Lipoplex-based RNA delivery system enhances RNAi efficiency for targeted Pest control in Spodoptera litura.

RNA interference (RNAi) represents a promising biotechnological strategy for sustainable pest control by silencing essential insect genes, resulting in increased mortality. However, its practical application remains limited due to environmental instability and delivery inefficiency of RNA molecules. In this study, three novel RNA-delivery nanoparticles-Polyplex, CS-TPP, and Lipoplex- were developed and their ability to enhance RNA stability and gene silencing efficacy against the intestinal mesh gene in Spodoptera litura was evaluated. Among them, Lipoplex showed superior performance in protecting double-stranded RNA (dsRNA) and small interfering RNA (siRNA) from degradation caused by heat, UV radiation, and RNases. In vitro cellular uptake studies using the S. litura SL1A cell line revealed significantly enhanced siRNA internalization with Lipoplex compared to other formulations. In vivo bioassays demonstrated that siRNA-loaded Lipoplex efficiently suppressed mesh expression, impaired larval development, and caused high mortality rate in early-instar larvae. Furthermore, leaf bioassay confirmed Lipoplex's potential as a stable and effective delivery platform under environmental conditions. Our findings underscore the promise of Lipoplex nanoparticles as a robust nanocarrier system for RNAi-based pest control, offering both protection and efficient intracellular delivery of RNA molecules in target insect species.