How social contact with sick ants protects their nestmates

Apr 03, 2012
Weaver ants collaborating to dismember a red ant (the two at the extremities are pulling the red ant, while the middle one cuts the red ant until it snaps). Image: Wikipedia.

In a research article published April 3 in the online, open-access journal PLoS Biology, Prof. Sylvia Cremer and colleagues at the Institute of Science and Technology, Austria show how micro-infections promote social vaccination in ant societies. Like crowded megacities, ant colonies face a high risk of disease outbreaks. These are kept in check by the ants' social immune system—a set of collective hygienic behaviours and adaptive changes in interaction frequencies that acts in conjunction with the physiological, innate immune system of colony members. Prof. Cremer and colleagues now unravel how taking care of sick ants promotes disease protection in their group members.

Ants do not avoid sick colony members, but lick them to remove the pathogen from the exposed ant's body. This social grooming behaviour drastically increases the survival chances of exposed individuals, but bares the risk that helper contract the disease. By applying fluorescence-labelled fungal spores to some ants and allowing them to interact with healthy colony members, the researchers showed that the labelled spores spread throughout the colony. Interestingly, however, spore transfer occurs at very low levels, causing only sub-lethal micro-infections in the previously healthy colony members. The authors determined that these low-level infections induce the expression of a specific set of immune genes and increase the ants' capacity to fight the fungal pathogen. Additional mathematical modelling suggests that such social immunization enables colonies to recover more rapidly from an infection, providing new clues into its evolutionary significance.

Social low-level spread of infectious particles therefore constitutes the underlying mechanism of social immunisation against fungal infections in ant societies. This is nature's counterpart to the first human efforts in inducing immunity against deadly diseases like smallpox. At a time when vaccination with dead or attenuated strains was not yet invented, immunity was induced in people by actively transferring low-level infections through so-called variolation. The extent of any human implications is not yet clear, but this study allows for informed inferrences to be made for a wider context.

As Simon Babyan from Edinburgh University and David Schneider from Stanford note in an accompanying primer article also published in , "The authors used a combination of approaches to identify the mechanisms underlying social immunisation in : mathematical modelling, behavioural, microbiological, immunological and molecular techniques, which, taken together, offer an exciting proof-of-concept that group-level immunity may be experimentally manipulated and modelled… By studying social immunity at a system level in insects perhaps we can find emergent properties that we have been missing in another important social animal—the human."

Explore further: Orchid named after UC Riverside researcher

More information: Konrad M, Vyleta ML, Theis FJ, Stock M, Tragust S, et al. (2012) Social Transfer of Pathogenic Fungus Promotes Active Immunisation in Ant Colonies. PLoS Biol 10(4): e1001300. doi:10.1371/journal.pbio.1001300

Related Stories

Ant’s social network similar to Facebook

Apr 14, 2011

(PhysOrg.com) -- A recent study in the Journal of the Royal Society Interface presents findings that show that not all ants are as social as others. Similar to your friends on Facebook, some ants communicate with o ...

Chemical warfare of stealthy silverfish

Dec 01, 2011

A co-evolutionary arms race exists between social insects and their parasites. Army ants (Leptogenys distinguenda) share their nests with several parasites such as beetles, snails and spiders. They also s ...

Nature and nurture help ant societies run smoothly

Apr 22, 2011

Picture an ant colony: up to a million ants, all looking identical, harmoniously going about their busy ant lives. But with so many ants around, how on Earth do they know who's friend and who's foe?

Recommended for you

Orchid named after UC Riverside researcher

7 hours ago

One day about eight years ago, Katia Silvera, a postdoctoral scholar at the University of California, Riverside, and her father were on a field trip in a mountainous area in central Panama when they stumbled ...

In sex-reversed cave insects, females have the penises

9 hours ago

Researchers reporting in the Cell Press journal Current Biology on April 17 have discovered little-known cave insects with rather novel sex lives. The Brazilian insects, which represent four distinct but re ...

Fear of the cuckoo mafia

9 hours ago

If a restaurant owner fails to pay the protection money demanded of him, he can expect his premises to be trashed. Warnings like these are seldom required, however, as fear of the consequences is enough to ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Doug_Huffman
1 / 5 (1) Apr 03, 2012
Like soap and water for humans, diluting the infectious agent to sub-lethal/non-infective concentrations.

More news stories

Deadly human pathogen Cryptococcus fully sequenced

Within each strand of DNA lies the blueprint for building an organism, along with the keys to its evolution and survival. These genetic instructions can give valuable insight into why pathogens like Cryptococcus ne ...

Better thermal-imaging lens from waste sulfur

Sulfur left over from refining fossil fuels can be transformed into cheap, lightweight, plastic lenses for infrared devices, including night-vision goggles, a University of Arizona-led international team ...

Hackathon team's GoogolPlex gives Siri extra powers

(Phys.org) —Four freshmen at the University of Pennsylvania have taken Apple's personal assistant Siri to behave as a graduate-level executive assistant which, when asked, is capable of adjusting the temperature ...