Researchers have found that when foraging ants look for food, they create pheromone trails connecting their colony to various food sources if they are available. This is the first model that explains how these trails to multiple food sources come about.
It’s a familiar scene—ants moving in a straight line around obstacles from their nest to a food stash, following scent trails placed down by scout ants. But what occurs when those scouts discover a rich food source?
A group of researchers from Florida State University, led by Bhargav Karamched, an Assistant Professor of Mathematics, has made significant discoveries about foraging ant behavior. They found that ants will form pheromone trails that link their colony to multiple food locations when multiple options are present. This research has resulted in the creation of the first model to explain how these trails are formed to numerous food sources.
Karamched, who is also a faculty member at FSU’s Institute of Molecular Biophysics, along with graduate student Sean Hartman from the music arts administration program, published their findings in the Journal of Mathematical Biology in September under the title “Walk This Way: Modeling Foraging Ant Dynamics in Multiple Food Source Environments.”
“Mathematics has great power; it allows us to create models that replicate experimentally observed data and make specific predictions about future outcomes,” Karamched said. “In this study, we found something that hadn’t been captured well by previous models: when an ant has access to multiple food sources, it will start by creating multiple trails to each location.”
Karamched applies modeling, mathematical analysis, and computer simulations to address questions within neuroscience and cell biology. Hartman, who completed his dual bachelor’s degrees from FSU in Mathematics and Music in May 2023, plans to finalize his master’s degree studies this spring. He approached Karamched to help with a Directed Individual Study (DIS), which offers students in FSU’s Honors Program a chance to engage in hands-on research with faculty members and provide him an avenue to delve deeper into mathematical modeling.
“I have always been passionate about mathematics and wished to engage in research, but I never had that opportunity until now,” Hartman shared. “The ant trail research that Dr. Karamched shared piqued my interest, which led me to explore and develop models based on this prior work.”
Foraging for resources is vital for an ant colony’s survival. Ants use pheromones to organize themselves. When an ant finds a food source, it releases a chemical trail to guide others. Using computer simulations that mimic ants foraging for food, as well as stochastic modeling and a system of partial-differential equations, the researchers noted that over time, ants tend to move towards the food source that is closest to their nest when faced with multiple options.
“For this study, we categorized the ants into two groups: foragers and returners,” Karamched explained. “These groups act differently; foragers roam in search of food, while returners head straight back to the nest after finding food, resulting in less random motion. This allows us to predict with complete accuracy their actions and destinations.”
The team, including Shawn Ryan, an associate professor at the Department of Mathematics and Statistics at Cleveland State University, analyzed the concentration of pheromones that ants emit to signal the presence of food to others. The models were based on the pheromone dynamics, showing that returning ants would release fewer pheromones, depending on how near the food source was to the nest. A higher pheromone concentration results in a stronger scent for other ants to follow, which is crucial when food is farther away from the nest.
“Once I finalized and validated my code, the various trail patterns became clear and understandable,” Hartman noted. “It was fascinating to observe how equally distanced food sources could maintain multiple trails at equilibrium. However, if one source was just slightly closer to the nest, the ants would eventually converge onto a single trail to that closer source. It was rewarding to see that all our hard work had paid off.”
The model presented in this study is straightforward and can be applied to other organisms and biological systems that utilize pheromones for communication. This includes bacteria, slime molds, various insects, fish, and even certain reptiles and mammals.
“The foundation for understanding this collective behavior is rooted in the basic pheromone concentration gradient, from which further analysis can be done,” Karamched said. “Using chemical signaling to communicate enables different organisms to coordinate their activities over vast areas, which is truly captivating.”
