The corn rootworm (Diabrotica spp.) complex represents the primary insect pest of maize in the United States Corn Belt. Larval feeding on corn roots reduces nutrient uptake and growth, making plants susceptible to lodging and yield loss. Corn rootworm is considered a “continuous corn” pest because there is one generation per year, females lay eggs in corn fields, and eggs overwinter in the soil. Crop rotation normally provides a cultural control by disrupting the pest life cycle.
Feeding damage attributable to Diabrotica larvae and associated corn rootworm management costs have been estimated at approximately US$1 billion annually for American corn producers.
Our field research detected a Wisconsin population of the western corn rootworm behavioral variant (rotation-resistant western corn rootworm) that lays eggs in soybean to hatch out in corn the following year, rendering crop rotation ineffective. Applying science-based IPM scouting and economic thresholds for variant western corn rootworm beetles in soybean, our on-farm IPM demonstration network documented the variant’s range expansion into southeastern Wisconsin, delimiting affected and unaffected locations across a nine-county study area. Using a mail survey of 200 Wisconsin corn growers (60% response rate), we examined grower awareness, knowledge and perceptions of the variant western corn rootworm and IPM scouting and economic thresholds in first year corn. Results from this work contributed new information about grower adoption of IPM programs during the high risk period of pest range expansion into a new area. Communication and input from growers, as presented in our Wisconsin case study, are essential to move forward with joint research and extension pest management initiatives during a time of significant challenge and opportunity in field crop IPM.
Currently, we are participating in NCCC46 and NC205 research and extension coordination in response to the first documented case of field-evolved insect resistance to Bt corn in the continental U.S (Gassmann et al. 2011).
Porter P., E. Cullen, T. Sappington … et al. 2012. NCCC46 Letter to EPA Open Docket Plant-Incorporated Protectant Insect Resistance Management (IRM)
Cullen, E.M., J.K. Stute, K.L. Raymond and H.H. Boyd. 2008. Farmers’ perspectives on IPM field scouting during a period of pest range expansion: a case study of variant western corn rootworm (Coleoptera: Chrysomelidae) in Wisconsin. American Entomologist 54:170-178.