European Journal of Medicinal Plants

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.