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Phylogeography and genetic structure of Haemaphysalislongicornis (Asian longhorned tick)
Zainab Umar Abdullahi1, Dieter Bulach2, Joanne M. Devlin1, Glenn F. Browning1
1: Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, The University of Melbourne, Parkville, Australia; 2: National Centre for Antimicrobial Stewardship, The University of Melbourne, Parkville, Australia
The invasive tick Haemaphysalis longicornis is an important vector of veterinary and public health significance and has expanded beyond its native Asian range into Australia, Western Pacific Islands, and the USA. Despite its growing biosecurity importance, the global phylogeographic structure of this species remains unknown. This study investigated the evolutionary relationships and population structure of H. longicornis using 1,396 cytochrome c oxidase subunit I (COI). Sequences represented native populations from China, Japan, South Korea, and Russia, and invaded populations from Australia, New Zealand, Tonga, Pakistan, and the USA. A total of 166 haplotypes were identified, with high haplotype diversity (Hd = 0.88). Haplotype network and phylogenetic analyses identified two major lineages: a cosmopolitan lineage shared between native and invaded regions, and a second lineage restricted to Asia. Population genetic analyses demonstrated contrasting levels of genetic differentiation within and among countries, including high differentiation between Korea and the USA (FST = 0.73), while the lowest differentiation occurred between China and Korea (FST = 0.06). The cosmopolitan lineage displayed a star-like topology, suggesting demographic expansion and dispersal into invaded regions. These findings provide new insights into the invasion events, dispersal pathways, and evolutionary structure of H. longicornis.
