EmailEncouraging predator insects is crucial to managing crop pests sustainably – indeed, that's how organic farmers avoid pesticides, using natural processes to encourage beneficial predators. Your article (GM crops deliver green benefits, study suggests, 14 June) reports on a study that finds Bt cotton is a better habitat for such predators than cotton that has been sprayed with pesticides. What it doesn't cover is other recent research in China that has discovered increased insect resistance and increased numbers of pests developing in and around these GM cotton crops.
Studies show problems occurring with secondary pests in Bt cotton, which are not only affecting the cotton but also damaging surrounding crops. This suggests "spillover" problems rather than "spillover" benefits. Taking an organic approach to encouraging predators avoids this problem.
Emma Hockridge
Head of policy, Soil Association
