Bacillus thuringiensis Vip3Aa protein resistance in Helicoverpa zea (Lepidoptera: Noctuidae)

Evolution of resistance by insect pests can reduce the benefits of transgenic crops expressing insecticidal proteins from Bacillus thuringiensis (Bt). Due to widespread resistance of Helicoverpa zea to Cry Bt proteins in th U.S., the vegetative insecticidal protein Vip3Aa is the only Bt protein in Bt corn and cotton that remains effective against this polyphagous pest. In this study, we evaluated the susceptibility to Vip3Aa protein of 71 H. zea field population collected in 2016 to 2020; estimated the resistance allele frequency of Vip3Aa in the mid-South and Texas during 2018-2020; characterized the Vip3Aa resistance of different H. zea resistant populations; and evaluated the cross-resistance and fitness costs associated with the Vip3Aa resistance. Results generated from this study could help better understand the risks associated with the Vip3Aa resistance in H. zea.