High genetic diversity in hard ticks from a China-Myanmar border county

Abstract

BackgroundMany tick species have great morphological similarity and are thus grouped into species complexes. Molecular methods are therefore useful in the classification and identification of ticks. However, little is known about the genetic diversity of hard ticks in China, especially at the subspecies level. Tengchong is one of the epidemic foci of tick-borne diseases in China, but the tick species inhabiting the local area are still unknown.MethodsEighteen villages in Tengchong County, China, were selected for sampling carried out from September to October 2014. Infesting hard ticks were removed from the body surface of domestic animals and questing ticks were collected from grazing fields. After morphological identification, molecular characteristics of each tick species were analyzed based on both 16S rRNA and cytochrome c oxidase subunit 1 (cox1) gene fragments.ResultsSix tick species were identified based on morphology: Rhipicephalus microplus, R. haemaphysaloides, Ixodes ovatus, Haemaphysalis longicornis, H. shimoga and H. kitaokai. Phylogenetic analysis using the cox1 gene revealed that R. microplus ticks from the present study belong to clade C. For tick samples of both R. haemaphysaloides and I. ovatus, three phylogenetic groups were recognized, and the intergroup genetic distances exceeded the usual tick species boundaries. Haemaphysalis longicornis ticks were clustered into two separate clades based on the cox1 gene. For ticks from both H. shimoga and H. kitaokai, two phylogenetic groups were recognized based on the phylogenetic analysis of the 16S rRNA gene, and the intergroup genetic distances also exceeded the known boundaries for closely related tick species.ConclusionsAccording to molecular analyses, new species or subspecies closely related to R. haemaphysaloides, I. ovatus, H. shimoga and H. kitaokai probably exist in the China-Myanmar border Tengchong County, or these ticks form species complexes with highly divergent mitochondrial lineages. Morphological comparisons are warranted to further confirm the taxonomic status of these tick species.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-3048-5) contains supplementary material, which is available to authorized users.

Morphological and molecular identification of ixodid tick species (Acari: Ixodidae) infesting cattle in Uganda

“…Maximum likelihood analysis was performed in MEGA v7.0.14 (Kumar et al 2016 ) with 1000 bootstraps, as well as calculation of pairwise p-distances. Average p-distances between conspecific sequences from GenBank and collected samples were calculated to determine species identification validity according to the generally accepted threshold of 5% or greater sequence divergence between species (Bakkes et al 2020 ; Bakkes et al 2018 ; Chitimia-Dobler et al 2017 ; Lado et al 2018 ; Li et al 2018 ; Mans et al 2019 ).…”

Comparative population genetic structure of two Ixodidae ticks (Ixodes ovatus and Haemaphysalis flava) in Niigata Prefecture, Japan 

“…Our cox1 I. ovatus gene tree showed Japanese individuals to form a group that was distinct from haplotypes from southern China [20]. Despite the low gene flow we found in cox1 I. ovatus, haplotypes found from Niigata were closely related to the published sequence from Hokkaido, Japan which may indicate that these ticks originated from a diverse set of geographical locations in Japan which might be transported by its hosts or is undergoing recent population expansion from northern Japan (Hokkaido) to south (Niigata) or vice versa.…”

“…We applied HKY and GTR nucleotide substitution models for cox1 and 16S, respectively, as suggested by jModelTest ver 2 [32]. [20]), Japan (Hokkaido, Yamanashi and Aomori) (AB231670, AB819241, AB819243, AB819244 [33][34]) and the USA (U95900; [35]) were included. We used Ixodes canisuga as an outgroup (KY962023, KY962074; [36]).…”

“…In addition to tick population structure studies, genetic studies may also reveal the presence of cryptic species, where morphologically identified individuals might represent more than one species [17]. Previous studies on Rhipecephalus appendiculatus [18], I. holocylus [19] and I. ovatus [20] have revealed the presence of cryptic species based on the clustering of haplotypes in a phylogenetic tree, and concluded that morphological criteria for species differentiation alone are equivocal and that genetic analysis is important. A putative I. ovatus species complex was identified based on the presence of 3 distinct haplotype clusters in both cox1 and 16S rRNA genes; 2 groups in China and one in Japan that included haplotypes from North America [20].…”

Molecular Characterisation using 16S rRNA and COI Gene Sequences in Hard Ticks of Gwalior, India

“…In the present study, using the 16S rRNA gene, Rh. microplus ticks clustered in clade A 34 along with other Indian ticks, whereas using the COI gene, these ticks were classified as part of clade C based on their closest relatives for which there are sequences available in GenBank 32 . The virtual analysis of this study resulted in the formation of three distinct clades, similar to the results of Low 32 , et al Rh.…”