BEHAVIORAL AND FEEDING ASSAYS REVEAL A WESTERN CORN-ROOTWORM (COLEOPTERA, CHRYSOMELIDAE) VARIANT THAT IS ATTRACTED TO SOYBEAN

Economic injury by western corn rootworm, diabrotica virgifera virgife ra LeConte, larvae to corn grown in rotation with soybean has been inc reasing in areas of northwestern Indiana and east central Illinois. To ascertain whether behavioral changes in adults are resulting in larva l damage to corn in these areas, the attractiveness of soybean, corn, and associated cropping environments to western corn rootworm beetles from Indiana, Iowa, and Nebraska was compared using laboratory assays. In a 6-choice host preference assay, beetles from Indiana preferred s oybean without crop residue and pollinated corn more than water wicks, corn residue, pollinating corn, or soybean with corn residue. Beetles from Nebraska favored pollinating and pollinated corn. Western corn r ootworm beetles from Indiana selected soybean without residue more tha n beetles from either Iowa or Nebraska In a no-choice feeding assay, b eetles from Indiana consumed a greater amount of soybean leaf area tha n did beetles from either Iowa or Nebraska. Results were obtained usin g laboratory assays and thus may not always be applicable to the field . However, Endings indicated that a western corn rootworm variant may be present in a portion of the population in northwestern Indiana. Thi s variant preferred soybean environments over corn environments. Risk of economic injury to corn planted after soybean may be greater where this variant is prevalent.