多位点生物杀虫毒素BtA害虫敏感性的研究

多位点生物杀虫毒素BtA是通过氨基-羧基偶联剂EDC将两种生物毒素Bacillus thuringiensis (Bt)晶体原毒素和阿维菌素]进行键合反应,形成的具有多个作用位点的生物藕合产物。通过研究小菜 蛾(Plutella xylostella L.)对BtA敏感性的消减和恢复,以及不同地域小菜蛾对其敏感性的差异,来初步 评估多位点生物杀虫毒素BtA害虫敏感性变化的规律。试验结果表明:小菜蛾室内相对敏感种群对BtA 以及它的反应底物Bt伴胞晶体和阿维菌素的敏感性稳定(LC50为0．0004-0．0020mg/ml)。在三种生物杀 虫剂的选择压力之下小菜蛾敏感性下降,2代后对BtA抗性比的增长(2．29)显著地低于Bt伴胞晶体 (8．351和阿维菌素(22．5)。小菜蛾田间种群在脱离杀虫剂的选择压力后敏感性会增加,2代后对BtA的 敏感性显著地增加了4．7倍．高于对Bt伴胞晶体的1．28倍和对阿维菌素的2．00倍。福建省七个地市 小菜蛾表现出敏感性的多态性,对BtA、Bt伴胞晶体和阿维菌素的抗性比分别为1．18-6．85、1．22- 23．93和1．58-4．77。聚类分析结果在福建省以中部地区的小菜蛾具有相对较低水平的敏感性。说明多 位点生物杀虫毒素BtA有助于延缓抗性的产生、降低抗性和迅速恢复害虫敏感性的作用。

Study on Pest Susceptibility to Multi-bioinsecticidal-toxin BtA

Multi-bioinsecticidal-toxin BtA is a bioconjugation product with multiple acting-sites, formed by biochemical bond-linking reaction between two biotoxins, protoxin of Bacillus thuringiensis and Abamectin, through the amino and carboxyl conjugator EDC. The variation of pest susceptibility to Multi -bioinsecticidal-toxin BtA was evaluated by studying the decline and recovery of susceptibility of Plutella xylostella L. to BtA and the susceptibility diversity of P. xylostella populations collected from different regions. The results showed that the susceptibilities of the relatively susceptible lab population were stable to BtA and its two reactants, Bt crystal and Abamectin, with LC50s of 0.0004 -0.0020mg/ml. Under the selection pressure, the pest susceptibility reduced, with Resistance Ratio (RR) of 2.29 to BtA after 2 generations comparing with 8.35 and 22.5 to Bt crystal and Abamectin respectively. While the field population was released from the selection pressure, the pest susceptibility increased 4.7-fold to BtA after 2 generations in comparison to 1.28-fold Bt crystal and 2.00-fold to Abamectin. The P. xylostella from seven regions of Fujian province represented polymorphism of susceptibility, while the RRs to BtA, Bt crystal and Abamectin were 1.18-6.85, 1.22~23.93 and 1.58-4.77 respectively. The result of cluster analysis displayed that P. xylostella in middle part of Fujian province had lower susceptibility. It was concluded that the Multi-bioinsecticidal-toxin BtA could help to delay the resistance development, reduce the resistance and rapidly recovery of pest susceptibility.