Challenges to Monitoring Bt Resistance in Helicoverpa Zea

Transgenic crops that produce insecticidal proteins from Bacillus thuringiensis (Bt) are widely grown in many countries. Bt proteins have provided protection for multiple crops against damage by lepidopteran pests. The baseline susceptibility of larvae of Helicoverpa zea to Cry1Ac and other Bt toxins has provided a basis for monitoring resistance. In this poster, we discuss the challenges and limitations of resistance monitoring as it relates to H. zea in the southern U.S.