LACK OF RELAY TOXICITY IN FERRET HYBRIDS FED CARBARYL-TREATED PRAIRIEDOGS

Carbaryl (1-napthol methylcarbamate) is being considered for control o f fleas on prairie dogs (Cynomys spp.) used in black-footed ferret (Mu stela nigripes) recovery in the western United States. The potential f or relay toxicity in ferrets was determined by feeding carbaryl treate d prairie dogs to black-footed ferret X Siberian polecat (M. eversmann i) hybrids. Adult prairie dogs were treated topically with 2.5 g of co mmercial 5% carbaryl dust sold as flea powder. After 14 days prairie d ogs were killed and fed to ferrets. Potential for relay toxicity was e valuated by analyzing ferret blood cholinesterase (CHe), prairie dog b rain Che, and hepatic carbamate concentration. There was no difference between pre- and post-exposure blood CHe activity nor did treated pra irie dog brain Che differ significantly from controls. Post-exposure b lood CHe did not exhibit reactivation after dilution in aqueous buffer . Hepatic carbaryl concentrations were less than detection limits (50 ppb). Based on these results, we conclude that short-term use of carba ryl for flea control on prairie dogs does not pose a hazard of relay t oxicity in black-footed ferrets.