Degree-day models are useful tools for estimating the development of different insects, allowing us to predict when potential pests might begin to impact a crop. For the Western Corn Rootworm, degree-day calculations can be used to determine the onset of egg hatch in an area, peak egg hatch, and the timing of adult emergence.
Western corn rootworm resistance to Bt corn continues to be an issue in continuous corn in the United States. Fueled in part by repeated use of the same Bt traits and low refuge compliance during the early phases of adoption, field evolved resistance was first detected in 2009. To date, resistance to every commercially available Bt trait package has been detected in major corn production areas of the country. However, resistance is not uniform across all corn growing regions so be sure to check local conditions when making planting decisions.