Lawo N C, Mahon R J, Milner R J, Sarmah B K, Higgins T J V, Romeis J
Agroscope Reckenholz-Tänikon Research Station ART, Reckenholzstr. 191, 8046 Zurich, Switzerland.
Appl Environ Microbiol. 2008 Jul;74(14):4381-9. doi: 10.1128/AEM.00484-08. Epub 2008 May 16.
The use of genetically modified (Bt) crops expressing lepidopteran-specific Cry proteins derived from the soil bacterium Bacillus thuringiensis is an effective method to control the polyphagous pest Helicoverpa armigera. As H. armigera potentially develops resistance to Cry proteins, Bt crops should be regarded as one tool in integrated pest management. Therefore, they should be compatible with biological control. Bioassays were conducted to understand the interactions between a Cry2Aa-expressing chickpea line, either a susceptible or a Cry2A-resistant H. armigera strain, and the entomopathogenic fungus Metarhizium anisopliae. In a first concentration-response assay, Cry2A-resistant larvae were more tolerant of M. anisopliae than susceptible larvae, while in a second bioassay, the fungus caused similar mortalities in the two strains fed control chickpea leaves. Thus, resistance to Cry2A did not cause any fitness costs that became visible as increased susceptibility to the fungus. On Bt chickpea leaves, susceptible H. armigera larvae were more sensitive to M. anisopliae than on control leaves. It appeared that sublethal damage induced by the B. thuringiensis toxin enhanced the effectiveness of M. anisopliae. For Cry2A-resistant larvae, the mortalities caused by the fungus were similar when they were fed either food source. To examine which strain would be more likely to be exposed to the fungus, their movements on control and Bt chickpea plants were compared. Movement did not appear to differ among larvae on Bt or conventional chickpeas, as indicated by the number of leaflets damaged per leaf. The findings suggest that Bt chickpeas and M. anisopliae are compatible to control H. armigera.
利用表达源自土壤细菌苏云金芽孢杆菌的鳞翅目特异性Cry蛋白的转基因（Bt）作物是控制多食性害虫棉铃虫的有效方法。由于棉铃虫可能对Cry蛋白产生抗性，Bt作物应被视为综合虫害管理中的一种工具。因此，它们应与生物防治兼容。进行了生物测定，以了解表达Cry2Aa的鹰嘴豆品系、敏感或抗Cry2A的棉铃虫菌株与昆虫病原真菌绿僵菌之间的相互作用。在第一次浓度响应试验中，抗Cry2A的幼虫比敏感幼虫对绿僵菌更具耐受性，而在第二次生物测定中，该真菌在喂食对照鹰嘴豆叶的两个菌株中导致了相似的死亡率。因此，对Cry2A的抗性不会导致任何因对真菌易感性增加而显现的适合度代价。在Bt鹰嘴豆叶上，敏感的棉铃虫幼虫比在对照叶上对绿僵菌更敏感。苏云金芽孢杆菌毒素诱导的亚致死损伤似乎增强了绿僵菌的有效性。对于抗Cry2A的幼虫，无论喂食哪种食物来源，真菌导致的死亡率相似。为了研究哪种菌株更有可能接触到真菌，比较了它们在对照和Bt鹰嘴豆植株上的活动。如每片叶子受损的小叶数量所示，Bt鹰嘴豆或传统鹰嘴豆上幼虫的活动似乎没有差异。研究结果表明，Bt鹰嘴豆和绿僵菌在控制棉铃虫方面是兼容的。
