Location: Application Technology ResearchTitle: Effects of chlorantraniliprole residual on Helicoverpa zea in Bt and non-Bt cotton
|BABU, ARUN - University Of Georgia|
|REISIG, D - North Carolina State University|
|PES, M - Sumitomo Chemical Australia|
|CHAMKASEM, NARONG - Us Food & Drug Administration (FDA)|
|Reding, Michael - Mike|
Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2021
Publication Date: 1/26/2021
Citation: Babu, A., Reisig, D.D., Pes, M.P., Ranger, C.M., Chamkasem, N., Reding, M.E. 2021. Effects of chlorantraniliprole residual on Helicoverpa zea in Bt and non-Bt cotton. Pest Management Science. 77(5):2367-2374. https://doi.org/10.1002/ps.6263.
Interpretive Summary: The cotton bollworm (Helicoverpa zea), also known as corn earworm is a pest of cotton and certain varieties of Bt cotton to which it is resistant. It is managed by foliar sprays of insecticides on these varieties. Some evidence suggests combinations of the insecticide in combination with Bt toxin is more effective than either alone, and can be used for Bt resistance management in cotton bollworm. Laboratory and field trials were used to test treatments of chlorantraniliprole + Bt toxin to chlorantraniliprole or Bt cotton alone on survival of bollworm larvae. The research found foliar sprays of chlorantraniliprole were as effective as the combination treatment and Bt toxin alone. Using treatments of chlorantraniliprole + Bt toxin does not appear to be useful for managing Bt resistance in cotton bollworms.
Technical Abstract: Helicoverpa zea is resistant to several Bt toxins in the US Cotton Belt and is managed with foliar applications of chlorantraniliprole in cotton varieties that do not express the Vip3Aa19 toxin. Previous studies have suggested that foliar insecticides and Bt can interact to influence larval susceptibility. Therefore, it has been suggested that chlorantraniliprole can be used as a tool for Bt resistance management. We designed field and laboratory studies to test the hypothesis that the interaction of Bt toxin and chlorantraniliprole application would result in lower H. zea larval survival when compared to the individual effect of Bt or chlorantraniliprole alone. We also tested for these interactions over time, since chlorantraniliprole residual has not been studied in cotton. Results from two field experiments and two laboratory experiments were similar. We found very few interactions, and no interactions with Bt and chlorantraniliprole, indicating that these factors do not interact to influence survival. Moreover, we found that Bt and chlorantraniliprole did not interact to influence larval weight and instar. Chlorantraniliprole had lethal and sublethal effects on H. zea larval growth parameters feeding on cotton tissue up to 22 days after application, the final time period that we tested. Finally, concentration of chlorantraniliprole in the leaf was associated with larval survival, but not larval growth or instar. Our findings complement the recommendation to use chlorantraniliprole for managing H. zea in cotton, given its long-residual effects. However, the utility of chlorantraniliprole as a Bt-resistance management tool for H. zea remains unclear.