Prevalence and molecular characterization of Wolbachia infection in lone star ticks (Amblyomma americanum) from central Georgia

Wolbachia are vertically-transmitted intracellular bacteria associated with >60% of arthropods worldwide. Infection can alter host phenotypes or protect against pathogens, thus promoting the spread of the bacteria within the host population. Manipulation of Wolbachia infections in mosquito vectors has also been used to reduce the transmission of human pathogens. A similar manipulation of the host-bacterium relationship may be possible to limit the transmission of tick-borne pathogens, but little is known about tick-Wolbachia interactions in North America. We detected Wolbachia DNA in 7.6% of 173 individual and 11 pools of lone star ticks (Amblyomma americanum) collected from seven sites in four states using 16S rDNA metagenomics on a Roche 454. Wolbachia-positive nymph and adult male individuals were detected, but within site sample sizes were small and did not allow for prevalence comparisons between sites. An additional 336 A. americanum nymphs were collected from disturbed and undisturbed areas in Panola Mountain State Park near Atlanta, Georgia, USA from May-July 2011. They were assayed by PCR for a fragment of the Wolbachia ftsZ gene. Wolbachia detection was higher in ticks collected from the undisturbed site (Fisher’s exact test, p=0.006), which was also the site with the lower tick population density. We are characterizing this tick-associated Wolbachia to determine if they originated from Wolbachia-infected parasites of ticks. Understanding the ecological interactions of this important bacterial agent with this aggressive tick provide important new tools for controlling the diseases it transmits.