Diagnosis of anticholinesterase poisoning in birds: Effects of environmental temperature and underfeeding on cholinesterase activity

Brain cholinesterase (ChE) activity has been used extensively to monitor exposure to organophosphorus (OP) and carbamate (CB) insecticides in wild birds. A series of factorial experiments was conducted to assess the extent to which noncontaminant-related environmental conditions might affect brain ChE activity and thereby confound the diagnosis of OP and CB intoxication. Underfeeding (restricting intake to 50% of control for 21 d or fasting for 1–3 d) or exposure to elevated temperature (36 ± 1°C for 1 d) caused only slightreductions (10–17%)in brain AChE activity in adult male Japanese quail (Coturnix coturnix japonica). This degree of “reduction” in brain AChE activity is considerably less than the 50% “inhibition” criterion employed in the diagnosis of insecticide-induced mortality, but nevertheless approaches the 20% “inhibition” level used as a conservative estimate of sublethal exposure to a known insecticide application.