Altered Expression of Chemosensory and Odorant Binding Proteins in Response to Fungal Infection in the Red Imported Fire Ant,

Social insects have evolved acute mechanisms for sensing and mitigating the spread of microbial pathogens within their communities that include complex behaviors such as grooming and sanitation. Chemical sensing involves detection and transport of olfactory and other chemicals that are mediated by at least two distinct classes of small molecular weight soluble proteins known as chemosensory- and odorant binding proteins (CSPs and OBPs, respectively) that exist as protein families in all insects. However, to date, a systematic examination of the expression of these genes involved in olfactory and other pathways to microbial infection has yet to be reported. The red imported fire ant, , is one of the most successful invasive organisms on our planet. Here, we examined the temporal gene expression profiles of a suite of () and () in response to infection by the broad host range fungal insect pathogen, . Our data show that within 24 h post-infection, i.e., before the fungus has penetrated the host cuticle, the expression of and is altered (mainly increased compared to uninfected controls), followed by suppression of and select expression 48 h post-infection and mixed responses at 72 h post-infection. A smaller group of , however, appeared to respond to fungal infection, with expression of consistently higher during fungal infection over the time course examined. These data indicate dynamic gene expression responses of and to fungal infection that provide clues to mechanisms that might mediate detection of microbial pathogens, triggering grooming, and nest sanitation.