Degradation of an alkaloid pheromone from the pale-brown chafer, Phyllopertha diversa (Coleoptera : Scarabaeidae), by an insect olfactory cytochrome P450

The pale-brown chafer, Phyllopertha diversa, utilizes an unusual alkaloid, 1,3-dimethyl-2,4-(1H,3H)-quinazolinedione as its sex pheromone, This compou nd is rapidly degraded in vitro by the antennal protein extracts from this scarab beetle. Demethylation at the N-1 position and hydroxylation of the a romatic ring have been identified as the major catabolic pathways, The enzy me responsible for the pheromone degradation is membrane-bound, requires NA D(P)H for activity and is sensitive to cytochrome P450 inhibitors, such as proadifen and metyrapone. The ability to metabolize this unusual pheromone was not detected in 12 species tested, indicating that the P450 system, spe cific to male P, diversa antennae, has evolved as a mechanism for olfactory signal inactivation. (C) 1999 Federation of European Biochemical Societies .