Collective defenses against internal pathogen infections in ants
Anna Franschitz, Anna Franschitz , Barbara Milutinovic , Sylvia Cremer
IST Austria (Institute of Science and Technology Austria), Klosterneuburg, Austria; IST Austria (Institute of Science and Technology Austria), Klosterneuburg, Austria ; IST Austria (Institute of Science and Technology Austria), Klosterneuburg, Austria ; IST Austria (Institute of Science and Technology Austria), Klosterneuburg, Austria
Ants prevent epidemics in their colonies by performing sanitary care towards pathogen-contaminated colony members. The removal of infectious particles by grooming or chemical disinfection by application of antimicrobial compounds, such as the formic acid-rich poison, are well-described components of sanitary care. These behaviors are highly effective in reducing the risk of infection after contamination with ‘external pathogens’, such as entomopathogenic fungi that attach and actively penetrate the cuticle. The expression of sanitary actions reduces the pathogen load on the contaminated individuals to below disease-causing levels. However, they may not be effective in combating bacterial and viral infections caused by wounding or by ingestion of contaminated food. We have therefore established experimental host-pathogen study systems of ants with bacterial, respectively viral pathogens to study individual and collective defenses against such ‘internal pathogens’. At the individual level, we study the immune responses after oral or wound-infection, as well as the internalization of antimicrobial compounds to perform self-medication. We then test, if these ants may share any of their individual disease defenses with their nestmates, and, in turn, if and how nestmates provide sanitary care to reduce disease progression and limit disease transmission in the colony. We present different strategies against bacterial and viral infections, highlighting the dynamical interplay between individual and social immunity across host-pathogen systems.