Genetic diversity of hard ticks (Acari: Ixodidae) in the south and east regions of Kazakhstan and northwestern China

Abstract

Background The Republic of Kazakhstan, located in Central Asia, ranks as the world’s largest landlocked country, and borders five countries including China. There is a 1783 km long borderline between the South and East regions of Kazakhstan and Xinjiang Uygur Autonomous Region (XUAR, northwestern China). To date, there is no report on the genetic diversity of ticks in these regions. Methods During 2015–2019, a total of 4392 hard ticks (representatives of ten species) were collected from 605 animals (sheep, cattle, camels, dogs and hedgehogs) at 24 sampling sites belonging to 15 districts in southeastern Kazakhstan. After morphological identification, 213 specimens of these ticks were selected for molecular analyses. In addition, 157 hard ticks collected from sheep and camels between 2015 and 2018 in seven districts of XUAR were used for comparison. Following DNA extraction, a fragment of the mitochondrial cytochrome c oxidase subunit I (cox1) gene, ranging from 631 bp to 889 bp, was used to analyze genetic diversity among these ticks. Findings: Phylogenetic analyses indicated that i) five tick species including Hyalomma detritum, Hyalomma asiaticum, Rhipicephalus turanicus, Dermacentor reticulatus and Haemaphysalis erinacei from Kazakhstan clustered together with conspecific ticks from XUAR; ii) the phylogenetic separation of Dermacentor marginatus from Kazakhstan and XUAR was highly supported; and iii) Rhipicephalus sanguineus sensu lato from Alamaty Oblast was more closely related to a specimen from Iran than to that from XUAR. The network diagram of haplotypes showed that iv) Hy. asiaticum from Almaty and Kyzylorda (Kazakhstan) together with that from Yuli County of XUAR constituted an ancestral haplogroup; and v) three lineages of Rh. turanicus (from Israel, Almaty and South Kazakhstan, as well as from Usu city, Ulugqat and Baicheng Counties of XUAR) might have originated from an ancestral lineage in Alataw city, XUAR. Conclusions These findings indicate that: (i) mitochondrial lineages of some tick species are shared between southern, eastern regions of Kazakhstan and northwestern China; (ii) common evolutionary origin of Hy. asiaticum and Rh. turanicus in these regions might be attributed to historical international trade and movements of wildlife; and (iii) certain tick species show clear differences between Kazakhstan and XUAR, either in terms of abundance (e.g. Hy. scupense, Hy. marginatum) or exhibiting a phylogenetic split between these regions (relevant to D. marginatus).