Evolution of acaricide resistance: Phenotypic and genotypic changes in field populations of Rhipicephalus (Boophilus) microplus in response to pyrethroid selection pressure

► There are few studies on tick field populations of evolution of pheno- and genotypic resistance to chemicals. ► Pheno- and genotypic markers of resistance increased on farms treated with cypermethrin. ► Markers of resistance remained unchanged on farms treated with amitraz for 2 years. ► Pyrethroid resistance is acquired much faster than it is lost. ► Rotation with other chemicals may result in stepwise acquisition of resistance.