ACUTE TOXICITY OF PERMETHRIN TO 4 SIZE CLASSES OF RED SWAMP CRAYFISH (PROCAMBARUS-CLARKII) AND OBSERVATIONS OF POSTEXPOSURE EFFECTS

The mean static acute 96-h LC50 of permethrin [(3-phenoxybenzyl (+) cis, trans, 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate)] to red swamp crayfish (Procambarus clarkii) 8 - 12 mm (0.017 g), 25 - 35 mm (0.64 g), 45 - 55 mm (2.45 g), and 65 - 75 mm total length (8.98 g) was 0.44, 0.85, 1.30, and 0.81-mu-g/L, respectively. Permethrin toxicity did not differ among immature or mature male and female P. clarkii. Crayfish surviving permethrin exposures exhibited no differences in post-exposure growth, survival, onset of sexual maturity, or the reproduction of viable young when compared to non-exposed controls. Teratogenisis was not observed in third-instar crayfish produced from permethrin-exposed parents.