Ligand binding profiles of Solenopsis invicta (red imported fire ant) chemosensory proteins

In the fire ant, Solenopsis invicta Buren, as in other eusocial insects, maintenance of colony cohesiveness, sociality, defense, and food acquisition rely on queen-worker and worker-worker recognition and communication. Chemosensory proteins (CSPs) are thought to participate in these and other chemical detection and/or transport processes by shuttling ligands to appropriate receptors. Fourteen putative CSPs have been identified in the genome of S. invicta. Some CSPs appear to be highly concentrated in the sensillar lymph, however, others have have been detected throughout the organism, suggesting that only a subset of CSPs may be involved in odor detention. Thus far, the lack of comparative ligand-binding data for individual CSPs and their differential (tissue) expression patterns has impeded the development of hypotheses regarding their physiological roles. In order to provide a framework for making predictions as to the functions of individual CSPs, a battery of potential ligands including cuticle hydrocarbons, plant extracts, and insects pheromones was tested against recombinant S. invicta CSPs. These data revealed unique and overlapping ligand binding specificities for these proteins.