低剂量多杀菌素继代处理对小菜蛾nAChR基因表达的影响

Expression of nicotinic acetylcholine receptor gene in Plutella xylostella( Lepidoptera: Plutellidae) after long-term exposure to low concentration of spinosad

【目的】探索多杀菌素对小菜蛾Plutella xylostella长期胁迫下的亚致死效应。【方法】采用低剂量(LC25)多杀菌素进行继代处理,应用叶片浸渍饲喂法分别测定不同处理世代小菜蛾种群Sub对多杀菌素的敏感性水平,并运用实时定量PCR法进一步检测低剂量多杀菌素处理后小菜蛾4龄幼虫烟碱型乙酰胆碱受体(n AChR)α亚基基因表达量变化。【结果】随着处理世代的增加,小菜蛾对多杀菌素的敏感性下降,至第10代(Sub10)其抗性倍数为2.70倍;同时对小菜蛾n AChRα亚基基因表达呈现一定的抑制作用,Sub10中n AChRα亚基基因的相对表达量较敏感种群SS下降了32.04%,且差异显著;而抗性种群RR(抗性倍数17.85)n AChRα亚基基因的相对表达量仅为SS的0.37倍。【结论】小菜蛾对多杀菌素敏感性可能与n AChRα亚基基因的表达量有关。本研究可为探究多杀菌素长期低剂量处理对小菜蛾抗药性发展的潜在影响提供一定依据。

【Aim】This study aims to investigate the sublethal effects of spinosad on Plutella xylostella after long-term exposure to low concentration of spinosad. 【Methods】The Sub strain of P. xylostella was continuously selected using the LC25 of spinosad. The susceptibility of the 4th instar larvae of various subpopulations of P. xylostella to spinosad was assayed by leaf dip feeding method,and the change of expression level of nicotinic acetylcholine receptor（ n AChR） α subunit gene in the 4th instar larvae of P.xylostella treated with low concentration of spinosad was determined by quantitative real-time PCR.【Results】The sensitivity of P. xylostella to spinosad decreased across generations. After selection with the LC25 of spinosad for ten generations（ Sub10）, the Sub strain developed 2. 70-fold resistance compared with the SS strain. Quantitative real-time PCR analysis indicated that the expression level of n AChR α subunit gene decreased with generations and significantly decreased by 32. 04% in the Sub10 generation compared to that in the SS strain,and the expression level in the spinosad resistant strain RR（ resistance ratio = 17. 85-fold） was only 37% of that in the SS strain. 【Conclusion】This multigenerational study found the possible correlation between spinosad susceptibility and the expression abundance of n AChR α subunit gene in P. xylostella,and this is helpful for further understanding of spinosad resistance mechanisms in P. xylostella.