InsecticidalPotential of Nanoemulsified Orange Essential Oil and D-limonene: AnEco-friendly Approach for Managing Drosophila suzukii and ImpactAssessment on Non-target Insects

Abstract

The increasing preoccupation with the ecotoxicological problems promoted by synthetic pesticides and pest resistance to insecticides has driven the search for more sustainable and environmentally friendly alternatives, such as essential oils. Consequently, these are attractive candidates for biopesticide development due to their biodisponibility, low toxicity towards mammals and non-target species, and potential affordability. Within this framework, the spotted wing fly, Drosophila suzukii, is a significant threat to global agricultural production as an invasive pest of many small and stone fruits and incurs heavy economic damage. This study explores an ecological and sustainable alternative, using emulsified and nanoemulsified formulations of sweet orange essential oil, Citrus sinensis and its main component, limonene, against adults, larvae, and pupae of D. suzukii. In addition, these formulations' toxicity was evaluated on Pachycrepoideus vindemmiae, a parasitoid wasp with relevant potential in the biological control of D. suzukii, to assess its impact on non-target organisms. Nanoemulsions of orange essential oil and limonene were prepared using high and low-energy emulsification techniques to compare their effectiveness, dispersion optimization, and particle stability. High-energy emulsification resulted in the production of stable nanoemulsions with droplet sizes in the nanometer range (< 450 nm) and a low polydispersity index (PDI < 0.3). In contrast, the emulsions obtained by low-energy methods showed less stability and larger droplet sizes. The toxicity tests indicated that the nanoemulsions produced by high-energy emulsification showed greater lethality against D. suzukii compared to the emulsified formulations and the nanoemulsions prepared by low-energy methods. As for the evaluation of P. vindemmiae, all the formulations showed low toxicity. These results indicate that essential oils, when formulated as nanoemulsions, can be effective in controlling pests such as D. suzukii, showing significant toxicity to the target pest and offering a viable alternative that is less harmful to the environment and non-target organisms compared to conventional chemical control methods.