Development of a low dose fipronil deer feed to systemically control medically important ticks species parasitizing white-tailed deer: A method for preventing tick-borne diseases

Odocoileus virginianus (the white-tailed deer) is a key reproductive host for medically important tick species, including Ixodes scapularis and Amblyomma americanum. Orally administering a systemic acaricide to white-tailed deer has potential to reduce tick reproduction, abundance, and pathogen-infected tick bites. We developed a low dose fipronil feed for oral administration to white-tailed deer to control parasitizing ticks.

Deer studies were conducted in collaboration with Penn State University (University Park, PA). Firstly, we screened attractants under semi-field conditions to determine the ideal formulation for delivering acaricides to deer. Secondly, range finding was conducted to determine the optimal fipronil dose to control I. scapularis parasitizing deer. Finally, we explicitly evaluated the efficacy of the optimal formulation in controlling I. scapularis and A. americanum parasitizing deer. The results indicated a granular, low dose fipronil formulation to be palatable and effectively control both tick species parasitizing deer up to 21-days post-exposure, with the efficacy contingent upon metabolite concentrations in plasma. Efficacy and toxicological results provide insights into appropriate treatment application rates, timing, and frequency in future field trials.

The results of these studies led to the development of a promising new vector control tool and provide proof-of-concept for its use in controlling medically important tick species parasitizing a key reproductive host. A field trial is the next step to confirm the efficacy and toxicology of the product in wild deer populations. Fipronil deer feed may provide a promising means of controlling multiple tick species parasitizing wild ruminants to be integrated into tick management programs.