DsRNA-based carriers with pH-tuneable release kinetics for effective control of Psylliodes chrysocephala

Spray-induced gene silencing (SIGS) employing double-stranded RNA (dsRNA) offers a promising, species-specific approach for protecting crops from insect pests such as the cabbage stem flea beetle (Psylliodes chrysocephala). However, the environmental instability of dsRNA presents a major limitation to its field application. In this study, we evaluate two distinct dsRNA formulation strategies for improved stability and delivery: a bottom-up approach using chitosan-based interpolyelectrolyte complexes (IPEC) and a top-down approach employing functionalized mesoporous silica carriers (SBA-15). Both systems were comprehensively characterized in terms of size, surface potential, porosity, and release behavior. The results revealed that IPECs exhibited release kinetics that were approximately one order of magnitude faster than those of SBA-15 across all tested conditions. The two formulations significantly improved dsRNA stability against UV and heat exposure compared to free dsRNA. In feeding assays with P. chrysocephala, both carriers achieved comparable gene silencing efficacy, though dsRNA@IPEC induced more immediate effects, while dsRNA@SBA-15 displayed delayed but ultimately stronger reduction in consumed leaf area, consistent with its slower release kinetics. We demonstrate that despite structural and mechanistic differences, both delivery platforms effectively stabilized and delivered dsRNA, and offered distinct advantages depending on application needs. This work highlights how formulation strategies are key to successful SIGS and supports the development of robust, field-adaptable formulation technologies for sustainable pest management.