Zanthoxylum bungeanum Essential Oil Nanoemulsion: Preparation, Characterization, and Insecticidal Activity Against Tribolium castaneum

ABSTRACT

Zanthoxylum bungeanum essential oil (ZBEO) is a promising botanical insecticide, but its volatility, poor stability, and low water solubility limit practical application. This study developed a ZBEO nanoemulsion (ZBEO‐NE) and evaluated its physicochemical properties, insecticidal activity, repellency, stability‐related bioactivity retention, and cytotoxicity. GC–MS identified linalool (53.78%) as the major component. The resulting ZBEO‐NE had a mean droplet size of 128.90 nm, a polydispersity index of 0.20, and a zeta potential of −41.90 mV. TEM revealed uniformly distributed spherical droplets, and rheological analysis showed shear‐thinning behavior. The formulation remained physically stable during 30 days of storage and after heating and centrifugation. Against Tribolium castaneum adults and larvae, ZBEO‐NE showed lower contact toxicity than free ZBEO, whereas its fumigant activity increased with exposure time. LC ₅₀ values decreased from 20.62 to 12.68 mg/L air in adults and from 14.05 to 7.06 mg/L air in larvae between 24 and 72 h. ZBEO‐NE also showed more persistent repellency and largely retained biological activity after stability treatments, although heating at 100°C reduced adult fumigant mortality. Cytotoxicity was concentration dependent, with good cytocompatibility at relatively low concentrations. These findings support ZBEO‐NE as a potential formulation for stored‐product pest management, with promise for practical stored‐product pest control applications.