嗜卷书虱种群遗传结构及分化机制研究

The psocid, Liposcelis bostrychophila is one of the most important insect pests in stored grains worldwide. This project targets the insect molecular population genetics of the international research hotspot. We focus on the scientific issue on population genetic and evolution of stored-product pest, L. bostrychophila. Based on the enriched microsatellite-libraries, the polymorphic microsatellite (SSR) loci will be isolated by high-throughput sequencing technology, and the population genetic structure of L. bostrychophila are examined using these polymorphic microsatellite loci as molecular markers. The study aims to investigate the genetic diversity, demographic history and the mode of gene flow as well as the extent of the genetic differentiation at the interspecific and intraspecific levels of populations, and explore the dispersal patterns of this psocid in China. Furthermore, the study will evaluate the mechanism of ecologically evolutionary process and the relationship between insecticide susceptibility and population genetic diversity. Based on microsatellite markers, a molecular technology will be established to monitor the susceptibility of natural populations of L. bostrychophila to insecticides. In theory, the findings in this project not only are crucial to gain insight for the population genetic structure and SSR of the psocids, but also provide invaluable information on the ecologically evolutionary mechanism and genetic variability of the psocids at molecular level. On the other hand, the studies like this will also be helpful to plan effective pest management strategies as well as guiding the appropriate distribution of stored-products and monitoring the development of resistance to insecticides.

嗜卷书虱是一种在世界范围内广泛发生并可造成严重经济损失的储藏物害虫。本项目瞄准昆虫分子种群遗传学这一国际研究热点领域，紧密围绕嗜卷书虱种群遗传与进化这一关键科学问题，在利用磁珠富集法构建微卫星文库的基础上，采用分子克隆和高通量测序技术发掘嗜卷书虱微卫星位点。以多态性微卫星位点作为分子标记，解析我国主要储粮生态区嗜卷书虱种群遗传结构变化规律、评估其遗传多样性，追溯种群历史动态，阐明基因交流模式，估计种内遗传分化程度，探讨嗜卷书虱在我国的扩散途径。明确其遗传分化机制及嗜卷书虱对储粮保护剂的敏感性与种群遗传结构的相互关系，建立基于微卫星标记的嗜卷书虱自然种群对杀虫剂敏感性的分子检测技术。研究结果将在理论上深化对书虱微卫星及种群遗传结构的认识，丰富生物进化和遗传变异的研究内容；在实践上可用于指导实仓储藏物合理布局、为深入理解嗜卷书虱适应性机制和制定科学防控策略提供理论依据。

本项目紧密围绕书虱种群遗传与进化这一关键科学问题，以仓储害虫书虱为研究对象，特别是以嗜卷书虱为主攻对象。研究通过书虱ITS基因的克隆与序列分析，建立了一种基于ITS2的快速鉴定书虱的多重PCR技术体系。通过磁珠富集法构建了嗜卷书虱和嗜虫书虱共13个基因组微卫星（gSSR）富集文库，筛选获得260个gSSR位点并进行适用性分析；同时，对嗜卷书虱、嗜虫书虱以及三色书虱等常见书虱类害虫进行了转录组测序，鉴定得到三种书虱的共1,797个可用于引物设计的功能微卫星（EST-SSR）位点，从而提出了一套简单、高效、操作性强的基于转录组数据库发掘微小昆虫EST-SSR的技术流程。利用线粒体Cytb基因和核ITS基因序列，对9个嗜卷书虱地理种群和11个嗜虫书虱地理种群的遗传多样性、种群遗传分化及基因交流模式进行解析。结果表明，嗜卷书虱和嗜虫书虱具有相对较高的遗传多样性，这可能是书虱在各地能够频繁成灾、对储粮保护剂快速产生抗性的遗传学基础；书虱多数种群间遗传分化显著，且具有高水平的基因流，在历史上经历了弱的种群扩张事件。此外，基于转录组数据，发掘了一批在书虱抗逆和生长发育中的关键基因并进行克隆与表达研究，为书虱的抗性治理和新杀虫剂的研发提供新的理论基础。本项目测序获得了嗜虫书虱、小眼书虱以及无色书虱的线粒体基因组序列，发现了嗜虫书虱和小眼书虱书线粒体基因组的不对称双裂化现象，提出了"线粒体基因组核型"的新概念。总之，项目研究结果深化了对书虱微卫星、不同地理种群的遗传多样性、种群遗传分化及基因交流等种群遗传与进化问题的认识，有利于从分子水平上了解嗜卷书虱等书虱类害虫的生态适应机制和成灾规律，同时为指导实仓储藏物合理布局、书虱抗性监测及持续控制策略的制定提供种群遗传信息。