External secretions and antifungal defense in subterranean termites
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Type of Workapplication/pdf
vi, 49 pages
DepartmentTowson University. Department of Biological Sciences
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Termites face strong pathogenic pressures associated with their social organization and ecological attributes. Reticulitermes subterranean termites are exposed to the entomopathogenic fungus Metarhizium anisopliae, which is a natural pathogen ubiquitous in the soil that these termites nest and forage in. M. anisopliae can effectively evade insect innate immune defenses after penetrating the cuticle. Here, I describe an external antifungal defense system utilized by Reticulitermes in which salivary gland antifungal secretions with strong GNBP-associated B-1,3-glucanase activity are spread over the cuticle. Inhibition of B-1,3-glucanase activity decreases antifungal activity and increases mortality in termites exposed to a local strain of M. anisopliae. RNA interference shows that GNBP2 and termicin are essential antifungal molecules in these termites, and important components of external defenses. This external defense strategy targets fungal pathogens before cuticular penetration, and could have been important in overcoming the pathogenic pressures associated with group living and nesting in soil.