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United States Department of Agriculture

Agricultural Research Service

Title: Estimating the Biological Efficacy of Gypchek Aerially-Applied Against a Low-Density Leading Edge Gypsy Moth Population

item Webb, Ralph
item Podgwaite, J. - USDA FOREST SERVICE
item Schumacher, D - WISCONSIN DEPT. AGR
item White, Geoffrey
item Reardon, R. - USDA FOREST SERVICE
item Sukontarak, Tod

Submitted to: Gypsy Moth Research Review Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: January 1, 2000
Publication Date: N/A

Technical Abstract: State Action Agencies prefer to use a single application, rather than a more expensive double application, of the species-specific viral insecticide Gypchek against the gypsy moth, a serious forest pest; however, scant information existed on the operational efficacy of a single application. This study evaluates the use of the one-application option as spart of the State of Wisconsin Gypsy Moth Control Program. Since Wisconsi lies on or near the "transition zone" of the expanding gypsy moth population, much of the control program consists of negatively impacting "trace" populations. The use of Gypchek against trace populations required new evaluation technology. To this end, a technique (a "bugs-in-bags" approach) was developed and evaluated to measure the operational efficacy of Gypchek application against this trace population. First or second instar gypsy moth larvae we replaced, one per bag or 10 per bag, in sleeve cages placed over treated foliage one hour post-treatment. Mortality observed for larvae placed ten per bag was equivalent to that recorded for larvae placed one per bag. While this study was conceived as a test of the evaluation technique an insight into Gypchek performance under operational conditions was gained. A single application of Gypchek applied in 9.5 liters of Carrier 038 at 10(12) polyhedral inclusion bodies per ha was found to perform best in blocks treated in the early morning; efficacy decline was correlated with a lowering of relative humidity and an increase in temperature and wind speed. Results will aid all Federal, State and Private applicators seeking to control gypsy moths using Gypchek.

Last Modified: 4/19/2015
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