Toxicity of the synthetic pyretroid Ciflutrin to the red swamp crayfish (Procambarus clarkii).

Several experiments show that synthetic pyrethroids are toxic for freshwater crayfish. Laboratory studies were conducted to determine the acute toxicity of synthetic pyrethroid cyfluthrin (commercial formulation Solfac WP 10 -Bayer-, with 10% active ingredient) in view of a potential eradication of red swamp crayfish (Procambarus clarkii). We tested the effects of 10 different concentrations. Cyfluthrin was highly toxic to red swamp crayfish at concentration as low as 0.04 µg/l after 48 hours of exposition. The 24-h LC50 was determined at a temperature of 20°C  1°C and calculated by graphic method. The values of the 24-h LC50 and the 48-h LC50 were respectively 0.13 µg/l and 0.08 µg/l. Neurological symptoms such as loss of coordination of the movements and paralysis occurred before the death of the crayfish. In parallel, we assessed the selectivity of the insecticide testing it in goldfish (Carassius auratus) and evaluating its toxicity and the residues in the whole carcass.