Ever the opportunistic photophile, I perchanced upon these foraging major workers of the common weaver ant, Oecophylla smaragdina, locked together in a deep kiss, though even if it does seem like the ants are passionately kissing each other, it serves a whole different purpose altogether.
Ants frequently indulge in this ‘kissing’ action, which in scientific terminology, is called stomodeal trophallaxis, meaning mouth-to-mouth feeding. This way, only a couple of ants have to go out to get food, after which they can pass it around the colony by trophallaxing or ‘kissing’ their hungry sisters. This function has long been known among the ants.
Recently however, Ms. Casey Hamilton and her co-workers uncovered a whole new function of trophallaxis, whilst observing two separate groups of ants, under laboratory conditions. One group was starved, while the other, well fed. These well fed ants were ‘vaccinated’ against bacteria, having, beside food, a spate of antibacterial substances in their body (also known as anti-microbial peptides).
Trophallaxis occurs once the two groups come together, with the well fed ants sharing food with their hungry sisters.
Now comes the interesting part. After the hungry ants were fed by their vaccinated sisters, they were exposed to disease causing bacteria. And while these ants should, by all rights, should have succumbed to disease, it appeared they were now more resistant to it than before. This showed that the ants can spread their ‘immunity’ to other individuals while exchanging food.
Pheromones are also exchanged as compounds mixed with food and passed along, when trophallaxis occurs, providing the ants all the information they need about each other’s health and nutrition, including being able to detect which task group their sisters belong to. (e.g. foraging or nest maintenance)
- Hamilton, C., Lejeune, B.T., Rosengaus, R.B. (2010). Trophallaxis and prophylaxis: social immunity in the carpenter ant Camponotus pennsylvanicus. Biology letters 7, 89-92
- Ugelvig, L.V., Cremer, S. (2007). Social prophylaxis: Group interaction promotes collective immunity in ant colonies. Current Biology 17, 1967-1971
- Konrad, M et al. (2012). Social Transfer of Pathogenic Fungus Promotes Active Immunisation in Ant Colonies. PLoS Biology 10(4) e1001300