Moths fight back: arms race in the cloud forest

Moths and bats engage in a coevolutionary arm race, where the same signals bats use to find moths are being used by moths to avoid bats. Moths evolve not only behavioral but acoustic responses to avoid predation by bats. This research examines one small component of a complex, multispecies arm race between moths and bats. In this study we found that the moth Amastus hyalina displayed both flight and acoustic responses to ultrasonic stimuli. In tethered flight the tiger moth Amastus hyalina (Arctiinae) exhibits a complex array of reactions to ultrasonic tones that includes changes in flight and production of ultrasonic clicks. The changes in flight included change in wing beat frequency, amplitude of the stroke, a rotation of the wings, and deflection of the abdomen, legs, and antennae. The changes in flight displayed by moths reduce the cues that bats use for prey capture including the amplitude modulation of echoes from wingbeats. Moths produce the biggest returning echoes for frequencies between 20 to 35 kHz, which coincides with the frequencies used by most insectivorous bats in the location. The species of tiger moth that we studied is but one of many species at our field site, but we believe that similar antipredator mechanisms are widespread among tiger moths, and may also be found in other families of moths that have tympanic organs