Microbiome of Invasive Tick Species Haemaphysalis Longicornis in North Carolina, USA

Simple Summary The Asian longhorned tick (ALHT), Haemaphysalis longicornis, is an invasive pest that threatens domestic livestock. Normally found in Asia and the Pacific islands, where it is a vector of human disease, this tick was reported for the first time in the United States in 2017. In this study, we collected H. longicornis ticks of different developmental stages and used bacterial 16S rDNA amplicon sequencing to examine their microbiome. We identified numerous bacterial taxa, with Coxiella, Sphingomonas, Staphylococcus, Acinetobacter, Pseudomonas, Sphingomonadaceae, Actinomycetales, and Sphingobium as the most prevalent in the bacterial community. We documented a remarkable turnover in bacterial assemblage between life stages. These findings reveal important associations between life stages and their bacterial community and provide important insights to guide future research.Abstract Ticks are one of the most important vectors of human and animal disease worldwide. In addition to pathogens, ticks carry a diverse microbiota of symbiotic and commensal microorganisms. In this study, we used next-generation sequencing (NGS) to survey the microbiomes of Haemaphysalis longicornis (Acari: Ixodidae) at different life stages collected from field populations in North Carolina (NC), USA. Sequence analyses were performed using QIIME2 with the DADA2 plugin and taxonomic assignments using the Greengenes database. Following quality filtering and rarefaction, the bacterial DNA sequences were assigned to 4795 amplicon sequence variants (ASVs) in 105 ticks. A core microbiome of H. longicornis was conserved across all ticks analyzed, and included bacterial taxa: Coxiella, Sphingomonas, Staphylococcus, Acinetobacter, Pseudomonas, Sphingomonadaceae, Actinomycetales, and Sphingobium. Less abundant bacterial taxa, including Rickettsia and Aeromonas, were also identified in some ticks. We discovered some ASVs that are associated with human and animal infections among the identified bacteria. Alpha diversity metrics revealed significant differences in bacterial diversity between life stages. Beta diversity metrics also revealed that bacterial communities across the three life stages were significantly different, suggesting dramatic changes in the microbiome as ticks mature. Based on these results, additional investigation is necessary to determine the significance of the Haemaphysalis longicornis microbiome for animal and human health.