Acaricidal activity of Palicourea marcgravii, a species from the Amazon forest, on cattle tick Rhipicephalus (Boophilus) microplus

Leaves of Palicourea marcgravii were extracted successively with hexane, ethyl acetate and ethanol in order to evaluate their acaricidal activity on larvae and adult stages of the cattle tick Rhipicephalus (Boophilus) microplus. The ethyl acetate extract showed the highest bioactivity of the tested extracts, which contained 0.12% monofluoroacetic acid. On engorged female, the ethyl acetate extract showed a lethal concentration 50% – LC50 = 30.08 mg ml−1, inhibitory concentration 50% – IC50 = 5.79 mg ml−1 and lethal time 50% – LT50 = 4.72 days; 100% reproduction was controlled at concentrations of 50 mg ml−1 and on larvae the ethyl acetate extract showed a LC50 = 2.46 mg ml−1. No alkaloids were detected in any of the extracts. This is the first report on the acaricidal activity of P. marcgravii extracts against R. microplus as well as the acaricidal properties of a plant species containing monofluoroacetic acid.