The detection and decay of Cry1Ab Bt-endotoxins within non-target slugs, Deroceras reticulatum (Mollusca: Pulmonata), following consumption of transgenic corn

Abstract

With greater acreages being planted to transgenic crops, the exposure of non-target species to bioengineered material is increasing. Although the slug, Deroceras reticulatum (Müller), is a major agricultural pest throughout the world, Bacillus thuringiensis crops were not intended to target these species. Molluscs are readily consumed by many generalist predators; if these Cry1Ab-endotoxins are taken up by slugs during feeding on transgenic plants, predators would therefore be exposed to elevated endotoxin concentrations. Using a biochemical assay, we tested the hypothesis that slugs fed transgenic corn would accumulate detectable quantities of Cry1Ab-endotoxins for prolonged periods of time. Characterization indicated that at low dilution rates, Cry1Ab-endotoxins were detectable in slugs fed Bt-corn but no reactivity was elicited by specimens fed non-transgenic food. It was possible to detect Cry1Ab-endotoxins in slugs for 95.9 h after consumption of Bt-corn. Although quantities were small, these long detection periods indicated potential exposure of generalist predators to low concentrations of transgenic insecticidal toxins in the field.

Keywords:

• Bacillus thuringiensis
• non-target effects
• decay rates
• ELISA
• risk assessment
• detection protocols

Acknowledgments

The authors would like to thank Katie Russell for collecting and maintaining the slug populations and three anonymous reviewers for helpful comments on an earlier draft. This research was funded by the Kentucky Science & Engineering Foundation (grant award KSEF-148-502-04-121). JDH and JJO are supported by the Kentucky Agricultural Experiment Station State Project KY099004. This is publication number 05-08-017 of the University of Kentucky Agricultural Experiment Station.