Digestion of Bt Proteins by Slugs

Corinne Zurbrugg and Wolfgang Nentwig from Bern University in Switzerland assessed the effects of Cry1Ab and Cry3Bb1 proteins from Bt corn on two slug species to gauge the exposure of non-target predators and decomposer organisms to the insecticidal toxins. Their work appears in the recent issue of Transgenic Research.

The researchers measured Bt protein concentration in intestines and feces of corn leaf-fed Arion lusitanicus (spanish slug) and Deroceras reticulatum (grey field slug) using enzyme-linked immunosorbent assay (ELISA) and determined how much of the ingested protein is excreted by the slugs. Both Cry proteins were detectable in the intestines of both species after having been fed with Bt corn for three days in a row. The scientists also observed that after slugs had ceased feeding on Bt corn, Cry1Ab was detectable in fresh slug feces for a significantly longer time and often in higher amounts than the Cry3Bb1. The scientists, however, found that there is no significant difference on the mortality of European corn borer larvae fed with diet containing Bt corn exposed slug feces.

The results indicate that both Cry1Ab and Cry3Bb1 are likely to be transferred to higher trophic levels and to the decomposer food web, albeit they have different transfer probabilities. Since the study was conducted in a laboratory set-up, the scientists recommend further examinations to be carried out, specifically on the potential adverse effects of Bt proteins on slugs.

The paper is available at http://www.springerlink.com/content/4716x157u8r4p5q6/fulltext.pdf or http://dx.doi.org/10.1007/s11248-008-9208-1