Have you ever observed an ant in your home only to discover that the entire colony moved in a week later? Only a few of these ants are caught by the traps you set, but the rest of the colony soon vanishes on its own. Now, a study that was published on June 14 in the journal Cell investigates how certain danger-signaling pheromones, which are the scent markers that ants use to communicate with one another, can change the behavior of an entire nest by activating a specific part of the ants’ brains.
Lead author Taylor Hart of The Rockefeller University states, “Humans aren’t the only animals with complex societies and communication systems.” Compared to other insects, ants have evolved extremely complex olfactory systems that enable them to communicate with a wide variety of pheromones that can convey a variety of meanings.
“Ants have evolved extraordinarily complicated olfactory systems compared to other insects, which allows them to communicate using many different types of pheromones that can imply different things. Humans aren’t the only animals with intricate communities and communication systems.”
Lead author Taylor Hart of The Rockefeller University.
According to the findings of this study, unlike humans, ants possess their own distinct communication center within their brains. This center is capable of interpreting other ants’ “danger signals,” or alarm pheromones. This part of their brain may be more advanced than that of some other insects, like honeybees, which, according to previous research, instead use many different parts of their brain to work together to respond to a single pheromone.
Response to a colony’s alarm. Credit: According to corresponding author Daniel Kronauer of The Rockefeller University, “There seems to be a sensory hub in the ant brain that all the panic-inducing alarm pheromones feed into.” Lindsey Lopes
The brain activity of clonal raider ants that were exposed to danger signals was scanned by the researchers using an engineered protein called GCaMP. The fluorescent chemical compound that results from GCaMP’s binding to calcium ions, which are triggered by activity in the brain, can be observed using high-resolution microscopes made for viewing them.
The researchers discovered during the scans that while the ants still displayed immediate and complex behaviors in response to danger signals, only a small portion of their brains lit up in response. Because they involved evacuating the nest, fleeing, and transporting their offspring to a safer location, these behaviors were referred to as the “panic response.”
In addition, different species of ants with varying colony sizes communicate via a variety of pheromones. According to Hart, “We think that in the wild, clonal raider ants typically have a colony size of just tens to hundreds of individuals, which is pretty small in terms of ant colonies.” Because their primary objective is to escape and survive, these small colonies frequently exhibit panic responses and alarm behaviors. They cannot put many people at risk. The cousins of the clonal raider ant, army ants, can be much more aggressive and have massive colonies of hundreds of thousands or millions of individuals.
Regardless of the species, ants in a colony are divided into castes and roles, and the bodies of ants in different roles and castes are slightly different. The researchers chose clonal raider ants as the species for this study because they are simple to control. Female worker ants, which were of the same sex and belonged to the same caste and role, were used to guarantee consistency and make it simpler to observe widespread patterns. Researchers may be able to better comprehend how distinct ant brains process identical signals once they have a clearer understanding of the neural differences between castes, sexes, and roles.
According to Hart, “We can begin to look at how these sensory representations are similar or different between ants.” “We’re looking at the division of labor,” Kronauer states. Why do members of the same genetic family take on different roles within the colony? How does this labor division function?”
More information: Daniel J. C. Kronauer, Sparse and stereotyped encoding implicates a core glomerulus for ant alarm behavior, Cell (2023). DOI: 10.1016/j.cell.2023.05.025. www.cell.com/cell/fulltext/S0092-8674(23)00544-5
