Social insect colonies are protected against disease by cooperative disease defences of their colony members, providing social immunity to the colony. We use ants as a model system to understand the emergence, mechanisms and fitness effects of social immunity.
The colonies of ants and other social insects represent a special form of social organization. They are „superorganismal societies“.
This means that on one hand – like in other societies – disease spread between host individuals is affected by their social interaction networks. Ants are actively modulating their behaviors and hence social contact networks upon pathogen contact, thereby using „organizational immunity“ to reduce epidemics. On the other hand – very much in contrast to most other societies – they form a superorganism, in which all colony members form only a single reproductive entity. Just like a single organism, in which all cells cooperate, all colony members cooperate in superorganisms, even if they are separated individuals. The social immune system of a superorganism hence shows many parallels to the immune system of, e.g. a vertebrate body.
We study the behavioural, chemical and immunological mechanisms of individual and social immunity in ants, and how they affect epidemiology in the colony and ultimately colony fitness.
Animal social networks are shaped by multiple selection pressures, including the need to ensure efficient communication and functioning while simultaneously limiting disease transmission. Social animals could potentially further reduce epidemic risk by altering their social networks in the presence of pathogens, yet there is currently no evidence for such pathogen-triggered responses.