Preparation, Characterization and Biological Efficacy of Eucalyptus Oil Nanoemulsion against the Stored Grain Insects

Abstract

Nanotechnology has enormous potential for developing alternative pest control strategies and reducing the risk of insecticide molecules. The present study aimed to develop a stable nanoemulsion (NE) of eucalyptus oil (EO) by the spontaneous emulsification method and evaluate its insecticidal and repellent effect against Sitophilus oryzae (L.), Rhizopertha dominica (F.) and Tribolium-castaneum (Herbst.). The prepared nanoemulsion formulation having a small particle size 8.57 nm with polydispersity index (PDI) 0.28. The study of the stability and physicochemical properties showed that the prepared formulation had good physical stability without any change in the macroscopic parameters. In addition, results showed that theinsecticidal activity of the prepared NE was higher than the original EO against the three tested insect speciesand the mortality increased with increasing concentrations and extending of exposure time. The contact toxicity of NE film revealed that, adults of R. dominica was more susceptible to all treatments followed by S. oryzae adults, while adults of T. castaneum was the least susceptible one, however, adults of S. oryzae was more susceptible followed by T. castaneum adults while, adults of                    R. dominica was the least susceptible one according to the fumigant toxicity and repellency. Our results suggested that the prepared formulation may be used in an integrated pest managementprogramfor controlling stored grain insects.