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Objective: This study aims to determine the acute toxicity of binary insecticide Pyro FTE 472 EC (Chlorpyrifos 400 g/l; Cypermethrin 72 g/l) on the egg and embryo of African catfish Clarias gariepinus.
Methodology and Results: The fertilized eggs were exposed to six concentrations (T0: 0; T1: 20; T2: 70; T3: 120; T4: 170 and T5: 220 ppm) of Pyro in troughs placed in aquariums to determine the effects on survival, hatching, and development. The arithmetic method of Karber was used to calculate LC50 values. Results showed that eggs/embryos mortality significantly increased with increasing Pyro concentrations. The 24h-LC50 and 48h-LC50 values of Pyro for eggs/embryos were 102.26 and 90.40 ppm, respectively. Paradoxically, hatching success increased significantly from T1 to T3. Rates of tailless and short-tail embryos and immobility and agglutination of embryos increased with increasing Pyro concentrations.
Conclusions and application of findings: The present study revealed that Pyro FTE 472 EC, a binary pesticide used extensively in the fields against insect pests of cotton plants during the flooding period of reproduction of C. gariepinus could harm the development of this specie. A reduction in the quantity of this biocide in the cotton fields is essential in order not to reach the lethal doses for the eggs/embryos of C. gariepinus. This study, first report, indicates thus for biomonitoring the limit values of Pyro in aquatic biotopes to preserve the eggs/embryos of C. gariepinus in particular and of other fish in general.