Investigation of potential resistance to Cry3Bb1 in populations of western corn rootworms in northwestern Illinois

The western corn rootworm is a serious pest of corn in the midwestern United States. Economic losses caused by this pest are estimated to exceed $1 billion annually. A widely accepted management practice is the use of transgenic crop technology where corn has been engineered to produce an insecticidal toxin from the soil bacterium Bacillus thuringiensis (Bt). The aim of this experiment is to investigate populations of western corn rootworms in northwestern Illinois that exhibit suspected resistance to Cry3Bb1. Two trial locations were established in areas that contained corn rootworm Bt hybrids (Cry3Bb1) in 2011 that experienced greater than expected damage by corn rootworm larvae. These locations were also in continuous corn for three or more years and have employed the same rootworm Bt event for each year (Cry3Bb1). The corn rootworm management products evaluated include YieldGard VT3 (Cry3Bb1), Herculex RW (Cry34/35Ab1), Agrisure RW (mCry3A), SmartStax (Cry3Bb1 and Cry34/35Ab1), and Agrisure 3122 (Cry34/35Ab1 and mCry3A). Adult population densities, sex ratios, and levels of fitness will be measured from beetles collected in single plant emergence cages. Adult beetles will also be collected for rearing and determination of levels of resistance. Root injury and lodging caused by corn rootworm larvae will be sampled. Results from the first year of this multi-year research project will be discussed.