Cry1Ba3、Cry1Ia8蛋白对Cry1Ac抗性小菜蛾的杀虫活性研究

利用2种苏云金芽胞杆菌原毒素Cry1Ba3、Cry1Ia8及其组合,分别对Cry1Ac抗性种群小菜蛾幼虫进行生物活性测定。结果表明Cry1Ba3、Cry1Ia8对2种目标试虫均有高毒力,LC50分别为0.2175、0.6706μg/mL;Cry1Ba3毒力3倍于Cry1Ia8。2种蛋白混配的结果也表现出高毒力,LC50为0.4375μg/mL,没有显著的协同增效作用,也不存在拮抗。敏感与抗性小菜蛾种群生测结果统计分析比较,结果表明这2种蛋白及其组合与Cry1Ac并无交互抗性。

Activity of Cry1Ba3 and Cry1Ia8 in Bacillus thuringiensis to the Cry1Ac-resistant strain of Plutella xylostella

The bioactivity of the protoxins Cry1Ba3 and Cry1Ia8 expressed in Bacillus thuringiensis and E. coli were studied against the larvae of Plutella xylostella (Linnaeus)strain with high resistance to Cry1Ac toxin. The results demonstrated that Cry1Ba3 and Cry1Ia8 were highly toxic against the resistant larvae of P. xylostella. The 50% lethal concentrations (LC_(50)s) were 0.217 5 and 0.670 6μg/mL, respectively. Toxicity of Cry1Ba3 was three folds as that of CryllaS. The mixture of Cry1Ba3 and Cry1Ia8 exhibited intense insecticidal activity, with 0.437 5μg/mL of 50% lethal concentration. The calculated synergistic factor suggested that there were neither obvious synergism nor antagonism between Cry1Ba3 and Cry1Ia8. Statistical analysis indicated that the two pro-toxins had no cross resistance with Cry1Ac.