Acaricidal Activities of Hyptis suaveolens and Ocimum sanctum Against African Dog Tick (Rhipicephalus sanguinneus)

Abstract

Aim: To determine the acaricidal activities of some solvent extracts (chloroform, methanol and n-hexane) and crude extracts of Hyptis suaveolens and Ocimum sanctum against African dog tick (Rhipicephalus sanguinneus). Study Design: The study design involves a 24 h LC50 dose-mortality static non-renewal bioassay. Place and Duration of Study: The study was carried out at Rohi Biotechnology Toxicity Laboratory, Port-Harcourt, Rivers State Nigeria, between August and November 2014. Methodology: The solvent extracts were assessed against the ticks at varying concentrations in a 2-phased rapid and final screening test. Results: All extracts showed moderate activities during the bioassay, except the crude extract which was not active beyond the rapid screening phase (i.e. LC100>500 ppm). The chloroform, methanol and n-hexane extracts of H. suaveolens induced LC50 values of 175.00, 81.25 and 225.00 ppm respectively. On the other hand O. sanctum induced mortalities of 200.00, 137.50 and 287.50 ppm for chloroform, methanol and n-hexane extracts respectively. Meanwhile, the positive control was lethal at 1ppm, while the tick survived in the negative control. Conclusion: The result demonstrates that solvent extracts of H. suaveolens and O. sanctum can be used as acaricides for the control of dog tick.