Scientists have suspected for a long time that ants use body odor in order to organize their colonies. Now researchers have discovered that ants even use their sense of smell to distinguish intruders from fellow-ants by identifying chemical compounds on ants’ bodies that are different. The study conducted by researchers from the University of California at Riverside was published in the journal Cell Reports.
The ants’ outer shells have their own body odor. Moreover the castles in a colony of ants have a different body odor. This enables ants to distinguish the workers from the queen. As a natural consequence workers from a colony have a slightly different smell compared to workers from another colony.
The lead author of the study neuroscientist Anandasankar Ray explained that it has always been a curiosity to know how social insects such as ants can live in such massive colonies in which they have very specialized tasks. The answer lies in the fact that ants communicate very well, but unlike humans that use language ants use chemistry. Ray further developed adding the following:
These guys can smell almost any hydrocarbon we offered to them. Along with it, we also discovered not only did they have a very extensive olfactory system, they are also able to distinguish very well between very closely related compounds. They are able to tell the difference between a hydrocarbon with 25 carbon atoms versus 24 atoms.”
For the study researchers used an electrophysiology method with which they analyzed the electrical activity of the hairs on the worker ants’ antennae when they were exposed to hydrocarbon chemicals. This works more or less like an EKG for chemicals. Afterwards the scientists trained the ants to link particular hydrocarbon chemicals to sugar water. The outcome was that the ants were able to make the difference among chemicals.
In spite of the fact that the body odor is relatively the same ants are endowed with a nuanced perception of detection. When they sense an outsider they are able to tell it apart immediately. According to Ray this can lead to an aggressive behavior and in most cases the intruder is killed.
Now that researchers are one step closer in understanding the functional roles of the insects’ odorant receptors they believe that they could even detect those that identify pheromones from the queen that keeps the colony in order.
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