Auditory sensitivity of Hawaiian moths (Lepidoptera : Noctuidae) and selective predation by the Hawaiian hoary bat (Chiroptera : Lasiurus cinereus semotus)

The islands of Hawaii offer a unique opportunity for studying the auditory ecology of moths and bats since this habitat has a single species of hat, t he Hawaiian hoary bat (Lasiurus cinereus semotus), which exerts the entire predatory selection pressure on the ears of sympatric moths. I compared the moth wings discarded by foraging bats with the number of surviving moths o n the island of Kauai and concluded" that the endemic noctuid Haliophyle eu clidias is more heavily preyed upon than similar-sized endemic (e.g. Agroti s diplosticata) and adventive (Agrotis ipsilon and Pseudaletia unipuncta) s pecies.. Electrophysiological examinations indicated that, compared with sp ecies less preyed upon, H. euclidias has lower auditory sensitivities to th e bat's social and echolocation calls, which will result in shorter detecti on distances of the bat. The poor ears of H. euclidias suggest that this mo th coevolved with the bat using non-auditory defences that resulted in audi tory degeneration. This moth now suffers higher predation because it is dra wn away from its normal habitat by the man-made lights that are exploited b y the bat.