湖南三地区麦氏安瘿蜂体内Wolbachia 的感染及其wsp基因序列分析

为检测麦氏安瘿蜂Andricus mairei Kieffer有无Wolbachia感染， 本研究对其岳阳、 长沙和邵阳3种群雌、 雄成虫体内Wolbachia的wsp基因进行了PCR检测， 进而对获得的基因片段进行了序列分析。结果显示， 麦氏安瘿蜂岳阳、 长沙及邵阳种群雌、 雄成虫均有Wolbachia感染， 除邵阳种群雌成虫的感染率为80%之外， 其他均为100%。3个种群Wolbachia的wsp基因序列长度皆为561 bp， 且序列完全一致。麦氏安瘿蜂Wolbachia的wsp基因序列与已知瘿蜂族(Cynipini) Neuroterus macropterus、 Biorhiza pallida及Andricus solitarius （strain 1）以及Synergini族Synergus crassicornis感染的Wolbachia的一致性达95%。除Synergini族Ceroptres cerri感染的Wolbachia属于B群（B group）之外， 瘿蜂感染的Wolbachia均属于A群（A group）。在NJ系统树中， 麦氏安瘿蜂与瘿蜂族Neuroterus macropterus、 Biorhiza pallida和Andricus solitarius （strain 1）及Synergini族Synergus crassicornis感染的Wolbachia聚合在同一分支。此外， 麦氏安瘿蜂岳阳、 长沙和邵阳种群均获得了雌、 雄成虫， 其雌性率分别为15.3%， 12.1%和19.8%， 表现出明显的雄性比偏高。结果提示与瘿蜂族的其他已报道的种类一样， Wolbachia与麦氏安瘿蜂的共生并不诱导其营产雌孤雌生殖。

Sequencing and phylogenetic analysis of the wsp gene of Wolbachia in three geographic populations of an oak gall wasp, Andricus mairei (Hymenoptera: Cynipidae), from Hunan, South China

To understand the effects of Wolbachia in Andricus mairei Kieffer, an oak gall wasp (Cynipini, Cynipidae) that forms clusters of up to 30 monothalamous galls in the catkins of Quercus glandulifera var. brevipetiolata Nakai, we examined the presence and infection frequency of Wolbachia in three widely separated geographic populations of A. mairei in Hunan Province, South China, using polymerase chain reaction and sequence determination of the wsp gene of Wolbachia from the three populations. Our survey results showed that Wolbachia infection rates were unusually high in the three test populations: 100% for the male wasps from all populations, while 100%, 100% and 80% for the Yueyang, Changsha and Shaoyang populations of the female wasps, respectively. The sequencing results showed that the gene from all the three populations is 561 bp in length. Comparison with the wsp gene sequences in A. mairei and Neuroterus macropterus, Biorhiza pallida, Andricus solitarius (strain 1) and Synergus crassicornis revealed a 95% identity. The phylogenic relationship of Wolbachia strains in Cynipidae with the known wsp sequences indicated that the Wolbachia strain of A. mairei is closely related to that of N. macropterus, B. pallida, A. solitarius (strain 1), and S. crassicornis, and belongs to the A group. We also discovered strikingly male-biased sex ratios in all the test populations: females only accounted for 15.3%, 12.1%, and 19.8% of the Yueyang, Changsha, and Shaoyang populations, respectively, indicating the extremely male-biased sex ratios. These results suggest that the symbiosis of Wolbachia with A. mairei does not induce parthenogenesis in A. mairei, which can not be properly explained and is worth further investigation.