Determination of acaricide resistance in Rhipicephalus sanguineus and evaluation of resistance mechanisms

Determination of acaricide resistance in Rhipicephalus sanguineus and evaluation of resistance mechanisms Amanda L. Eiden1, Phillip E. Kaufman1, Faith M. Oi1, Michael J. Dark2,3 and Robert Miller4 1Entomology and Nematology Dept., University of Florida, Gainesville, FL 2College of Veterinary Medicine, University of Florida, Gainesville, FL 3Emerging Pathogens Institute, University of Florida, Gainesville, FL 4USDA, ARS, Cattle Fever Tick Research Laboratory, Edinburg, TX The brown dog tick, Rhipicephalus sanguineus (Latreille), is a common ectoparasite of dogs worldwide. In addition, R. sanguineus is a vector for several Rickettsia, Babesia, and Ehrlichia spp. This three-host tick can complete its entire lifecycle indoors and infest homes, and as such, chemical control methods are heavily relied upon to eliminate household infestations and control ticks on pets. To evaluate acaricide resistance levels, ticks were collected from residences and kennel facilities experiencing tick infestations that were difficult to eliminate. Using the larval packet test, we have confirmed resistance to permethrin and fipronil in several Florida R. sanguineus populations. This is the first time acaricide resistance in R. sanguineus has been documented in the United States. In order to accelerate detection and reduce costs for resistance profiling of field-collected ticks, a discriminating dose has been established using a susceptible tick strain. Increased metabolic activity and target site mutations are resistance mechanisms that are currently being evaluated with Florida tick populations. Preliminary results have demonstrated an increase in esterase metabolic activity, which is known to aid in acaricide detoxification. Knowledge of resistance status and resistance mechanisms is crucial in developing a best management program for the brown dog tick and to reduce unnecessary acaricide exposure in the home.