Detectability of Coleopteran-specific Cry3Bb1 Protein in Soil and Its Effect on Nontarget Surface and Below-Ground Arthropods

Abstract

Corn engineered to produce the Cry3Bb1 protein from Bacillus thuringiensis (Bt ) kumamotoensis has provided unprecedented control for corn rootworm (Diabrotica spp.). However, the Bt protein may be released in soil by root exudates or decaying plant residues that may affect soil organisms. Field studies were conducted to determine the abundance of surface and below-ground nontarget arthropods in fields planted with Bt or non-Bt corn for the first year or planted over 3 consecutive yr. Results of these studies showed that there were no significant differences in numbers of surface and below-ground arthropods in soil planted with Bt and non-Bt corn at any of the studied locations. Enzyme-linked immunosorbent assay (ELISA) showed no detectable Cry3Bb1 protein in any of the soil samples collected in a field planted with a Bt corn hybrid and its non-Bt isogenic hybrid for the first year or planted over 3 consecutive yr near Manhattan, KS. However, a small amount of Cry3Bb1 protein (3.38–6.89 ng/g dry soil) was detected in the soil samples collected from an area near plants in a Bt corn field that was planted for the first year near Scandia, KS. These findings indicate that the Cry3Bb1 protein released from root exudates or decaying plant residues does not persist and is rapidly broken down in the soil. The rapid degradation of Cry3Bb1 in soil results in none or trace amounts of protein being detected by ELISA.