Evaluation of the commonly used acaricides against different stages of Rhipicephalus sanguineus by in vitro tests

The efficacy of three commonly used acaricides cypermethrin, deltamethrin (0.05, 0.1 and 0.2% concentrations) and amitraz (0.1, 0.2 and 0.3% concentrations) was evaluated against the dog tick Rhipicephalus sanguineus. The in vitro methods viz. tea bag, filter paper impregnation and immersion (Shaw larval immersion) methods were used. Adult immersion test with discriminating doses recommended by FAO, 1999 was used to note resistance development if present. Comparison of different in vitro methods was done based on the efficacy against different stages of the tick. The immersion method fared better in efficacy followed by tea bag and filter paper methods. Amitraz was highly effective against R. sanguineus, whereas 30% resistance was observed with both cypermethrin and deltamethrin.