Chen Mao, Zhao Jian-Zhou, Collins Hilda L, Earle Elizabeth D, Cao Jun, Shelton Anthony M
Department of Entomology, Cornell University/New York State Agricultural Experiment Station (NYSAES), Geneva, New York, United States of America.
PLoS One. 2008 May 28;3(5):e2284. doi: 10.1371/journal.pone.0002284.
The ecological safety of transgenic insecticidal plants expressing crystal proteins (Cry toxins) from the bacterium Bacillus thuringiensis (Bt) continues to be debated. Much of the debate has focused on nontarget organisms, especially predators and parasitoids that help control populations of pest insects in many crops. Although many studies have been conducted on predators, few reports have examined parasitoids but some of them have reported negative impacts. None of the previous reports were able to clearly characterize the cause of the negative impact. In order to provide a critical assessment, we used a novel paradigm consisting of a strain of the insect pest, Plutella xylostella (herbivore), resistant to Cry1C and allowed it to feed on Bt plants and then become parasitized by Diadegma insulare, an important endoparasitoid of P. xylostella. Our results indicated that the parasitoid was exposed to a biologically active form of the Cy1C protein while in the host but was not harmed by such exposure. Parallel studies conducted with several commonly used insecticides indicated they significantly reduced parasitism rates on strains of P. xylostella resistant to these insecticides. These results provide the first clear evidence of the lack of hazard to a parasitoid by a Bt plant, compared to traditional insecticides, and describe a test to rigorously evaluate the risks Bt plants pose to predators and parasitoids.
表达来自苏云金芽孢杆菌（Bt）的晶体蛋白（Cry毒素）的转基因杀虫植物的生态安全性一直存在争议。大部分争议集中在非靶标生物上，尤其是在许多作物中有助于控制害虫种群的捕食者和寄生蜂。尽管已经对捕食者进行了许多研究，但很少有报告研究寄生蜂，不过其中一些报告称有负面影响。以前的报告都未能明确说明负面影响的原因。为了提供批判性评估，我们采用了一种新的模式，使用一种对Cry1C具有抗性的小菜蛾（食草动物）品系，让其取食Bt植物，然后被小菜蛾的一种重要内寄生蜂——岛甲腹茧蜂寄生。我们的结果表明，寄生蜂在寄主体内接触到了具有生物活性形式的Cy1C蛋白，但并未因此受到伤害。对几种常用杀虫剂进行的平行研究表明，它们显著降低了对这些杀虫剂具有抗性的小菜蛾品系的寄生率。这些结果首次明确证明，与传统杀虫剂相比，Bt植物对寄生蜂没有危害，并描述了一种严格评估Bt植物对捕食者和寄生蜂所构成风险的测试方法。
