CBS Special Seminar by Arthur Comte, Emmanuelle Jacquin-Joly, and Sebastien Fiorucci (Paris/Nice)
Where’s Waldo? A hunt for functionally divergent odorant receptor orthologs in the context of host shifts
Olfactory adaptation plays a key role in initiating or stabilizing dietary shifts by reshaping the insect’s responsiveness to host-specific chemical cues. Modulating gene expression or altering the specificity and sensitivity of odorant receptors (ORs) can influence an insect’s ability to recognize host volatiles. However, highlighting these specific molecular changes remains a challenge. Insects possess tens to hundreds of ORs, most of which are still orphan receptors with unknown ligands, limiting current efforts to identify functionally divergent orthologs.
Structure-based virtual screening (SBVS), which employs molecular docking simulations, offers a promising solution to overcome this limitation. While widely used for predicting ligand–receptor interactions in mammalian G protein-coupled receptors, SBVS has only recently been adapted to insect ORs. This strategy enables rapid, repertoire-wide prediction of odorant binding profiles, facilitating cross-species comparisons of olfactory tuning and the identification of functionally divergent receptors associated with ecological specialization.
In this study, we present the first application of SBVS to the entire OR repertoires of insects, leveraging this approach to explore peripheral olfactory system adaptation associated with host plant shift in the genus Spodoptera. We focused on three closely related moth species that exhibit contrasting feeding diets: two are polyphagous, and one is oligophagous, feeding exclusively on Amaryllidaceae. The analysis of the predicted OR response profiles suggests differences in the chemical detection spaces between species. We thus conducted functional studies on a promising OR and revealed contrasting sensitivity and selectivity to volatiles emitted by Amaryllidaceae between species. These findings reveal a receptor-level change associated with dietary specialization and demonstrate the potential of SBVS as a powerful tool for predicting ecologically relevant olfactory adaptations across insect lineages.