Expression Profiles and Functional Characterization of Chemosensory Protein 15 (HhalCSP15) in the Brown Marmorated Stink Bug Halyomorpha halys

Chemosensory proteins (CSPs) have been identified in the sensory tissues of various insect species and are believed to be involved in chemical communication in insects. However, the physiological roles of CSPs in Halyomorpha halys, a highly invasive insect species, are rarely reported. Here, we focused on one of the antennal CSPs (HhalCSP15) and determined whether it was involved in olfactory perception. Reverse transcription PCR (RT-PCR) and quantitative real-time PCR (qRT-PCR) analysis showed that HhalCSP15 was enriched in nymph and male and female adult antennae, indicating its possible involvement in the chemosensory process. Fluorescence competitive binding assays revealed that three of 43 natural compounds showed binding abilities with HhalCSP15, including beta-ionone (K-i=11.9 +/- 0.6 mu M), cis-3-hexen-1-yl benzoate (K-i=10.5 +/- 0.4 mu M), and methyl (2E,4E,6Z)-decatrienoate (EEZ-MDT; K-i=9.6 +/- 0.8 mu M). Docking analysis supported the experimental affinity for the three ligands. Additionally, the electrophysiological activities of the three ligands were further confirmed using electroantennography (EAG). EEZ-MDT is particularly interesting, as it serves as a kairomone when H. halys forages for host plants. We therefore conclude that HhalCSP15 might be involved in the detection of host-related volatiles. Our data provide a basis for further investigation of the physiological roles of CSPs in H. halys, and extend the olfactory function of CSPs in stink bugs.

Automated summary

Chemosensory protein HhalCSP15 was found to be enriched in the antennae of Halyomorpha halys, suggesting its involvement in olfactory perception. Three natural compounds showed strong binding abilities with HhalCSP15, with EEZ-MDT acting as a kairomone during host plant foraging in H. halys. These findings provide insight into the physiological roles of CSPs in H. halys and expand the understanding of CSPs' olfactory function in stink bugs.