Metabolism of Methaphoxide in Mosquitoes, House Flies, and Mice

Abstract

The metabolic fate of a phosphorus³²-labeled sample of the chemosterilant methaphoxide (tris(2-methyl-1-aziridinyl) phosphine oxide) was investigated. In both larvae and adults of the mosquito Culex tarsalis Coquillett, degradation of the chemical was complete within 48 hours of administration. Adult house flies (Musca domestica L.) degraded 50% of large dosages of the chemical within 2 hours. The rates of degradation were similar in a susceptible fly strain and in two organophosphate-resistant strains. In mice the observed rate of degradation was about the same as in house flies. Methaphoxide and one major breakdown product, presumably phosphoric acid, were characterized by paper chromatography from excretory products of both house flies and mice.