Extrapolating non-target risk of Bt crops from laboratory to field

Abstract

The tiered approach to assessing ecological risk of insect-resistant transgenic crops assumes that lower tier laboratory studies, which expose surrogate non-target organisms to high doses of insecticidal proteins, can detect harmful effects that might be manifested in the field. To test this assumption, we performed meta-analyses comparing results for non-target invertebrates exposed to Bacillus thuringiensis (Bt) Cry proteins in laboratory studies with results derived from independent field studies examining effects on the abundance of non-target invertebrates. For Lepidopteran-active Cry proteins, laboratory studies correctly predicted the reduced field abundance of non-target Lepidoptera. However, laboratory studies incorporating tri-trophic interactions of Bt plants, herbivores and parasitoids were better correlated with the decreased field abundance of parasitoids than were direct-exposure assays. For predators, laboratory tri-trophic studies predicted reduced abundances that were not realized in field studies and thus overestimated ecological risk. Exposure to Coleopteran-active Cry proteins did not significantly reduce the laboratory survival or field abundance of any functional group examined. Our findings support the assumption that laboratory studies of transgenic insecticidal crops show effects that are either consistent with, or more conservative than, those found in field studies, with the important caveat that laboratory studies should explore all ecologically relevant routes of exposure.

Effects of multiple Bt proteins and GNA lectin on in vitro-reared honey bee larvae

“…The general question of whether laboratory studies on transgenic insecticidal crops can be extrapolated to the field situation has been recently addressed by Duan et al (2010). They showed that indeed laboratory studies on GM crops show effects that are either consistent with, or more conservative than, those found in field studies, provided that ecologically relevant routes of exposure have been addressed properly.…”

A review of the environmental safety of the Cry1Ac protein

“…Papers must meet the following criteria to be included in the database: (i) involve a field crop species that has been genetically transformed to express one or more cry genes derived from Bacillus thuringiensis; (ii) measure effects of the transformed crop for compiling this information has been created to facilitate continuing study (Duan et al, 2008(Duan et al, , 2010Marvier et al, 2007;Naranjo, 2009;Wolfenbarger et al, 2008). When GE plants that express Cry proteins, including Cry1Ac cotton, were compared to control plants that were not treated with chemical insecticide there was a reduction in arthropod abundance, but when control plants are treated with insecticide arthropod abundance is significantly higher in GE plants expressing Cry proteins (Marvier et al, 2007;Naranjo, 2009Wolfenbarger et al, 2008.…”

Interactions betweenBt-expressing tomato and non-target insects: the aphidMacrosiphum euphorbiaeand its natural enemies

“…As recently reported by Duan et al (2010), field studies with Coleopteran-active Cry proteins have either confirmed lab results or over- estimated the possible negative effects. In this view, our results confirm that, at least for the species selected, the use of GM tomato in the field has no appreciable effects on non-target pests and antagonists.…”