Tick distribution in border regions of Northwestern China

Ticks are important vectors of emerging and re-emerging pathogens. The aim of this study was to determine tick species occurring in Xinjiang Uygur Autonomous Region (XUAR), especially on border regions. A total of 22,994 ticks (including 22,629 adults, 365 larvae and nymphs), belonging to six tick genera (i.e. Dermacentor, Hyalomma, Rhipicephalus, Haemaphysalis, Ixodes and Argas) and fourteen tick species, were collected from ten animal hosts in thirty-five counties (cities) in XUAR during 2011 - 2017. Rhipicephalus turanicus, Dermacentor niveus, Hyalomma asiaticum and Dermacentor marginatus were dominantly sampled from domestic animals while Dermacentor nuttalli, Haemaphysalis punctata, Haemaphysalis concinna, Rhipicephalus sanguineus sensu lato, Dermacentor silvarum, Hyalomma scupense and Argas persicus were sporadically found. Based on 16S rDNA, phylogenetic analyses showed that: i) R. turanicus genotypes in XUAR showed geographical separation, and belonged to clade I (major distribution in the Central Asian) rather than clade II (major distribution in the Mediterranean Basin); ii) Ixodes kaiseri, firstly sampled from Asian badgers (Meles leucurus), was in ancestral position compared to European tick species when combining COI haplotypes; and iii) Haemaphysalis erinacei from marbled polecats in China was a separate genotype compared with that in Mediterranean and Europe. Our findings suggest that geographical range plays a more important role than host-association in tick phylogeny, especially for R. turanicus, I. kaiseri and H. erinacei.