Functions of the Madeira Cockroach (Leucophaea maderae) Alimentary Tract in the Absorption, Metabolism, and Excretion of Ronnel1

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Abstract
The role of the alimentary tract of the Madeira cockroach, Leucophaea maderae (F.), in the in vivo processes of absorption, transport, metabolism, and excretion of P32-labeled ronnel (O,O-dimethyl O-(2,4,5-trichlorophenyl) phosphorothioate) was investigated together with the qualitative and quantitative nature of the phosphorus-containing metabolites eliminated. The wall of the foregut was found to be permeable to orally injected ronnel but not to certain of its water soluble hydrolysis products while the hindgut was permeable to both. The midgut primarily accumulated the water soluble metabolites when direct movement of ronnel from the foregut was blocked, and evidence suggests it as a site for hydrolytic degradation of the insecticide. More than 97% of the radioactivity accumulating in the hindgut was in the form of water-soluble degradation products with about two-thirds entering with the discharge of the malpighian tubules. Only small quantities of radioactivity passed directly from the mid- to the hindgut. Sublethal doses of ronnel progressively inhibited elimination of excreta while the hydrolysis products had little effect. The major metabolite of ronnel eliminated in the feces was identified as dimethyl thiophosphate. This compound gradually diminished with time while the minor metabolites dimethyl phosphate and monomethyl ronnel increased.