Nanoencapsulation of essential oil of Piper aduncum: Evaluation of insecticidal activity and phytotoxicity of a botanical pesticide

Insect pests are an integral part of the agro-ecosystems. Among them, the fall armyworm (Spodoptera frugiperda - S. frugiperda), one of the most destructive cereal pests in the world, represents a significant threat to global food production. Botanical insecticides offer an eco-friendly pest management strategy to combat this serious issue. Piper aduncum (P. aduncum) provides an available source of essential oil with significant plant protection effects, including biological activity against fall armyworm. However, challenges such as low solubility, instability under environmental conditions, and potential phytotoxicity have limited the P. aduncum essential oil (OPA) widespread use. Nanoencapsulation emerges as a promising strategy to enhance the efficiency of botanical insecticides. This study describes the process of obtaining zein-based nanocarriers loaded with the P. aduncum essential oil using the anti-solvent precipitation method and analyzes the phytotoxicity and biological activity of the nanoformulations against fall armyworms. The P. aduncum essential oil (OPA) was successfully encapsulated in zein nanoparticles with 96 % encapsulation efficiency and exhibited an average size of 220 ± 20 nm, polydispersity indices lower than 0.3, pH 4.3, and positive charge. Phytotoxic OPA effects were not observed in bean plants exposed to the nanoformulation even at the highest concentration applied and an elevated germination index was obtained for seeds exposed to the nanoformulation. Encapsulated essential oil provoked higher mortality rates of S. frugiperda than emulsified ones. Thus, nanoencapsulation can be an efficient strategy for developing botanical pesticides and enhancing insecticidal activity, reducing the phytotoxicity of essential oils like P. aduncum, and promoting sustainable agricultural practices.