Lignin Nanoparticle-Stabilized Pickering Emulsion System with Enhanced Stability for Co-Delivery of Avermectin and Clove Oil toward Antimicrobial and Insecticidal Activities

Abstract Hydrophobic pesticide formulations often struggle to combine high payload capacity, efficient foliar deposition, controlled release, and low environmental risk. In this study, lignin nanoparticles (LNPs) were used to stabilize a Pickering emulsion for the co-delivery of avermectin (AVM) and clove essential oil (CEO), yielding AVM-CEO-PE for concurrent insect pest control and suppression of plant pathogenic microorganisms. The formulation achieved an AVM loading content of 11.78% and an encapsulation efficiency of 87.72%. A dense interfacial LNPs shell suppressed burst release, while laccase-triggered interfacial disassembly enabled enzyme-responsive release. AVM-CEO-PE substantially improved foliar wetting, deposition, retention, and rainfastness. It also markedly enhanced AVM photostability: after 9 h of ultraviolet irradiation, the AVM retention rate remained 72.56%, approximately 13 times that of free AVM. The emulsion inhibited Staphylococcus aureus, Escherichia coli, and Botrytis cinerea, and displayed stronger sustained insecticidal activity against Plutella xylostella larvae than free AVM. At low concentrations, larval survival after 30 h was substantially lower with AVM-CEO-PE than with free AVM. Compared with free AVM, the formulation reduced apparent acute toxicity to zebrafish by approximately 60%. Thus, AVM-CEO-PE integrates sustained release, photoprotection, foliar retention, antimicrobial activity, and insecticidal efficacy within a single formulation, offering a promising strategy for efficient, durable, and environmentally responsible pesticide delivery. The findings demonstrate that lignin-based interfacial engineering can coordinate multiple functions while reducing active-ingredient exposure, supporting integrated crop protection and more sustainable agricultural chemical use under concurrent pest and disease pressure.