For the past few years, we have been warning about the presence of Bt-resistant western corn rootworms. The western corn belt has been experiencing greater than expected damage on Bt-corn expressing the single trait Cry3Bb1.
Most often these observations are found in continuous corn, although a report a couple of weeks ago in the Bulletin (from the University of Illinois) reported damage in first-year corn (see http://bulletin.ipm.illinois.edu/?p=1629). We have not yet detected the presence of resistant rootworms in Ohio, but detecting damage is often difficult.
As corn producers begin their harvest, keep a sharp eye out for any areas of significant lodging that may be indicative of western corn rootworm damage in corn expressing Bt, specifically Cry3Bb1 and in continuous corn. Keep in mind that many factors can cause lodging including wind damage and poor root growth, so a careful examination of the roots is necessary. If you suspect damage, please contact entomology state specialists (firstname.lastname@example.org;email@example.com) or your local OSU extension educator.