Inheritance and fitness costs of Bt resistance for a field-derived strain of western corn rootworm (Diabrotica virgifera virgifera LeConte)

Resistance of western corn rootworm, Diabrotica virgifera virgifera LeConte to transgenic corn producing Bt toxin Cry3Bb1 has been appearing in fields in Iowa, USA since 2009. The current understanding of interactions between western corn rootworm and Bt corn is based primarily on computer modeling, interactions of susceptible insects with Bt corn, and experiments on lab-derived strains of Bt-resistant insects. Furthermore, there are few data on the inheritance of the resistance and fitness costs for Bt resistance in western corn rootworm currently available. This study seeks to examine the inheritance of resistance and fitness costs for a western corn rootworm strain with field-derived resistance to Cry3Bb1 corn, which was originally collected from an Iowa cornfield in 2010. An array of bioassays were employed to gather data on survival of resistant, susceptible, and reciprocally crossed heterozygous insects. Future experiments will test ecological factors that may affect western corn rootworm mortality; as well as fitness costs and genetic bases of resistance. These data will aid in the development of more effective insect resistance management strategies.