Key cuticular proteins mediating molting and environmental stress response in Panonychus citri

Cuticular proteins (CPs), key structural components of the insect cuticle, play essential roles in growth, metamorphosis, and defense against environmental stresses. Panonychus citri, a globally significant pest mite, severely impacts citrus orchard productivity. Targeting critical CP genes offers a promising strategy to disrupt its development and environmental adaptation.

In this study, 37 CPR genes (defined by the Rebers and Riddiford consensus) and 14 CPAP genes (characterized by six cysteine-rich chitin-binding domains) were identified in P. citri. Most exhibited high expression during molting stages. During the deutonymph-to-adult transition, PcCPR27 showed downregulation followed by upregulation, whereas PcCPR28 and PcCPAP3-E displayed an opposite pattern. RNAi-mediated silencing of each gene significantly reduced eclosion rates. Notably, PcCPAP3-E was significantly downregulated in adults, and its knockdown led to substantial mortality in newly emerged adults. Moreover, PcCPAP3-E was uniquely upregulated under stress conditions, such as high temperature and cyflumetofen exposure. Silencing PcCPAP3-E impaired thermal tolerance and enhanced susceptibility to acaricide, thereby increasing mite mortality.

Our findings indicate that PcCPR27, PcCPR28 and PcCPAP3-E are involved in molting in P. citri, with PcCPAP3-E also playing a pivotal role in environmental stress adaptation. These genes represent promising molecular targets for RNAi-based control strategies, particularly PcCPAP3-E, which may enhance acaricidal efficacy when targeted during vulnerable developmental stages. © 2026 Society of Chemical Industry.