Encapsulated essential oil-based nanoemulsion beads: a green innovation for storage pest control against Tribolium castaneum

Abstract

Essential oil nanoemulsion formulations offer environmentally friendly, safer alternatives to synthetic insecticides for integrated pest management, thereby reducing food loss and financial losses caused by the infestations of pests like Tribolium castaneum. In order to manage the infestations caused by Tribolium castaneum, we formulated nanoemulsion beads with cinnamon and clove essential oils and purified eugenol. Initially, we formulated the nanoemulsion beads with sodium alginate, characterized the formulations, and investigated their properties for repellent, ovicidal, fumigant and larvicidal activities against T. castaneum to analyze the efficacy of the essential oils. Characterization analysis showcased the formulated NE bead size of 1.34 mm and surface characterization showed the adsorption–desorption isotherms, revealing the porous structure. Moreover, FT-IR spectroscopy and GC-MS analysis showed the presence of essential oils in the formulated beads. Further, in vitro analysis revealed the CNN excellence in the fumigant activity, showcasing the highest mortality rate of approximately 8% at the highest time point of 36 h exposure. Nevertheless, it also excelled in the ovicidal and larvicidal activities. Cinnamon NE beads showed highest mortality rate at 98 h and 30 h time point respectively, followed by EGN and CLN beads. Meanwhile, in all in vitro assessments, the control sodium alginate beads showed no effect, indicating that its presence does not impact Tribolium castaneum. Based on these in vitro assessment results, it is evident that the Cinnamon NEs beads have significant effect on the treating Tribolium castaneum, also proving the formulated NEs beads with sodium alginate doesn't infer in the any toxic effect against the insects. In conclusion, the study depicts that the development of nanoemulsion beads of the essential oils improved their stability compared with nanoemulsions. Moreover, essential oils enhanced the efficacy of the beads, paving the way for reduced use of harmful synthetic insecticides and pesticides against the stored grain pests.