Movement and survival of larval western corn rootworm and European corn borer within blended refuges of short-stature corn

Short-stature corn is expected to be adopted by corn producers in the United States in the coming years. Short-stature corn has some advantages over its taller counterparts, which should help facilitate its adoption in the US Corn Belt. However, knowledge gaps exist concerning how certain insect pests might interact with short-stature corn and the implications of these interactions for insect resistance management (IRM). Western corn rootworm, Diabrotica virgifera virgifera, and European corn borer, Ostrinia nubilalis, are important pests inhabiting the US Corn Belt. To protect crops from these pests, transgenic corn producing insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) is commonly planted by farmers. Planting blended refuges that contain a mixture of Bt and non-Bt plants is one IRM strategy commonly used to delay resistance to Bt crops. We studied larval pest movement and survival in blended refuges of short-stature corn and tall corn. Six arrays, in which the positions of Bt and non-Bt plants varied, were tested for both short-stature corn and tall corn. The central plant of an array received either eggs of western corn rootworm or neonate larvae of European corn borer. After several days, plants were sampled to measure pest abundance at the different positions within arrays to assess patterns of larval movement. Larvae of both pests were found mostly on the center plant and the plant next to the center. The findings of this study may help to improve IRM strategies for short-stature corn.