The dual role of the RR-2 cuticular protein gene in development and acaricide susceptibility of Panonychus citri (Acari: Tetranychidae).

Panonychus citri, a major pest mite globally, causes substantial economic damage in the citrus sector. Due to the prolonged use of acaricides, P. citri has developed resistance; thus, identifying alternative control measures is imperative. The study successfully cloned and characterized three genes from the RR-2 subfamily of cuticular proteins (CP) in P. citri, PcCPR14, PcCPR15.7, and PcCPR16.8. These genes exhibited their highest expression in eggs aged 4 and 5 days and showed relatively high expression in larvae and nymphs on day 1. Inhibitin PcCPR16.8 expression in eggs resulted in only 23% hatching success. Similarly, silencing PcCPR16.8 is inhibited in nymphs led to cuticle rupture and a mortality rate of 81.77%. Silencing in female mites reduced the oviposition rate by 31.06% and significantly decreased chitin content and the expression of key chitin metabolism genes in P. citri. This indicates the crucial role of CP genes in the development and reproduction of P. citri. Moreover, exposure to the acaricides spirobudiclofen and etoxazole typically triggers high expression of PcCPR16.8, and silencing this gene increases the mite's sensitivity to these chemicals. CPs are vital in defending against environmental changes, making them potential targets for developing P. citri control strategies.