南京小菜蛾对拟除虫菊酯的抗性机制

通过解毒酶活性测定与钠离子通道基因片段的克隆、测序,研究了南京小菜蛾对拟除虫菊酯产生高水平抗性的生化和分子机制。结果表明,南京抗性种群的酯酶和多功能氧化酶O-脱甲基活性分别是敏感种群的1.06和1.16倍,无显著差异;以2,4二硝基氯苯(CDNB)和1,2-二氯-4-硝基苯(DCNB)为底物,南京抗性种群的谷胱甘肽S-转移酶活性分别是敏感种群的0.68倍和1.03倍;进一步利用聚合酶链式反应(PCR)分别从敏感和抗性小菜蛾基因组DNA中扩增出了位于钠离子通道结构域IIS6的232bp和248bp的DNA片段;与敏感种群相比,南京抗性种群钠离子通道基因存在一个保守性点突变,即C突变为T,并导致亮氨酸突变为苯丙氨酸,表明神经不敏感性是南京小菜蛾对拟除虫菊酯产生高水平抗性的主要机制。

Mechanisms of pyrethroids resistance in diamondback moth, Plutella xylostella

Biochemical and molecular mechanisms of pyrethroids resistance in diamondback moth,Plutella xylostella(L),from Nanjing,have been investigated in this study by enzyme assays of esterases(ESTs),glutathione S-transferases(GSTs)and microsomal multifunctional oxidase(MFO)and cloning and sequencing of sodium channel gene.The enzymatic activities of ESTs and MFO were 1.06 and 1.16 folds higher in Nanjing resistant population than that in susceptible population.With CDNB and DCNB being substrate,the enzymatic activity of GSTs were 0.68 folds lower and 1.03 folds higher in Nanjing resistant population than that in susceptible population,respectively.With the usage of specific upstream and downstream primer,two fragments of 232 and 248 bp in IIS6 region of para-type sodium channel were amplified from susceptible and resistant individual fourth instar larva,respectively.Analysis of the DNA sequences revealed that there is a kdr-associated conservative mutation(Leu to Phe) in the sodium channel gene of this pyrethroid-resistant diamondback moth population,suggesting that nerve insensitivity was the principal mechanism of pyrethroids resistance in diamondback moth from Nanjing.