Microbial Ecology of Ixodes Scapularis from Central Pennsylvania, USA

(1) Background: Native microbiota represent a potential resource for biocontrol of arthropod vectors. Ixodes scapularis are mostly inhabited by the endosymbiotic Rickettsia buchneri, but the bacterial communty composition varies with life stage, fed status, and/or geographic location. We investigated sex-specific bacterial community diversity from I. scapularis collected from central Pennsylvania between populations within a small geographic range. (2) Methods: We sequenced the bacterial 16S rRNA genes from individuals and pooled samples and investigated the abundance or infection frequency of key taxa using taxon-specific PCR and/or qPCR. (3) Results: Bacterial communities were more diverse in pools of males than females. When R. buchneri was not the dominant taxon, Coxiellaceae was dominant. We determined that the infection frequency of Borrelia burgdorferi ranged between 20 to 75%. Titers of Anaplasma phagocytophilum were significantly different between sexes. High Rickettsiella titer in pools were likely due to a few heavily infected males. (4) Conclusion: Bacterial 16S sequencing is useful for establishing the baseline community diversity and focusing hypotheses for targeted experiments. However, care should be taken not to overinterpret data concerning microbial dominance between geographic locations based on a few individuals as this may not accurately represent the bacterial community within tick populations.