Reproductive Toxicity of Anamirta cocculus (L.) Wight and Arn and Sphagneticola trilobata (L.) Pruski Extracts on Culex pipiens Linn. (Diptera: Culicidae)

Abstract

Acute toxicity of the acetone extracts of Anamirta cocculus (L.) Wight and Arn (fruits) and Sphagneticola trilobata (L.) Pruski (leaf) was tested against Culex pipiens (L.). Bioassay tests were conducted using different larval instars of Culex pipiens and determined the LC₅₀ values. Fecundity of the Culex pipiens that emerged from the treatments and hatchability of the eggs were also estimated. I instar larvae of Culex pipiens were exposed in various sublethal concentrations and allowed them to moult and pupate. The pupae from each of the treatment set and control set were collected separately and allowed them to emerge in the emergence cages. A bowl with water was kept inside the emergence cage to enhance oviposition. The eggs laid by the females were collected, counted and compared, and fecundity rates were calculated. The data shows that the effect of the selected plant extracts is dose dependent and reduced the fecundity level very significantly when compared with the control. However, A. cocculus fruit extract in acetone showed a significant reduction in fecundity and hatchability of the C. pipiens. The findings of the present study evidenced that both the selected plant extracts have effective role in the reduction in fecundity and can be utilized further for developing formulations. The insecticidal property of these plant extracts may serve as a suitable alternative to synthetic insecticides in the future as they are relatively safe and easily degradable.