Acaricidal effects of seven Brazilian plant extracts

This investigation was carried out to evaluate the effects of the plant extracts of Rheedia longifolia (Clusiaceae), Garcinia xanthochymus (Clusiaceae), Plumbago scandens (Plumbaginaceae), Hovenia dulcis (Rhamnaceae), Malpighia glabra (Malpighiaceae), Euphorbia tirucalli (Euphorbiaceae) and Nerium adelfa (Apocynaceae) on eggs of Dermacentor (Anocentor) nitens and Ripicephalus sanguineus (Acari: Ixodidae) at concentrations of 1,000 ppm. The extracts had a significant effect on the hatching rate of eggs. The extracts of R. longifolia, H. dulcis, M. glabra and E. tirucalli delayed the hatching of R. sanguineus eggs by three days; however, the group treated with the extracts of G. xanthochymus and P. scandens did not hatch until day fourteen. For the tick D. (A.) nitens, extracts of H. dulcis and N. oleander delayed egg hatching by three days; however, the action of extracts from R. longifolia, G. xanthochymus, P. scandens and E. tirucalli caused a delay of seven days. For the control groups of both species, eggs hatched in one day. H. dulcis and M. glabra were effective in vitro on eggs of R. sanguineus and D. (A.) nitens (89 and 100 %, respectively), and can be considered to be potential candidates for the biocontrol of those ticks.