根虫抗毒性的拓宽指出轮作的重要性。

即使是转基因作物，农民仍然需要使用传统方法如农作物轮作来抵制虫害。这是从最新发现的害虫对添加到玉米的毒素产生抗性而得到的教训。

根据爱荷华州立大学昆虫学家Aaron Gassmann团队的研究，在爱荷华的部分田地中，一种被称为西方玉米根虫(Diabrotica virgifera virgifera LeConte) 的甲虫已经对转基因玉米产生的三种芽孢杆菌(Bt)毒素中的两种有抗性。最近几年来，已经出现抗一种Bt毒素的蠕虫，但是现在出现一个变数—研究人员发现那类Bt毒素抗性也具有保护另一个最近转化的毒素类型的作用。他们的研究成果发表在美国国家科学院院刊。（编译：中国科学院成都生物研究所 王芋华，王海燕）

Field-evolved resistance by western corn rootworm to multiple Bacillus thuringiensis toxins in transgenic maize

Abstract  The widespread planting of crops genetically engineered to produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) places intense selective pressure on pest populations to evolve resistance. Western corn rootworm is a key pest of maize, and in continuous maize fields it is often managed through planting of Bt maize. During 2009 and 2010, fields were identified in Iowa in which western corn rootworm imposed severe injury to maize producing Bt toxin Cry3Bb1. Subsequent bioassays revealed Cry3Bb1 resistance in these populations. Here, we report that, during 2011, injury to Bt maize in the field expanded to include mCry3A maize in addition to Cry3Bb1 maize and that laboratory analysis of western corn rootworm from these fields found resistance to Cry3Bb1 and mCry3A and cross-resistance between these toxins. Resistance to Bt maize has persisted in Iowa, with both the number of Bt fields identified with severe root injury and the ability western corn rootworm populations to survive on Cry3Bb1 maize increasing between 2009 and 2011. Additionally, Bt maize targeting western corn rootworm does not produce a high dose of Bt toxin, and the magnitude of resistance associated with feeding injury was less than that seen in a high-dose Bt crop. These first cases of resistance by western corn rootworm highlight the vulnerability of Bt maize to further evolution of resistance from this pest and, more broadly, point to the potential of insects to develop resistance rapidly when Bt crops do not achieve a high dose of Bt toxin.

原文链接：http://www.pnas.org/content/early/2014/03/12/1317179111.full.pdf+html