Effect of Bt corn for corn rootworm control on nontarget soil microarthropods and nematodes

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 as a method to control the larval stage of corn rootworms. These hybrids express Cry3Bb1 toxin and are expected to only directly impact chrysomelids and possibly related taxa. Soil samples were examined to evaluate the effect of Bt corn for corn rootworm control on soil microarthropods and nematodes in Kansas in 2000 and 2001. Soil samples from soil close to Bt corn and to its isoline were taken on three occasions (early, mid, and late season) from eight locations in 2000 and three locations in 2001. Soil mites and Collembola were extracted using a modified Tullgren high-gradient extractor. Nematodes were extracted using a centrifugal-flotation procedure. In general, numbers of soil mites (Prostigmata, Mesostigmata, and Oribatei), Collembola, and nematodes were similar in soil planted with Bt corn and soil planted with its isoline.