中文摘要：

蚜小蜂Bemisia tabaci是烟粉虱的重要天敌,其中双斑恩蚜小蜂Encarsia bimaculata,丽蚜小蜂E.formosa以及浅黄恩蚜小蜂E.sophia是国内烟粉虱寄生蜂3个优势种。本研究以采自中国华南、华东、华北、西南地区以及马来西亚、埃及的E.bimaculata、E.formosa和E.sophia3个优势种的8个不同地理种群为研究对象,对其28S rRNA D2和D3扩展区序列进行了测定和分析。结果表明：Encarsia属的恩蚜小蜂其28S rRNA D2和D3序列在种间水平上高度保守;与丽蚜小蜂相比,双斑蚜小蜂与浅黄恩蚜小蜂在遗传关系上更为接近。依据28S rRNA和D2序列的系统发育分析结果显示,同一种的蚜小蜂其种内也存在一定的遗传分化,比如中国广东的浅黄恩蚜小蜂种群与澳大利亚、西班牙、埃及和埃塞俄比亚的浅黄恩蚜小蜂种群接近,而与泰国的种群的亲缘关系则较远。在系统发育树上,来自不同国家的（苏丹、埃及和危地马拉以及澳大利亚）的双斑蚜小蜂种群聚集在同一分支上;同时,来自中国衡水和昆明的丽蚜小蜂种群也与来自美国的丽蚜小蜂种群聚集在一起,却与埃及的种群相距较远。对造成这种同种寄生蜂不同种群之间在遗传距离和地理距离不对称的原因进行了探讨。

英文摘要：

Encarsia Frster consists of important parasitoids of whitefly （Bemisia tabaci） pests, including E. bimaculata, E. formosa and E. sophia, the three most important aphelinid parasitoids in China. Eight populations of Encarsia from the South, Southeast, North and Southwest of China, as well as two populations from Malaysia and Egypt, respectively, were collected in the present study, and their inter-species phylogenetic relationships were analyzed based on 28S rRNA D2 and D3 expansion regions. The D2 and D3 regions were consistent with each other, confirmed a closer genetic relationship between E. sophia and E. bimaculata since they both belong to the Encarisa strenus species group, compared to those between these two species and En. formosa. Results of the genetic distance analysis using 28S rRNA D2 sequences revealed that there are certain genetic divergences within single species of the Encarsia parasitoids. The Guangzhou population of Encarsia sophia is more close to populations from Australia, Spain, Egypt and Ethiopia, but further from the population from Thailand. E. bimaculata populations from Sudan, Egypt and Guatemala as well as one population from Australia cluster together, while E. formosa Hengshui and Kunming populations cluster together with those from USA, UK and Greece, but are further from the Egypt population. The reasons for the inconsistency between the genetic and geographical distances of the Encarsia species are discussed.