Expressional and functional comparisons of five clustered odorant binding proteins in the brown marmorated stink bug Halyomorpha halys

Odorant-binding proteins (OBPs) play essential roles in the functioning of insect peripheral olfactory systems. To fully understand the olfactory roles of OBPs in Halyomorpha halys, an important invasive pest found worldwide, we studied the expression and functional characterization of five OBP-associated genes from H. halys that are clustered in the genome. The tissue distribution of the OBP gene cluster suggests that these genes were enriched in nymph and adult antennae, indicating their possible involvement in the chemosensory process. The different expression levels of the five OBPs in nymph and adult antennae suggest that this gene cluster is regulated independently. Ligand-binding experiments have shown similar specificities of these five OBPs towards several organic compounds, including the alarm pheromone of H. halys (trans-2-decenal), the aggregation pheromone of Plautia stali (methyl (2E, 4E, 6Z)-decatrienoate), and plant volatile compounds (e.g., cis-3-hexenyl benzoate and β-ionone). In particular, trans-2-dodecenal, an alarm pheromone analog, exhibited high affinity to the five OBP proteins and alarm pheromone activity towards H. halys. Thus, this OBP cluster may mediate the response of stink bugs to the both the alarm pheromone and host-related volatiles and could be an interesting target to design novel olfactory regulators for the management of H. halys infestations.