A tentative role of vibration-based communication in locust collective behavior

Abstract

Abstract Locusts are renowned for their coordinated locomotion, in which juveniles swarm and walk in a synchronized fashion. While it is generally accepted that vision is the main form of communication enabling this behavior, it is suggested here that mechanical vibrations may also contribute to communication within the group. Using a laser Doppler vibrometer and accelerometer, the substrate vibration signals generated by locust walking, jumping, and coordinated marching were quantified in terms of frequency and amplitude. These mechanical signals were then artificially produced by a vibration generator and directly applied to the mechanical sensory receptors of experimental tethered locusts. A sensory threshold curve of the mechanical response of the locusts was established, in order to quantify and compare their ability to sense specific forms of locomotion. While the vibrations generated by individuals walking in an unsynchronized fashion were below the sensory threshold of the locust, our findings indicate that locusts are capable of sensing the vibration signals generated by locust hopping or by the collective marching of conspecifics. It is suggested that locusts in a swarm may use substrate-borne mechanical vibrations for communication within the group, and that vibration-based communication may have a role in locust collective behavior and coordinated marching.