The Remarkable Pheromone Response and Communication in Ant Brains

Caption: A wild type ant pupa surrounded by transgenic clonal raider ant pupae. Image credit: Taylor Hart

Ants possess a unique communication processing center that sets them apart from other social insects.

A recent study has shed light on how ants utilize specific pheromones to communicate danger, triggering intricate responses such as nest evacuation and protection of offspring. These responses vary depending on the size of the ant colony, prompting further investigation into how different ant groups process identical signals.

Have you ever observed a single ant in your home, only to discover that the entire colony has relocated within a week? Despite capturing only a few ants in your traps, the rest of the colony mysteriously vanishes. On June 14, a study published in the journal Cell explored how certain pheromones, known as danger-signaling pheromones, activate a specific region in ant brains, effectively influencing the behavior of an entire nest.

“Complex societies and communication systems are not exclusive to humans,” says Taylor Hart, the lead author from The Rockefeller University. “Over time, ants have evolved highly sophisticated olfactory systems compared to other insects. This enables them to communicate using various types of pheromones, each conveying distinct meanings.”

The study suggests that ants possess their own communication center within their brains, akin to humans. This center interprets alarm pheromones, also known as “danger signals,” emitted by other ants. This section of their brain appears to be more advanced than that of certain insects like honeybees, which previous research has suggested rely on multiple brain regions to coordinate responses to a single pheromone.

Daniel Kronauer, the corresponding author from The Rockefeller University, explains, “There appears to be a sensory hub in the ant brain that receives all panic-inducing alarm pheromones.”

To study the brain activity of clonal raider ants exposed to danger signals, the researchers employed a modified protein called GCaMP. GCaMP attaches itself to calcium ions that become active during brain activity, producing a fluorescent chemical compound visible under high-resolution microscopes adapted for this purpose.

During the scans, the researchers observed that only a small region of the ant brains illuminated in response to danger signals. Nevertheless, the ants exhibited immediate and intricate behaviors, collectively referred to as the “panic response.” These behaviors included fleeing, nest evacuation, and moving offspring to safer locations.

Different ant species, based on their colony sizes, employ distinct pheromones to communicate various messages. Hart explains, “In the wild, clonal raider ants typically have small colonies comprising tens to hundreds of individuals, which is relatively small for ant colonies. Such small colonies often exhibit panic responses as their defensive behavior, aiming primarily to escape and survive. They cannot afford to risk a large number of individuals. On the other hand, army ants, cousins of clonal raider ants, have massive colonies consisting of hundreds of thousands or even millions of individuals, and they tend to display more aggressive behavior.”

Regardless of the species, ants within a colony divide themselves into castes and assume different roles, each with slight anatomical variations. For this study, the researchers chose clonal raider ants due to their ease of control. They specifically used female worker ants of a single sex, caste, and role to ensure consistency and facilitate the observation of widespread patterns. Once researchers gain a better understanding of the neural variances between castes, sexes, and roles, they can delve deeper into comprehending how different ant brains process identical signals.

Hart notes, “We can now examine the similarities and differences in sensory representations among ants.” Kronauer adds, “Our focus is on the division of labor. Why do genetically identical individuals perform different tasks within the colony? How does this division of labor operate?”

For more details on this research, refer to the article “World’s First Transgenic Ants Reveal How Colonies Respond to an Alarm.”

Reference: “Sparse and stereotyped encoding implicates a core glomerulus for ant alarm behavior” by Taylor Hart, Dominic D. Frank, Lindsey E. Lopes, Leonora Olivos-Cisneros, Kip D. Lacy, Waring Trible, Amelia Ritger, Stephany Valdés-Rodríguez, and Daniel J.C. Kronauer, 14 June 2023, Cell.
DOI: 10.1016/j.cell.2023.05.025

This work received support from the National Institute of General Medical Sciences of the National Institutes of Health, the National Institute of Neurological Disorders and Stroke, the Howard Hughes Medical Institute, the National Science Foundation, and the Kavli Neural Systems Institute.

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More about Ant communication

• Study: “Sparse and stereotyped encoding implicates a core glomerulus for ant alarm behavior”

  • Link: DOI: 10.1016/j.cell.2023.05.025

• Article: “World’s First Transgenic Ants Reveal How Colonies Respond to an Alarm”

  • Link: [Article Link](insert article link if available)