Biochemical mode of action of the acaricide fenazaflor

Abstract

Abstract The active ingredient of ‘Lovozal’ (fenazaflor) is hydrolysed in solution to 5,6‐dichloro‐2‐trifluoromethyl‐benzimidazole (DTFB). Rat liver mitochondria were uncoupled by fenazaflor after a lag phase, while uncoupling by DTFB was immediate, and a similar situation occurred with mitochondria isolated from Tetranychus telarius L. (This is the first report of isolation of mite mitochondria.) Since both compounds ultimately have the same uncoupling activity, it is likely that fenazaflor exerts its effect only after hydrolysis to DTFB. Living mites showed a stimulation of respiration of 70% on addition of either fenazaflor or DTFB before death occurred, suggesting that the acaricidal effect of fenazaflor is due to uncoupling of oxidative phosphorylation after hydrolysis to DTFB.