Interactive effects of prochloraz and malathion in pigeon, starling and hybrid red‐legged partridge

Abstract

AbstractRecent laboratory studies with hybrid red‐legged partridges have shown that the interaction of certain combinations of agricultural pesticides can lead to an enhancement of toxicity. In view of this finding, captive feral pigeons (Columba livia) and European starlings (Sturnus vulgaris), in addition to hybrid red‐legged partridges (Alectoris rufa cross), were used in a laboratory study to extend investigations of the enhancement of toxicity of the organophosphorus (OP) insecticide malathion in birds predosed with the ergosterol‐biosynthesis‐inhibiting (EBI) fungicide, prochloraz. Following pretreatment with either 90 or 180 mg/kg prochloraz, both pigeons and partridges showed significantly greater inhibition of serum butyrylcholinesterase (BuChE) activity (1.4‐ to 2.1‐fold increase for pigeons and 1.3‐ to 3.8‐fold increase for partridges) when dosed with malathion than control birds; this difference was evident at some or all of the blood‐sampling time points. On the other hand, starlings given either 180 or 300 mg/kg prochloraz showed no difference from controls in serum BuChE inhibition after dosing with malathion. The enhanced inhibition of serum BuChE in the pigeon and the partridge after malathion dosing was attributed to the increased activation of malathion to malaoxon following induction of the hepatic monooxygenase system by prochloraz. Serum BuChE inhibition may be useful in studying the interactive effects of OPs and EBI fungicides in the field.