REVERSE CHEMICAL ECOLOGY EXPANDS THE LIST OF LIGANDS FOR A CROP PEST INSECT ODORANT RECEPTOR

Abstract

Insects are exposed to many odorant molecules in their environment, some of them carrying important information for essential activities such as the identification of food sources, the location of nesting sites, the search for sexual partners, or the detection of predators. The recognition of these molecules is done by transmembrane proteins called odorant receptors (ORs), located in the olfactory sensory neurons in the antennae. A first functional analysis of a large OR repertoire in the moth Spodoptera littoralis, an important pest of crops, was conducted in our laboratory, providing an unprecedented number of ligand-receptor pairs. These results were used to search for new potential ligands by in silico prediction based on Quantitative Structure Activity Relationships (QSAR). Such an approach has already been used to explore the chemical space of mammalian ORs, but its use in insects remains limited to two model species, the Anopheles and the Drosophila melanogaster fly. Focused on an OR involved in the recognition of attractive odorants for S. littoralis larvae, the QSAR approach has made it possible to propose a new range of potential ligands of this OR. The activity of these ligands was then experimentally tested on the target OR, expressed in a heterologous system in vivo, using electrophysiology. The results show that computer science coupled with experimentation is very effective in expanding the chemical space of insect ORs. This approach could ultimately enable the identification of OR agonists or antagonists, capable of modifying the olfactory behavior of insect pests, opening up new perspectives in biocontrol.