Jensen Peter D, Dively Galen P, Swan Christopher M, Lamp William O
Integral Consulting, Annapolis, 200 Harry S Truman Parkway, MD 21401, USA.
Environ Entomol. 2010 Apr;39(2):707-14. doi: 10.1603/EN09037.
Corn (Zea mays L.) transformed with a gene from the bacterium Bacillus thuringiensis (Bt) comprises 49% of all corn in the United States. The input of senesced corn tissue expressing the Bt gene may impact stream-inhabiting invertebrates that process plant debris, especially trichopteran species related to the target group of lepidopteran pests. Our goal was to assess risk associated with transgenic corn debris entering streams. First, we show the input of corn tissue after harvest was extended over months in a stream. Second, using laboratory bioassays based on European corn borer [Ostrinia nubilalis (Hübner)], we found no bioactivity of Cry1Ab protein in senesced corn tissue after 2 wk of exposure to terrestrial or aquatic environments. Third, we show that Bt near-isolines modify growth and survivorship of some species of invertebrates. Of the four nontarget invertebrate species fed Bt near-isolines, growth of two closely related trichopterans was not negatively affected, whereas a tipulid crane fly exhibited reduced growth rates, and an isopod exhibited reduced growth and survivorship on the Cry1Ab near-isoline but not on the stacked Cry1Ab + Cry3Bb1 near-isoline. Because of lack of evidence of bioactivity of Bt after 2 wk and because of lack of nontarget effects on the stacked near-isoline, we suggest that tissue-mediated differences, and not the presence of the Cry1Ab protein, caused the different responses among the species. Overall, our results provide evidence that adverse effects to aquatic nontarget shredders involve complex interactions arising from plant genetics and environment that cannot be ascribed to the presence of Cry1Ab proteins.
用来自苏云金芽孢杆菌（Bt）的基因转化的玉米（Zea mays L.）占美国所有玉米的49%。表达Bt基因的衰老玉米组织的输入可能会影响处理植物残体的溪流无脊椎动物，特别是与鳞翅目害虫目标群体相关的毛翅目物种。我们的目标是评估转基因玉米残体进入溪流所带来的风险。首先，我们表明收获后玉米组织在溪流中的输入会持续数月。其次，通过基于欧洲玉米螟[Ostrinia nubilalis（Hübner）]的实验室生物测定，我们发现衰老玉米组织在暴露于陆地或水生环境2周后，Cry1Ab蛋白没有生物活性。第三，我们表明Bt近等基因系会改变一些无脊椎动物物种的生长和存活率。在喂食Bt近等基因系的四种非靶标无脊椎动物物种中，两种密切相关的毛翅目昆虫的生长没有受到负面影响，而一种大蚊表现出生长率降低，一种等足类动物在Cry1Ab近等基因系上生长和存活率降低，但在Cry1Ab + Cry3Bb1叠加近等基因系上没有。由于缺乏2周后Bt生物活性的证据，且缺乏对叠加近等基因系的非靶标影响，我们认为是组织介导的差异而非Cry1Ab蛋白的存在导致了物种间的不同反应。总体而言，我们的结果提供了证据，表明对水生非靶标分解者的不利影响涉及植物遗传学和环境产生的复杂相互作用，而不能归因于Cry1Ab蛋白的存在。
