Effects of Single Vs. Pyramided Bt Corn Hybrids on the Development and Fecundity of Helicoverpa zea

The majority of corn planted in the U.S. has been genetically engineered to express Bt insecticidal toxins. Insect resistance to Bt crops is the primary threat to their success and longevity. In order to delay resistance, it is essential to understand the ecological effects of various Bt corn hybrids on key pests such as Helicoverpa zea. In this study, we investigated the development, fecundity, and egg viability of H. zea collected from Bt and non-Bt corn hybrids currently used in the southern United States to control lepidopteran pests. Pupae were collected from hybrids in NC, SC, and MS and reared to produce moths. Across two years of study, pupal weights were consistently reduced in some of the Bt hybrids compared to non-Bt near-isolines. Fecundity and egg viability were not significantly affected by corn hybrid. These data will be incorporated into IRM models, which can be used to improve risk management decisions regarding H. zea in Bt crops in the complex landscapes of the southern United States.