OVICIDAL ACTIVITY OF AZADIRACHTIN AND BACILLUS THURINGIENSIS ISRAELENSIS AGAINST EGGS OF MOSQUITO CULEX PIPIENS

Introduction : The mosquito Culex pipiens L is a common and abundant species in the world. This species serve as bridge vectors of the West Nile virus from birds to humans. Objective: Under the laboratory conditions, toxicological evaluation of two compounds Azadirachtin and Bacillus thuringiensis israelensis ( B.t.i ) against eggs of  mosquito Cx. pipiens and biological effect of these compounds on larvae, pupae and adult emergence Methods :  The ovicidal activity was determined after 24 h of exposure to  concentrations of Azadirachtin and B.t.i . Results: indicated high reduction in percentage of egg hatch resulted from treated eggs by azadirachtin, estimated by 31.41% at 1mg /L and 91.51% at 0.125 mg /L, the obtained results show a high mortality with the increase in the concentration,  and prolongation in larval and pupal developments resulted from treated eggs by azadirachtin, estimated by 4.55 days at 0.125mg/L and 7.66 days at 1 mg/L in first instar , larval and pupal duration increased with the increase in the concentration of azadirachtin. The results indicated high augmentation in the percentages of the malformations with the decrease in the concentration of azadirachtin. In contrast, in adult stage, the results indicated high reduction in total eggs laid, percentage of hatchability and longevity. No effect was observed after treated eggs by B.t.i. Conclusion: From the results, it can   be concluded the Azadirachtin are excellent potential for controlling the mosquito Culex pipiens .