Potential effects of pollen from stacked Bt maize on non-target Lepidoptera in agrarian systems

Abstract

The cultivation of genetically engineered (GE) maize expressing Lepidopteran specific Bt proteins poses potential risk for non-target butterflies. Pollen is dispersed by wind in the surroundings of maize fields, deposited on weeds and taken up by non-target butterfly lavae. While MON810 contains low concentrations of Bt protein in pollen, this is not necessarily true for new GE maize lines.Species appropriate for a post market environmental monitoring (PMEM) should (i) have a small host range to ensure a comprehensive inventory, (ii) be representative and (iii) be common in agrarian landscapes. Rare species seem to be inappropriate (Aviron et al. 2009). We selected the Small Tortoiseshell (Aglais urticae) and the Peacock (Inachis io) the larvae of which are monophage on the Stinging nettle (Urtica dioica). We analysed the suitability of these species for PMEM by mapping patches of U. dioica and populations of the butterflies in two different agrarian regions of Germany during maize anthesis.There was high temporal variability in the occurrence of butterflies and in the spatial distribution of U. dioica patches. In general, methods and species used seem to be appropriate for PMEM.