Progress 11/17/05 to 05/17/07
Outputs
Progress Report Objectives (from AD-416) Develop strategies for the effective control of gypsy moth and whiteflies with reduced use of chemical pesticides, enhanced use of microbials and other natural products (e.g., pheromones and regulatory peptides) and natural enemies (e.g., predators). Specific objectives include the development of methods for improved management of gypsy moths in non-forest and newly infested forested areas of the United States, the identification and evaluation of the effectiveness of potential biopesticides for control of whiteflies, and the identification of key predators of the sweet potato whitefly, Bemisia tabaci strain B. Approach (from AD-416) Studies will be conducted to evaluate new gypsy moth mating disruption formulations and to evaluate new strains and formulations of the gypsy moth nucleopolyhedrosis virus. Experiments will be conducted in conjunction with aerial applications of mating disruption formulations to determine the efficacy of new products, to refine the criteria used to determine application dose relative to gypsy moth population density, to improve methods used to evaluate efficacy, and to better understand the mechanisms by which mating is disrupted. Compounds with activity against the sweet potato whitefly will be characterized, dose-response curves generated and mode of action studies undertaken. The B. tabaci juvenile hormone(s), a molecule involved in the regulation of many life processes, will be identified using an established physico-chemical method combined with gas chromatography. To facilitate conservation of generalist predators of whiteflies, state-of-the-art molecular methods will be used to perform predator gut analysis, and a simple model incorporating incidence of whitefly DNA in the gut and half-life of DNA detectability will be used to identify key whitefly predators. Accomplishments The following accomplishments are reported from FY 2006 as the termination report for this project. All SYs retired and left the project in the first quarter of FY 2007. Project funds were redirected by National Program Staff. Sugar ribose found to be toxic to whiteflies. We determined that ribose, a simple sugar, is even more toxic to sweet potato whiteflies than arabinose, xylose and mannose. These four simple sugars act as antifeedants. We also discovered that two other simple sugars, melibiose and trhehalose, act as mild antifeedants when administered in the whitefly diet, but are not toxic to whiteflies. Determination of toxicity is an important first step in the development of new biopesticides, and will be followed by efforts to determine the mode of action underlying antifeedant activity of the sugars (NP304, component 2). 4b. List other significant research accomplishments, if any. Persistence of gypsy moth mating disruption treatments. We determined that the effects of gypsy moth mating disruption treatments persist for up to two years after the treatment. Mating success is reduced the year after treatment by up to 80%. Capture of males in pheromone traps is also reduced, by up to 50%. These findings are significant to managers involved in area-wide gypsy moth control efforts because they suggest that the currently-used method of deploying pheromone traps in previously- treated areas to detect residual populations may not be as effective as previously thought, and new or modified methods may need to be developed (NP304, component 1). Juvenile hormone of Bemisia tabaci identified. In collaboration with scientists from Purdue University and Washington State University, the juvenile hormone of Bemisia tabaci eggs was identified as JH III and the titer per whitefly egg was determined. The identification of the whitefly JH is important because the potency of several insect growth regulators is based on their ability to mimic JH activity. This finding could lead to the development of useful growth regulating insecticides for use in whitefly management programs (NP304, component 2). Ground-based applications of gypsy moth mating disruption treatments found to be effective. Two ground-based gypsy moth mating disruption systems were tested with positive results. One involved a modified hydroseeder that sprayed a tank mix containing plastic laminated flakes containing gypsy moth pheromone, and the other used a novel formulation that was injected into paintballs and applied to trees using paintball guns. Both methods provided effective mating disruption, but the paintball method was faster than other ground-based methods that have been tested. A ground-based method of mating disruption treatment application would be useful to government agencies or pest control managers in areas where aerial application is not feasible (NP304, component 2). New structures discovered on larvae of parasitic wasp. In collaboration with collaborator at the Tel Aviv University, protuberances emanating from wasp larvae that parasitize B. tabaci were discovered; their structure is being examined in collaboration with the Electron Microscopy Laboratory (ARS, Beltsville, MD). Determination of the structure and function of these protuberances could provide important new information regarding how the parasite manipulates its host whitefly as well as novel mechanisms used by parasites to facilitate their own development in their hosts. This information could help in the development of biological control programs against whiteflies. Genes toxic to diamondback moth identified and sequenced. In collaboration with the Rural Development Administration of South Korea, and scientists at ARS�s Soybean Genetics and Improvement Laboratory in Beltsville, eight Cry genes from strains of Bacillus thuringiensis (Bt) that are toxic to the diamondback moth (DBM) were identified and sequenced. One of the eight genes sequenced was Cry 1Ba, a gene that is present in an IBL strain (#425) that is toxic to a DBM biotype that is resistant to the commercial strain of Bt. A new CinA gene was also sequenced and registered in GenBank. This information will assist in the development of pest control agents against this serious pest (NP304, component 2).
