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

Locusts are renowned for their coordinated locomotion, or collective marching, 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, namely: individual walking, jumping, and coordinated group marching. 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.

蝗虫以其协调运动行为——即集体行进——而闻名，其蝗蝻会集群并以同步化的方式行进。尽管学界普遍认为视觉是介导此类行为的主要通信方式，但本研究提出，机械振动或许也可在种群内部起到通信作用。本研究借助激光多普勒测振仪（laser Doppler vibrometer）与加速度计，对蝗虫行走、跳跃以及协调行进时产生的基底振动信号，从频率与振幅层面进行了量化分析。随后，研究人员通过振动发生器人工复现了此类机械信号，并将其直接施加于实验用束缚蝗虫的机械性感觉感受器之上。为量化并比较蝗虫对特定运动形式的感知能力——即个体行走、跳跃以及群体协调行进——研究人员构建了蝗虫机械响应的感觉阈值曲线。尽管个体以非同步方式行走所产生的振动低于蝗虫的感觉阈值，但本研究结果显示，蝗虫能够感知同类跳跃或群体协调行进所产生的振动信号。据此可以推测，集群中的蝗虫或可借助基底传递的机械振动实现种群内部通信，而基于振动的通信方式或许在蝗虫的集群行为与协调行进中发挥着重要作用。