General Odorant Binding Protein 2 and Odorant Binding Protein 36 facilitate the recognition of adult sex pheromone components by Hyphantria cunea larvae

The fall webworm (Hyphantria cunea) is a globally recognized quarantine pest with a wide host range, causing serious ecological and economic damage. Olfactory-based pest control using semiochemicals is an environmentally sound strategy, but little is known about larval olfactory mechanisms. Here, we identified 48 Odorant Binding Protein (OBP) genes in H. cunea larvae and investigated their roles in perceiving its adult sex pheromone components. Behavioral assays revealed that two female-produced sex pheromone components, Z9,Z12-18Ald and Z9,Z12,Z15-18Ald, significantly attracted H. cunea larvae. Exposure to these compounds upregulated six larval OBPs. Fluorescence binding assays confirmed that both HcunOBP36 and HcunGOBP2 bind to these two pheromone components. Larvae injected with dsGOBP2 showed significantly reduced attraction to the two pheromone components, whereas injection of dsOBP36 had little effect; co-silencing both genes further diminished attraction compared with the dsGOBP2 alone. These findings indicate that HcunGOBP2 was essential in the larval orientation toward adult sex pheromone-containing food sources, while HcunOBP36 had an auxiliary role. This study offers novel insights into the pheromone perception of insect larvae, thereby enhancing our understanding of larval olfactory biology and pheromone-mediated ecological interactions.