Sound Perception by Two Species of Wax Moths (Lepidoptera: Pyralidae)1

Abstract

Both the greater wax moth, Galleria mellonella L., and the lesser wax moth, Achroia grisella (Fabricius), can detect sounds with their tympanic hearing organs over an exceptional frequency range of less than 20 kHz to over 300 kHz. Laser vibrometry studies showed that the tympana of both species vibrate in response to sound from 26 to 260 kHz with a peak between 55 and 80 kHz. Although the hearing range for both species is similar, behavioral responses are different. The tests also showed that both moths tilt the tympanum immediately in response to ultrasound; however, the angle and characteristics of tilting are distinctive for each species. The tympanum of the lesser wax moth tilts about 7 degrees and tends to remain somewhat tilted while continuous sound is applied. The tympanum of the greater wax moth tilts about 3 degrees, returns to the original position and tilts again repeatedly for several hours when continuous sound is applied. Tympanic vibration and tilting are important indicators that these moths respond to a wide range of ultrasonic frequencies.