Effects of prochloraz and malathion on the red-legged partridge: a semi-natural field study

A semi-natural field study was carried out to assess the likelihood of a potentiation of toxicity between the ergosterol biosynthesis inhibiting (EBI) fungicide, prochloraz, and the organophosphorus (OP) insecticide, malathion, in the red-legged partridge (Alectoris rufa). Groups of partridges kept in four large grassland enclosures were exposed to either prochloraz-treated or control wheat for 7 days after which two of the enclosures were sprayed with malathion whilst the remaining two were sham-sprayed. Cytochrome P-450, aldrin epoxidase and 7-ethoxyresorufin-O-deethylase (EROD) activities were found to be significantly higher in the group exposed to prochloraz alone compared to controls, suggesting that induction of the hepatic microsomal monooxygenase system had occurred by ingestion of prochloraz-treated wheat. However, the level of induction produced was not sufficient to cause a potentiation of malathion toxicity. There was evidence for induction of several forms of P-450 recognised by antibodies raised against 1A1, 2C6 and 4A1 in the prochloraz-exposed partridges.