Natala, A.J.Agyei, A.D.Awumbila, B.2019-03-212019-03-212005-03Natala, A.J., Agyei, A.D. & Awumbíla, B. Exp Appl Acarol (2005) 35: 259. https://doi.org/10.1007/s10493-004-2206-yVolume 35, Issue 3, pp 259–268https://doi.org/10.1007/s10493-004-2206-yhttp://ugspace.ug.edu.gh/handle/123456789/28751The susceptibility of unfed and fed stages of larvae, nymphs and adult females of Amblyomma variegatum ticks were tested using Shaw's filter paper dip method against four acaricides; chlorfenvinphos and dioxathion, chlorfenvinphos, gamma benzene hexachloride and amitraz at four different concentrations including the recommended dose rates. Based on their lethal concentrations (LC50 & LC90) chlorfenvinphos and dioxathion combined and chlorfenvinphos alone placed first and second, respectively, in all stages except at the unfed nymphal stage where gamma benzene hexachloride topped with a LC50 of 0.001629, while chlorfenvinphos and dioxathion combined and chlorfenvinphos alone had LC50 of 0.001794 and 0.002258, respectively. Amitraz appeared to have a quick knock-down effect on larvae and nymphs but at the recommended dose rate, showed no mortality of the ticks at that stage. However, at a concentration of 0.040%, amitraz showed a 100% inhibition of oviposition and hatching of laid eggs. Gamma benzene hexachloride produced only 66% inhibition of oviposition while chlorfenvinphos and dioxathion combined and chlorfenvinphos alone produced 100% inhibition of oviposition at their recommended dose rates. Fed nymphs were more susceptible than the unfed nymphs. Eggs laid by engorged female ovipositing ticks, applied with gamma benzene hexachloride, hatched. © Springer 2005.enAcaricidesAmblyomma variegatumControlEfficacyGhanaSusceptibilityTicksArticle