The new work shows that the ear of the yellow underwing moth changes its frequency (pitch) sensitivity in response to sound. As a bat gets closer to a moth, both the loudness and frequency of sound increase. Surprisingly, the sensitivity of the moth’s ear to the bat’s calls also increases, as the moth ear dynamically becomes more sensitive to the frequencies that many bats use when attacking moths. Furthermore, the ear remains tuned up in this way for several minutes after the sound stops, ready in case there is another attack.
To date, this phenomenon has apparently not been reported for insects, or in fact for any other hearing system in the animal kingdom. This finding changes our understanding of the co-evolution of bats and moths—for example, as the moth cleverly tunes its ear to enhance its detection of bats, do some bats in turn modify their calls to avoid detection by moths" The authors point out that, in view of the vast diversity of bat calls, this is to be expected.