A team of scientists has discovered the system that ants use to determine who belongs to the colony.
Ants can update their internal model of who belongs in the colony throughout adulthood while maintaining an intrinsic recognition of their own identity. genotype.
According to , the ability to instantly distinguish nestmates from strangers who might invade the colony is crucial for ants.
In new, published this month in Current Biologywe observed how clonal invasive ants update their perception of the identity of their nestmates throughout adulthood through repeated exposure, while maintaining a recognition of their relatives.
“We have long known that ants are good at distinguishing between an ant from a different colony and one from their own, but little was known about the flexibility of this behavior,” says the study’s lead author, Daniel Kronauer.
Experts turned to the clonal invasive ant (Ooceraea biroi). This species reproduces asexuallyallowing them to generate genetically identical ants from different strains. By combining these lineages, they were able to build mixed colonies and study how ants learn and update social signals.
Then, the chemical analysis revealed that colonies share the same set of chemical compounds, but that each colony has a distinct odor by combining them in different proportions.
The researchers then introduced individual ants of other genotypes into standardized colonies and recorded aggressive behaviors, such as biting. These tests confirmed that the ants consistently attacked foreign genotypes.
By placing young ants, whose chemical profiles were still little noticed, in strange colonies, they found that prolonged exposure could reshape their olfactory profile and behavior.
After a month, these ants chemically resembled their host colonies and did not show aggression towards them when tested separately — similar to ants born in the colony.
Even ants separated from their relatives still accepted ants with their own genotype, suggesting that experience can enhance recognition but cannot replace an ant’s sense of identity.
If contact between the newcomer and the host colony was interrupted, aggression returned in about a week. Over time, the ants’ chemical profile also returned to its original form, eventually leading their host nestmates to attack them.
At the same time, brief, occasional encounters were sufficient to maintain tolerance, suggesting that the effect may involve a longer-lasting olfactory memory rather than a short-lived sensory desensitization that typically disappears within minutes or hours, as the ants maintained tolerance even after five days of total separation.
The phenomenon echoed what is observed in the immune system, where repeated, low-level exposure to a foreign signal can gradually dampen defensive responses.
For example, when patients are given small, controlled doses of a substance like pollen, their immune system slowly learns to tolerate it rather than creating an allergic reaction.
Ants appear to behave in a similar way: individuals consistently exposed to strange odors gradually stop treating them as threats, while occasional meetings were enough to maintain this tolerance.
“Now we can combine the neurobiological tools with this behavioral system and visualize neural activity as an ant encounters a nest member or a stranger. With this information, we can begin to question where learning and adaptation occur in the brain,” concludes Kronauer.
Ultimately, the results provide a behavioral basis for future experiments that could reveal where in the brain this social learning occurs.
