Preparation of organic–inorganic composite lambda‐cyhalothrin microcapsules and evaluation of their efficacy against <i>Hyblaea puera</i> and safety

Abstract BACKGROUND Conventional lambda‐cyhalothrin formulations are limited by rapid photodegradation, short field persistence, high aquatic toxicity, and insufficient active ingredient loading for large‐scale agricultural applications. Herein, a high‐loading (23%) lambda‐cyhalothrin microcapsule suspension (CS) with an organic‐inorganic hybrid shell was developed by integrating interfacial polymerization with a sol–gel process using isophorone diisocyanate (IPDI) and tetraethyl orthosilicate (TEOS). This hybrid strategy was designed to simultaneously enhance sustained release, photostability, insecticidal efficacy and environmental safety. RESULTS The optimized formulation produced spherical microcapsules with an average particle size of 0.832 μm, D50 = 0.762 μm, D90 = 1.204 μm, an encapsulation efficiency of 76.46% and a suspension rate of 95.26%. The high‐performance liquid chromatography (HPLC) method exhibited excellent linearity ( R 2 = 0.99977). The microcapsules showed controlled release without burst release, reaching a cumulative release of 78.3% after 7 days, compared with 92.3% for the emulsion in water (EW) and almost complete release of the technical material within 24 h. After 4 h of UV irradiation (365 nm), the degradation rate of the microcapsules was only 52.25%, markedly lower than that of the EW (70.79%) and technical material (96.84%). Against 3 rd ‐instar Hyblaea puera larvae, the CS achieved 69.52% corrected mortality at 0.5 mg/L after 12 h and 100% mortality across all tested concentrations within 36 h. Furthermore, the 96 h median lethal concentration toward juvenile crucian carp was 2.17‐fold higher than that of the EW, indicating reduced acute aquatic toxicity. CONCLUSION The organic–inorganic hybrid microcapsule integrates high active ingredient loading with sustained release, enhanced UV resistance, superior insecticidal performance, and improved ecological compatibility. This study provides a promising formulation strategy for stabilizing photolabile pyrethroids and offers a practical platform for developing next‐generation controlled‐release pesticide formulations suitable for sustainable crop protection. © 2026 Society of Chemical Industry.