Abstract

BACKGROUND The German cockroach ( Blattella germanica ) is a major urban pest managed primarily with chemical insecticides, raising concerns over resistance and environmental impact. RNA interference (RNAi) offers a species-specific and sustainable alternative, but its utility depends on identifying lethal gene targets and developing efficient delivery systems. RESULTS We developed an oral-induced nanoparticle-delivered gene silencing (OI-NDGS) platform using star polycation (SPc) nanocarriers to stabilize and deliver dsRNAs in B. germanica . Twelve candidate genes, selected from lethal Tribolium castaneum homologs, were tested. Efficient transcript knockdown was achieved for all targets. Four genes ( Bgsrp54k, Bgrpt3a, Bgrpt3b and Bgrpn7 ) produced 100% mortality with severe molting and growth defects, whereas Bghsc70-3 and Bgpp-α also yielded <7% cumulative survival at the 40-day endpoint. The identification of duplicated rpt3 transcripts in B. germanica underscores evolutionary divergence and expands proteasome-related targets for RNAi. CONCLUSION The present study highlights species-specific lethal genes in cockroaches and validates a scalable SPc-based oral delivery system, together establishing a practical framework for RNAi biopesticide development. These advances provide both new biological insights and applied innovations for sustainable urban pest management. © 2026 Society of Chemical Industry.