LARVICIDAL AND REPELLENT EFFECT OF LEAF AND STEM EXTRACTS FROM CESTRUM NOCTURNUM (SOLANACEAE) AGAINST CULEX PIPIENS L. (DIPTERA: CULICIDAE)

The larvicidal and repellent effects of the crude ethanol and acetone leaf and stem extracts of the widely grown plant, Cestrum nocturnum, against Culex pipiens 3rd instarlarvae and adults were evaluated. Ethanolic leaves extract was found to be the most effective against the larvae, with LC50 value of 377.1ppm followed by acetone leaves and stems extracts with LC50 values of 484.2 and 994.0ppm; respectively and finally ethanolic leaves extract with LC50 value of 1043.8ppm. The plant extracts tested reduced the percentages of pupation and adult emergence. Also, varying degrees of morphogenic abnormalities in immature and adult stages were observed. Moreover, the acetone stem extract showed a highly delayed toxic effect on pupae resulted from the treated larvae, where the pupal mortality % was 100% at all concentrations used. All concentrations of plant extracts used in the present study exhibited a repellent activity against the adult mosquitoes. The repellent action of the plant extracts tested was varied depending on plant part, solvent and the dose of the extract. Because of the high larvicidal and pupicidal potential of plant extracts tested, they can be used as effective alternatives to the existing synthetic pesticides for the control of Culex pipiens.