Phytochemcal and larvicidal evaluations of extracts of Hyptis suaveolens (Magnoliopsida: Lamiaceae) as potential source of lead-agent for vector control of mosquito borne microbial pathogens

Abstract

The paucity of sustainable insecticidal lead-agents of public health importance was the reason why this study was carried out to evaluate the potentials of extracts of Hyptis suaveolens in vector control of Mosquito-borne diseases. Multi-solvent extracts of vegetative parts (i.e., leaves, stems and roots) of H. Suaveolens were prepared and bio-assayed against 4th instar larvae of Culex pipiens mosquitoes, following World Health Organisation’s recommended protocols for testing the efficacy of insecticides. The results showed that the vegetative parts of the plant species contained seven phytochemical compounds namely, balsam, carbohydrates, glycosides, saponnins, steroids, tannins and terpenes, though in varied relative concentrations. Larvicidal tests revealed that, irrespective of solvent type, the leaf extracts were most toxic to the mosquitoes followed by those of the stem while, the roots extracts were the least toxic. The lethal concentrations of the extracts varied considerably both among solvent types within a plant material as well as among the vegetative parts. The mean LC50 and LC90 were respectively 0.35±0.18 and 0.86±0.59 mg/l, 0.53±0.27 and 0.90±0.51 mg/l, 1.08±0.79 and 1.90±1.26 mg/l for the leaf, stem and root extracts, respectively. These results indicate that H. Suaveolens contains bio-active phytochemicals with significant mosquito larvicidal activities and hence is a potential veritable source of sustainable lead-agent for reducing the burdens of mosquito-borne diseases.