Acute Oral Mammalian Toxicity and Effect of Solvents on Efficacy ofMaerua edulis(Gilg. & Ben.) De Wolf againstRhipicephalus (Boophilus) decoloratusKoch, 1844 (Acarina: Ixodidae), Tick Larvae

Abstract

Efficacy and toxicity of aqueous and organic solvents extracts ofMaerua edulisagainst ticks and mice, respectively, were determined. Ground leaves were extracted separately using cold water, cold water plus surfactant (1% v/v liquid soap), hot water plus surfactant, hexane, or methanol to make 25% w/v stock solutions from which serial dilutions of 5, 10, 20, and 25% were made. For each concentration, 20Rhipicephalus decoloratustick larvae were put in filter papers impregnated with extracts and incubated for 48 h at 27°C and 85–90% RH for mortality observation after 24 h and 48 h. In the toxicity experiment, hot water plus surfactant treatments of 5, 10, 20, and 25% (w/v)M. eduliswere administered in suspensionper osto sexually mature Balb/C mice and observed for clinical signs and mortality for 72 h. Larvae mortality was highest (>98%) in methanol-extractedM. edulistreatments (20 and 25%), which was not different from the amitraz-based control (Tickbuster®). Mortality was also higher in the hot water than in cold water plus surfactant treatments (P<0.05). No postadministration adverse health effects were observed in the mice. These results suggest thatM. edulisis an effective tick remedy best extracted using methanol or hot water plus surfactant.