P450s介导的新烟碱类杀虫剂对褐飞虱与天敌拟环纹豹蛛的选择毒力

The application of selective insecticides plays important roles on the balance of chemical control and biocontrol. It can conserve natural enemies, thus the pest populations would be suppressed by the surviving natural enemies, which in turn will reduce the rate of insecticide application. Most of the studies about insecticide selectivity were focused on target differences between insect pests and natural enemies. However, metabolic detoxification reduces a large proportion of the insecticides before it acts on the targets, which may play more important role on insecticide selectivity. In our previous studies, key amino acid differences in the nAChRs between the brown planthopper (Nilaparvata lugens), one of the major rice pests in China and many other parts of Asia, and its natural enemy Pardosa pseudoannulata were found to contribute directly to neonicotinoid sensitivities. In order to understand the roles of metabolic detoxifications on neonicotinoid selectivity, the differences in the cytochrome P450 monooxygenases (P450s) between these two species were also preliminarily analyzed. In this research, further studies of P450s in P. pseudoannulata will be performed. The differences in P450s classification, expression profit, and key P450s associated with neonicotinoid detoxifications will be compared with that of brown planthopper. The functional expression and structure analysis of the homologous P450 genes will also be carried out to demonstrate the mechanism of insecticide selectivity conferred by metabolic detoxification.

杀虫剂选择性为靶标害虫高效防治和天敌安全提供了保证，起到协调化学防治与生物防治的关键作用。关于杀虫剂选择性的研究，目前大都集中在杀虫剂靶标差异上，但大部分杀虫剂在到达靶标前，都被解毒酶降解了。因此，解毒代谢水平的差异可能对杀虫剂的选择性具有同样重要的贡献。在新烟碱类杀虫剂对水稻重要害虫褐飞虱及其重要天敌拟环纹豹蛛的选择性机制方面，本课题组开展了长期研究，不仅在靶标蛋白关键氨基酸差异导致杀虫剂选择性方面取得了阶段性进展，也对两个物种的关键解毒酶P450s的差异开展了初步研究。在此基础上，本项目将深入开展拟环纹豹蛛P450s的特征研究，系统分析褐飞虱与拟环纹豹蛛P450s在成员组成、家族分布、表达丰度、参与新烟碱类杀虫剂代谢的关键P450s以及同源P450s代谢能力等方面的差异，从代谢水平上阐述新烟碱类杀虫剂在两个物种间的选择性机制，为合理、协同使用化学防治和生物防治提供理论基础。

杀虫剂选择性为靶标害虫高效防治和天敌安全提供了保证，起到协调化学防治与生物防治的关键作用。新烟碱类杀虫剂在靶标害虫褐飞虱及其捕食性天敌拟环纹豹蛛之间具有较高的选择性。本研究系统分析褐飞虱与拟环纹豹蛛P450s在成员组成、家族分布、表达丰度等方面的差异。基于拟环纹豹蛛基因组和转录组数据库，对拟环纹豹蛛P450基因进行了鉴定和命名，获得P450全长基因93个，片段35个。其中，CYP2和CYP4家簇基因较多，分别为41个和49个；CYP3和Mito家簇基因数量相对较少，分别为20个和18个。而在昆虫中CYP3和CYP4家簇的P450s基因所占比例最高，预示着二者P450酶系在外源化合物代谢方面存在差异。通过系统进化分析获得与褐飞虱中参与新烟碱类杀虫剂代谢的P450s具有较高相似性的基因18个，其中，12个基因在消化道和/或脂肪体中特异性高表达。通过吡虫啉诱导试验进一步筛选发现，CYP41H2在吡虫啉处理48h后表达量显著高于对照组，可能在拟环纹豹蛛对吡虫啉的解毒代谢中发挥重要作用。