Impacts
(N/A)
Publications
|
Progress 10/01/05 to 09/30/06
Outputs
Progress Report 1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter? Gypsy moths and whiteflies take an enormous toll on forests, residential plantings, and croplands. Damage due to whitefly activity in the U.S. is more than $1 billion annually, and crop losses by whiteflies exceed $2 billion worldwide. Since 1924, gypsy moth has defoliated more than 81 million acres of U.S. forests, and millions of acres have been sprayed with insecticides to prevent defoliation. Along the leading edge of the infestation alone, economic impacts are estimated to be greater than $500 million per year. Current management practices for these pests include the use of broad-spectrum pesticides that may carry the risk of unwanted impacts on the environment and human health. The proposed project seeks to develop new and improved methods to reduce the damage caused by these
pests, to minimize negative effects on non-target organisms and the environment, and to increase the cost effectiveness of management activities. The objectives of the research are to: 1) identify and test the effectiveness of microbial-derived toxins and insect-derived regulatory molecules in killing whiteflies; 2) identify key predators of the sweet potato whitefly, Bemisia tabaci, biotype B; and 3) develop and evaluate improved gypsy moth virus and mating disruption formulations. We will conduct experiments to determine the ability of small regulatory molecules and insect-specific bacterial toxins to inhibit or prevent whitefly maturation. Results will contribute to the development of effective, safe biopesticides for use in the greenhouse and the field. Molecular gut analysis of field-collected predators will be used to identify predator species capable of exerting the greatest impact on B. tabaci numbers. Gypsy moth impacts are currently being reduced by efforts to slow the
rate of gypsy moth expansion. A research program will be conducted to assist in the development and evaluation of effective strains of gypsy moth virus, mating disruption formulations, and improved understanding of gypsy moth population dynamics at the low densities that occur along the expanding front. This research is in the scope of National Program 304, Crop Protection and Quarantine Action Plan (100%). Components addressed include: 1) Plant, Pest, and Natural Enemy Interactions and Ecology, and; 2) Pest Control Technologies. The use of parasites, predators and associated augmentative release technology as well as biopesticides and mating disruption to reduce whitefly and gypsy moth impacts addresses high priority needs. Information as to the insecticidal action of selected hormonal regulatory agents, of microbial-derived biopesticides in preventing the completion of the whitefly life cycle, the identification of key predators of B. tabaci, and improvements in gypsy moth
virus strains and mating disruption formulations and application methods will contribute to the development of new strategies for controlling populations of these pests in the field, greenhouses, and in forests. Whitefly research findings will be used by the pesticide industry to develop new products for whitefly control and by growers and pest management practitioners to help in the development of integrated pest management programs. Gypsy moth research findings will assist government agencies involved in gypsy moth management programs and pest control managers. Growers, government agencies, and the general public will eventually benefit from our research outcomes. 2. List by year the currently approved milestones (indicators of research progress) Year 1 (FY2006) Objective 1: Complete evaluation of female deployment methods. Objective 2: Complete studies to identify the juvenile hormones of B. tabaci nymphs. Objective 3: Complete development of whitefly primers and PCR protocols
for predator gut analysis; determine DNA half-lives for model predators fed whiteflies. Year 2 (FY2007) Objective 1: Complete study of trap catch/mating success in experimental plots; complete laboratory assays of virus strains. Objective 2: Determine toxicities of selected bacterial extracts. Objective 3: Complete pilot study to optimize field sampling protocols. Year 3 (FY2008) Objective 1: Complete moth density/dose experiments at 15 and 37.5 g/ha; complete studies of distribution of trap catch and mating success in grids. Objective 2: Determined toxicities of selected bacterial extracts and diuretic/antidiuretic peptides. Objective 3: Determine DNA half-lives for field-collected predators fed whiteflies and alternate prey; complete first year field sampling and gut analysis; analyze data set. Year 4 (FY2009) Objective 1: Complete sleeve cage tests of candidate virus strains and formulations. Objective 2: Complete studies to characterize preparations/molecules toxic to B.
