Selection for resistance to acequinocyl in Amblyseius andersoni (Chant) (Anactinotrichida: Phytoseiidae). The majority of pesticides used in pest control in orchards are found to be harmful to beneficial arthropods. However, the development of resistant predators and parasitoids could contribute to their enhanced use in crops where the use of pesticides is necessary. The goal of the current work was to select a line of predatory mite Amblyseius andersoni resistant to acequinocyl acaricide belonging to a group of mitochondrial complex III electron transport inhibitors. A selective dose used in experiments was that causing 55–65% mortality of phytoseiid gravid females. A laboratory population had a nine-fold increase in resistance to acequinocyl after two selection cycles, and over 30-fold increase after four cycles. This selected population of A. andersoni also developed medium cross-resistance to fenpyroximate.