Identification and functional verification of active volatiles recognition by the olfactory co-receptor Orco in Chrysopa pallens (Rambur) (Neuroptera: Chrysopidae).

Insect olfactory receptor co-receptor (Orco) plays a key role in olfactory organ formation and odor recognition during insect growth and development. In predatory insects, the olfactory system is important for the orientation, identification, and selection of hosts or prey. The cloning of the Orco gene in Chrysopa pallens (Rambur) holds significant importance, enabling evolutionary comparisons of olfactory systems among Neuroptera insects and opening possibilities for developing Orco-based biological control strategies through the manipulation of odor perception. The olfactory recognition mechanisms of the lacewing, C. pallens (Rambur), are poorly understood. One of the more significant findings to emerge from this study is that we cloned and sequenced the full-length Orco gene (CpalOrco) from C. pallens. It has been demonstrated that CpalOrco is highly conserved and similar to Orco genes of coleopterous insects. Real-time quantitative PCR analysis showed that CpalOrco was mainly expressed in C. pallens antenna. Compared to the control group injected with dsRNA targeting enhanced green fluorescent protein (dsEGFP), RNA interference-mediated silencing of CpalOrco through targeted double-stranded RNA (dsOrco) delivery resulted in significant suppression of gene expression. Experimental evidence from electroantennogram assays indicated that downregulation of CpalOrco transcripts substantially compromised the olfactory perception of nonanal in C. pallens. Overall, the current study has confirmed that CpalOrco may play an important role in the C. pallens odor recognition process.