RNAi-Induced Disruption of <i>Spodoptera frugiperda</i> Life Cycle Using shRNA-Cell-Penetrating Poly(disulfide) Nanocarriers

RNA interference (RNAi) efficacy in lepidopterans faces challenges. Here, a chemically engineered nanocarrier system was developed for efficient RNAi in the <i>Spodoptera frugiperda</i>. High-efficacy siRNA sequences targeting two essential genes: chitin synthase (<i>CHSB</i>) and coatomer subunit beta-like (<i>COPIβ</i>) were selected via in silico screening, engineered into RNase-resistant shRNAs, and complexed with a cell-penetrating poly(disulfide) (CPD) nanocarrier. This approach overcomes the variability in silencing efficiency associated with siRNA sequences in long dsRNA and prolongs the retention time of RNA complexes in the midgut of pests due to the protective effects of CPD. Feeding larvae diets containing 6 μg/g shRNA@CPD complexes significantly downregulated <i>CHSB</i> (72.4%) and <i>COPIβ</i> (56.4%) expressions versus ddH₂O-treated controls. Silencing induced larval mortality (44.4% and 34.9%, respectively) and severe developmental disruption (reduced pupation, adult emergence, and malformations). These findings indicate that the proposed strategy effectively promotes gene silencing and pest control in lepidopteran species, presenting a novel RNAi-based approach for sustainable pest management.