Effects on Birds: Acephate is considered moderately toxic to upland game birds. The LD50 for acephate in mallard ducks is 350 mg/kg; 140 mg/kg in pheasants; > 5,000 ppm for the mallard and 1,280 ppm for the bobwhite quail. Acephate may affect behavior and breeding success.
Effects on Aquatic Organisms: The compound is considered relatively non-toxic to fish with an LC50 for goldfish of 9,550 mg/l and rainbow trout >1,000 mg/l over 96 hours. Another study noted that the LC50 was >1,000 ppm for both the rainbow trout and the bluegill. Acephate did not increase "coughing" (interruption of normal ventilating cycle, with a more rapid expansion and contraction of the buccal and opercular cavities, which serves the purpose of clearing the gills of accumulated debris) frequency of rainbow trout. In laboratory studies, the cholinesterase activity in the erythrocytes, gills, and serum of rainbow trout was reduced within 3 hours of exposure to acephate. With methamidophos, the extent of brain and liver AChE inhibition in carp was proportional to the insecticide concentration and exposure time. Smaller fish started dying when the AChE inhibition was 40 to 50%, but very large fingerlings survived an inhibition of more than 80%. In field studies, however, subsequent to aerial spraying of acephate to control spruce budworm, no significant depression of brain AChE activity of brook trout and salmon in streams near the target area occurred; but, there was a significant depression of brain AChE activity in suckers, which returned to normal by the eighth day.
Effects on Other Animals (Nontarget species): Acephate is considered toxic to bees. The LC50 for bees is 1.2 ug/bee. In studies examining the residual toxicity of insecticides on beneficial species in citrus, it was found that acephate had the longest residual activity toward Aphytis melinus, DeBach, and that mortality with dimethoate treatment occurred for a shorter period of time than with acephate treatment. This same study showed that residues of acephate caused greater mortalities over a longer period of time to A. melinus than other materials tested. In some cases, there is no effect on fecundity of the beneficial, but survival of the offspring is affected. For example, fecundity of Diaeretiella rapae was not reduced by treatment of Myzus persicae host mummies with acephate, but acephate significantly affected survival for the first day after emergence. In studies of insecticides commonly used in cotton, acephate was shown to be very toxic to adult Microplitis croceipes parasitoids, and caused 100% mortality at the lowest recommended field rates. |
