The effects of pure and nanocapsulated formulations of Thymus daenensis Celak. (Lamiaceae) essential oil on life-table parameters of cabbage aphid (Brevicoryne brassicae L.) (Hem.: Aphididae)

Plant essential oils are secoundary metabolites that protect the plants against wide range of arthropods and plant pathogens. Encapsulation of essential oils can improve their stability and efficacy for pest control. In this study, the essential oil of Thymus daenensis Celak. (Lamiales: Lamiaceae) was extracted using hydro-distillation, and urea-formaldehyde nanocapsule of the essential oil was then prepared using in situ polymerization technique. In addition, the effects of sublethal concentrations (LC25) of pure and nanocapsulated formulations of T. daenensis essential oil on the life-table parameters of Brevicoryne brassicae L. (Hem.: Aphididae) were examined using leaf-dipping method under laboratory conditions. According to the obtained results, the intrinsic rate of increase (r) was 0.16, 0.21, 0.29 and 0.29 day-1 for nanocapsulated formulation, pure formulation, 1st control (distilled water + Tween 80 (0.5%)) and 2nd control (distilled water), respectively. The finite rate of increase (λ) was also significantly lower for aphids treated by nanocapsulated formulation (1.17 day-1) than aphids in pure formulation treatment (1.24 day-1), and 1st (1.34 day-1) and 2nd (1.33 day-1) control groups. Furthermore, the net reproductive rate (R0) was 5.24 and 9.84 nymphs for nanocapsulated and pure formulations, respectively, which were significantly lower than that for controls. The greatest and lowest mean generation time (T) were observed for the 2nd control (11.25 days) and nanocapsulated formulation (10.32 days), respectively. According to findings of this study, the nanocapsulated formulation of T. daenensis essential oil is recommended for use in the integrated pest management of B. brassicae.