马尾松毛虫区域化成灾的分子与化学生态机制

The masson pine moth, Dendrolimus punctatus Walker (Lepidoptera: Lasiocampidae), is a widely distributed pest, with regional populations that frequently reach outbreak status and cause significant damage to pine forests in south China. In this project, the complete mtDNA genomes and rDNA internal transcribed spacer (ITS) sequences will be used to investigate the genetic variation patterns among regional populations of D. punctatus distributed in south China. The phylogenetic relationships and potential dispersal routes of geographic populations will be also constructed based on combined sequence analyses of mtDNA and ITS fragments in order to further understand the mechanism of molecular ecology about regional disaster of D. punctatus. In addition, the sex pheromone polymorphisms in D. punctatus will be surveyed throughout its distribution range by coupled solid-phase microextraction (SPME)/gas chromatography (GC)/mass spectrometry (MS) and coupled SPME-GC-electroantennographic detection (EAD). Especially, the fluctuation law of chemical communication signals during populations outbreak will be clarified in this project. Furthermore, we will conduct single cell recording (SCR) with pheromone-sensitive olfactory receptor neurons (ORNs) housed in sensillum trichodeum of male antennae in order to learn the reciprocal response features of ORNs to incomplete and aberrant blend ratios of pheromone components. At the same time, the behavioral discrimination of male moth to incomplete and aberrant blend ratios of pheromone components will also be studied by means of wind tunnel and field tests. In addition, a series of electrophysiological responses of gustatory receptor neurons (GRNs) to phagostimulants and feeding deterrents will be elucidated in this project in order to understand the feeding selection mechanism. These results produced by this project will provide basis for decision making in management of regional populations of D. punctatus and improve the integrated pest managemnt level aiming at the control of the pine defoliator pests.

马尾松毛虫是广域种，生境区域化，经常暴发成灾。在马尾松毛虫整个分布区内进行大规模群体采样，利用线粒体基因组本身的遗传特性及ITS基因序列的特点，深入研究马尾松毛虫地理居群的遗传变异格局，构建不同地理居群的亲缘关系及可能的迁移路径，阐明马尾松毛虫区域化成灾的分子生态机制。利用固相微萃取-质谱分析和固相微萃取-气相色谱-触角电位仪联用技术分析马尾松毛虫性信息素的地域多态性；特别是种群暴发过程中化学通信信号的波动规律；利用行为生测及嗅觉受体神经元单细胞记录的方法研究雄虫对失真的化学信号检测灵敏度；进一步利用味觉电生理方法研究幼虫的食性选择机制；阐明马尾松毛虫区域化成灾的化学生态机制。研究成果将为马尾松毛虫区域化防治措施提供决策依据，提高对马尾松毛虫综合治理的水平。

马尾松毛虫是广域种，生境区域化，经常爆发成灾，种群爆发具有周期性和突发性的特点。在马尾松毛虫整个分布区内进行大规模采样，利用线粒体基因组本身的遗传特性及ITS基因序列的特点，深入研究马尾松毛虫地理种群的遗传变异格局，构建不同地理种群的亲缘关系及可能的迁移路径，阐明马尾松毛虫区域化成灾的分子生态机制。利用质谱和触角电位技术分析马尾松毛虫性信息素的地域多态性；特别是种群暴发过程中化学通信信号的波动规律；阐明马尾松毛虫区域化成灾的化学生态机制。研究结论如下：1）阐明了马尾松毛虫线粒体全基因组的碱基组成、结构特点及其在高级阶元下与其他物种间的系统发育关系。2）采用系统发育分析、遗传分化和溯祖分析等分子生物学手段，利用线粒体基因组和核基因ITS1相结合，对马尾松毛虫的遗传多样性和遗传结构进行综合分析。最终推测四川种群是马尾松毛虫在中国的祖先种群，即冰期结束后马尾松毛虫繁衍的起点。中性检验和错配分布都显示马尾松毛虫种群近期发生过种群扩张。马尾松毛虫的迁移路径是：起源于四川盆地地区，自西向东、向北、向南扩散，目前广泛分布于我国长江以南广大地区，已经形成了明显的遗传分化。3）确认马尾松毛虫不同危害程度种群变动过程中雌雄性比偏离规律。雄虫对化学信号敏感性分析表现出地域差异、危害程度差异及行为差异的特点。特别是马尾松毛虫3种性信息素成分顺5,反7-十二碳二烯醇、顺5,反7-十二碳二烯乙酸酯和顺5,反7-十二碳二烯丙酸酯比例为100:80:30时对同地域发生的轻度和重度种群诱捕效果没有差异；该比例诱蛾效果与100:80:20和100:80:40的比例诱芯诱蛾效果差异也不显著，但是与100:80:50和100:100:20配比的诱芯诱蛾效果差异显著。雄虫对3种性信息素成分比例林间行为响应存在一定的比例宽度，比例较大偏离会直接影响其行为活性。研究成果将为马尾松毛虫区域化防治措施提供决策依据，提高对马尾松毛虫的综合治理水平。