Research
Social immunity
In addition to the individual immunity of all colony members, social insects protect their colonies from disease by cooperative defences. This social immunity acts to prevent contamination of the colony, infection of colony members and disease transmission, hence to improve fitness of the colony.
The concept
Protection of the superorganism
Social insect colonies are „superorganisms”. Like cells in a body, the different insects specialize on different tasks: queens and males reproduce, whilst the workers are typically sterile and perform colony maintenance tasks. Social immunity describes how the colonies as reproductive entities are protected from disease.
Sanitary care
Preventing current infection
Pathogen-exposed ants receive immediate sanitary care by their healthy colony members, effectively preventing infection of the contaminated individuals. Sanitary care combines mechanical removal of infectious particles by grooming and antimicrobial sanitation.
Nest hygiene
Preventing colony contamination
Pathogens need to enter and establish in the colony to later cause infection of colony members. To prevent colony contamination, ants constantly and prophylactically disinfect their nest, particularly their brood pile, with antimicrobials like their formic-acid rich poison.
Treating infection
Preventing pathogen replication
Ants treat infections and thereby prevent pathogen replication and hence disease transmission through the colony. They are able to detect infections already during the non-infectious incubation period by chemical cues and to treat them by complex behaviors and use of antimicrobials. This allows them to prevent the pathogen from producing new infectious particles, a highly efficient way to stop disease spread through the colony.
Social immunisation
Preventing future infection
Social contact with infectious colony members causes pathogen transmission to previously healthy colony members. Often, this cross-contamination only leads to low-level infection of the colony members, which does not cause disease but induces a protective immunisation.
Organisational immunity
Preventing disease spread
Pathogens use the social interaction networks of their hosts for transmission to new host individuals. Social insect colonies react to pathogen entry into the colony by re-organisation of their social interaction networks. Contaminated ants, but also their peers, reduce contact to the remaining colony members. This leads to a highly efficient reduction of disease spread through the colony.
Our research
-
(Roy Soc Open Sci, 2017) Ant queens increase their reproductive efforts after pathogen infection
The authors demonstrate that a fungal infection prompts ant queens to increase their reproductive efforts. This boost in reproduction aligns with the terminal investment hypothesis and is observed here for the first time in a… Read more
-
(J Theor Biol, 2015) Fungal disease dynamics in insect societies: optimal killing rates and the ambivalent effect of high social interaction rates
Entomopathogenic fungi are potent biocontrol agents that are widely used against insect pests, many of which are social insects. The authors develop a model that takes into account the main distinguishing features between traditionally studied diseases and obligate… Read more
-
(Proc Roy Soc B, 2015) Anti-pathogen protection versus survival costs mediated by an ectosymbiont in an ant host
The authors look at potential costs and benefits of Laboulbenia formicarum – a fungal extosymbiont of Lasius neglectus – levels under Metarhizium exposure. Read more
-
(Behav Ecol Sociobiol, 2014) Increased grooming after repeated brood care provides sanitary benefits in a clonal ant
The authors tested whether experience gained by repeated tending of low-level fungus-exposed (Metarhizium robertsii) larvae may alter the performance of sanitary brood care in the clonal ant, Platythyrea punctata. Read more