REPEATED COPULATIONS AS A STRATEGY TO MAXIMIZE FERTILIZATION IN THE FLY, DRYOMYZA-ANILIS (DRYOMYZIDAE)

In the fly, Dryomyza anilis, males copulate repeatedly with the same f emale during oviposition. Each copulation bout consists of intromissio n followed by several tapping sequences during which the male touches the external genitalia of the female with his claspers. The relative f ertilization success of the last male to mate with the female increase s with the number of tapping sequences. In this study, male benefits o f repeated copulation bouts were examined by comparing matings with th e same number of tapping sequences in one and several copulation bouts . The relative fertilization success for the last male increased with successive copulation bouts. Simulated oviposition patterns showed tha t fertilization success in matings with many copulation bouts was high er than in matings with one bout only if eggs were distributed between bouts in a certain way. These predicted oviposition patterns were com pared with natural ones. Although males may benefit from repeated copu lation, females are likely to prefer matings with quick oviposition. T his intersexual conflict may also affect natural oviposition patterns. It is suggested that repeated copulation in D. anilis may have evolve d in connection with males trying to secure their paternity because fe males can discharge sperm at any moment during mating.