Abstract:The Orchidaceae, one of the largest families of angiosperms, exhibited a unique pollination strategy where approximately one-third of its species attracted pollinating insects through deceptive mechanisms rather than traditional reciprocal relationships. The volatile substances in orchids exhibited significant diversity, while pollinators demonstrated distinct preferences for specific floral scent profiles. These volatile compounds not only formed a unique chemical communication system between orchids and their pollinators but also appeared integral to their coevolutionary relationships. This study conducted comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOF MS) analysis and interspecific comparative analysis of floral volatiles in three traditional Chinese orchid species: Cymbidium faberi, Cymbidium sinense and Neofinetia falcata. The results showed that there were 3,177, 2,838 and 3,098, volatile compounds identified from C. faberi, C. sinense and N. falcata respectively. Among these, the major classes of volatile compounds were alkanes, alcohols, esters, and ketones. Sensory flavor characterization revealed that the three orchid species predominantly exhibited sweet, fruity, and green-plant notes. A total of 1,241 volatile compounds were shared by all three orchid species, with 2-methylbutanal being the primary contributor to the floral aroma, followed by butyl acetate, 2-pentylfuran, nonenal, butyl acrylate, α-pinene, undecanone, and others. In addition, the differential compounds between the three orchid species were 240 (C. faberi/C. sinense), 220 (C. faberi/N. falcata), and 171 (C. sinense/N. falcata), respectively. Seven candidate volatile compounds were screened, and their attractiveness to Apis cerana was evaluated through Electroantennogram (EAG) and behavioral orientation bioassays to characterize the effects of orchid floral volatiles. Notably, the results demonstrated that all seven major orchid volatiles elicited significant EAG responses in Apis cerana, with benzaldehyde and 2-methylbutanal showing the highest reaction values. At low concentrations, benzaldehyde elicited the highest electrophysiological response, while 2-methylbutanal showed the strongest response at high concentrations. Behavioral assays revealed that α-pinene exhibited significantly stronger attraction than benzaldehyde (P < 0.05). However, no significant differences (P>0.05) were observed in bee attraction among the other volatile compounds at varying concentrations. In summary, the volatile components of the three Chinese orchid species exhibited significant diversity, with specific key compounds eliciting distinct electrophysiological responses in Apis cerana. These findings provided new insights into the chemical interactions between orchids and their pollinators, and offered a scientific basis for exploring the co-evolution between plants and pollinators.