بررسی سمیت نانو فرمولاسیون اسانس گیاه نعناع فلفلی (.Mentha piperita L) روی کرم غوزه پنبه،(Helicoverpa armigera (Lep.: Noctuidae

Helicoverpa armigera Hubner is an important agricultural pest with worldwide distribution. annually causes significant damage. Controlling this pest mostly relies on chemical insecticides that cause many environmental and health issues. Searching alternative environmentally friendly insecticides for controlling insect pests is necessary. Using of biorational insecticides such as plants with insecticidal properties, can be a suitable alternative to chemical pesticides. Plant essential oils have shown a reliable pest control potential, but they cannot be used extensively for pest control due to their volatility and rapid oxidation. Nano-capsulation is a logical and new technology for solving physico-chemical problems of plant essential oils. The present work was carried out to evaluate the insecticidal effects of chitosan nanocapsules loaded with Mentha piperita L. essential oil against H. armigera. Nano-formulations of essential oil was prepared using TPP and low molecular weight biodegradable chitosan (CS) nano polymer. The bioassay tests were done on 3rd instar larvae by fumigant method. During 48 h exposure, the LC50 values for M.EO was 185 µl (essential oil) / lit (air) and for nano-encapsulated EO was 296 µl (essential oil) / lit (air). The sublethal effects studies were carried out by exposing 3rd instar larvae to LC30 concentration of free essential oil. The LC30 (127.75 µl (essential oil) / lit (air)) of essential oil showed significantly increased larval (Control=19.68; Mentha=24.2 days) and pupal (Control=12.03; Mentha=14.62 days) developmental times and reduced their weights (larval weight: Control=257; Mentha=141.43 mg; pupal weight: Control=291.75; Mentha=213.65 mg) in comparison to control insects. Furthermore, the number of eggs laid per female (Control=405.6; Mentha=85.8) was negatively affected by the tested essential oil. The loaded nanoparticles have spherical shape and the average size of EO@NP was found to be 45.5 nm (PDI=54.5) for M.EO@NPs. Fumigant toxicity studies of nanoformulated EO revealed the slow and persistent release of the active ingredient from nanomaterials, proving the effectiveness of chitosan (CS) nano-encapsulation in extending the insecticidal effect. the LC90 (calculated based on 48 h exposure study) concentration of EOs was used for durability activity study. This nanoformulated EO with high biological activity and insecticidal properties represent an alternative approach in the protection of greenhouse plants against H. armigera and also a great potential as part of an integrated pest management (IPM) strategy to manage this insect.