Courtship of Drosophila Melanogaster : Rejection Without Extrusion

Abstract

Abstract1. The experiments reported were designed to study the courtship behaviour of male D. melanogaster with virgin and inseminated decapitated females, which do not extrude their genitalia in response to courtship, and do not move. 2. Two new elements of behaviour which occur during the male's courtship were described. The names suggested for these are 'grasping' and 'rubbing'. 3. A clear distinction was seen in the behaviour of males towards virgin and inseminated decapitated females. Fewer males courted the latter, and those males which did court did so for a shorter period. 4. The courtship to the inseminated females contained a relatively lower proportion of attempted copulation than that to virgin females. 5. Operations were conducted on the tarsi of the fore legs and sex combs of the males to elucidate aspects of their possible role in courtship. 6. Males lacking both tarsi and sex combs performed very little courtship either to virgin or to inseminated decapitated females. Males with tarsi removed below the sex combs, and those with the tarsi of the hind legs removed did not court significantly less than normals, but the relative frequency of attempted copulation in courtship was changed. 7. Removal of the sex combs, leaving the tarsi intact, led to the total absence of attempted copulation, although other elements of courtship occurred frequently. 8. Hypotheses are offered concerning the evolution of the behaviour of extrusion, and concerning the possible roles of the sex combs in courtship.