M2iOR: a quantitative, context-resolved atlas of insect odorant receptor-odorant interactions

Olfactory detection in insects relies on interactions between odorant molecules and odorant receptors (ORs) expressed in olfactory sensory neurons. Although numerous studies have characterized insect OR-ligand interactions, these data remain scattered across the literature and heterogeneous in terms of species, experimental systems, and reporting standards, limiting their systematic analysis. Here, we present the Molecule to Insect Odorant Receptor database (M2iOR, https://m2ior.chemsensim.fr/), a curated, publicly accessible resource designed to centralize and standardize odorant-receptor interaction data. In its current release, M2iOR compiles 35 891 bioassay experiments describing 30 348 distinct insect OR-molecule pairs, extracted from 41 peer-reviewed publications and public databases. The resource integrates ligand structures, receptor sequences, species names, mixture information, and detailed experimental metadata. M2iOR provides flexible query tools allowing users to retrieve activity profiles for individual molecules or compound sets, and identify agonists and nonagonists for specific insect ORs, enabling comparative analyses across receptors, species, or bioassay systems. Advanced filtering based on curated metadata and batch search functionality support high-throughput analyses. For each query, users can visualize and download a curated aggregation of experimental results, including a binarized combinatorial representation of olfactory coding suitable for downstream computational studies. M2iOR provides a comprehensive framework for data-driven research in insect olfaction and comparative chemosensory biology.