Qi Zhao, Qiwei Xuan, Yukai Cui, Jinyuan Sun, Zhuyan Zhang, Yuancheng Luo, Zhuoyuan Li, Yiping Chen, Zirui Wang, Siyuan Ge, Zhaojun Sheng
Mosquitoes, as primary vectors for diseases such as dengue fever, malaria, chikungunya, and Zika virus, pose a significant threat to global public health. Repellents are a principal strategy for preventing mosquito bites. While a nutmeg and melissa essential oil (EO) blend was previously identified as a highly potent spatial repellent, its practical application is severely limited by high volatility and short-lived efficacy. This study aimed to overcome this barrier by developing a stable, long-acting formulation using a scalable microencapsulation technology. Prior to formulation, GC-MS analysis confirmed that nutmeg EO was dominated by α‑pinene, limonene, and α‑terpineol, while melissa EO featured citral isomers alongside geraniol and citronellal. The nutmeg-melissa EO blend was then successfully encapsulated via complex coacervation, achieving both high encapsulation efficiency (93.3%) and yield (96.8%), indicating its economic feasibility for industrial production. The resulting microcapsules demonstrated significantly enhanced stability, effectively addressing the inherent volatility of EOs. Crucially, this translated into a dramatic extension of performance: while the unencapsulated EO lost its repellent effect rapidly, the microcapsule formulation maintained a potent repellent rate of over 75.0% against Aedes albopictus for 96 h at a dosage of 0.5 g. This work provides a viable pathway for converting this potent botanical blend into a stable, long-acting, and commercially viable biopesticide, demonstrating a valuable strategy for the value-added application of industrial crops in vector control. • Bioactive-rich nutmeg-melissa EO blend is successfully microencapsulated. • High encapsulation efficiency (93.3%) and yield (96.8%) were achieved. • Microcapsules show enhanced thermal stability over free essential oil. • Repellent efficacy against Aedes albopictus extended to 96 h. • Creates a path for a long-lasting, commercial EO-based biopesticide.