Impacts of Decreased Measurements of Bollworm Susceptibility to Cry1Ac on Survival and Damage to Bt Cottons

Interpreting variable laboratory responses of Helicoverpa zea Boddie to toxins from Bacillus thuringiensis Berliner (Bt) has been challenging due to the lack of a clear relationship to field control. Research that links laboratory measurements of susceptibility to survival on Bt crops is vital for accurate characterization of and subsequent response to the occurrence of an implied H. zea resistance event. Therefore, we initiated experiments to link insect survival and damage on dual- and multi-gene Bt cottons to laboratory estimates of two H. zea colonies with different levels of susceptibility to Cry1Ac. This information will allow for better predictions of H. zea control in Bt cottons based on laboratory measurements of susceptibility to Cry1Ac.