In Vitro Effects of Some Plant Extracts on the Development of <i>Culex quinquefasciatus</i> in the Laboratory

Abstract

Control mosquito vectors concentrated mainly on the application of broad spectrum insecticides but causes development of resistance in vector species and environmental pollution. Ethanol and acetone extracts of five species of plants, Euphorbia cotinofolia , Melia azedarach , Ocimum canum , Ricinus common and Tagetes erecta were tested in respect to their influence on the development of Cx. quinquefasciatus in the laboratory. The plants extracts were prepared by agitating the dried and ground in ethanol and acetone separately for 24 hours followed by filtration and later recuperation of solvent using rotavapor. Ten experiments were conducted, four replications in each case. For each experiment, concentration of 100 mg/L, 10 mg/L and 1 mg/L in distilled water of each plant extract was used (150 ml). 25 first stage larvae were putted in each dish of experiment and control after removing the water through the filter paper to avoid alteration the concentration of extracts. The developments of larvae were daily observed and all changes in the experimental dishes and controls were recorded. The duration of the development of pre-imaginal stages of Cx. quinquefasciatus were prolonged by both of extracts of all plants at high concentration. Also acetone extract of E. cotinofolia and ethanol extract of R. communis principally at 10 mg/L in L3 and L4. In addition, Acetone extract of R. communis and T. erecta were more effective at 10 mg/L and 1 mg/L. Mortality of larvae during development was increased in 100 mg/L of ethanol extract of E. Cotinofolia and both extracts of M. azedarach . Acetone extract of R. communis at 100 mg/L killed all larvae of first stage. The extracts of T. erecta caused high mortality in ethanol and acetone extracts 95% and 100% respectively. The results indicate that the natural insecticides could be taken in the place of synthetic insecticides and save our environment. Due to diversity of response presented, suggesting details on level of chemical of these products, for the possibility of isolation the real substances that have value for control of mosquitoes.