Fumigant Toxicity of Two Nano-Capsulated Essential Oils with Sublethal Rate of Phosphine against Three Stored- Product Pests

In this study, two essential oils including Cuminum cyminum (L.) and Lavandula angustifolia (Mill.) were nano-capsulated by solvent evaporation emulsion method and their fumigant toxicity was investigated against three important stored-products pest, Tribolium castaneum (Herbst), Sitophilus granarius (L.), and Oryzaephilus surinamensis (L.). Moreover, the sublethal concentrations of phosphine gas in combination with nanocapsules were evaluated to reduce their usage concentration. The synthetized nanocapsules were confirmed by Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR). The chemical compositions analysis of C. cyminum and L. angustifolia by GC-MS revealed that α- Pinene (44.63%) and Linalyl acetate (61.74%) were the major components of C. cyminum and L. angustifolia, respectively. The results showed that pure C. cyminum was more effective than L. angustifolia regarding the fumigant toxicity after 24 h treatment on the three mentioned stored products pests. The LC50 values of pure C. cyminum oil after 24 h treatment were obtained as 42.51 and 78.99 μL L-1 air by S. granarius and T. castaneum, respectively. However, the LC50 values of C. cyminum oil nano-capsule form were 220.34 (S. granaries) and 374.16 μL L-1 air (T. castaneum), which were determined as susceptible and resistant pests, respectively. The results indicated that the combination of nanocapsulated form of essential oil with reduced amounts of phosphine could be used as a suitable method for control of stored product pests.