EFFICACY OF TOPICALLY APPLIED PYRETHROIDS AGAINST EGGS OF BOOPHILUS-MICROPLUS (CANESTRINI) (ACARI, IXODIDAE)

Efficacy of three pyrethroid acaricides (permethrin, cypermethrin, and cyfluthrin) at concentrations of 0.1, 0.05, 0.01 and 0.005% active ingredient (AI) applied topically to Boophilus microplus (Canestrini) eggs of three different age classes was determined. At the rate of 0.1% AI, permethrin provided greater than or equal to 94% reduction of hatch in all age classes of eggs. However, at the two lower concentrations (0.01 and 0.005% AI) reduction of hatch was less than or equal to 35% except against 1-d-old eggs at the 0.01% AI concentration; thus permethrin was less effective at the lower concentrations than the other materials tested. Cypermethrin provided greater than or equal to 93% reduction of hatch at concentrations of greater than or equal to 0.01% AI, but was not effective against 10- and 21-d-old eggs at 0.005% AI (71.1 and 75.9% reduction, respectively). Based on the effect of concentration and age class, cyfluthrin provided greater than or equal to 96% reduction of hatch against all ages at all concentrations. It was concluded that all three compounds applied at manufacturers' recommended concentration (0.1% AI for permethrin and 0.05% AI for cypermethrin and cyfluthrin) would be excellent candidates in the cleaning and disinfesting of premises to eliminate B. microplus eggs.