EFFECT OF COPPER SULPHATE PENTAHYDRATE ON MOSQUITO LARVAL AEDES AEGYPTI, CULEX QUINQUEFASCIATUS, AND ANOPHELES QUADRIMACULATUS IN LABORATORY AND UNDER SEMI-FIELD CONDITIONS
Mosquito larval control has been conducted by various chemicals and biological agents to reduce mosquito population and mosquito-borne diseases. The larvicidal efficacy of Copper sulphate pentahydrate (CuSO4 ·5H2 O) on Aedes aegypti, Culex quinquefasciatus and Anopheles quadrimaculatus was evaluated separately in the laboratory and semi-field conditions. Different concentrations of CuSO4 ·5H2 O (ranging from 1 to 20 ppm) were tested against third (3rd ) instar larvae. Larval mortality was observed at 24, 48 & 72h after exposure and the LC 50 values were determined. In both conditions, larval mortality showed concentration and time dependent correlations i.e. larval mortality was higher with increasing concentration CuSO4 ·5H2 O and exposure time. No mortality was observed in the control (0 ppm). Of the three species tested, Cx. quinquefasciatus and An. quadrimaculatus were more sensitive to CuSO4 ·5H2 O than Ae. aegypti. It was demonstrated that 1.5 -2.25 ppm of CuSO4 ·5H2 O killed more than 50% of Cx. quinquefasciatus and An. quadrimaculatus larvae at 72 h in both laboratory and semi-field conditions, whereas Ae. aegypti could survive easily in these concentrations. Besides, CuSO4 ·5H2 O showed more toxicity to larvae in semi-field conditions than laboratory studies. These results suggest that CuSO4 ·5H2 O could be used as a potential larvicide especially for Cx. quinquefasciatus and An. quadrimaculatus as a low-cost alternative larvicidal agent. Further studies will be needed to confirm its effectiveness in large scale field trials.