Insecticidal activity of some medicinal plant essential oils combined with Proteus® against greenhouse whitefly, Trialeurodes vaporariorum (Westwood) under greenhouse conditions

Trialeurodes vaporariorum (Westwood) is one of the most important pests of vegetable and ornamental crops in the world. Generally, control of T. vaporariorum is based on the application of insecticides, but they are resistant to many synthetic chemicals. There is a necessity to evaluate non-chemical and low-risk ways against the pest. Accordingly, medicinal plants are promising because they are safe to human, eco-friendly and biodegradable components. However, chemical insecticides are an inevitable component of agricultural products. Hence, in the present study, we examined the synergistic/antagonistic interactions between Agastache foeniculum (Pursh) Kuntze, Cuminum cyminum L., Ferulago angulata (Schlecht) Boiss, Foeniculum vulgare Mill., Origanum vulgare Mill., Satureja hortensis L., Trachyspermum ammi I. Sprague and Ziziphora tenuior L. essential oils with Proteus® against T. vaporariorum adults and eggs. Probit analysis of essential oils showed that O. vulgare and T. ammi were the most effective essential oils against T. vaporariorum adults that both exhibited LC50 values equivalent to 0.44 µL/L air. F. vulgare essential oil had the highest mortality against the eggs of T. vaporariorum (LC50= 30.60 µL/L air). All essential oils synergized efficacy of Proteus® against adults of T. vaporariorum. The inclusion of Z. tenuior essential oil with Proteus® led to antagonistic interaction against T. vaporariorum eggs.