GONs-based delivery of a fused dsRNA targeting key cuticular genes (PcCPAP3-E and PcFTZ-F1): A novel strategy for Panonychus citri control

The arthropod cuticle serves as a critical barrier against environmental stressors and is essential for maintaining structural integrity. Its constituent cuticle proteins (CPs) represent promising targets for pest management. Panonychus citri, the citrus red Mite, is a major pest in the global citrus industry, making the development of eco-friendly and effective control strategies a priority. In this study, we identified and characterized a cuticle protein, PcCPAP3-E, from P. citri, which contains three chitin-binding domains (CBDs). Its expression profile was highly correlated with the mite's molting and developmental stages. RNA interference (RNAi)-mediated knockdown of PcCPAP3-E resulted in lethal phenotypes in nymphs, including a thinned cuticle and a ruptured dorsal plate, leading to a mortality rate of 41.29 % and accompanied by disrupted chitin architecture. Furthermore, in vitro biochemical assays confirmed the specific binding affinity of the recombinant PcCPAP3-E protein to chitosan. Mechanistic investigation revealed that the expression of PcCPAP3-E is regulated by the ecdysone signaling pathway, with the transcription factor FTZ-F1 acting as a key upstream regulator. A fused dsRNA targeting both PcCPAP3-E and FTZF1, delivered via graphene oxide nanosheets (GONs), achieved a 76.41 % synergistic mortality rate when co-applied with etoxazole, significantly outperforming single-gene interference strategies. In conclusion, this study defines the critical function of PcCPAP3-E and its regulation by FTZ-F1 in P. citri development. The established nanocarrier-based synergistic RNAi strategy provides a novel approach for the green control of piercing-sucking pests.

Cuticular protein; Nanocarriers; Panonychus citri; RNAi; Transcription factor.