Comparative toxicity effect of bush tea leaves (<i>Hyptis suaveolens</i>) and orange peel (<i>Citrus sinensis</i>) oil extract on larvae of the yellow fever mosquito <i>Aedes aegypti</i>

Abstract

The ethanolic extracts of the orange peel (Citrus sinensis) and bush tea leaves (Hyptis suaveolens) were compared for their toxicity effect on the larvae of the yellow fever mosquito Aedes aegypti collected from disused tyres beside College of Natural Sciences building University of Agriculture, Abeokuta, Nigeria. Eight graded concentrations, 0.9ppm, 0.8ppm, 0.7ppm, 0.6ppm, 0.5ppm, 0.4ppm, 0.3ppm and 0.2ppm of both plant extracts were tested on the larvae. The mean lethal dose LD10, was 0.15 ppm for C. sinensis, 0.01 for H. suaveolens, while LD50 for C. sinensis was 0.4ppm, H.suaveolens 0.60ppm and LD90 for C. sinensis was 0.9ppm and H.suaveolens was 1.45ppm. LD10 for the control 0.65ppm, LD50 0.9ppm and LD90 2.0 ppm. The extract of C. sinensis peel caused higher mortality rate at concentrations 0.8ppm (95%) and 0.3ppm (90%) of the larvae while the extract of H. suaveolens caused high mortality rate on the larvae at concentrations of 0.9ppm (80%) and 0.3ppm (80%). Significant differences were observed between untreated and treated larvae (exposed to either of the extract) at the various concentrations (P< 0.05).

Keywords: Citrus sinensis, Hyptis suaveolens, larvae, mortality, Aedes aegypti, Nigeria

Tanzania Health Research Bulletin Vol. 7(3) 2005: 174-178