Fenvalerate is a pyrethroid ester insecticide and acaricide.1,2 It is a slow activator of voltage-gated sodium channel 1.8 (Nav1.8).1 It induces mortality in pyrethroid-susceptible and -resistant strains of M. domestica (LD50s = 0.014-5 μg/fly).3 Fenvalerate also induces mortality in tobacco budworm larvae but is associated with pyrethroid resistance with an increase in LD50 values from 1.01 to 20.85 μg/g over a six-year timeframe.4 It induces mortality in 95.5% of T. macfarlanei spider mites when applied to leaves at a concentration of 0.015%.2 Formulations containing fenvalerate have been used in the control of insects in agriculture.

|1. Choi, J.S., and Soderlund, D.M. Structure-activity relationships for the action of 11 pyrethroid insecticides on rat Nav1.8 sodium channels expressed in Xenopus oocytes. Toxicol. Appl. Pharmacol. 211(3), 233-244 (2006).|2. Jose, V.T., and Shah, A.H. Chemical control of the spider mite, Tetranychus macfarlanei B & P, the pest of cotton. Pesticides 20(12), 19-23 (1986).|3. Pedersen, L.-E.K. The potency of cyclopropane pyrethroid ethers against susceptible and resistant strains of the house fly Musca domestica. Experientia 42(9), 1057-1058 (1986).|4. Martinez-Carrillo, J.L., and Reynolds, H.T. Dosage-mortality studies with pyrethroids and other insecticides on the tobacco budworm (Lepidoptera: Noctuidae) from the Imperial Valley, California. J. Econ. Entomol. 76(5), 983-986 (1983).