THE ULTRASONIC MATING SIGNAL OF THE MALE LESSER WAX MOTH

Male lesser wax moths, Achroia grisella (Fabricius) (Lepidoptera: Pyra lidae: Galleriinae), produce both a pheromone and an ultrasonic acoust ic signal that function in mate attraction. We describe the structure of the acoustic signal, in particular the interpulse intervals and the spectral properties of the pulses. The song consists of a train of ul trasonic pulses, The interpulse interval is usually bimodally distribu ted, but can sometimes be unimodal. This reflects variation in the dur ation of the up and down wing strokes. The pulses are also usually pai red which can produce multimodality of the interpulse intervals. These paired pulses probably reflect wingbeat asynchrony because they are n ot found in males in which the signalling capability of one wing's sou nd producing structure is abolished. The song's frequency spectrum has peaks at around 80 and 100 kHz. The first peak varies significantly w ith male size, with larger males producing a lower frequency peak. The second peak is associated with male age, with 1-day-old males produci ng songs with a lower frequency second peak. Thus the ultrasonic song of lesser wax moths is more complex in structure than previously repor ted and could provide potentially important cues to females. However, the ability of females to discriminate such detail is not known.