Mortality Effect of Origanum syriacum L. (Lamiaceae) and Satureja montana L. (Lamiaceae) Essential Oils on Pieris brassica L. (Lepidoptera: Pieridae)

Cabbage, Brassica oleracea var. capitata L. (Brassicaceae), is one of the most widely consumed vegetables worldwide, and one of its most significant pests is Pieris brassicae L. (Lepidoptera: Pieridae). In recent years, the use of plant essential oils in pest control has significantly increased as an alternative control method. This study investigates the lethal effects of essential oils obtained from Origanum syriacum (Lamiaceae) and Satureja montana (Lamiaceae) on P. brassicae larvae. The main components of the essential oil of O. syriacum were identified as o-cymene (39.77%), carvacrol (28.16%), and thymol (12.78%), while the essential oil components of S. montana were determined as carvacrol (50.03%), o-cymene (15.12%), and γ-terpinene (13.02%). The essential oils were applied to different developmental stages (L1-L5) of P. brassicae using a spraying technique at various concentrations (5-10-20-50-100 µL mL⁻¹). The experiment was designed with 10 replicates, each containing 10 larvae from different developmental stages of P. brassicae, with water used as the control. To determine larval mortality rates, dead and living larvae were counted at 24-hour intervals for a total of 72 hours. The results showed that both S. montana and O. syriacum essential oils had a lethal effect ranging from 50% to 100%. However, S. montana essential oil was found to be more effective against P. brassicae larvae than O. syriacum essential oil.