The most commercialized Bt maize plants in Europe were transformed with genes which express a truncated form of the insecticidal delta-endotoxin (Cry1Ab) from the soil bacterium Bacillus thuringiensis (Bt) specifically against Lepidoptera. Studies on the effect of transgenic maize on non-target arthropods have mainly converged on beneficial insects. However, considering the worldwide extensive cultivation of Bt maize, an increased availability of information on their possible impact on non-target pests is also required. In this study, the impact of Bt-maize on the non-target corn leaf aphid, Rhopalosiphum maidis, was examined by comparing biological traits and demographic parameters of two generations of aphids reared on transgenic maize with those on untransformed near-isogenic plants. Furthermore, free and bound phenolics content on transgenic and near-isogenic plants were measured. Here we show an increased performance of the second generation of R. maidis on Bt-maize that could be attributable to indirect effects, such as the reduction of defense against pests due to unintended changes in plant characteristics caused by the insertion of the transgene. Indeed, the comparison of Bt-maize with its corresponding near-isogenic line strongly suggests that the transformation could have induced adverse effects on the biosynthesis and accumulation of free phenolic compounds. In conclusion, even though there is adequate evidence that aphids performed better on Bt-maize than on non-Bt plants, aphid economic damage has not been reported in commercial Bt corn fields in comparison to non-Bt corn fields. Nevertheless, Bt-maize plants can be more easily exploited by R. maidis, possibly due to a lower level of secondary metabolites present in their leaves. The recognition of this mechanism increases our knowledge concerning how insect-resistant genetically modified plants impact on non-target arthropods communities, including tritrophic web interactions, and can help support a sustainable use of genetically modified crops.

欧洲商业化程度最高的 Bt 玉米植物是用表达截短形式的杀虫 δ-内毒素 (Cry1Ab) 的基因进行转化的，该基因来自土壤细菌苏云金芽孢杆菌(Bt)，专门针对鳞翅目昆虫。关于转基因玉米对非靶标节肢动物影响的研究主要集中在益虫上。然而，考虑到 Bt 玉米在世界范围内的广泛种植，还需要增加有关其对非目标害虫可能影响的信息的可用性。在本研究中，Bt 玉米对非目标玉米叶蚜Rhopalosiphum maidis的影响，通过比较在转基因玉米上饲养的两代蚜虫与在未转化的近等基因植物上饲养的蚜虫的生物学特征和人口统计学参数进行了检查。此外，还测量了转基因和近等基因植物上的游离酚和结合酚含量。在这里，我们展示了第二代R. maidis的增强性能对 Bt 玉米的影响可归因于间接影响，例如由于插入转基因导致植物特性的意外变化而降低了对害虫的防御能力。事实上，Bt-玉米与其相应的近等基因系的比较强烈表明，这种转化可能对游离酚类化合物的生物合成和积累产生了不利影响。总之，尽管有充分的证据表明蚜虫在 Bt 玉米上的表现优于在非 Bt 植物上的表现，但与非 Bt 玉米田相比，在商业 Bt 玉米田中没有报道蚜虫的经济损失。然而，Bt 玉米植物可以更容易地被R. maidis利用，可能是由于其叶子中存在的次生代谢物水平较低。对这一机制的认识增加了我们对抗虫转基因植物如何影响非目标节肢动物群落的认识，包括三养网相互作用，并有助于支持转基因作物的可持续利用。