Acaricidal effects of shirazi thyme, galbanum and savory essential oils on two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae)

The two-spotted spider mite, Tetranychus urticaeKoch, is one of the most important and polyphagous pests which damages a wide range of agricultural crops throughout the world. In recent decades, excessive conventional acaricide application leads to the development of pest resistance and environmental pollutions. In recent years, herbal essential oils have received attention as natural plant protection compounds. In this study, the fumigant toxicity of three medicinal plant essential oils including shirazi thyme (Zataria multiflora Boiss.), galbanum (Ferula gummosa L.) and savory (Satureja hortensis L.) were tested against the eggs and female adultsof T. urticae. The essential oils were obtained by Clevenger-type water distillation. Experiments were carried out at 25±1°C, 50±5% RH and under a photoperiod of 16L: 8D. The median lethal concentration (LC50) for shirazi thyme, savory and galbanum essential oils were recorded to be 21.962, 30.894 and 56.783 µl/L air, 24h after treatment, respectively. In ovicidal bioassays, the LC50 values for oils were 17.493, 43.07 and 101.61 µl/L air, respectively. According to the obtained results, the highest lethal effects were obtained for shirazi thyme oil against the eggs and adults of T. urticae as compared to the other essential oils.