Effect of transgenic Bacillus thuringiensis corn expressing the Cry3Bb1 toxin on above and below ground nontarget organisms

Corn rootworms are among the most pernicious insect pests in corn ( Zea mays L.), accounting for an estimated {dollar}1 billion annually in yield losses and control costs in the United States. Larval feeding significantly affects grain yield by reducing the plant's ability to absorb water and nutrients and increasing the plant's susceptibility to lodging. Corn engineered to produce the Cry3Bb1 toxin from Bacillus thuringiensis (Bt ) Berliner has provided unprecedented control of corn rootworm.; The objectives of the study were to: (1) determine the effect of transgenic Bt corn hybrid expressing the Cry3Bb1 toxin on above and below ground nontarget organisms (Orius, Coccinellidae, Carabidae, Collembola, soil mites), (2) determine the presence of the Cry3Bb1 toxin in soils where Bt corn has been continuously grown, and (3) determine the impact of Bt corn expressing the Cry3Bb1 toxin on earthworms exposed to soil containing Bt corn roots or biomass.; Experiments were conducted in the 2002 and 2003 crop years in Kansas. Seeds of a Bt corn hybrid (YieldGardRTM Rootworm) and its non-Bt isogenic hybrid without the cry3Bb1 gene were planted at Manhattan in 2002 and Manhattan and Scandia in 2003. Different sampling methods (visual inspection, predation survey, pitfall trapping, Tullgren funnel extraction) were used in the field to determine the abundance of above and below ground nontarget organisms in Bt and non-Bt corn fields.; Laboratory or greenhouse studies were also conducted to determine the effect of Cry3Bb1 toxin expressed in transgenic corn on Coleomegilla maculata, carabids and earthworms. ELISA tests were used to determine if the Cry3Bb1 toxin was present in soil from three fields and the gut and excreta of earthworms.; In general, my studies suggest Bt corn hybrid (YieldGard RTM Rootworm) expressing Cry3Bb1 toxin does not have deleterious effects on a broad range of above and below ground nontarget organisms and thus can be used in an integrated pest management system. Traces of the Cry3Bb1 toxin were detected in the soil from the gut and excreta of earthworms exposed to Bt roots or biomass. No Cry3Bb1 toxin was detected in any of the soil samples collected in field planted with Bt or a non-Bt corn hybrid in the first year or for three consecutive years at Manhattan, but traces were detected in a first year corn field at Scandia.