Determination of resistance levels of acaricides used in citrus areas of Adana province in Eutetranychus orientalis (Acari: Tetranychidae) and side effects of these acaricides on some predatory mite (Acari: Phytoseiidae) species

Despite the intensive use of pesticides for harmful mite species control in citrus orchards in Adana, the satisfactory management cannot be achieved. Due to this selection pressure, resistance has been determined in some citrus pest mite species. The citrus brown mite, Eutetranychus orientalis (Klein) (Acari: Tetranychidae) causes damage in citrus orchards in Turkey and produces many generations during the growing season. In this study, the resistance ratios of nine different populations of E. orientalis collected from commercial citrus orchards in Adana province to acaricides with the active ingredients abamectin, etoxazole, fenbutatin oxide, pyridaben and spirodiclofen were determined using bioassay and biochemical methods. In addition, effects of acaricides used in the study were determined on different biological stages and fecundity of Euseius finlandicus (Oudemans) and Euseius stipulatus (Athias-Henriot) (Acari: Phytoseiidae). The resistance ratios obtained by dividing the LC50 values of the orchard populations of E. orientalis with the LC50 values of the susceptible population were determined 1.67-2.50, 1.00-2.53, 1.85-3.68, 1.30-2.65 and 1.93-3.13 fold for abamectin, etoxazole, fenbutatin oxide, pyridaben and spirodiclofen, respectively. As a result of the bioassay analyses, it was determined that the populations showed low resistance to all acaricides. Carboxylesterase, glutathione S-transferase and cytochrome P450 monooxygenase enzyme activity values of the populations were found to be in the range of 21.419-24.160, 0.645-0.983 and 0.044-0.081 unit/mg/minute protein, respectively. In addition, the mortality rates obtained as a result of the side effect studies of acaricides at the label dose on predatory mites were classified according to the IOBC side effect scale. Consequently, all acaricides were found to be non-toxic or lowly toxic to eggs at the label dose. However, abamectin, etoxazole and pyridaben were toxic, fenbutatin oxide and spirodiclofen were non-toxic to larvae, while abamectin and pyridaben were toxic, etoxazole, fenbutatin oxide and spirodiclofen were non-toxic to adult females at the label dose. Etoxazole, fenbutatin oxide and spirodiclofen, which were non-toxic to adult females at the label dose, which were also found to be non-toxic or lowly toxic at doses 8 fold the label. Abamectin and pyridaben caused 100% mortality to adult females 24 hours after spraying at the label dose, and so the effect of these acaricides on fecundity could not be determined. Etoxazole and fenbutatin oxide had no effect on fecundity, whereas spirodiclofen reduced fecuntity of predatory mites at the label dose.