisture conditions in the soil. No infective juveniles emerged from cadavers at -500 MPa (dry soil), whereas some infective juveniles emerged at -40 MPa. As expected large numbers of infective juveniles emerged from cadavers in moist soil (-5 MPa). When nematode-killed insects were left in dry soil for varying lengths of time and rehydrated, infective juvenile emergence from cadavers declined the longer they remained in dry soil. This emergence pattern was species dependent because STEINERNEMA CARPOCAPSAE and HETERORHABDITIS BACTERIOPHORA tolerated desiccation conditions better than S. GLASERI. In other studies, a new species S. MONTICOLUM, from Korea was described, and S. GLASERI was isolated naturally for the first time in Korea.

Impacts
(N/A)

Publications

LEONG, K. L. H., YOSHIMURA, M. A., and KAYA, H. K. 1997. Occurrence of a neogregarine protozoan, OPHRYOCYSTIS ELEKTROSCIRRHA McLaughlin and Myers. IN: Populations of Monarch and Queen Butterflies. Pan-Pac.
LEONG, K. L. H., YOSHIMURA, M. A., KAYA, H. K., and WILLIAMS, H. 1997. Instar susceptibility of the monarch butterfly (DANAUS PLEXIPPUS) to the neogregarine parasite, OPHRYOCYSTIS ELEKTROSCIRRHA.
STOCK, S. P., CHOO, H. Y., and KAYA, H. K. 1997. An entomopathogenic nematode, STEINERNEMA MONTICOLUM sp. n. (Rhabditida, Steinernematidae) from Korea with a key to other species.
KOPPENHOFER, A. M., M. E. BAUR, M. E., S. P. STOCK, S. P., H. Y. CHOO, H. Y., B. CHINNASRI, B., and KAYA, H. K. 1997. Survival of entomopathogenic nematodes within host cadavers in dry soil. Appl.
STOCK, S. P., CHOO, H. Y., and KAYA, H. K. 1997. First record of STEINERNEMA GLASERI Steiner, 1929 (Nematoda: Steinernematidae) in Asia, with notes on intraspecific variation. Nematologica 43:377-381.

Progress 01/01/96 to 12/30/96

Outputs
The effect of combining two entomopathogenic species to determine whether it would result in synergistic, additive, or antagonistic effects was tested against second-stage larvae of the western spotted cucumber beetle. In the laboratory, combining two of four nematode species at the LC25 values always resulted in an additive effect, regardless of the effectiveness of the individual nematode species. In the greenhouse, the combinations of two nematode species was never significantly better than the better of the two species alone. The combined nematode treatments were always less effective than the most efficacious single nematode species STEINERNEMA CARPOCAPSAE. In another study, the root extracts of marigold and tomato did not adversely affect the infectivity of STEINERNEMA GLASERI compared with the control, but the presence of alpha terthienyl at concentrations of 20 and 40 ppm significantly reduced numbers of S. GLASERI that infected insect hosts.

Impacts
(N/A)

Publications

CHOO, H. Y., KOPPENHOFER, A. M., and KAYA, H. K. 1996. Combination of two entomopathogenic nematode species for suppression of an insect pest. J. Econ. Entomol. 89: 97-103.
KANAGY, J. M. N., and KAYA, H.K. 1996. The possible role of marigold roots and a - terthienyl in mediating host-finding by steinernematid nematodes. Nematologica 42: 220-231.
KAYA, H. K. and KOPPENHOFER, A. M. 1996. Effect of microbial and other antagonistic organism and competition on entomopathogenic nematodes. Biocontr. Sci. Technol. 6: 357-371.
KAYA, H. K., and STOCK, S. P. 1997. Techniques in insect nematology. IN: Manual of Techniques in Insect Pathology, L. A. Lacey, ed. Academic Press, London. In press.