SEXUAL CONFLICT IN THE DUNG FLY SEPSIS-CYNIPSEA

1. The interests of a male and female over whether mating should occur are often in conflict and in insects conflict resolution usually favours the female. 2. A male dung fly Sepsis cynipsea guards a female while she oviposits in fresh cow dung. 3. The amount of time a female spends laying depends only on the number of eggs laid. 4. When she leaves the dung. there is a conflict over whether or not mating should occur. 5. A discriminant analysis shows that features of both the female and male behaviour influence the outcome of the conflict. The proportion of time the female spends shaking to dislodge the male and how long she spends laying were more important than the male behaviour apparently aimed at establishing genital contact. 6. If a pair went on to copulate, only the duration of the conflict influenced the copula duration. 7. We conclude that the female largely determines if copula occurs, possibly on the basis of her sperm reserves, but if copula does take place then the male determines the duration. 8. A female may in general avoid copula because of the risk of internal injury by the male's armoured genitalia.