Biological and Chemical Properties of Dimethoate and Related Derivatives1

Abstract

Seventeen dimethoate derivatives were prepared in the laboratory, purified, and characterized. Derivatives containing dimethoxy groups were more effective against the house fly, Musca domestica L., than the diethoxy compounds. As the N-carbamoyl chain length increased in number of carbon atoms, the toxicity to house flies decreased; the monoalkyl-substituted amides were more effective than the dialkyl-substituted amides. Increase in chain length of the dialkoxy or N-carbamoyl groups resulted in increased stability to alkaline hydrolysis. The most toxic materials to t he house fly were those having the C = 0 band between 5.90 and 5.95 µ. The absorption, distribution, metabolism, and excretion or P32-labeled dimethoate were studied in rats and three species of insects; the house fly, the German cockroach. Blattella germanica (L.), and the American cockroach, Periplaneta americana (L.). Phosphorothioate oxidation was prevalent in rats, but the degrading rather than activating systems were predominant. Amidase activity was more pronounced in rats than in insects immediately following treatment with dimethoate; this major metabolic difference may partially explain selectivity. Phosphatase activity was also more evident in rats than in insects.