Overcoming Immune Deficiency with Allogrooming

SIMPLE SUMMARY: We investigated whether two closely related termite species differ in their reliance on social or individual immunity against two species of pathogenic fungi, which were all collected from the same location. Our results indicate that mutual grooming (allogrooming) is highly effective at limiting fatal infections to the extent that it can compensate for relatively weak individual immune defenses. After pathogens are encountered, termites use an alternate strategy for social distancing and limiting the spread of contagious disease and instead come together to clean each other. Variation in the intensity of this behavioral response indicates a nuanced response to the level of threat. ABSTRACT: Allogrooming appears to be essential in many social animals for protection from routine exposure to parasites. In social insects, it appears to be critical for the removal of pathogenic propagules from the cuticle before they can start an infectious cycle. For subterranean termites, this includes fungal spores commonly encountered in the soil, such as Metarhizium conidia, that can quickly germinate and penetrate the cuticle. We investigated whether there is a difference in reliance on social and innate immunity in two closely related subterranean termites for protection from fatal infections by two locally encountered Metarhizium species. Our results indicate that relatively weak innate immunity in one termite species is compensated by more sustained allogrooming. This includes enhanced allogrooming in response to concentrations of conidia that reflect more routine contamination of the cuticle as well as to heavy cuticular contamination that elicits a networked emergency response.