Susceptibility status of certain synthetic pesticides against the cattle tick Rhipicephalus ( Boophilus ) microplus (Acari: Ixodidae)

Results obtained by the adult and egg immersion test showed high grade susceptibility against Deltamethrin followed by Cypermethrin. Diazinon was the least effective against all the target stages. Deltamethrin was found the most potent as the adulticide with LC50 24.57 ppm and LC90 91.16 ppm and ovicide with LC50 13.78 ppm and LC50 63.42 ppm. In the case of larvicidal activity, Cypermethrin found the most effective with LC90 0.63 ppm and LC90 30.66 ppm. Complete occlusion of egg laying was found at the concentration 200, 250 and 300 ppm of Cypermethrin, 150, 200, 250 and 300 ppm of Deltamethrin and 400, 500 and 600 ppm of Diazinon. The values of percentage inhibition of reproduction were 98.77, 99.64, 99.90, 98.66 and 99.68 in treated groups with 50, 100, 150, 200 and 300 ppm. Present study clearly indicates that Cypermethrin, Deltamethrin and Diazinon were effective against all the life stages of cattle tick, Rhipicephalus (Boophilus) microplus.