D3236: Discovery and optimization of hypervariable microsatellites for Haemaphysalis longicornis to help unravel its expansion in the US

The invasive Asian longhorned tick, Haemaphysalis longicornis, was first detected in the United States in 2017 and has spread to 19 mid-Atlantic states, posing a growing threat to both human and animal health. This tick species is a realized vector in the US of bovine theileriosis and a potential vector of multiple Babesia species, as well as bacteria and viruses. Notably, H. longicornis exhibits unique reproductive characteristics with distinct bisexual and parthenogenetic strains. While both groups coexist in their native habitat in Asia, only parthenogenetic forms have so far been found in the US. Genetic analysis has identified three parthenogenetic mitochondrial haplotypes in the United States, with northern New Jersey as a probable introduction point. The potential for spread and public health risk associated with this tick species are exacerbated by the asexual reproduction that can generate extraordinarily large infestations from a single propagule. To understand the tick's genetics and parthenogenesis, we identified multiple regions of sequence simplicity in the H. longicornis genome and optimized several hypervariable 3-basepair repeats (microsatellites) in non-mitochondrial genome regions to obtain insights into genomic variability to enable population genetic analyses. This research contributes to our knowledge of tick ecology, genetics, and disease transmission dynamics, particularly in invasive species, while highlighting the urgent need for tick management and disease prevention strategies. Haemaphysalis longicornis presents an evolving challenge, necessitating continued investigation and monitoring as it proliferates throughout the United States and other non-native regions.