Phase transition between disordered and ordered foraging in Pharaoh's ants

Area of Science:

• Behavioral Ecology
• Collective Behavior
• Insect Social Systems

Background:

• Complex collective behavior in insect societies often requires a minimum worker threshold for effective functioning.
• Understanding the transition from disordered to ordered behavior is crucial for comprehending social insect colony dynamics.

Purpose of the Study:

• To investigate the transition between disordered and ordered foraging in Pharaoh's ants (Monomorium pharaonis).
• To determine the colony size at which organized, pheromone-based foraging emerges.
• To characterize the nature of this transition, particularly under challenging foraging conditions.

Main Methods:

• Experimental observation of foraging behavior in Pharaoh's ant colonies of varying sizes.
• Analysis of foraging patterns in relation to colony size and food source accessibility.
• Comparison of observed behavioral transitions with principles of first-order phase transitions in physics.

Main Results:

• Small Pharaoh's ant colonies exhibit disorganized foraging.
• Larger colonies transition to organized, pheromone-based foraging.
• This transition is a first-order phase transition with hysteresis when food is difficult to find.

Conclusions:

• Colony size is a critical factor regulating the emergence of organized foraging behavior.
• The observed behavioral transition mirrors physical phase transitions, offering a novel framework for studying collective behavior.
• This study provides the first experimental evidence of a behavioral phase transition from maladaptive to adaptive foraging in an insect society.