A Highly Expressed and Conserved Odorant Receptor for Identifying the Alarm Pheromone (<i>E</i>)-2-Decenal in <i>Halyomorpha halys</i>

(<i>E</i>)-2-decenal is the alarm pheromone of<i>Halyomorpha halys</i> and other Pentatomidae bugs as well. This chemical can trigger avoidance behavior from dangerous sources or defensive behavior against predators, thereby playing a crucial role in the survival and flourishing of the <i>H. halys</i> population. Revealing the molecular mechanism underlying this stink bugs's perception of alarm pheromone will facilitate the development of environmentally friendly biological control agents. In this study, we first examined the behavioral and antennal electrophysiological responses of<i>H. halys</i> to different doses of (<i>E</i>)-2-decenal. Then two candidate odorant receptors (ORs) for (<i>E</i>)-2-decenal detection, HhalOR107 and HhalOR114, were identified via tissue-specific expression patterns and phylogenetic analysis. Finally, HhalOR114 was found to recognize (<i>E</i>)-2-decenal in the <i>Xenopus</i> oocytes combined with a two-electrode voltage clamp system. Our results thus confirmed that HhalOR114 is an OR for alarm pheromone perception in <i>H. halys</i>, which will lend support to the development and application of pheromone receptor-based management of related pest insects.