LAUSR

BACKGROUND The black carabid beetle Calosoma maximoviczi is a successful predator which serves both as a beneficial insect and a severe threat to economic herbivores. Its hunting technic relies much on olfaction, but the underlined mechanism has not been tackled. Here, we reported electrophysiological, ecological, and molecular traits of bioactive components identified from a comprehensive panel of natural odorants in the beetle-prey-plant system. The aim of this work was to investigate olfactory perceptions and their influences on behaviours of C. maximoviczi. RESULTS Within 200 identified volatiles, 18 were concentrated in beetle and prey samples while 14 were concentrated in plants. Insect feeding damages to the plants led to shifted emission fingerprints. Twelve volatiles were selected by successive electrophysiological tests. Field trials showed that significant sex differences existed when trapping with single chemical and mixtures. Expression profiles indicated that sex-biased catches were related to expression of 15 annotated CmaxOBPs and 40 CmaxORs across 12 chemosensory organs. In silico evaluations were conducted with 16 CmaxORs by modelling and docking. It showed that better recognitions were predicted among pairs of CmaxOR5-(Z)-3-hexenyl acetate, CmaxOR6-β-caryophyllene, CmaxOR18-(E)-β-ocimene, and CmaxOR18-tetradecane, with higher binding affinity and suitable binding pocket. Lastly, 168Y in CmaxOR6 and 142Y in CmaxOR18 were predicted to be key amino acid residues for binding β-caryophyllene and tetradecane, respectively. CONCLUSION In all, this work provides an example pipeline for de novo investigation on C. maximoviczi baits and underlined olfactory perceptions. The outputs will benefit future development of trapping-based IPM strategies and deorphanization of odorant receptors in ground beetles. This article is protected by copyright. All rights reserved.