Spatial correlations in laboratory insect swarms

Area of Science:

• Collective animal behavior
• Insect swarm dynamics
• Non-biting midge biology (Chironomus riparius)

Background:

• Flocks, schools, and herds display global order, unlike midge swarms.
• Midge swarm collective behaviors are typically observed only during disturbances.
• Previous studies found weak long-distance velocity correlations in quiescent midge swarms.

Purpose of the Study:

• To investigate the underlying order and collective behavior in quiescent midge swarms.
• To identify novel forms of long-range ordering in insect swarms.
• To explain the mechanisms driving midge swarm spatial organization.

Main Methods:

• Observation of laboratory-based swarms of the non-biting midge Chironomus riparius.
• Analysis of individual midge positions to determine spatial correlations.
• Modeling of swarm dynamics based on attractive and repulsive forces.

Main Results:

• Midge positions within laboratory swarms are maximally anticorrelated over long distances.
• This novel ordering was previously unobserved in collective animal movement literature.
• The observed ordering is explained by a balance between attraction to the swarm center and mutual repulsion.

Conclusions:

• Midge swarms exhibit a unique form of long-range spatial ordering.
• This ordering is driven by a dual mechanism of attraction and repulsion.
• Midge swarms are positioned at the critical point of a stable-unstable phase transition.