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

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. LC50 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.