Molecular Basis of CO Sensing in .

Carbon dioxide (CO) released by plants can serve as a cue for regulating insect behaviors. is a widely distributed forestry pest that may use CO as a cue for foraging and oviposition. However, the molecular mechanism underlying its ability to sense CO has not been elucidated. Our initial study showed that CO is significantly attractive to adults. Subsequently, 44 gustatory receptors () were identified using transcriptome data, and 3 candidate CO receptors that are specifically expressed in the labial palps were identified. In vivo electrophysiological assays revealed that the labial palp is the primary organ for CO perception in , which is similar to findings in other lepidopteran species. By using the oocyte expression system, we showed that the and co-expressions produced a robust response to CO, but had an inhibitory effect on CO perception. Finally, immunohistochemical staining revealed sexual dimorphism in the CO-sensitive labial pit organ glomerulus (LPOG). Taken together, our results clarified the mechanism by which sense CO, laying the foundation for further investigations into the role of CO in the rapid spread of .