Ecotoxicity of Leaf Extracts of Azadirachta indica on Chironomids Larvae

Abstract

The present study was designed to evaluate acute ecotoxicity of aqueous and ethanolic leaf extracts of Azadirachta indica on Chironomus spp. Exposure of chironomd larvae to the crude aqueous extract (0.0 [control], 25.00, 50.00, 75.00, 150.00&200.00 mg/L) and ethanolic (0.0 [control], 6.00, 12.00, 25.00, 50.00&100.00 mg/L) concentrations resulted in LC 50 of 68.28mg/L and of 6.65mg/L respectively. Other toxic response by the larvae includes avoidance of sediment, impregnation of some segments with dark substances and bleaching/loss of respiratory pigments. Comparatively, mortality rate and other toxic responses was more in the ethanolic extract than in the aqueous extract test tanks. Impregnation of some larvae segments with dark substances suggests that feeding activity was going on during the toxicity test period and mortality of the larvae was partly due to contact with the polluted sediment and ingestion of contaminated particles of the sediment.