بررسی اثر سمیت و دور کنندگی سه اسانس بومی ایران روی دو جمعیت Tetranychus urticae

Tetranychus urticae Koch (Acari: Tetranychidae) is a serious pest of agricultural crops in open fields and greenhouses worldwide. The ability of T. urticae to rapidly develop resistance against a wide range of acaricides has resulted in control failure of the pest using convenient pesticides. In an effort to develop more environmentally friendly agents, alternative to chemical pesticides, in this study, the toxicity and repellency of essential oils extracted from three medicinal plants of the family Lamiaceae, including Thymus daenensis, Satureja khuzestanica and S. bakhtiarica to a resistant (MhR) and a susceptible (KrS) population of T. urticae was evaluated under laboratory condition. Based on probit analysis, the median lethal concentrations (LC50) of T. daenensis, S. khuzestanica, and S. bakhtiarica were estimated as 41.68, 31.16, and 44.06 µl/l air for KrS population and as 124.47, 56.29, and 105.39 µl/l air for MhR population. The LC50 of all essential oils was found to be repellent to adult females of both MhR and KrS populations, with higher repellency was detected for S. khuzestanica. We did a set of physiological bioassays to measure the activity of major detoxifying enzymes in resistant and susceptible mites treated with LC20 of the essential oils. When compared with KrS population, significantly higher activity of glutathione S-tranferases (GSTs), esterases and cytochrome P450 monoxygenases (P450) was detected in MhR population regardless of pesticide treatment. The activity of GSTs and esterases increased significantly in mites treated with all essential oils, while a tendency for decrease in P450 activity was detected following pesticide treatment. These results indicate that the essential oils of all selected plants, especially S. khuzestanica, have the potential to be used in integrated management programs of T. urticae.