The insect olfactory recognition system plays a crucial role in recognizing host plant volatiles. Orco is essential for the function of general odorant receptors to perceive odorants and trigger the corresponding behavior in insects. Our previous studies have revealed that C. chinensis adults showed significant preference for host plant volatiles (methyl heptenone, Nonana and Decanal) and rejection for nonhost plant volatiles (Eugenol and Anethole). However, the functions of the Orco in recognition of these volatiles in C. chinensis is unknown. In this study, we identified and characterized the conserved Orco in C. chinensis. The expression profiles showed that the CchiOrco gene was highly expressed in the adult antenna of C. chinensis. The RNAi technique was used to silence the CchiOrco gene successfully by reducing the expression 97.52% in female and 81.91% in male beetles after 24 h treatment. Electrophysiological assays showed that the responses to the five plant volatiles were significantly reduced in the group that underwent RNAi treatment. There were similar changes in behavior tests, in which the RNAi-treated beetles showed no response for all tested plant volatiles in C. chinensis. These results demonstrate that the CchiOrco knockdown resulted in impairment of the ability to perceive attractants or repellents. CchiOrco has the potential to be used as a target for developing ecofriendly pest control strategies by RNAi to disrupt chemical recognition through olfactory system. © 2025 Society of Chemical Industry.
Zheng et al. (Thu,) studied this question.