The biological activity against Boophilus microplus of extracts of the berries, bark, leaves and twigs of Pimenta dioica was examined and compared with that of eugenol, methyl eugenol and four commercial acaricides, namely dimethoate, farnesyl methyl ether, carbaryl and diazinon. The berry essential oil was more effective at inhibiting oviposition and causing mortality of the ticks than all the extracts, the commercial acaricides and methyl eugenol. At a dose of 1.0 mg/g it was 33, 12, 6, and 3 times as effective in inhibiting oviposition as the non-polar extracts of the leaves, bark, twigs and berries, respectively. The potency of the berry essential oil is attributable to eugenol, a phenyl propanoid derivative, which accounts for over 65% of the oil content.
