Spiromesifen is an insecticide and acaricide that reduces lipid biosynthesis via inhibition of acetyl-CoA carboxylase.1,2 It 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).3 It 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 of S. littoralis lab and field strains (LC50s = 0.44 and 0.68 ppm, respectively, at 72 hours post-application).1,2,3 Spiromesifen (600 mg/kg) also induces 50, 60, and 70% mortality in the Lepidoptera pests H. armigera, O. nubilalis, and P. xylostella, respectively, and induces 100% mortality in M. separata when used at a dose of 100 mg/kg.2 It induces toxicity in D. magna (EC50 = >0.092 mg a.s./L) and the fish species O. mykiss and L. macrochirus (LC50s = 0.016 and >0.034 mg a.s./L, respectively) but not rats (LD50 = >2,000 mg/kg).4 Spiromesifen also inhibits the human GST isozyme GSTA1-1 (IC50 = 12.1 μM).5
1.Karatolos, N., Williamson, M.S., Denholm, I., et al.Resistance to spiromesifen in Trialeurodes vaporariorum is associated with a single amino acid replacement in its target enzyme acetyl-coenzyme A carboxylaseInsect Mol. Biol.21(3)327-334(2012) 2.Liu, Z., Lei, Q., Li, Y., et al.Design, synthesis, structure, and acaricidal/insecticidal activity of novel spirocyclic tetronic acid derivatives containing an oxalyl moietyJ. Agric. Food Chem.59(23)12543-12549(2011) 3.Ismail, S.M., and Morshedy, M.Evaluation of some environmentally safe cemicals against Spodoptera littoralisAlexandria Sci. Exch. J.30(1)121-127(2009) 4.Authority, E.F.S.Conclusion on the peer review of the pesticide risk assessment of the active substance spiromesifenEFSA J.10(10)2879(2012) 5.Chronopoulou, E.G., Papageorgiou, A.C., Markoglou, A., et al.Inhibition of human glutathione transferases by pesticides: Development of a simple analytical assay for the quantification of pesticides in waterJ. Mol. Catal. B: Enzymatic8143-51(2012)