Nanoencapsulation of Helichrysum italicum (Roth) G. Don essential oil for eco-friendly control of citrus aphid (Aphis spiraecola)

Introduction: Sustainable citrus production requires effective alternatives to synthetic insecticides. Helichrysum italicum essential oil (EO) has demonstrated insecticidal potential, but its volatility and rapid degradation limit practical application. Nanoencapsulation offers a strategy to enhance EO stability and efficacy.
Methods: EO was nanoencapsulated in chitosan nanoparticles using ionotropic gelation. Physicochemical characterization assessed encapsulation efficiency, colloidal stability, and particle size distribution. In vitro bioassays against Aphis spiraecola compared nanoencapsulated EO with emulsified EO. Semi-field trials evaluated efficacy under environmental stress. Molecular docking was performed to explore interactions between EO constituents and acetylcholinesterase.
Results: Nanoencapsulation achieved high encapsulation efficiency (97.9%), strong colloidal stability (+45.5 mV), and uniform particle size (173.4 nm; PDI 0.27). In vitro assays revealed concentration- and time-dependent aphid mortality, with nanoencapsulated EO significantly more potent (LC50: 0.48 mg/mL at 90 h; 0.35 mg/mL at 96 h) than emulsified EO (LD50: 8.26 μL/mL at 60 h). Semi-field trials confirmed dose- and time-dependent mortality, though efficacy decreased by 10–28% under UV and oxidative stress. Molecular docking indicated EO constituents (caryophyllene, linalool) interact with acetylcholinesterase, supporting a neurotoxic mode of action.
Discussion: Nanoencapsulation improved EO stability, photoprotection, and residual activity, enhancing its insecticidal performance compared to conventional formulations. Despite reduced efficacy under environmental stress, the formulation demonstrated promising potential as a plant-based pesticide. These findings support the integration of nanoencapsulated EO into sustainable citrus pest management strategies.