Toxicity of the new pyrethroid insecticide, deltamethrin, to Daphnia magna

The toxicity of deltamethrin, a synthetic pyrethroid insecticide, was determined under standardized conditions (ISO, 1982) in neonates and juveniles of Daphnia magna . Neonates (6 to 24 h old) were more sensitive than juveniles (48 to 72 h old). The 24- and 48-h EC sub(50)s (immobilization) in neonates were 0.113 and 0.031 mu g/l, respectively. The toxicity of deltamethrin was highly toxic. The 96-h EC sub(50) was in the ppt ( mu g/l) range. Toxicity tests with Daphnia may be used to detect toxic residues in water and sediment areas treated with deltamethrin and other highly toxic pyrethroid pesticides.