Spiromesifen is an insecticide and acaricide that reduces lipid biosynthesisviainhibition of acetyl-CoA carboxylase.^1,2It inhibits chitinase from Egyptian cotton leafworm (S. littoralis) larvae (IC₅₀s = 0.60 and 0.72 μM for enzyme isolated from lab and field strains, respectively).³It induces toxicity in whitefly (T. vaporariorum) nymphs (LC₅₀= 0.61 mg/L), spider mite (T. cinnabarinus) eggs (LC₅₀= 0.16 mg/kg), and second instar larvae ofS. littoralislab and field strains (LC₅₀s = 0.44 and 0.68 ppm, respectively, at 72 hours post-application).^1,2,3Spiromesifen (600 mg/kg) also induces 50, 60, and 70% mortality in the Lepidoptera pestsH. armigera,O. nubilalis, andP. xylostella, respectively, and induces 100% mortality inM. separatawhen used at a dose of 100 mg/kg.²It induces toxicity inD. magna(EC₅₀= >0.092 mg a.s./L) and the fish speciesO. mykissandL. macrochirus(LC₅₀s = 0.016 and >0.034 mg a.s./L, respectively) but not rats (LD₅₀= >2,000 mg/kg).⁴Spiromesifen also inhibits the human GST isozyme GSTA1-1 (IC₅₀= 12.1 μM).⁵

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