Green pest control strategies: essential oil-based nano-emulsions for Delottococcus aberiae management

Increasing restrictions on synthetic pesticides due to environmental and health concerns have driven the search for alternative environmentally friendly pest management strategies. Essential oils (EOs) from plants like garlic (Allium sativum), clove (Syzygium aromaticum), and eucalyptus (Eucalyptus camaldulensis) have shown promise as bioinsecticides. However, their volatility, low water solubility, and short persistence limit their practical application in Integrated Pest Management programs. To address these challenges, we developed nano-emulsions of these EOs using a high-pressure microfluidization technique, achieving stable formulations with nano-sized droplets (< 200 nm) and optimal polydispersity index and zeta potential values. The insecticidal efficacy of these EO-based nano-emulsions was tested against the invasive citrus pest Delottococcus aberiae, with garlic nano-emulsion (GNE) exhibiting the highest mortality (100% within 24 h), significantly outperforming clove and eucalyptus formulations. GNE exhibited a dose–response mortality against D. aberiae while demonstrating no toxicity (100% of survival) toward Cryptolaemus montrouzieri and no phytotoxicity on citrus plants. Moreover, gene expression analysis revealed that GNE application triggered the overexpression of key genes involved in plant defense pathways, including ICS2, NPR1, PAL, and MYC2, suggesting the activation of both salicylic acid and jasmonic acid signaling pathways. This dual action—direct pest control and enhancement of plant defenses—positions GNE as a powerful tool in sustainable citrus pest management, with potential applications in real-world pest control. The study underscores the potential of EO-based nano-emulsions as a safe, effective, and environmentally sound alternative to chemical insecticides.