This study was the first to investigate ticks on lizards from the arid desert regions of Xinjiang, China, using molecular techniques. The results show that the 31 ticks from E. multiocellata lizards at four sampling sites in this study belonged to three genera and three species (H. sulcata, Hy. asiaticum, and R. turanicus). Among them, H. sulcata was the most abundant species and R. turanicus the rarest, with only four ticks. Hy. asiaticum and R. turanicus were reported in lizards in China for the first time.
The tick species H. sulcata is a three-host tick species. The adults have been reported to usually feed on domestic and wild ungulates, while the immature stages have a special preference for reptiles . In Turkey, H. sulcata was documented on A.cappadocica, L.stellio, and O. elegans . Recently, six lizard species have been found to be reptilian hosts of H. sulcata. Consistent with previous research , we found H. sulcata in lizards. In this study, the H. sulcata haplotypes obtained from the lizards were clustered together with the H. sulcata sequences derived from GenBank. Meanwhile, the MJ network (Fig. 3) showed that H. sulcata has a shorter distance to these haplotypes than to any others. Therefore, we can conservatively infer that 17 of the ticks collected from the lizards have been identified to the species H. sulcata
Interestingly, we found not only H. sulcata feeding on the lizards, but also found two local tick species that are dominant in Xinjiang, Hy. asiaticum and R. turanicus. A previous survey of ticks on livestock also reported that H. sulcata, Hy. asiaticum and R. turanicus were found in the Tarim Basin, in Xinjiang. As the prevalent species in Xinjiang [37, 38], Hy. asiaticum has a broad host range, reaching more than 50 species, mainly artiodactyls and small mammals. Furthermore, all hosts can be accidentally infested at all stages of Hy. asiaticum . This is the first report of Hy. asiaticum infestation on lizards in China. Hy. asiaticum mostly occurs in desert type habitats in Asia, including China, Kazakhstan, and Mongolia . The MJ network based on the COI haplotype of Hy. asiaticum showed that Z3 shared the same haplotype as two ticks from Gansu and three from Kazakhstan (Fig. 5). The reason could be their geographical origins, as Gansu and Kazakhstan both border Xinjiang. However, there are still unique lizard-tick haplotypes (Z2 and Z4) in Xinjiang.
In a previous study, R. turanicus was a widely distributed species in desert and semi-desert areas in the southern region of Xinjiang [40, 41]. However, the abundance of this species seems to be partly reduced owing to the limited sample size in the present study. Although this species has been reported to feed on lizards , the record of R. turanicus collected from lizards in China was blank until we found the three lizard-ticks in this study. As shown in Fig. 4, in the R. turanicus clade, one haplotype (Z1, three sequences from lizards and three from hedgehogs) shared an identical sequence with one Chinese R. turanicus and was clustered with two sequences derived from GenBank. To extend the knowledge of tick species infesting lizards and their potential to cause tick-borne diseases, more investigations are needed. Reptile-ticks could perhaps be believed to be less widely distributed in China only because of the lack of research on them.
Thousands of lizards were captured by our lab in the summers of 2015 to 2019. They belonged to the genera Eremias and Phrynocephalus and were caught at various sampling sites in arid desert regions, covering 68 counties in Xinjiang [12, 42]. No ticks were found on the lizards of other species belonging to the genus Eremias or on any species of Phrynocephalus. In addition, no ticks were found on E. multiocellata lizards from sampling sites other than the four sites used in this study (all in the north of the Tarim Basin). Several factors may affect the distribution of tick species, such as the climate, human land-use patterns, geographical habitats, and hosts. The Tarim Basin, an endorheic basin in southern Xinjiang, is located between the Kunlun Mountains, the Tianshan, and the Altun Mountains. Various landscapes in the Tarim Basin are composed of desertified grassland, salinised desert, and human and animal inhabited oases . This was consistent with the adapted living environment of the three tick species found in the lizards [20, 34, 38]. In conclusion, we suggest that the characteristics found in this study of ticks in Xinjiang is closely related to the geographical environment.
Xinjiang, adjacent to eight countries (Russia, Kazakhstan, Kyrgyzstan, Tajikistan, Pakistan, Mongolia, India, and Afghanistan), is an important transportation hub. The economic system of Xinjiang is mainly agriculture and animal husbandry; thus, farmers and herders are in close contact with livestock, reptiles, and ticks. Therefore, the spread and epidemic risk of tick-borne disease in this area is grim, and the potential for the early warning, prevention, and control of tick-borne diseases should be improved. Further studies on the storage and transmission of pathogens in ticks are needed to help us control ticks and tick-borne diseases efficiently.