New research reveals secrets about locust swarm movement

A team of researchers, including Greg Sword, Ph.D., Regents Professor and Charles R. Parencia Chair in Cotton Entomology in the Texas A&M College of Agriculture and Life Sciences Department of Entomology, is challenging the long-standing theories about how order emerges from disorder in animal collectives.

Sword, along with a team of researchers from the Max Planck Institute of Animal Behavior and Centre for the Advanced Study of Collective Behavior at the University of Konstanz, Germany, recently published "The behavioral mechanisms governing collective motion in swarming locusts." This study proposes that locusts move in an uncoordinated version of follow-the-leader behavior rather than a synchronized collective motion, as previously believed.

Greg Sword, Ph.D., studies desert locusts and other swarming insects like crickets and is a researcher in the Behavioral Plasticity Research Institute at Texas A&M University. New research provides a new, science-based theory about how these pests move as a collective. (Sam Craft/Texas A&M AgriLife)

Finding patterns in locust swarm behavior

Environmental factors like topography or food availability may influence the direction of travel for locusts at the head of the swarm, Sword said. But the swarm movement is ultimately dictated by individual locusts reacting to their nearest neighbors.

Desert locusts, one of 20 locust species, undergo a dramatic transformation called locust phase polyphenism -- a density dependent shift that alters their biology, morphology, color and behavior.

When populations are low, they remain solitary and avoid each other. But when densities increase, they become highly social, forming massive swarms that migrate. These swarms can cause billions of dollars in agricultural damage and lead to food insecurity that spans multiple continents.

"Patterns emerge at the group level as they interact with their neighbors," Sword said. "They're all acting in their own interest but are all following the same rules that create the pattern of movement. Knowing how these swarms move can help us predict where they are going, which could revolutionize the way we try to stop their devastating march."

New theory could help mitigate locust damage

This study's insights could improve locust monitoring and intervention strategies, helping minimize their agricultural production and habitat.

Sword, who is also a member of the Behavioral Plasticity Research Institute at Texas A&M, said the findings could help researchers in North America better understand Central American and South American locust species and other swarming insects like Mormon crickets.

"Do those species have the same behavioral mechanism?" he asked. "We're uniquely positioned here at Texas A&M to start asking those questions. It's crucial to find answers because, while the U.S. doesn't currently face locust swarms, the Central American locust has swarmed within 150 miles of the Texas-Mexico border."