Social interactions lead to motility-induced phase separation in fire ants

Area of Science:

• Physics
• Biology
• Collective Behavior

Background:

• Active matter systems are composed of self-propelled units.
• Motility-induced phase separation (MIPS) is a key phenomenon in active matter, typically driven by crowding or external forces.
• Previous experimental MIPS studies have not fully explored self-generated interactions within social insect colonies.

Purpose of the Study:

• To investigate fire ant colonies as a model of active matter.
• To demonstrate that social interactions in fire ants can drive motility-induced phase separation.
• To provide a unifying framework for understanding diverse active matter systems.

Main Methods:

• Observational studies of fire ant collections.
• Analysis of ant movement patterns and interactions.
• Theoretical modeling of active matter dynamics applied to insect behavior.

Main Results:

• Fire ant collections exhibit characteristics of active matter.
• Ant interactions, specifically slowing down upon approach, create an effective attraction.
• This effective attraction leads to the formation of space-filling clusters and dynamical heterogeneities, consistent with MIPS.

Conclusions:

• Social interactions in fire ants can induce phase separation, similar to physical active matter systems.
• Motility-induced phase separation provides a unifying framework for understanding collective behavior in fire ants and other active matter.
• This research bridges the gap between social insect behavior and fundamental physics principles.