华北地区玉米蚜对吡虫啉和高效氯氟氰菊酯的抗性及其细胞色素P450基因表达分析

Resistance of corn leaf aphid Rhopalosiphum maidis to imidacloprid and lambda-cyhalothrin and analysis of cytochrome P450 gene expression in northern China

中文关键词:玉米蚜  抗药性  吡虫啉  高效氯氟氰菊酯  细胞色素P450单加氧酶  抗性机制

keywords:Rhopalosiphum maidis  insecticide resistance  imidacloprid  lambda-cyhalothrin  cytochrome P450 monooxygenase  resistance mechanism

中文摘要:为明确华北地区玉米蚜Rhopalosiphum maidis对新烟碱类杀虫剂吡虫啉和拟除虫菊酯类杀虫剂高效氯氟氰菊酯的抗性现状及其分子机制，采用浸叶法对采自华北地区的10个地理种群进行抗性监测与细胞色素P450单加氧酶（简称P450）基因表达分析，并通过RNA干扰试验进行关键基因的功能验证。结果显示：玉米蚜10个地理种群均对吡虫啉和高效氯氟氰菊酯产生了不同程度的抗性，抗性倍数分别介于1.6～32.7倍和1.1～12.5倍之间，且呈现明显的地理差异，其中，河南原阳种群和镇平种群的抗性水平最高，对吡虫啉的抗性倍数分别达32.7倍和26.2倍，对高效氯氟氰菊酯的抗性倍数分别为12.5倍和9.7倍。高抗种群中多个P450基因（RmCYP6ER1、RmCYP6C71、RmCYP6C72）的本底表达量极显著高于敏感种群；在LC₅₀吡虫啉和高效氯氟氰菊酯胁迫下，这些基因的表达量在24 h内显著上调，并在48 h内维持高表达水平；且不同地理种群的抗性水平与P450基因表达量呈显著正相关。沉默上述关键P450基因可显著恢复玉米蚜高抗种群对两种杀虫剂的敏感性。表明华北地区玉米蚜对吡虫啉和高效氯氟氰菊酯均已产生抗性，P450介导的代谢增强是其产生抗性的关键分子机制。

Abstract:To clarify the resistance status and molecular mechanisms of the corn leaf aphid Rhopalosiphum maidis to neonicotinoid insecticides, such as imidacloprid and pyrethroid insecticides, such as lambda-cyhalothrin, resistance monitoring and cytochrome P450 monooxygenase(P450) gene expression analysis was conducted in ten geographical populations collected from northern China using the leaf-dip method, and key genes were functionally validated by RNA interference. The results showed that all ten geographical populations of R. maidis had developed varying degrees of resistance to imidacloprid and lambda-cyhalothrin, with resistance ratios ranging from 1.6-to 32.7-fold and from 1.1- to 12.5-fold, respectively, showing clear geographical variation. Among them, the Yuanyang(Henan) and Zhenping(Henan) populations showed the highest resistance levels, with resistance ratios of 32.7-and 26.2-fold to imidacloprid and 12.5-and 9.7-fold to lambda-cyhalothrin, respectively. In highly resistant populations, the baseline expression levels of several P450 genes(RmCYP6ER1, RmCYP6C71, RmCYP6C72) were significantly higher than those in the susceptible population. Under exposure to the LC₅₀of imidacloprid or lambda-cyhalothrin, the expression levels of these genes were significantly upregulated within 24 h and remained high within 48 h. Moreover, resistance levels in different geographical populations were significantly positively correlated with P450 gene expression levels. Silencing these key P450 genes significantly restored the susceptibility of highly resistant populations to both insecticides. These results indicate that R. maidis populations in northern China have developed resistance to both imidacloprid and lambda-cyhalothrin, and that P450-mediated enhanced metabolism is a key molecular mechanism underlying this resistance.