Cypermethrin

Cypermethrin is a type II pyrethroid insecticide.^1,2,3,4 It prolongs opening of sodium channels resulting in membrane depolarization and a conductance block of the insect nervous system, and point mutations in sodium channels induce cypermethrin-resistance in house flies, cockroaches, and mosquitos.³ Cypermethrin (1-1.5 mg) reduces survival of ticks (H. anatolicum) in vitro in a concentration-dependent manner.² Topical administration of cypermethrin reduces the number of ticks on infested cattle. Cypermethrin (5 and 10 ppm) reduces survival of lice (D. ovis) in sheep fleece and prevents re-infestation in contact-challenged sheep for 7 and 19 weeks, respectively.¹ It induces developmental neurotoxicities in zebrafish, increasing mortality and edema and inducing body-axis curvature when used at concentrations ranging from 50 to 200 μg/L.⁵ Cypermethrin (15 mg/kg twice weekly for 24 weeks) also induces Parkinson's disease-like neurodegeneration in rats, decreasing locomotor activity, dopamine production, and the number of tyrosine hydroxylase positive (TH⁺) neurons in the substantia nigra.⁴

1.Hall, C.A.The efficiency of cypermethrin (NRDC 149) for the treatment and eradication of the sheep louse Damalinia ovisAust. Vet. J.54(10)471-472(1978) 2.Sajid, M.S., Iqbal, Z., Khan, M.N., et al.In vitro and in vivo efficacies of ivermectin and cypermethrin against the cattle tick Hyalomma anatolicum anatolicum (Acari: Ixodidae)Parasitol Res.105(4)1133-1138(2009) 3.Hu, Z., Du, Y., and Dong, K.A sodium channel mutation identified in Aedes aegypti selectively reduces cockroach sodium channel sensitivity to type I, but not type II pyrethroidsInsect Biochem. Mol. Biol.41(1)9-13(2011) 4.Singh, A.K., Tiwari, M.N., Prakash, O., et al.A current review of cypermethrin-induced neurotoxicity and nigrostriatal dopaminergic neurodegenerationCurr. Neuropharmacol.10(1)64-71(2012) 5.DeMicco, A., Cooper, K.R., Richardson, J.R., et al.Developmental neurotoxicity of pyrethroid insecticides in zebrafish embryosToxicol. Sci.113(1)177-186(2010)