Variation in the repellency effects of the leaves of Mentha piperita against adults of Amblyomma hebraeum

Abstract

The repellency effects of Mentha piperita leaves, collected from two different locations in South Africa, (Ga-Rankuwa and Malelane) on adults of Amblyomma hebreaum were studied. Leaves extraction was carried out using two different solvents (dichloromethane (DCM) and ethylacetate) to make concentrations of 0.24 g/10 ml, 0.24 g/15 ml and 0.24 g/20 ml (w/v). The extracts were tested for repellency on the adults of A. hebraeum using glass plate repellency bioassay. The separation and qualitative analysis of plant extracts (0.24 g/10 ml (w/v)) extracted with DCM were investigated using TLC. Trace elements concentration from the soil and leaves samples from each study areas were determined by ICP – OES. The result shows that plant extract of both DCM and ethylacetate solvents from Ga-Rankuwa plants were more effective at all concentrations in repelling adults’ A. hebraeum when compared with extracts of the plant collected from Malelane. Significantly, higher concentrations of trace metals were reported from the soil and plant collected from Malelane (p < 0.05). TLC plates showed that there are differences in the chemical composition of the DCM extracts of M. piperita from Ga-Rankuwa and Malelane. The study shows that plant species collected from different geographical areas can produce contrasting results.

Key words: Mentha piperita, repellency bioassay, Amblyomma hebraeum