Ant pupae, the immature stage of ants, exhibit a remarkable form of self-sacrifice to protect their colonies from disease. Researchers at the Institute of Science and Technology Austria (ISTA) have uncovered a unique mechanism where infected ant pupae release specific scents that signal their imminent death, prompting worker ants to take action. This behavior not only safeguards the colony but also aids in the survival of shared genetic material.
When an ant pupae becomes infected with an incurable illness, it emits a distinctive scent detectable only from the exterior of its cocoon. Worker ants, upon detecting this signal, remove the cocoon and create small openings in the pupae’s body by biting. Subsequently, they apply formic acid, a natural antimicrobial substance produced by the ants, to disinfect the infected pupae, leading to its death.
According to Erika Dawson, the first author of the study, “What appears to be self-sacrifice at first glance is, in fact, also beneficial to the signaler: it safeguards its nestmates, with whom it shares many genes.” By alerting the colony to the presence of a deadly infection, these terminally ill ants contribute to the overall health of the colony, which can then continue to thrive and produce new generations.
Ants Functioning as a Superorganism
The findings support the concept of an ant colony operating as a superorganism, where individual ants behave similarly to cells within a body. The actions of worker ants during this disinfection process mirror how immune cells respond to diseased cells in humans, guided by chemical signals. This phenomenon is known in immunology as the “find-me-and-eat-me signal.”
To validate their findings, the ISTA team, along with Thomas Schmitt from the University of Würzburg, conducted an experiment in which they transferred the scent molecules from infected ant pupae to healthy ones. The worker ants responded by destroying the pupae that emitted the disease-associated scent. Notably, the researchers found that only worker ant pupae released this particular scent, while queen ant pupae did not. The researchers hypothesize that queen pupae possess stronger immune systems, allowing them to better withstand infections.
Implications of Altruistic Behavior in Ants
These research findings align with earlier studies indicating that ants infected with fungal spores engage in social distancing from their nestmates, even altering their nesting habits by constructing separate entrances and tunnels. Additionally, it is already established that ants nearing the end of their lives tend to isolate themselves from the colony, a behavior known as “terminal altruism.”
Published in the journal Nature Communications, this study titled “Altruistic disease signaling in ant colonies” sheds light on the intricate social behaviors of ants and their strategies for maintaining colony health. The research highlights the fascinating dynamics within ant societies and their ability to function collectively in the face of disease, illustrating the complex relationships that facilitate both individual and communal survival.
