BAT-DEAFNESS IN DAY-FLYING MOTHS (LEPIDOPTERA, NOTODONTIDAE, DIOPTINAE)

Assuming that bat-detection is the primary function of moth ears, the ears of moths that are no longer exposed to bats should be deaf to ech olocation call frequencies. To test this, we compared the auditory thr eshold curves of 7 species of Venezuelan day-flying moths (Notodontida e: Dioptinae) to those of 12 sympatric species of nocturnal moths (Not odontidae: Dudusinae, Noctuidae and Arctiidae). Whereas 2 dioptines (J osia turgida, Zunacetha annulata) revealed normal ears: 2 (J. radians, J. gopala) had reduced hearing at bat-specific frequencies (20-80 kHz ) and the remaining 3 (Thirmida discinota, Polypoetes circumfumata and Xenorma cytheris) revealed pronounced to complete levels of high-freq uency deafness. Although the bat-deaf ears of dioptines could function in other purposes (e.g., social communication): the poor sensitivitie s of these species even at their best frequencies suggest that these m oths represent a state of advanced auditory degeneration brought about by their diurnal life history. The phylogeny of the Notodontidae furt her suggests that this deafness is a derived (apomorphic) condition an d not a retention of a primitive (pleisiomorphic), insensitive state.