烟粉虱及其优势寄生蜂内共生菌的种类及系统发育分析

摘要

为了研究入侵我国的2个主要烟粉虱隐种Bemisia tabaci MEAM1和MED及其3种优势寄生蜂(浅黄恩蚜小蜂Encarsia sophia、丽蚜小蜂E. formosa、海氏桨角蚜小蜂Eretmocerus hayati)体内感染内共生菌的种类丰度,并进一步探讨其系统发育关系,本文利用分子生物学手段对昆虫体内细菌的16S rRNA基因序列进行扩增、测序和分析,并采用邻接法(Neighbor-Joining, NJ)和最大似然法(Maximum Likehood, ML)分别构建优势内共生菌的系统发育树.结果表明,烟粉虱2个隐种内共生菌的种类丰度大于其3种优势寄生蜂,3种优势寄生蜂中丽蚜小蜂内共生菌的种类丰度最高;同源性分析发现烟粉虱和寄生蜂所携带的Rickettsia基因同源性达到99%,属于Rickettsia bellii种,进一步的进化树分析也发现所研究物种的Rickettsia和Hamiltonella均可各自聚为同一进化分支.烟粉虱及其优势寄生蜂体内含有种类丰富的内共生菌,其中优势内共生菌Rickettsia和Hamiltonella各自亲缘关系很近,说明内共生菌在烟粉虱和寄生蜂间可能进行水平传播.%To determine the diversity and phylogenetic affiliation of endosymbionts harboured by two mainly invasive cryptic species Bemisia tabaci MEAM1 and MED and its three dominant parasitoids (Encarsia sophia,En. formosa,Eretmocerus hayati), the 16S rRNA gene sequences of the endosymbionts was cloned, sequenced and analyzed using molecular biology methods. Phylogenetic trees based on the sequences of the dominant endosymbionts were constructed with Neighbor-Joining (NJ) and Maximum Likehood (ML). The results showed that the symbiotic diversity of B. tabaci MEAM1 and MED was greater than those of the three dominant parasitoids. Among three dominant parasitoids, the diversity of endosymbionts in En. formosa was the highest. In the homology analysis, the Rickettsia in the five insect species had 99% similarity, and all belonged to Rickettsia bellii group. The phylogenetic trees showed that the Rickettsia in the five insect species were clustered together, and the Hamiltonella showed similar results. It suggested that B. tabaci and its three dominant parasitoids contained a variety of endosymbionts, and the dominant endosymbionts Rickettsia in the five insect species have a close genetic relationship, which is conformed to the Hamiltonella, indicating that the endosymbionts could occur horizontal transmission between B. tabaci and parasitoids.