tabaci. Objective 3: Complete second year field sampling and gut analysis; analyze data set. Year 5 (FY2010) Objective 1: Complete field tests of candidate mating disruption formulations; complete moth density/dose test at additional densities and doses. Objective 2: Complete studies on modes of action of toxic compounds; complete identification of active compounds with high potential to serve as biopesticides. Objective 3: Complete third year field sampling and gut analysis; analyze three-year data set. 4a List the single most significant research accomplishment during FY 2006. Sugar ribose found to be toxic to whiteflies. We determined that ribose, a simple sugar, is even more toxic to sweet potato whiteflies than arabinose, xylose and mannose. These four simple sugars act as antifeedants. We also discovered that two other simple sugars, melibiose and trhehalose, act as mild antifeedants when administered in the whitefly diet, but are not toxic to whiteflies. Determination of
toxicity is an important first step in the development of new biopesticides, and will be followed by efforts to determine the mode of action underlying antifeedant activity of the sugars (NP304, component 2). 4b List other significant research accomplishment(s), if any. Persistence of gypsy moth mating disruption treatments. We determined that the effects of gypsy moth mating disruption treatments persist for up to two years after the treatment. Mating success is reduced the year after treatment by up to 80%. Capture of males in pheromone traps is also reduced, by up to 50%. These findings are significant to managers involved in area-wide gypsy moth control efforts because they suggest that the currently-used method of deploying pheromone traps in previously- treated areas to detect residual populations may not be as effective as previously thought, and new or modified methods may need to be developed (NP304, component 1). Juvenile hormone of Bemisia tabaci identified. In
collaboration with Kansas State University and Purdue University, the juvenile hormone of Bemisia tabaci eggs was identified as JH III and the titer per whitefly egg was determined. The identification of the whitefly JH is important because the potency of several insect growth regulators is based on their ability to mimic JH activity. This finding could lead to the development of useful growth regulating insecticides for use in whitefly management programs (NP304, component 2). Ground-based applications of gypsy moth mating disruption treatments found to be effective. Two ground-based gypsy moth mating disruption systems were tested with positive results. One involved a modified hydroseeder that sprayed a tank mix containing plastic laminated flakes containing gypsy moth pheromone, and the other used a novel formulation that was injected into paintballs and applied to trees using paintball guns. Both methods provided effective mating disruption, but the paintball method was
faster than other ground-based methods that have been tested. A ground-based method of mating disruption treatment application would be useful to government agencies or pest control managers in areas where aerial application is not feasible (NP304, component 2). New structures discovered on larvae of parasitic wasp. In collaboration with the Tel Aviv University, protuberances emanating from wasp larvae that parasitize B. tabaci were discovered; their structure is being examined in collaboration with the Electron Microscopy Laboratory (ARS, Beltsville, MD). Determination of the structure and function of these protuberances could provide important new information regarding how the parasite manipulates its host whitefly as well as novel mechanisms used by parasites to facilitate their own development in their hosts. This information could help in the development of biological control programs against whiteflies. Genes toxic to diamondback moth identified and sequenced. In
collaboration with the Rural Development Administration of South Korea, and scientists at ARSs Soybean Genetics and Improvement Laboratory in Beltsville, eight Cry genes from strains of Bacillus thuringiensis (Bt) that are toxic to the diamondback moth (DBM) were identified and sequenced. One of the eight genes sequenced was Cry 1Ba, a gene that is present in an IBL strain (#425) that is toxic to a DBM biotype that is resistant to the commercial strain of Bt. A new CinA gene was also sequenced and registered in GenBank. This information will assist in the development of pest control agents against this serious pest (NP304, component 2). 5. Describe the major accomplishments to date and their predicted or actual impact. Ribose, a simple sugar, was found to be a potent sweet potato whitefly toxin and antifeedant. The juvenile hormone (JH) of young sweet potato whiteflies and their eggs was determined. The identification of the whitefly JH is important because the potency of several
