大湄公河次区域(GMS)稻飞虱天敌-黑肩绿盲蝽的种群遗传结构及迁飞虫源分析

Cyriorhinus lividipennis (Reuter) is an important predator of rice brown planthopper (Nilaparvata lugens Stal) and white-backed planthopper (Sogatella furcifera Horváth) eggs or younger nymphs. It plays a key role in suppressing the planthoppers’ population in field. This predator had a migratory behavior and accompany the migrating populations of BPH and WBPH simultaneously, but very little is known about the population genetic structure, gene flow of this natural enemy in the Greater Mekong Subregion (GMS), which includes Cambodia, Laos, Myanmar, Thailand, Vietnam, and China's Yunnan Province. Previous filed survey results showed that C. lividipennis was the major natural enemy of planthoppers in GMS rice area, but the population dynamics were different among these countries. In the present study, COI molecular markers were used to analyze the genetic diversity of 42 WBPH population in GMS., The results showed that there are 3 migratory population sources in Yunnan province from others countries. Based on the results, we want to ⅰ) Investigate the population genetic diversity of C. lividipennis populations across the six countries in the Greater Mekong Sub-region by intensive sampling using mitochondrial genes. ⅱ) Infer the haplotype network of mtCOI genes and analyze the gene flow among the populations, evaluate the dispersal ability of different geographic populations to know the migratory population sources in Yunnan Province. ⅲ) Analyze the genetic differentiation among different geographic populations and the correlation between population differentiation and geographical distance. The findings of this study will provide guidance for the conservation and utilization of different geographical populations of C. lividipennis in the future.

黑肩绿盲蝽(Cyriorhinus lividipennis Reuter)是捕食褐飞虱和白背飞虱的卵和低龄若虫的重要天敌，对稻飞虱田间种群有显著的控制作用，黑肩绿盲蝽有随稻飞虱同时迁飞的伴迁行为，但目前尚未清楚不同地理种群的种群遗传结构和基因流。田间调查表明黑肩绿盲蝽是大湄公河次区域（GMS）各稻区稻飞虱的主要天敌，但稻区间种群发生特点差异明显。我们已经研究了GMS区域42个白背飞虱种群的遗传多样性。在此基础上，本项目拟采用线粒体COI分子标记研究：1）越南、老挝、泰国、柬埔寨、缅甸及云南省黑肩绿盲蝽不同地理种群的种群遗传多样性；2）构建mtCOI基因的单倍型网络分布图，分析不同种群间的基因流，评价不同地理种群的扩散能力，明确云南省黑肩绿盲蝽的迁入来源；3）分析不同地理种群间的分化程度，明确种群分化程度和地理距离的相关性。研究结果今后可为黑肩绿盲蝽不同地理种群的保护和利用提供理论依据。

黑肩绿盲蝽是稻飞虱的重要天敌，对稻飞虱田间种群的控害效果明显，有随稻飞虱迁飞的伴迁行为，本项目的研究内容为筛选适合扩增黑肩绿盲蝽COⅠ序列的引物、同源性比较和种群遗传多样性，不同地理种群之间的基因流。本项目采用线粒体COI分子标记研究了黑肩绿盲蝽不同地理种群的种群遗传多样性单倍型网络结构图和不同种群间的基因流，推测了云南省黑肩绿盲蝽的迁入源。主要研究结果如下：各种群的单倍型多样性指数Hd、核苷酸差异平均数K、Fu's Fs 指数和Tajima's D指数的变化范围较为类似，大部分种群的Fu's Fs 指数和Tajima's D指数都为负值，表明在GMS区域内黑肩绿盲蝽种群经历了种群扩张历程。46个种群的种群遗传变异的分子生物学方差分析结果及地理距离和遗传分化系数的相关性分析结果表明各个种群间的基因交流频繁。雌雄比例、采样时期和取样量水平会影响种群遗传多样性，因此采样时需尽量采集足够数量的雌虫。黑肩绿盲蝽的单倍型网络结构图以共享单倍型为中心呈星状分布，表明黑肩绿盲蝽在GMS区域内经历过种群扩张过程。本研究共鉴别出139个单倍型（简称h1-h139），其中单倍型H1、H9是每个种群的优势单倍型，占各种群的50%以上；境外36个黑肩绿盲蝽种群与云南的8个种群间间存在较高基因流。M值介于8.19（缅甸M9种群至云南勐海(MH）种群）到724.96（缅甸M10种群至云南楚雄(CX)种群）之间。根据单倍型网络结构图和种群间的基因流结果，推测滇西（沧源）地区的迁飞虫源主要来自缅甸；滇西南（勐海）和滇南（金平、文山）地区的迁飞虫源主要来自越南、缅甸和泰国；黑肩绿盲蝽境外虫源进入云南后，又进一步迁飞至滇东北彝良等地区。研究结果为其迁飞区域内，分时段、分批次大量释放黑肩绿盲蝽，开展跨区域协同开展黑肩绿盲蝽的保护利用提供科学依据。项目主持人获2020年度云南省中青年学术和技术带头人-后备人才项目（202005AC160031）支持，培养期限5年。