Determination of lethal concentrations of indoxacarb in fingerling Cyprinus carpio at two temperatures

Acute (24-96 hrs) toxicity of indoxacarb, a new insecticide generation, was determined in Cyprinus carpio under the semi-static condition. Fish (~5 g) were exposed to increasing concentrations of indoxacarb over 24-96 hrs at 17ºC, and over 24 hrs at 22ºC, and mortality was recorded every 24 hrs. Indoxacarb-LC50 values at 17ºC were found to be 37.55, 20.92, 18.77 and 16.85 ppm after 24, 48, 72 and 96 hrs, respectively. LC50 after 24 hrs at 22ºC was 21.55 ppm, which was significantly lower than that obtained at 17ºC. The lowest observed effect concentration (LOEC) values at 17ºC were 14 ppm for 24, 48, 72 hrs, and 11 ppm for 96 hrs. No observed effect concentration (NOEC) values at 17ºC were 11 ppm for 24, 48, 72 hrs, and 8 ppm for 96 hrs. NOEC and LOEC values after 24 hrs at 22ºC were 8 and 11 ppm, respectively. The results indicated that indoxacarb is classified as "harmful" substance in common carp and, the higher temperature, the more toxicity of indoxacarb.