Larvicidal activity of some tropical plants on the mortality of Anopheles gambiae s.l mosquitoes

This study investigated the larvicidal activities of methanol leaf extracts of six tropical plants against Anopheles gambiae s.l mosquitoes. 10 healthy laboratory stabilized larvae were treated with extracts of Ocimum gratissimum, Chromolaena odorata, Terminalia catappa, Carica papaya, Vernonia amygdalina and Cymbopogon citratus with different concentrations (0, 200, 400, 600, 800 and 1000 ppm) for 24, 48 and 72 hours after which the percentage mortality was calculated. All extracts tested were seen to possess moderate to good larvicidal effect against An. gambiae larvae in a concentration dependent manner with the highest mortality observed in O. gratissimum with 100%, Cy. citratus with 93%, Ca. papaya and V. amygdalina with 83%, T. catappa with 73% and the least being Ch. odorata with 63%at the end of the exposure period of 72 hours. These results showed that these plant extracts may be used as alternative insecticides against An. gambiae mosquitoes, with a further study on their phytochemicals, characterization and synergistic activities and their adaptability to field assay highly recommended.