Contact toxicity of pine, laurel and juniper essential oils to spirodiclofen-resistant and -susceptible Tetranychus urticae Koch, 1836 (Acari: Tetranychidae) populations

Abstract

Tetranychus urticae Koch, 1836 (Acari: Tetranychidae) causes significant losses in agricultural production because of it is a polyphagous pest and develops resistance to pesticides in a short time. This study was conducted in 2017-2018 in Isparta, Turkey. Contact toxicities of pine, laurel and juniper essential oils to different developmental stages of a highly spirodiclofen-resistant and a spirodiclofen-susceptible population of T. urticae were investigated. The was aim was to contribute to the development of alternative methods to control in resistant populations. The essential oil solutions were applied using a spray tower at 100 kPa to the leaf surface at 1.2-1.6 mg/cm 2 . The experiments were conducted with three replicates , with 15 individuals each treatment replicate. The highest mortality in adults was 100 % for pine, juniper and laurel oil in the susceptible population, and 59.5% for pine oil, 57.5% for laurel oil and 51.2% for juniper oil in the spirodiclofen-resistant population. In addition, the highest mortality for nymphs was 81.6% for pine oil, 95.2% for laurel oil, 95.7% for juniper oil in the susceptible population, and 50.0% for pine oil, 56.3% for laurel oil and 58.0% for juniper oil in the spirodiclofen-resistant population. In toxicity tests on egg the highest mortality was lower than 55.0% in both populations. As a result, the three essential oils were showed to have a significant effect in the T. urticae population with high level resistance to spirodiclofen.