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主题:美国多州农田出现能对抗转基因玉米的根虫(转载) -- xiaobailong

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家园 不是说美国人不吃转基因玉米吗

怎么一下成了美国食品65%了?

这种抗药的虫子出现基本是个必然现象,自然选择。此外Bt基因向普通作物扩散也迟早要出现的。所以说转基因作物,最值得担心的问题之一,就是生态影响。

查到一篇文献,去年7月发表的。据摘要里讲,可能是第一个报导这个抗Bt根虫的,同时也是鞘翅目昆虫的第一例。讨论里认为田里杂种的普通玉米(refuges,故意让虫子啃的)不足有可能是原因之一,另一方面抗药性可能是非隐性遗传的(所以抗药虫扩散得快一些)。“Insufficient planting of refuges and non-recessive inheritance of resistance may have contributed to resistance.”

http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0022629

Field-Evolved Resistance to Bt Maize by Western Corn Rootworm

Aaron J. Gassmann*, Jennifer L. Petzold-Maxwell, Ryan S. Keweshan, Mike W. Dunbar

Abstract Top

Background

Crops engineered to produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) are planted on millions of hectares annually, reducing the use of conventional insecticides and suppressing pests. However, the evolution of resistance could cut short these benefits. A primary pest targeted by Bt maize in the United States is the western corn rootworm Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae).

Methodology/Principal Findings

We report that fields identified by farmers as having severe rootworm feeding injury to Bt maize contained populations of western corn rootworm that displayed significantly higher survival on Cry3Bb1 maize in laboratory bioassays than did western corn rootworm from fields not associated with such feeding injury. In all cases, fields experiencing severe rootworm feeding contained Cry3Bb1 maize. Interviews with farmers indicated that Cry3Bb1 maize had been grown in those fields for at least three consecutive years. There was a significant positive correlation between the number of years Cry3Bb1 maize had been grown in a field and the survival of rootworm populations on Cry3Bb1 maize in bioassays. However, there was no significant correlation among populations for survival on Cry34/35Ab1 maize and Cry3Bb1 maize, suggesting a lack of cross resistance between these Bt toxins.

Conclusions/Significance

This is the first report of field-evolved resistance to a Bt toxin by the western corn rootworm and by any species of Coleoptera. Insufficient planting of refuges and non-recessive inheritance of resistance may have contributed to resistance. These results suggest that improvements in resistance management and a more integrated approach to the use of Bt crops may be necessary.

试着翻译一下结果部分:

我们报道如下:从农民报告有严重根虫啮咬损害的玉米田里收集的西部根虫,跟未受到此虫危害的玉米田里收集的根虫相比,在实验室喂食Cry3Bb1玉米后,有显著增高的存活率。在所有案例中,受到严重损害的玉米田里都种植有Cry3Bb1玉米。与农民的访谈表明这些地块已经至少三年连续种植Cry3Bb1玉米。地块种植Cry3Bb1玉米的年数与实验室生物测试中存活的根虫数目呈明显正相关。然而,(在实验室中)喂食Cry34/35Ab1玉米的虫存活数与喂食Cry3Bb1玉米的并无明显相关性,这暗示此虫对不同的Bt毒素没有交叉抗性。

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