UTTAR PRADESH JOURNAL OF ZOOLOGY

The synthetic pyrethroid cypermethrin (10 EC) was used to evaluate the toxicity and its effect on the control of predatory Notonecta insects in experimentation tanks. After the acclimatization of insects and fishes for fifteen days, healthy insects and fishes were selected and distributed into 27 experimentation tanks having 80 litre water capacity. The experiment was divided into nine different groups, control and treatments from T₁ to T₈. The eight different concentrations of cypermethrin 0.4, 14, 2.4, 3.4, 4.4, 5.4, 6.4, 7.4 µl/l used for control of aquatic insects were further tested on fish seed using static bioassay. The experiment was repeated in triplicates in experimentation tanks. In observation arena, a fix number of Notonecta were released in experimentation tanks carrying IMC seed. The optimum dose of Cypermethrin for the control of aquatic insects viz. Notonecta has been selected on the basis of 100 percent insect mortality and bioassay studies. The cypermethrin concentrations of 7.4 µl/l resulted 0% survivability of Notonecta spp.  The LC₅₀ values for Notonecta at different time intervals were recorded between 2.66 and 1.53. The carp seed displayed a varying degree of survivability at different concentrations of cypermethrin.