Low acaricide resistance levels in citrus orchards field populations of the invasive spider mite Eutetranychus orientalis (Acari: Tetranychidae) collected from southern Türkiye

The citrus brown mite Eutetranychus orientalis (Klein), is known as one of the most significant pests in citrus growing areas worldwide. It has recently caused outbreaks in the Mediterranean region of Türkiye. This study aimed to determine the resistance levels of E. orientalis populations between 2020 and 2021 collected from 9 commercial citrus orchards in Adana province against 5 different acaricides, in order to determine whether the observed population outbreak was due to acaricide resistance. The resistance ratios were changed between 1.67 and 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. The enzyme activity levels of carboxylesterase, glutathione S-transferase, and cytochrome P450 monooxygenase ranged between 1.00 and 1.13, 1.02–1.52, and 0.94–1.72-fold, respectively. As a result of the resistance study carried out for the first time on this species in Türkiye, the resistance ratios were determined to be low for E. orientalis against acaricides. Although the current resistance rates were low, certain populations exhibited a noteworthy surge in enzyme activities when compared to the susceptible population. Based on these findings, it was concluded that by implementing an appropriate resistance management strategy using acaricides with different modes of action, it is possible to prevent potential resistance development and use these acaricides effectively on this spider mite species for many years through rotation.