Larvicidal Efficacy of <i>Cleistanthus patulus</i> Muell. Arg. (Euphorbiaceae) Leaf Extract against Filarial Vector <i>Culex quinquefasciatus</i> (Say 1823)

Abstract

As resistance against synthetic insecticides has been increasing day by day; mosquito control becomes a great problem around the world. So it is crucial to manage the vector population to overcome the mosquito borne diseases. The present study was executed to assess the larvicidal activities of Cleistanthus patulus leaf extract against filarial vector Culex quinquefasciatus. Crude extracts of C. patulus mature leaf with different concentration gradients ranging from 1000-5000 ppm were applied against all the larval instars of Cx. quinquefasciatus. Three solvent extractives namely petroleum ether, ethyl acetate and acetone were applied in different graded concentrations against all the larval instars. Through log-probit analysis LC 50 and LC 90 values were determined. Regression and ANOVA analyses were done for further statistical justification. Activities of bioactive fraction against the non-target organism were carried out in laboratory condition. In addition to these, a qualitative phytochemical analysis of leaf extract was also done. The highest mortality was observed at 5000 ppm concentration of crude extract against all the larval instars after 72 hours of exposure. Among three used solvent extracts ethyl acetate exhibited the best larvicidal potentiality against target mosquito. 1 st instar larvae showed 100% mortality at 250 ppm concentration after 48 hours of exposure. Preliminary qualitative phytochemicals analyses of leaf extract revealed the presence of tannin, steroid and flavonoid as secondary metabolites. Non-target organism was found non-responsive to both extracts. Above experiment indicates that the leaf of C. patulus has the prospective to be used as larvicidal agent against Cx. quinquefasciatus.