Genetic Diversity Of Haemaphysalis Longicornis Populations From Four Geographic Regions In China

Haemaphysails longcornis are widely dispersed in China. Haemaphysalis longicornis are blood sucking ectoparasites and served as one of the most important vectors transmitting bacteria, viruses, parasites and rickettsia. They cause great financial losses to livestock farming and seriously threaten the public health and safety. The aim of this study was to assess the genetic diversity of Haemaphysalis longicornis using COI, 16 S r RNA, ITS2 sequences as molecular marker, to investigate what had influence Haemaphysalis longicornis genetic diversity and to provide some theoretical basis for the control of tick.In this study, COI gene received a total of 93 individuals gene sequences. In the sequence 802 sites, including 723 conserved sites, 79 variable sites. The sequence had no insertion and flaw. A+T content was higher than the G+C content, displaying obvious AT deviation. Transition was higher than Transversion. Tv/Ts=4.256:1. 16 S r RNA gene received a total of 73 individuals gene sequences. In the sequence 406 sites, including 389 conserved sites, 17 variable sites. The sequence had flaw. A+T content is higher than the G+C content, displaying obvious AT deviation. Transition is higher than Transversion. Tv/Ts=4.711:1. ITS2 gene received a total of 79 individuals gene sequences. In the sequence 671 sites, including 639 conserved sites, 32 variable sites. The sequence had insertion and flaw, G+C content was higher than the A+T content, displaying obvious GC deviation. Transition is higher than Transversion. Tv/Ts=3.756:1.48 haplotypes were identified in COI, including two shared haplotypes. The shared haplotypes accounted for 21.5%. The haplotype diversity and nucleotide diversity respectively were 0.958 and 0.00847, The haplotype diversity of Xiaowu Tai mountain is the highest. 12 haplotypes were identified in 16 S r RNA, including one shared haplotype. The shared haplotype accounted for 81.3%. the haplotype diversity and nucleotide diversity respectively were 0.33838 and 0.00112. The haplotype diversity of Wuhan is the highest. 26 haplotypes was identified in ITS2, including two shared haplotypes. The shared haploutypes accounted for 68.4%. The haplotype diversity and nucleotide diversity respectively were 0.76731 and 0.000327. The haplotype diversity of Lanzhou is the highest. In a word, high level of genetic diversity was found in populations of Haemaphysails longcornis.The genetic variation within populations was higher than among population by molecular variance analysis(AMOVA) using COI, 16 S and ITS2 gene. FST values about COI were less than 0.25 showed that there was genetic differentiation between the populations, the FST is the highest between Wuhan and Xiaowu Tai moutain. FST values about 16 S r RNA were less than 0.25 showed that there was genetic differentiation, The FST is the highest between Maolan and Xiaowu Tai moutain. But part of FST about ITS2 was high(FST>0.25), because evolutionary rate of ITS2 was fast, The FST is the highest between Maolan and Wuhan.The network of COI, 16 S r RNA and ITS2 sequence demonstrated mixed structure. The phylogenetic tree of COI, 16 S r RNA and ITS2 sequence demonstrated that different individuals were distributed different clusters, which the branches of clusters are parallel. There are no evident clusters between different areas. Mantel test showed correlationt that was not found between genetic and geographical distance.Tajima’s D of COI gene was not significant,Fu’s Fs of 16 S r RNA and ITS2 was not significant. Mismatch distribution analysis(COI) showed bimodel. The result showed that H.longcornis did not experience population expansion. Mismatch distribution analysis(16S r RNA, ITS2) showed unimodal. The result didn’t match neutrality test, because the data was less.