Evaluation of Bt oilseed rape on the non-target herbivore Athalia rosae

Laboratory feeding experiments using two transgenic Bacillus thuringiensis (Bt) rape cultivars (Bt-Westar and Bt-Oscar) both expressing the Cry1Ac protein, and the corresponding untransformed lines, were carried out to study the effects of transgenic Bt rape on the non-target herbivore Athalia rosae ( L.) ( Hymenoptera: Tenthredinidae). Furthermore, Cry1Ac protein concentration in Bt rape leaves, A. rosae larvae fed Bt rape, their faeces, eonymph instars, pupae, and adults were quantified using an enzyme-linked immunosorbent assay ( ELISA). There were no significant differences in mortality, larval development, and weight between transgenic Bt rape and non-transgenic rape fed A. rosae. Additionally, we did not detect any significant differences in the fecundity and fertility of adult females either fed as larvae with transgenic Bt or with non-transgenic rape. However, results of the ELISA indicated that Cry1Ac protein was detectable in larvae and faeces (Bt-Westar 1.1+/- 0.2 and Bt-Oscar 0.3 +/- 0.2 mug Cry1Ac protein/g fresh weight) although this was less than in the leaf material, where concentrations were 2.2 +/- 0.8 mug Cry1Ac protein/g fresh weight for Bt-Westar and 7.5 +/- 2.9 mug Cry1Ac protein/g fresh weight in Bt-Oscar. In contrast, Cry1Ac protein could not be detected in eonymphs, pupae, or adults of A. rosae. Our results suggest that Cry1Ac protein in Bt rape does not have a significant effect on the herbivore A. rosae but the protein is still detectable after ingestion and excretion by these herbivores, thus providing the possibility of exposure to organisms other than herbivores.