Predictive early stage laboratory models would make evaluation of potential acaricides more efficient and cost effective. Historically, stall studies using cattle infested with a variety of tick species have been used as laboratory methods to evaluate compound efficacy. A modified version of this model, described in this abstract, is currently being used to determine the activity and potency of potential acaricides on cattle. Adult lone star ticks (Amblyomma americanum) are contained to a defined area so that smaller amounts of compound may be used. Presented are the results using this method to evaluate the activity of permethrin, a known acaricide. Based upon EC50 values derived from a surrogate animal rat model, 0.008 mg/cm2, 0.08 mg/cm2, and 0.8 mg/cm2 of permethrin were chosen as treatment levels and applied to tick containment fields attached to the backs of the cattle. Ten days post treatment, calculated EC50 values were 0.028 mg/cm2 based on tick mortality and 0.023 mg/cm2 based on average tick mass. Four days post treatment, permethrin’s EC50 value for mortality on cattle and the surrogate animal rat model compared favorably, 0.034mg/ cm2 (95% CI=0.019 to 0.063) and 0.059mg/ cm2 (95% CI=0.030 to 0.115) respectively. This cattle model is a useful tool in evaluating the activity and potency of acaricides and may be used to confirm and compare the activity of potential new acaricides to marketed acaricides using relatively small amounts of compound.
Species 1: Acari Ixodidae Amblyomma americanum (Lone Star Tick)
Keywords: Acaricide, Target Animals
Back to Display Presentations, Section D. Medical and Veterinary Entomology
Back to Posters
Back to The 2003 ESA Annual Meeting and Exhibition