PS-4 Evaluating the Effects of Artificial Rainfall and Permethrin Resistance Status on the Efficacy of Common Pour-On Formulation Delivered to Beef Heifers in a Controlled Environment

Abstract The objective of this study is to determine the impact rainfall on duration efficacy a commercial pour-on against susceptible (SS) and permethrin resistant (PR) horn flies. Eighteen Angus-Hereford crossbred heifers (BW) were used in completely randomized design with repeated measures longevity permethrin-based pour-on. Animals randomly assigned one two fly infestations (SS or PR) within infestation three regimens [no rain (NR), no (NP) treatment, (RP) treatment]. All housed outdoor roofed pens corresponding treatment group animals NP RP groups treated once day 0 at label rate. Once week for four weeks all placed into individual indoor screened rooms where administered. Live counts acquired 24 h following each infestation. Animal received approximately 2.54 cm artificially provided 2 hours weakly count. A × x interaction (P < 0.01) was observed. In general, NR maintained higher 0.05) populations SS PR 22 8 days post-treatment, respectively. Regardless, species, had > influence product efficacy. conclusion, insecticide resistance status appears be more influential than heavy products.