Lethality of the aqeous extracts of Acacia nilotica, Guiera senegalensis, Kigelia africana and Securidaca longepedunculata on culex mosquito larva

Abstract

Cytotoxic activity indicated by lethal effects (that is mortality rate) of aqueous extracts of fruits of Acacia nilotica, stem bark of Kigelia africana, roots of Securidaca longepedunculata, and leaves of Guiera senegalensis on the culex mosquito larva was investigated by direct contact method. Larvicidal effects were observed with dose concentration ranging from 400 μg/ml down to 40 μg/ml of all the plant extracts tested except for G. senegelensis where no death was observed at the dose of 40/ml. Distilled water with 0 μg/ml concentration served as the control. S. longepedunculata was found to be most active with average percentage mortalities of (80%), (50%) and (13.3%) at 400/ml, 200/ml and 40/ml respectively. K. Africana caused 70%, 40% and 10% of average percentage mortalities accordingly. A. nilotica and G. senegalensis seemed to show similar larvicidal activity but their activities differed in one respect. At 400 μg/ml G. senegalensis killed 53.3%, 200/ml killed 30%and at 40 μg/ml there was no larvicidal activity, whereas A. nilotica killed about 50%, 20% and 7% respectively. The study revealed that all the four plant species could impart a dose dependent lethality effect on Culex larvae. For this reason, it is therefore recommended that the LC50 of the extract be determined later, since it became difficult to evaluate at the time of the present study. However, the current result could serve as additional baseline data valuable for use in the development of ethnopharmacologically active substance(s) with the potential for use as insecticides and in modern medicine.

Keyword: Lethality, Acacia nilotica, Guiera senegalensis, Kigelia africana, Securidaca longepedunculata, Culex mosquito

Ife Journal of Science Vol.6(2) 2004: 115-118