Prolonged mating in the melon fly,Dacus cucurbitae (Diptera: Tephritidae): Competition for fertilization by sperm-loading

Summary Males of the melon flyDacus cucurbitae mate with females for 10 hours or more, usually starting at dawn and terminating at dusk. We tested the sperm-loading hypothesis (Dickinson, 1986) that males remaining with females for long periods of time benefit by numerically overwhelming the sperm of their competitors. The amount of sperm transferred to a female increased with time after mounting. The number of feamles which laid eggs at least once during experimental periods was positively correlated with mating duration. Oviposition rate was positively correlated with mating duration, as well. Egg hatchability was not influenced by mating duration. Mating duration was a major determinant of paternity when females were doubly mated with one male for 6 hours and another male for 2 hours. Females whose first matings were longer showed first male sperm predominance, while females whose second matings were longer showed last male sperm predominance. The adaptive significance of prolonged mating by male melon flies is discussed.