insect growth regulators is based on their ability to mimic JH activity. These findings are important first steps in the discovery and development of new pest control agents against whiteflies (NP304, component 2). The effects of gypsy moth mating disruption treatments persist for up to two years after the treatment. This finding is significant because this persistence could interfere with the detection of populations surviving the treatment. This information has been provided to government agencies and gypsy moth managers, and has led to additional research to solve the problems that this previously unknown effect can cause (NP304, component 1). 6. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? Our whitefly staging system is now available for use by
scientists who require synchronous populations of whiteflies for fundamental and applied studies. Since 2000, 82% of the nearly 2.9 million acres treated in the national Slow-The-Spread of the gypsy moth (STS) project used mating disruption. Results from ongoing evaluations of new and existing mating disruption formulations are currently providing information needed by that program to serve the state and local jurisdictions involved in the program. Every year, this information is communicated directly to the national program through the Gypsy Moth Mating Disruption Working Group, which is chaired by the administrator of the STS program and is composed of individuals from within USDA, state governments, and Universities. In addition, the USDA Forest Service publishes non-technical reviews on the subjects of gypsy moth mating disruption and virus at regular intervals, and ARS research results are included. The large-scale use of the mating disruption technique against gypsy moth
populations as part of the STS program leads to rapid adoption of improvements identified through ARS research. 7. List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below). Greenstone, M.H. Molecular methods in predation research. Invited presentation, Department of Entomology, Michigan State University, September, 2005. Thorpe, K.W. Ground-based application of gypsy moth mating disruption formulations. Association of Virginia Gypsy Moth Managers Meeting, Luray, VA, March 7 9, 2006.
Impacts
(N/A)
Publications
- Webb, R.E., White, G.B., Podgwaite, J., D'Amico, V., Slavicek, J., Swearingen, J., Onken, B., Thorpe, K. 2005. Aerially-applied baculovirus and naturally-occurring entomophaga maimaiga provide outstanding control of gypsy moth (lepidoptera: lymantriidae). Journal of Entomological Science. 40(3):446-460.
- Gelman, D.B., Gerling, D., Blackburn, M.B., Hu, J.S. 2005. Host-parasite interactions between whiteflies and their parasitoids. Archives of Insect Biochemistry and Physiology. 60:209-222.
- Gelman, D.B., Gerling, D., Blackburn, M.B. 2005. Host-parasite interactions relating to penetration of bemisia tabaci by its parasitoid eretmocerus mundus. Journal of Insect Science. 5(46).
- Margam, V.M., Gelman, D.B., Palli, S.R. 2006. Ecdysteroid titers and developmental expression of ecdysone-regulated genes during metamorphosis of the yellow fever mosquito, aedes aegypti (diptera: culicidae). Journal of Insect Physiology. 52:558-568.
- Tcheslavskaia, K., Brewster, C., Thorpe, K.W., Sharov, K., Leonard, D., Roberts, E. 2005. Effects of intentional gaps in spray coverage on the efficacy of gypsy moth mating disruption. Journal of Applied Entomology. 129(9-10):475-480.
- Thorpe, K.W., Tcheslavakaia, K.S. 2006. Disparlure persistence in the forest. Proceedings of the Spray Efficacy Research Group (SERG). International & USDA Forest Service Worskshop, Banff, ALberta, Canada. February 13-16, 2006. pg. 27-33.
- Thorpe, K.W., Tcheslavskaia, K.S. 2006. Gypsy moth mating disruption research. Meeting Abstract. North American Forest Insect Work Conference (NAFIWC) Meeting held in Asheville, NC, May 22-25, 2006.
- Thorpe, K.W., Tcheslavskaia, K.S. 2005. Temporal and spatial dynamics of gypsy moth mating success at low population densities. Annual Gypsy Moth Review Proceedings. Annual Gyspy Moth Review, Philadelphia, PA October 31, 2005 - November 11, 2005
|