WING-FLICK SIGNALS IN THE COURTSHIP OF THE AFRICAN CAVE CRICKET, PHAEOPHILACRIS-SPECTRUM

The male of the African cave cricket Phaeophilacris spectrum (Saltator ia: Grylloidea: Phalangopsidae) possesses tegmina without stridulatory organs, and both females and males lack tympanal organs. Therefore ac oustic communication in the usual sense, which is typical for most cri ckets, is absent in this species. However, adaptations of the wing art iculation allow the males to hick their wings forward over their heads . During courtship these movements are performed in series of 4-5 wing -flicks at a rate of 8-12 Hz (called wing-flick series = WFS) which el icit low-frequency air movements. Such signals may have taken over the functional significance of an acoustic 'courtship song'. A quantitati ve analysis of the cricket's behaviour showed that in terms of frequen cy and total duration, 'wing-flick series' and 'rocking' behaviour are the most prominent signals of the the male's courtship display. Moreo ver, analysis of the spatial relationships between male and female dem onstrates that the wing-flicking is directed towards the female. The r esponse of a female to a wing-flicking, courting male seems mainly to be calmed down and to reach a passive, receptive state, necessary for subsequent copulation. Females confronted with a male's courtship disp lay exhibited a significantly higher threshold to disturbing stimuli t han uncourted ones.