Ph.D. Student Louisiana State University Baton Rouge, Louisiana
Subterranean termites are eusocial insects that heavily rely on chemical cues to communicate. Olfaction is essential for communication in many insects, however, little is known about how termites perceive and process olfactory cues. In this study, we investigated the external morphology of the antennae along with its gene expression profiles in workers, soldiers, and alate reproductives of the Formosan subterranean termite. Through morphological analysis of the antennae, we identified nine types of antennal sensilla which are present in all castes with a characteristic abundance and distribution. At the molecular level, through transcriptomic analysis of the antennae of all castes, we identified more than 100 putative chemosensory genes including chemosensory proteins (CSPs), odorant-binding proteins (OBPs), odorant-receptors (ORs), and ionotropic receptors (IRs). Our differential gene expression analysis revealed that greater differences are found between reproductives versus non-reproductive castes. Among these genes, the odorant receptor co-receptor (orco) is fundamental for chemosensory function. We Investigated its spatial (tissue) and temporal (developmental stage) gene expression profiles. Our results indicate that its expression occurs mainly in the antennae, and is detectable in all stages of development. In addition, its expression is higher in the antennae of alate reproductives than workers and soldiers. Overall, our results provide evidence of differences at the morphological and molecular levels of the chemosensory system across castes of the Formosan termites. However, further investigation is required to elucidate if these differences relate to their reproductive division of labor or behavioral repertoire.
