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【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。
【Objective】 To investigate the sublethal effects of spinosad against Plutella xylostella (DBP) under long-term stress. 【Method】 Subsequent treatments with low dose (LC25) spinosad were carried out. The susceptible level of Sub to spinosad of Plutella xylostella in different treatment generations was determined by leaf immersion feeding method. Real-time quantitative PCR was used to further detect low Changes of gene expression of nicotinic acetylcholine receptor (nAChR) α subunit of 4th instar larvae of Plutella xylostella after exposure to spinosad. 【Result】 The sensitivity of spinosad to spinosad was decreased with the increase of treatment generations. The resistance to spinosad was reduced by 2.70 folds up to the 10th generation (Sub10), and the expression of n AChRα subunit gene was inhibited to some extent , The relative expression level of n AChRα subunit gene in Sub10 was 32.04% lower than that in the susceptible population SS, and the difference was significant. However, the relative expression level of RR (17.85) n AChRα subunit gene in resistant population was only SS 0.37 times. 【Conclusion】 The sensitivity of spinosad to spinosad may be related to the expression of n AChRα subunit gene. This study may provide some evidence for exploring the potential impact of long-term low-dose spinosad treatment on the development of resistance to Plutella xylostella.