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 with strains developed through laboratory based selection. Furthermore, there are few data on the inheritance of the resistance and fitness costs for Bt resistance in western corn rootworm. 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. Inheritance of resistance was measured with diet-based bioassays and seedling-mat bioassays. The magnitude and genetic dominance of fitness costs were measured for numerous life-history parameters through a growth chamber experiment. These data will aid in the development of more effective insect resistance management strategies.