Composition and Seasonal Variation of Rhipicephalus turanicus and Rhipicephalus sanguineus Bacterial Communities

Abstract

ABSTRACTA 16S rRNA gene approach, including 454 pyrosequencing and quantitative PCR (qPCR), was used to describe the bacterial community inRhipicephalus turanicusand to evaluate the dynamics of key bacterial tenants of adult ticks during the active questing season. The bacterial community structure ofRh. turanicuswas characterized by high dominance ofCoxiellaandRickettsiaand extremely low taxonomic diversity. Parallel diagnostic PCR further revealed a novelCoxiellaspecies which was present and numerically dominant in all individual ticks tested (n= 187).Coxiellasp. densities were significantly higher in female versus male ticks and were overall stable throughout the questing season. In addition, we revealed the presence of the novelCoxiellasp. inRh. sanguineusadult ticks, eggs, and hatched larvae, indicating its vertical transmission. The presence of both spotted fever groupRickettsiaspp. (SFGR) and non-SFGR was verified in the various individual ticks. The prevalence and density ofRickettsiaspp. were very low compared to those ofCoxiellasp. Furthermore,Rickettsiasp. densities were similar in males and females and significantly declined toward the end of the questing season. No correlation was found betweenCoxiellasp. andRickettsiasp. densities. These results suggest different control mechanisms in the tick over its different bacterial populations and point to an obligatory and facultative association between the two tick species andCoxiellasp. andRickettsiaspp., respectively.