# Molecular characterization of Rhipicephalus microplus and Haemaphysalis bispinosa ticks from cattle across Thailand: Regional identification and evidence of different genetic sub-structures between mainland and peninsular populations

## TL;DR

This study characterizes tick species in Thailand, revealing genetic differences between mainland and southern populations, which could help improve tick control strategies.

## Contribution

The study provides new insights into the genetic sub-structures of Rhipicephalus microplus ticks in Thailand and confirms the presence of H. bispinosa in the northeastern region.

## Key findings

- Rhipicephalus microplus clades A and C were identified, with no evidence of clade B in Thailand.
- H. bispinosa showed low genetic diversity, suggesting a bottleneck or founder effect.
- Significant genetic differences were found between mainland and peninsular R. microplus populations.

## Abstract

Phylogenetic and population genetic analyses were conducted on tick specimens collected from cattle in northern, northeastern, central, and southern regions of Thailand. Morphological identification indicated these ticks consisted of three species, Rhipicephalus microplus from all four regions, R. sanguineus from the northern and northeastern regions, and a Haemaphysalis species only collected from the northeastern region. Analysis of cytochrome c oxidase subunit I gene (COI) sequences identified R. microplus clades A and C, while clade B was not detected in this study. The same analysis indicated specimens morphologically identified as Haemaphysalis were H. bispinosa, confirming previous reports of their prevalence in northeastern Thailand. H. bispinosa showed low haplotype and nucleotide diversity, suggesting either a bottleneck or founder effect. Both R. microplus clades displayed high haplotype diversity and low nucleotide diversity, a pattern associated with population expansion. Genetic structural analysis revealed significant genetic differences in R. microplus clade A, especially between mainland (northern, northeastern, and central regions) and peninsular (southern region) populations, which indicated limited gene flow between these areas while suggesting movement of these ticks across the mainland. The sequence analyses described in this report enhance understanding of the natural history of ticks in Thailand and are expected to guide and strengthen tick control strategies across Southeast Asia.