Effect of Bt corn expressing the Cry3Bb1 toxin for corn rootworm control on aboveground nontarget arthropods

The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a major pest of corn in Kansas. Planting Bt corn hybrids resistant to this pest is being tested for control of the larval stage of corn rootworms. These hybrids express the Cry3Bb1 toxin and are expected to only directly impact chrysomelids and possibly related taxa. A 2-yr study was conducted to evaluate the effect of Bt corn expressing the Cry3Bb1 toxin on foliar and ground-dwelling nontarget arthropods in Kansas. Visual inspections of adult and immature Coleomegilla maculata (DeGeer), Orius insidiosus (Say), Hippodamia convergens Gurin-Meneville, and Scymnus spp. occurring in Bt corn and its isoline were made at eight locations in Kansas in 2000 and three locations in 2001. Pitfall traps were installed at three locations in 2000 and two locations in 2001 to collect ground-dwelling arthropods in Bt corn and its isoline. In general, no significant differences in numbers of C. maculata, O. insidiosus, H. convergens, and Scymnus spp. were detected between Bt corn and its non-Bt isoline. There were also no significant differences in number of insects collected in pitfall traps installed in plots of Bt corn and its isoline. Bt corn for corn rootworm control had no deleterious effects on beneficial and other nontarget arthropods sampled in this study.