title: Possible mechanisms for sensitivity to organophosphorus and carbamate insecticides in eastern screech-owls and American kestrels.
abstract: Effects of a single dietary exposure to fenthion and carbofuran on the survival, feeding behavior and brain ChE activity of eastern screech-owls, Otus asio and American kestrels, Falco sparverius, were evaluated. Birds were exposed to fenthion (23.6-189.0 ppm) or carbofuran (31.7-253.6 ppm) via meatballs. Carbofuran-exposed owls ate either < or = 10% or > or = 80% of the meatball whereas all kestrels ate < or = 10% of the meatball before exhibiting acute signs of toxicity. Fenthion-exposed owls and kestrels displayed a wide spectrum of meatball consumption (< 10-100%). Significant brain ChE inhibition was observed in dead and surviving kestrels exposed to fenthion and carbofuran and dead owls exposed to fenthion (P < 0.0001). Brain ChE activity of owls exposed to carbofuran that survived was not different from that of controls (P = 0.25). Data suggest: (1) slow feeding on a carbamate-contaminated item may provide limited protection from the toxicity of the chemical at certain rates of exposure; (2) the degree of ChE inhibition at neuromuscular junctions may be critical in determining the sensitivity of a species to a carbamate insecticide; (3) sensitivity may be a function of the ChE affinity for the carbamate inhibitor; and (4) the importance of neuromuscular junction ChE depression in determining the sensitivity of an animal may be species-specific.
authors.affiliation: US Geological Survey, Biological Resources Division, Patuxent Wildlife Research Center, Laurel, MD 20708, USA. Nimish_Vyas@brd.usgs.gov
authors.forename: N B
authors.initials: NB
authors.lastname: Vyas
authors.forename: L A
authors.initials: LA
authors.lastname: Thiele
authors.forename: S C
authors.initials: SC
authors.lastname: Garland
mesh_terms: D000818:Animals; D001717:Birds / Q000502:physiology*; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002235:Carbofuran / Q000633:toxicity*; D002800:Cholinesterase Inhibitors / Q000633:toxicity*; D002802:Cholinesterases / Q000378:metabolism; D004032:Diet; D005247:Feeding Behavior / Q000187:drug effects; D005260:Female; D005284:Fenthion / Q000633:toxicity*; D007306:Insecticides / Q000633:toxicity*; D008297:Male; D012680:Sensitivity and Specificity; D020305:Strigiformes / Q000502:physiology*
chemical_list: D002800:Cholinesterase Inhibitors; D007306:Insecticides; D005284:Fenthion; D002802:Cholinesterases; D002235:Carbofuran