Migrating locusts can detect polarized reflections to avoid flying over the sea

Area of Science:

• Entomology
• Animal Behavior
• Sensory Ecology

Background:

• Desert locusts (Schistocerca gregaria) undertake long-distance migrations in massive swarms.
• Locust swarms have been observed to alter flight paths to avoid crossing bodies of water.
• Understanding navigation and avoidance behaviors in migrating insects is crucial for ecological studies.

Purpose of the Study:

• To investigate the sensory mechanisms underlying locusts' avoidance of flying over water.
• To determine if polarized light reflections from water surfaces play a role in this behavior.
• To understand the ecological implications of this avoidance behavior for locust migration.

Main Methods:

• Field observations of a locust swarm near the Gulf of Aqaba.
• Laboratory experiments using tethered locusts and controlled light-reflecting surfaces.
• Comparative choice experiments with non-polarizing and polarizing reflecting surfaces.

Main Results:

• Locust swarms were observed to fly along the coast rather than over the Gulf of Aqaba.
• Tethered locusts demonstrated avoidance of flying over a light-reflecting mirror.
• Locusts showed a preference for flying over non-polarizing surfaces compared to surfaces reflecting polarized light.

Conclusions:

• Locusts possess the ability to detect polarized light reflected from water bodies.
• This detection mechanism enables locusts to avoid crossing water, particularly at lower flight altitudes.
• The findings provide insights into the navigation strategies of migrating insects and their interaction with the environment.