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 pop

Authors: SANGTHONG, DANAI - Kasetsart University; SANGTHONG, PRADIT - Kasetsart University; RANGUBPIT, WARIN - Kasetsart University; PONGPRAYOON, PRAPASIRI - Kasetsart University; EUKOTE, SUWAN - Kasetsart University; WONGPANIT, KANNIKA - Kasetsart University; CHIMNOI, WISSANUWAT - Kasetsart University; MORAND, SERGE - Centre National De La Recherche Scientifique; Stich, Roger; JITTAPALAPONG, SATHAPORN - Kasetsart University

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/4/2025
Publication Date: 11/20/2025
Citation: Sangthong, D., Sangthong, P., Rangubpit, W., Pongprayoon, P., Eukote, S., Wongpanit, K., Chimnoi, W., Morand, S., Stich, R.W., Jittapalapong, S. 2025. 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. PLOS ONE. https://doi.org/10.1371/journal.pone.0337052.
DOI: https://doi.org/10.1371/journal.pone.0337052

Interpretive Summary: Ticks are important parasites that affect cattle health and productivity, and understanding the distribution and genetic structure of tick populations can improve control strategies by elucidating how these populations became distributed in regions where they are indigenous. The objective of this study was to determine the diversity of tick populations that feed on cattle indigenous to Thailand, which is thought to be the original geographic region of the tropical cattle fever tick, arguably the most impactful tick parasite of livestock worldwide. Three tick species were found on Thai cattle, tropical cattle fever ticks, brown dog ticks and a species belonging to the hard tick genus, Haemaphysalis, which further genetic analysis identified as bispinose ticks. Genetic analysis revealed two previously described subspecies of cattle fever ticks (groups A and C) but did not detect a third known subspecies (group B). By analyzing genetic diversity, this report provided evidence of population expansion of cattle fever ticks, while genetic structuring indicated limited gene flow between mainland and peninsular tick populations. These insights enhance understanding of tick populations across Thailand, providing useful information to monitor their movement and for targeted tick control measures to protect livestock and agricultural productivity.

Technical Abstract: Phylogenetic and population genetic analyses were conducted on tick specimens collected from cattle in northern, northeastern, central, and southern regions of Thailand. Morphologic 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 oxidase subunit I (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, demonstrating these ticks in the northeastern region, confirming previous reports of their prevalence in northeastern Thailand. H. bispinosa showed low haplotype and nucleotide diversity, suggesting 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 improve understanding of the natural history of ticks in Thailand and are expected to focus and facilitate tick control strategies across the region.