Studies on Larvicidal Activity of Some Plant Extracts against Filarial Vector Culex quinquefasciatus

Background & Objectives: Vector control is facing a threat due to the emergence of resistance to synthetic insecticides. Insecticides of botanical origin may serve as suitable alternative in near future. In the present study, crude plant extracts of 32 commonly available plants were evaluated at different concentrations against third instars larvae of Culex quinquefasciatus to establish their mosquito larvicidal activity.  Methods : Three different Concentrations (0.1, 0.5 and 1.0%) of crude extracts were prepared from selected plants and observed larval mortality after 24h, 48h & 72h of post exposure against third instars larvae of Cx. quinquefasciatus . LC 50 and LC 90 were determined by using log-probit analyses. Effects on non target organisms were also tested. Result : Among the tested concentrations, highest mortality was recorded at 1% concentration of crude extract within 72 hours of exposure in all plant extracts. In laboratory based larvicidal bioassay, lowest LC 50 and LC 90 values were recorded in fruit extracts of Solanum nigrum and Solanum sisymbrifolium respectively. Mosquito larvicidal property of Clerodendrum viscosum , Cleome viscosa, Alangium salvifolium, Murraya k oenigii, Polyalthia longifolia and Derris indica were also satisfactory. Tested non-target organisms were entirely safe against the tested concentrations during study. Interpretation & Conclusion : Among tested 32 plants, the crude extracts ofeight plantshave the potent larvicidal activity against filarial vector Cx. quinquefasciatus without harmful effect on non target organisms.