Mosquito larvicidal activity of Solanum nigrum berry extracts.

Phytochemicals are widely used as biocontrol agent against vector mosquitoes. The present study was undertaken to isolate and evaluate the mosquitocidal activity of various extracts of berries of S. nigrum against Culex quinquefasciatus. Crude and chloroform: methanol (1:1, v/v) extracts of fresh, mature, green berries of S. nigrum were tested against Cx. quinquefasciatus. The lethal concentration was determined and the chemical nature of the active substance was evaluated. A qualitative phytochemical analysis of chloroform: methanol (1:1, v/v) extract was performed in search of the active ingredient. The appropriate lethal concentrations at 24 h for chloroform: methanol (1:1, v/v) extract was also studied on non-target organisms. In a 72 h bioassay experiment with crude extract, the highest mortality was recorded in 3 per cent extract. In the chloroform: methanol (1:1, v/v) solvent extract, the maximum mortality was recorded at a concentration of 120 μg/ml. The log probit analysis (95% confidence level) recorded lowest LC 50 value at 72 h of exposure. Both crude and chloroform: methanol (1:1, v/v) extracts showed good larvicidal activity against Cx. quinquefasciatus. The isolated active ingredient may be tested as a potential larvicide after determination of its structure.