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 nano-capsules were evaluated to reduce their usage concentration. The synthetized nano-capsules 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 nano-capsulated form of essential oil with reduced amounts of phosphine could be used as a suitable method for control of stored product pests.