Comparative susceptibility of cypermethrin in Ornithodoros lahorensis Neuman and Argas persicus Oken (Acari: Argasidae) field populations.

The toxicity of cypermethrin was determined in five different soft tick strains of Argas persicus Oken and Ornithodoros lahorensis Neuman by topical application method. The O. lahorensis Bij, O. lahorensis west O1, O. lahorensis Mesh, A. persicus Lor, A. persicus West Ap strains were collected from Bijar, Kurdistan province, Takab, Western Azerbaijan province, Meshkinshar, Ardebil province, Khoramabad, Lorestan province, Takab, Western Azerbaijan province of different areas of Islamic Republic of Iran, respectively during 2004 and 2005. In the topical application bioassay, the average LD50 of O. lahorensis Bij, West O1, Mesh and A. reflexus Lor and West AP strains were 0.03, 0.04, 1.7, 0.7 and 1.7 microg tick(-1), respectively and the steep slopes of dose-response curves indicated that the field population of these soft tick strains were homogenous in response to cypermethrin. Comparison of the resistance ratio of collected strains with susceptible strain showed a resistance ratio of 56.7 and 2.4-folds for cypermethrin in O. lahorensis Mesh and A. reflexus West Ap strains, whereas the O. lahorensis West O1 completely susceptible to cypermethrin.