Efficacy of two tropical plant extracts for the control of mosquitoes

The larvicidal activity of seed and leaf extracts of Calophyllum inophyllum and leaf extract of Rhinacanthus nasutus on the juveniles of Culex quinque fasciatus, Anopheles stephensi and Aedes aegypti was determined. Ethyl acet ate (EA) soluble fractions of C. inophyllum and petroleum ether (PE) fracti on of R. nasutus extracts showed very high larvicidal activity. Irrespectiv e of the species of the mosquitoes tested, at concentrations ranging from 3 .91 to 9.39 ppm, 9.04 to 35.49 ppm and 13.21 to 28.92 ppm of the active fra ctions of seed and leaf extracts of C. inophyllum and the leaf extract of R . nasutus, respectively, killed 50% of the treated larvae. The fractions al so interfered with adult emergence. Exposure of the mosquitoes at any stage of their larval development to less than 0.86, 5.49 and 6.81 ppm of the ac tive fractions of seed and leaf extracts of C. inophyllum and the leaf extr act of R. nasutus, respectively, inhibited 50% of the treated larvae from e merging as adults. Experiments under laboratory and semi-field conditions s howed that the activity of the extracts persisted for up to 10 days.