西藏部分地区血蜱、革蜱形态和分子生物学鉴定

Morphological and molecular identification of Haemaphysalis, and Dermacentor ticks in some areas of Tibet

为了解西藏部分地区牛体表寄生的硬蜱种类,试验分别从西藏林芝、拉萨地区采集硬蜱样本,首先用形态学方法对采集的硬蜱进行初步鉴定,然后根据硬蜱线粒体12S rDNA、16S rDNA、COXⅠ基因进行序列扩增并测序,再应用MEGA 7.0软件采用邻近法(Neighbor-joining method)构建系统进化树,进行分子进化分析,并与形态学结果相互验证。结果表明:通过形态学初步鉴定西藏林芝地区所采集的样本为血蜱属成蜱,西藏拉萨地区所采集的样本为革蜱属成蜱。西藏林芝地区所采集的血蜱COXⅠ、12S rDNA、16S rDNA基因序列与GenBank中已知血蜱Haemaphysalis formosensis、Haemaphysalis longicornis、Haemaphysalis danieli核苷酸序列相似性分别仅为87.36%、91.28%、90.31%,而西藏拉萨地区所采集的革蜱COXⅠ、16S rDNA和12S rDNA基因序列与GenBank中已知革蜱Dermacentor everestianus核苷酸序列相似性分别为98.88%、98.76%和97.70%。根据不同基因所建系统进化树有所不同,但同一属内基因序列均能聚为一支。说明本次所采集的西藏拉萨蜱虫为西藏革蜱,西藏林芝所采集的蜱虫与GenBank中现有蜱虫核苷酸序列相似性较低,且进化树分析提示不同目标基因所建进化树结构不一致,因此其具体种属还需进一步研究。

In order to understand the species of ticks that parasitized the surface of cattle in some areas of Tibet, the samples of ticks were collected in this experiment from Nyingchi and Lhasa areas, Tibet. Firstly the collected ticks were identified by morphological methods;then based on the 12 S rDNA, 16 S rDNA and COXⅠ genes of tick mitochondria, the sequences were amplified and sequenced;lastly the MEGA 7.0 software was used to construct a phylogenetic tree and perform molecular evolution analysis with the Neighbor-joining method, which was verified with the morphological results. The results showed that adult ticks collected in Nyingchi area, Tibet, belonged to Haemaphysalis through preliminary identification of morphology;adult ticks collected in Lhasa area, Tibet, belonged to Dermacentor. The nucleotide similarities between the COXⅠ, 12 S rDNA and 16 S rDNA gene sequences of the Haemaphysalis collected in Nyingchi area, Tibet and the known Haemaphysalis formosensis, Haemaphysalis longicornis, and Haemaphysalis danieli in GenBank were only 87.36%, 91.28%, and 90.31%, respectively. While the nucleotide similarities between the COXⅠ, 12 S rDNA and 16 S rDNA gene sequences of the Dermacentor collected in Nyingchi area, Tibet and the known Dermacentor everestianus in GenBank were 98.88%, 98.76% and 97.70%, respectively. The phylogenetic trees built according to different genes were different, but the gene sequences in the same genus could be clustered into one branch. The results suggested that the ticks collected in Lhasa area, Tibet in this experiment were Dermacentor everestianus;the ticks collected in Nyingchi area, Tibet had low nucleotide similarity with the existing ticks on GenBank, and the molecular evolutionary tree analysis indicated that the molecular evolutionary tree structure of different target genes was inconsistent;therefore, its specific species needed to be further studied.