Why do these beetles emit ultrasound aimed at bats?

When nocturnal tiger beetles (Cicindelinae) detect the presence of bats, they emit ultrasonic signals. But what do they actually aim to achieve against their predator with this sound strategy?


For more than three decades, scientists have wondered about the function of the sounds emitted by tiger beetles in response to bats. A recent study led by Harlan Gough at the Florida Museum of Natural History has finally shed light on this mystery. While these sounds might potentially draw more attention from bats, the beetles gain a significant advantage.

Researchers confirmed that these beetles produce ultrasound in reaction to bat attacks. In the lab, they observed that seven species of tiger beetles moved their elytra to create a noise perceivable by bats. These vibrations, inaudible to humans, are perfectly captured by the nocturnal predators.

However, unlike some moths that use complex signals to jam the echolocation of bats, the ultrasound signals of tiger beetles are simpler. The answer lies in acoustic mimicry. By imitating the ultrasonic signals of toxic moths, tiger beetles hope to trick bats into thinking they are also harmful. This strategy provides them with a certain level of protection against their predators.

However, this sophisticated adaptation is not universal among tiger beetles. Diurnal species, which are not subjected to bat predation pressure, do not react in the same way. They have lost this ultrasonic emission capability, demonstrating the importance of selective pressure in the evolution of behaviors.