棉花抗虫工程菌对棉铃虫的离体及活体生物测定

棉花抗虫工程菌是以能在棉株体内定殖的优势内生细菌Bacillus cereus (Bc9102)为宿主菌，将Bt kurstaki的δ-内毒素基因cryIA©整合到其染色体上形成的内生工程菌。以棉铃虫Helicoverpa armigera为供试昆虫的离体生测结果表明：在同一剂量水平上，HE-1、HE-2、ME14-2、ME14-3、MK14-1等工程菌株对棉铃虫幼虫的毒力高于或等于Bt野生菌株HD-73，浓度最高时这几个工程菌处理的棉铃虫死亡率分别为96.7%、83.3%、93.3%、83.3%、80.0%，而HD-73为80.0%，死亡率与浓度呈正相关。在用上述工程菌接种棉花的活体生测中，注射处理和喷雾处理法杀虫效果均优于浸种处理法。以HE-1为例，注射、喷雾、浸种处理4周后棉铃虫校正死亡率分别达到90.0%、76.0%和23.3%。工程菌对棉铃虫的生长发育也有抑制作用。

In vitro and planta bioassay of engineered endophyticbacteria in cotton with cotton bollworms

Insecticidal engineered bacteria of cotton are recombinant bacteria by introducing the cryIA© gene from Bacillus thuringiensis subsp. Kurstaki into the chromosome of Bacillus cereus(Bc9102) which is a dominant endophytic bacterium in cotton. In vitro bioassays with cotton bollworm (Helicoverpa armigera) was conducted and the results showed: at each concentration level, engineered strains HE-1,HE-2,ME14-2,ME14-3 and MK14-1 had a higher insecticidal activity than Bt strain HD-73, causing 96.7%,83.3%,93.3%,83.3%,80.0% mortality respectively at the highest concentration while Bt HD-73 had 80% mortality. The concentration mortalitey curves of these strains showed a linear correlation. In planta bioassays, the results showed that insecticidal activity of cotton injected or sprayed with engineered bacteria was obviously better than that of cotton seed treated with engineered bacteria. For example, engineered strain HE-1 had larval mortality respectively 90.0%、76.0% and 23.3% after injection,spraying and seed treatment 4 weeks. At the same time, engineered bacteria restrained the development of cotton bollworms.