Mosquito Larvicidal Activity of Four Tanzanian Aromatic Plants

O Ngassapa; S M Maregesi; A R Majala

O Ngassapa Department of Pharmacognosy, Faculty of Pharmacy, Muhimbili University College of Health Sciences, P.O. Box 65013, Dar-es-Salaam, Tanzania
S M Maregesi Department of Pharmacognosy, Faculty of Pharmacy, Muhimbili University College of Health Sciences, P.O. Box 65013, Dar-es-Salaam, Tanzania
A R Majala Department of Parasitology and Entomology, Institute of Public Health, Muhimbili University College of health Sciences, Dar-es-Salaam, Tanzania

Keywords: Anopheles Gambiae, aromatic plants, Culex quinquelasciatus, larvicidal activity

Abstract

As part of continuing efforts to search for pesticides from plants, four essential oil-containing plants were screened for mosquito larvicidal activity in the laboraroty. The plants included Curcuma longa L. (Zingiberaceae), Hyptis suaveolens Poit. (Labiatae), Piper nigrum L. (Piperaceae) and Zingiher officinale Roscoe (Zingiberaceae). Third to fourth instar larvae of Anopheles gambiae and Cule.v quinquefasciatus were exposed to various concentrations (0.32 — 200 ppm) of methanol extracts and essential oils from these plants. Mortality was assessed after a 24-hour exposure period and LCso values were determined by probit analysis. Of all extracts and oils, the essential oil of H. Suaveolens was found to be the most active against both types of larvae, followed by P. nigrum extract. The methanol extract of H. Suaveolens was the least active. Anopheles gainhiae larvae were, generally, more susceptible than Cv. Quinquefasciatus larvae. These preliminary findings have shown the potential of these plants for development as agents for the control of malaria and other mosquito-transmitted diseases.