Abstract
Carbon dioxide (CO(2)) released by plants can serve as a cue for regulating insect behaviors. Hyphantria cunea is a widely distributed forestry pest that may use CO(2) as a cue for foraging and oviposition. However, the molecular mechanism underlying its ability to sense CO(2) has not been elucidated. Our initial study showed that CO(2) is significantly attractive to H. cunea adults. Subsequently, 44 H. cunea gustatory receptors (GRs) were identified using transcriptome data, and 3 candidate CO(2) 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(2) perception in H. cunea, which is similar to findings in other lepidopteran species. By using the Xenopus oocyte expression system, we showed that the HcunGR1 and HcunGR3 co-expressions produced a robust response to CO(2), but HcunGR2 had an inhibitory effect on CO(2) perception. Finally, immunohistochemical staining revealed sexual dimorphism in the CO(2)-sensitive labial pit organ glomerulus (LPOG). Taken together, our results clarified the mechanism by which H. cunea sense CO(2), laying the foundation for further investigations into the role of CO(2) in the rapid spread of H. cunea.