Free Flight of Western Corn Rootworm (Coleoptera: Chrysomelidae) to Corn and Soybean Plants in a Walk-In Wind Tunnel

Abstract

Oviposition in soybean fields by western corn rootworm, Diabrotica virgifera virgifera LeConte, is threatening the effectiveness of crop rotation in east-central Illinois and adjoining counties in northwestern Indiana. Attraction to soybean, Glycine max L., plants has been hypothesized as a mechanism underlying rootworm oviposition in soybean fields. In this study, female western corn rootworms were allowed to fly freely for 0.5 h within a wind tunnel array of potted soybean and corn, Zea mays L., plants before rootworm distribution patterns on corn and soybeans were determined. Test insects were collected in corn and soybean plantings from both within and outside of areas where adults oviposit in soybean fields. We found no evidence of an increased tendency for rootworms from various populations to be associated with soybeans regardless of collection location, cropping history at the collection site, or the area’s status with respect to western corn rootworm oviposition in soybean fields. The difference between corn and soybean plant height influenced postflight distribution of adults in the wind tunnel. More rootworms accumulated on plants whose foliage projected above the height of the insect release platform. Distance moved during a 0.5-h period of free flight was greatest when the foliage of nearby plants did not extend above the level of the insect release platform. Regardless of how corn and soybean plants were configured in the wind tunnel, a significantly greater proportion of rootworms was recovered on corn plants. We found no evidence for attraction to soybeans based on postflight plant association.