New ticks on the block: Diversity and composition of the lone star tick microbiome in areas of recent range expansion

The lone star tick, Amblyomma americanum, is an aggressive tick found in the eastern United States, but it is expanding its geographic range both westward and northward. The lone star tick carries a variety of pathogenic bacteria that affect humans, including Ehrlichia which causes ehrlichiosis and Rickettsia which causes tick-borne spotted fever. Characterizing the microbiome of lone star ticks in areas of recent range expansion is crucial to mitigating the spread of tick-borne diseases. We collected wild ticks from Oklahoma, New York, and New Jersey near the boundary of the lone star tick’s current range. We extracted DNA from adult wild ticks as well as from adult ticks reared in a captive colony maintained at Oklahoma State University. We used Illumina sequencing of the 16S rRNA bacterial gene to characterize the diversity and composition of the lone star tick microbiome. Analyses of beta diversity show that there is significant clustering by region and by site. Analyses of alpha diversity show that ticks in older populations have a significantly more diverse microbiome than ticks in areas where they are more recently established, both in Oklahoma and New York. Additionally, wild ticks in Oklahoma have a significantly more diverse microbiome than colony-reared ticks. Coxiella is the most abundant bacteria found in ticks from all sites, including the colony. Borrelia, Rickettsia, and Ehrlichia are more prevalent in ticks from New York and New Jersey than ticks from Oklahoma. Further work will evaluate how microbiome diversity affects pathogen prevalence.