Characterization of olfactory proteins and their roles towards xenobiotic adaptation in Leptinotarsa decemlineata

The Colorado potato beetle (CPB), a prolific pest of Solanaceae crops, incurs significant losses in crop yield and threatens agricultural security worldwide. Success of CPB depends on recognition of volatile compounds that act as chemical cues of vital resources, such as host plants, conspecifics, or predators. As the main olfactory organ, antennae are extremely sensitive to chemical cues and particularly vulnerable to airborne toxins, due to the numerous pores that line their surface. Co-evolution between insects and plants has rendered the antennae as an opportune target for plant defense, wherein an essential process can also be an Achilles heel. Odorant binding proteins (OBPs), which are the primary liaisons between insects and their environment, serve as the first point of interaction with xenobiotics in the olfactory system. However, the dynamic roles of OBPs towards xenobiotic adaptation in CPB remain unclear. Here, we identified two OBPs from the CPB genome that are highly expressed in the antennae of neonicotinoid resistant CPB adults and are significantly induced by herbivore-induced plant volatiles. To characterize the functions of these OBPs in xenobiotic adaptation in CPB, we first suppressed gene expression of both OBPs through a no-choice feeding bioassay mediated by RNA interference. Afterwards, we conducted behavioral and toxicity bioassays, electrophysiological analysis and/or substrate spectrum screening to investigate the potential roles of OBPs in host plant recognition, pheromone perception, and insecticide resistance. This work will broaden our understanding of the intricate system of insect olfaction and may potentially lead to novel management strategies for CPB.