Toxicity and action of fluenethyl acaricide and related compounds in the mouse, housefly and twospotted spider mite.

x. The toxicity and action offluenethyl or 2-fluoroethyl(4-biphenylyl ) acetate, several other monofluoroethyl esters, monofluoroethanol, monofluoroacetic acid and fluoroacetamide were studied in mice, houseflies (Musca dornestica L.) and twospotted spider mites (Tetranychus urticae Koch). 2. Toxicity varied markedly with the test compound, method of application and biological species. Generally, monofluoroacetic acid, monofluoroethanol and fluenethyl were the most active materials examined. Intoxicated mice and houseflies exhibited classic symptoms of organofluorine poisoning; spider mites exhibited a brief period of hyperactivity. 3Ethanol, isoniazid, triazole, acetamide, sodium acetate and monoacetin afforded some protection against the toxicity offluenethyl and monofluoroethanol to mice, suggesting that metabolic transformation of these two fluorine-containing compounds was essential for toxicity. 4. Mice, houseflies and spider mites poisoned with fluenethyl and other fluorinecontaining compounds accumulated high levels of citrate as compared to controls, providing evidence that aconitase or citrate (isocitrate) hydrolyase (E.C. 4.2.1.3) was attacked. 5. It was concluded that the monofluoroethanol released upon esteratic cleavage of fluenethyl was oxidized to monofluoroacetic acid which, after conversion to fluorocitrate, inhibited aconitase. This appeared to be the mechanism for the toxic action of fluenethyl and the other monofluoroethyl esters in the mouse, housefly, and twospotted spider mite. FLUEN~THVL acaricide/insecticide is very effective for the control of phytophagous mites, aphids, scale insects, and certain other pests (Anonymous, I968 ). Chemically fluenethyl (FLU) is 2-fluoroethyl(4-biphenylyl ) acetate, and its structure is given in FIo. x.