Autogenous reproduction by Ornithodoros turicata (Ixodida: Argasidae) females and vertical transmission of the tick-borne pathogen Borrelia turicatae (Spirochaetales: Borreliaceae)

Ornithodoros turicata is a vector of relapsing fever spirochetes in North America and transmits Borrelia turicatae to a variety of vertebrate hosts. The remarkably long lifespan of O. turicata and its ability to maintain spirochetes horizontally (between life stages) and vertically (to progeny) promote the perpetuation of B. turicatae in nature. Nevertheless, the reproductive biology of O. turicata is poorly understood. In this report, we collected ticks from a park within a neighborhood of Austin, TX. They were reared to adulthood, and male ticks were individually housed with females. We observed autogenous reproduction, which is the ability to produce eggs without the need for a blood meal, and further investigated vertical transmission of B. turicatae by quantifying filial infection rates in a cohort of progeny ticks. These results indicate that O. turicata transovarially transmits B. turicatae during autogenous reproduction and further signify the tick as a natural reservoir of the spirochetes. IMPORTANCE: Previous research has implicated Ornithodoros ticks, including Ornithodoros turicata, as long-term reservoirs of relapsing fever (RF) spirochetes. Considering the tick’s long lifespan and their efficiency in maintaining and transferring spirochetes within the population, the infection could persist in a given enzootic focus for decades. However, little is known about the relative importance of horizontal and vertical transmission routes in the persistence and evolution of RF Borrelia. Our observations on the reproductive biology of O. turicata in the absence of vertebrate hosts indicate an additional mechanism by which Borrelia turicatae can be maintained in the environment. This work establishes the foundation for studying O. turicata reproduction and spirochete-vector interactions, which will aid in devising control measures for Ornithodoros ticks and RF spirochetes.