1st Place: Is Vip3Aa binding altered in resistant corn earworm (Helicoverpa zea)?

Corn and cotton genetically modified to produce Cry and Vip3A insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) are valuable for the management of lepidopteran pests. These proteins target receptors and form pores in the midgut epithelium, allowing invasion of the hemocoel by gut bacteria, resulting in septicemia and death. The corn earworm (Helicoverpa zea) is one of the most relevant pests of corn and cotton in the U.S. that has evolved widespread field resistance to Cry (Cry1A and Cry2A) proteins. While Vip3Aa remains effective against H. zea, isolation of field resistance alleles suggests resistance is imminent. The goal of this project is to identify resistance mechanisms and genes in a strain of H. zea from Texas displaying >588-fold resistance to Vip3Aa. Results from binding and proteomic assays suggest association of reduced Vip3Aa binding to midgut receptors and resistance. Transcriptomic analysis will help identify alleles responsible for resistance. Information gathered from this project helps assess resistance management tools and guides the design of more effective plant incorporated protectants.