Trypsin-encoding gene function of efficient star polycation nanomaterial-mediated dsRNA feeding delivery system of Grapholita molesta.

Background: Grapholita molesta is an important and harmful fruit pest worldwide, with widespread feeding hosts. Trypsin, an indispensable hydrolytic digestive protease in the insect gut, is crucial in digestion, growth and development. We analyzed the characteristics of the trypsin-encoding genes, screened for the optimal dose of RNAi mediated by nanocarriers, and investigated various indices of larval growth and development of G. molesta.

Results: Gut content (GC) and RNase A degraded double-stranded RNA (dsRNA), with a faster degradation rate at higher concentrations. Star polycation (SPc) nanomaterials protected dsGFP from degradation by anion-cation binding and did not migrate through agarose gel. The key conserved motifs of the trypsin-encoding genes were similar, exhibiting high homology with those in other lepidopteran insects. An interference efficiency of ≈70% was achieved with SPc nanomaterial-mediated RNA interference with 0.05 μg dsRNA. The efficiency of continuous interference was stable. Trypsin activity, body weight of 8-day-old larvae, pupal weight and emergence rate were significantly reduced, and the larval stage was significantly prolonged.

Conclusion: The investigated trypsin gene is a key target gene in the growth and development of G. molesta. We investigated the efficiency and convenience of feeding SPc nanomaterials in a functional study of insects. Our results provide valuable data for the development of efficient trypsin-targeting pesticides. © 2024 Society of Chemical Industry.