Determination of the relationship between Wolbachia endosymbiont and biochemical and molecular mechanism of pyridaben resistance in Tetranychus urticae Koch (Acari: Tetranychidae) populations in apple orchards of Isparta province

Tetranychus urticae, a polyphagous species, is an important pest of apple trees. Because of its ease of application and rapid effect, chemical control is usually preferred first. However, T. urticae has developed resistance to many acaricides due to genetic and biological characteristics. In this study, pyridaben LC values, resistance ratios, detoxification enzyme activities, synergism tests, the H92R target-site mutation, and the presence of Wolbachia endosymbionts were investigated in T. urticae populations collected from apple orchards in Isparta, one of the major regions for apple cultivation in Türkiye. LC values of GSS and orchard populations were determined by spray tower-leaf disk method. Pyridaben susceptibility levels of the collected in 2023 T. urticae populations ranged from 1.5 to 14.8 folds compared to the LC50 values of the susceptible population. Synergism tests show that PBO, a P450 synergist, increased pyridaben toxicity. Cytochrome P450 monooxygenase enzyme activities determined using a microplate reader varied between 0.0037 and 0.0072 mOD/min/mg protein. Among the collected populations, the H92R mutation was detected only in the GO population. Wolbachia, which is thought to potentially play a role in pesticide metabolism, was detected in all populations, with approximately 63% of individuals testing positive; additionally, the possible relationship between pyridaben resistance and Wolbachia presence in T. urticae populations was investigated. In addition, 13 selections applied to a hybrid population, created by combining T. urticae populations collected in the summer of 2024, resulted in a 46-fold resistance increase, accompanied by a rise in H92R mutation frequency from 27% to 100%. It is believed that these findings will provide valuable data on pyridaben resistance, genetic characteristics, and Wolbachia association in T. urticae populations from Isparta, contributing to sustainable agricultural practices.