Bt Crops and Invertebrate Non-target Effects – Revisited

The controversy continues Who could have guessed that an unassuming soil bacterium, known for over a century to possess insecticidal properties1, would come to rest at the center of a seemingly never-ending debate about environmental risk, food safety, and agricultural sustainability, among other issues? The ability of Bacillus thuringiensis (Bt), to control select insect pests has been appreciated for over 70 years, and it occupies 90 % of the bio-pesticide market. Yet only in the last 13 years have Bt’s genes become ubiquitous in major crop plants throughout the world, via recombinant DNA technology, enabling host plant resistance to major lepidopteran and coleopteran pests and at the same time provoking continued controversy (e.g.,2-6). By 2007, the 11th year of commercial production, Bt cotton and Bt maize were commercially produced on a total of ≈40 million hectares in 20 countries.7 For Bt cotton and Bt maize this represented ≈40 and 19 % of the global cotton and maize production area, respectively. The assessment of environmental safety continues to be a key component of transgenic crop technology, and a recent article attempted to review our current knowledge of two issues: effects on non-target invertebrates and changes in insecticide use patterns.8 This short piece will focus on the former, as it has clearly been the most contentious. Meta-analysis to the Rescue – Again In a recent article in this newsletter, Marvier9 outlined the virtues of using meta-analyses to address environmental risk questions and provided an example of such an analysis for honey bees. Hundreds of original research papers and dozen