Abstract
The purpose of this study was to evaluate the genetic diversity of ticks from free-ranging hosts in some areas of Qinghai Province and perform a phylogenetic analysis among different geographical populations, in order to establish a foundation for the prevention and control of ticks and tick-borne diseases in Qinghai Province. In March and April 2024, a total of 935 ticks were collected from goats, yaks, and horses in Jianzha and Haiyan counties. The tick species were identified by taxonomic key and 16S ribosomal RNA (16S rRNA) sequencing, and haplotype analysis, phylogenetic tree construction, and genetic differentiation index were performed using DNASP v.6, Popart, MEGA 11, and Arlequin v.3.5 software. The 935 collected tick samples belonged to three categories: Haemaphysalis spp., including H. qinghaiensis (n = 525) and H. danieli (n = 199); Dermacentor spp., containing D. nuttalli (n = 8) and D. silvarum (n = 201); and Hyalomma marginatum (n = 2), which was first identified in Qinghai Province. Haplotype and nucleotide polymorphism analyses indicated that there were 19 haplotypes in H. danieli, with haplotype H13 as the dominant haplotype (119/199); six haplotypes in D. nuttalli, with H3 and H4 haplotypes as the dominant haplotypes (4/8); and 20 haplotypes in D. silvarum, with H1 as the dominant haplotype (149/201). The genetic differentiation of D. silvarum, H. danieli, and D. nuttalli occurred both within and among populations. The phylogenetic analysis revealed that the tick species obtained from this study formed clades with the corresponding tick populations. These findings show that the tick species in Jianzha and Haiyan in Qinghai Province underwent population expansion and exhibited enhanced genetic diversity, providing a vital basis for understanding the distribution of ticks and tick-borne diseases in Qinghai Province.