Location: Corn Insects and Crop Genetics Research
Project Number: 5030-22000-019-006-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Sep 1, 2021
End Date: Jul 31, 2025
Objectives of this proposal are to estimate the baseline susceptibility of western bean cutworm (WBC) populations in the United States to the Bacillus thuringiensis (Bt) pesticidal protein Vip3A using laboratory bioassays, and to monitor for any changes over a three-year duration.
Laboratory Vip3A dose-response pesticidal protein overlay bioassays have been developed for WBC by the ARS and will be applied to test survival across a determined range of purified Vip3A protein exposures. WBC eggs for bioassays will be collected by an established network of cooperators from Kansas, Nebraska, Michigan, Ohio, and New York. For comparisons across populations and years, Probit analyses will be used to estimate lethal concentrations resulting in mortality of 50 (LC50) and 99% (LC99) of individuals within each population sample. To address the impact of variable Vip3A exposures across WBC development, feeding arenas containing diets with different proportions of Bt corn tissue incorporated will be infested with WBC neonates and later instars. Estimates of feeding levels on different diets, and assay endpoint larval survival and weights will be evaluated. These parameters will be applied to modeling survivorship under different insect resistance management scenarios with different rates of larval movement and Vip3A exposures.