Blade-running: an efficient yet simple behaviour to potentially combat summit disease in ants.

BACKGROUND: Social systems are attractive targets for parasites. Once infiltrated they are able to manipulate the host to contribute to their further dispersal. A wide array of parasites causes summit disease: driving their host up on elevated points on plants from where propagules are then dispersed. In ants, previous observations suggested the existence of a simple social prophylactic strategy that could help reduce the pathogen's dispersal success through early corpse disposal e.g., in the case of summit-causing pathogenic Pandora fungus.

RESULTS: We experimentally tested the efficiency of prophylactic corpse disposal in a large nest complex by imitating summit diseased ants with the use of fresh uninfected ant corpses and dummies fixed to grass blades. Indeed, ants discovered and disposed of corpses very efficiently, primarily of those close to the nest margin.

CONCLUSIONS: We argue that while this behaviour is not necessarily specific to summit disease but rather part of a general sanitary repertoire, its efficiency in removing elevated corpses before sporulation could reduce pathogen transmission and might contribute to the low prevalence observed in our field population.