Rejection Responses By Female Drosophila Melanogaster : Their Ontogeny, Causality and Effects Upon the Behaviour of the Courting Male

Abstract

1. The experiments reported were designed to study the causes and consequences of various responses emitted by female Drosophila melanogaster in relation to the behaviour of the courting male. 2. The female responses studied were: flicking, kicking, curling, extruding and fending. These were recorded simultaneously with male behaviours, from single pair courtships, onto a multi-channel time-event recorder. The male behaviours recorded were: orientation, vibration, licking, attempted copulation, locomotor activity, preening and male stationary. 3. Four groups of female were examined for modal response and the associated pattern of male behaviour. The groups were selected in order to elucidate developmental changes in the nature of the rejection response and any changes consequent upon fertilisation. 4. Three methods of analysis were employed. A description of the frequency response for each group of females was followed by an analysis of the temporal pattern of male behaviours associated with the modal response. 5. A finer resolution of the relationship between male and female behaviour was obtained by a transitional analysis of the females' responses with the various male activities. 6. Both fertilised females and aging virgins showed extrusion of the ovipositor as the modal response. 7. Fending and curling occurred rarely and did not lead to any changes in male behaviour. 8. Kicking and flicking were deduced to be responses to different aspects, or intensities of courtship. Kicking was largely contingent upon attempted copulation, whereas flicking resulted from licking and sometimes non-courtship behaviours. Flicking is also correlated with a high level of locomotor activity. 9. Extrusion by aged virgins and fertilised females was associated with the wing vibration display of the male, and in both groups was followed, rather than preceded, by attempted copulation. However, the aged virgins were receptive, whereas the fertilised females were not. Extrusion was interpreted as a means of physically preventing copulation, rather then producing long term inhibition of courtship. 10. It is suggested that the ontogeny of extrusion is associated with development in the female's egg producing system. 11. The temporary reluctance of the 3 day old virgin females, exemplified by their kicking, was discussed in the context of EWING'S (1969) concept of a 'reference oscillator' used by the female to identify the auditory signals produced by a conspecific.