Cadmium and zinc toxicity to an aquatic insect, Ranatra elongata (Fabr.)

Cadmium chloride and zinc chloride were used to measure their short-term toxicity to an aquatic insect Ranatra elongata (Fabr.). The LC50 values were 0.497, 0.438, 0.355 and 0.288 mg/l for cadmium chloride and 2.853, 2.456, 1.934 and 1.658 mg/l for zinc chloride after 24, 48, 72 and 96 h, respectively. Cadmium chloride was found to be more toxic than zinc chloride.