Ants have a dedicated brain center for interpreting alarm pheromones

A recent study published in the journal Cell on June 14 sheds light on the fascinating world of ant communication. The research, conducted by Taylor Hart of The Rockefeller University, explores how certain pheromones emitted by ants can activate a specific region of their brains and influence the behavior of an entire colony.

Ants, it seems, possess intricate societies and communication systems that rival those of humans. Throughout the course of evolution, they have developed highly sophisticated olfactory systems, enabling them to utilize various types of pheromones with distinct meanings.

The study proposes the existence of a communication center within the ant brain, akin to the human brain. This specialized region is capable of interpreting alarm pheromones, also known as “danger signals,” emitted by fellow ants. Interestingly, this communication center appears to be more advanced in ants compared to certain other insects like honeybees. Previous research has suggested that honeybees rely on multiple brain regions to coordinate their response to a single pheromone.

So, the next time you spot a solitary ant in your home, be aware that it could be the tip of the iceberg. Behind the scenes, these industrious insects are orchestrating complex chemical conversations, utilizing their remarkable brains to ensure the survival and success of their entire colony.

Colony alarm response. Credit: Lindsey Lopes

According to Daniel Kronauer, the corresponding author from The Rockefeller University, there appears to be a central hub in the ant brain where all the alarm pheromones that induce panic converge. To investigate this phenomenon, the researchers employed a specially engineered protein called GCaMP. This protein binds to calcium ions, which become active during brain activity, and produces a fluorescent compound that can be visualized using high-resolution microscopes.

During their scans, the researchers observed that only a specific region of the ant brain became activated in response to the danger signals. However, despite this localized brain activity, the ants displayed immediate and intricate behaviors, collectively termed the “panic response.” These behaviors encompassed actions like fleeing, evacuating the nest, and relocating their offspring to safer areas.

Different species of ants employ distinct pheromones to communicate various messages, depending on the size of their colonies. Taylor Hart explains that clonal raider ants, the focus of this study, typically have relatively small colonies consisting of tens to hundreds of individuals. As a result, these colonies exhibit panic responses as their alarm behavior since their primary objective is survival, and they cannot afford to risk large numbers of individuals. On the other hand, army ants, which are relatives of clonal raider ants, possess massive colonies comprising hundreds of thousands or even millions of individuals, and they tend to display more aggressive behavior.

In ant colonies, members segregate themselves based on caste and role, and ants in different castes and roles exhibit slight anatomical variations. For the purposes of this research, the scientists selected clonal raider ants due to their ease of control. They specifically focused on female worker ants, ensuring consistency and facilitating the observation of widespread patterns. By gaining a better understanding of the neural distinctions between castes, sexes, and roles, researchers hope to unravel how different ant brains process identical signals.

Taylor Hart mentions that examining the similarities and differences in sensory representations across ant species can offer valuable insights. Furthermore, Daniel Kronauer expresses interest in investigating the division of labor within ant colonies—why genetically identical individuals assume different tasks—and understanding the mechanisms underlying this division of labor.

Source: Cell Press

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