Abstract
Sperm competition in the melon fly, Dacus cucurbitae, was studied by sequential mating with normal males and virgin or 'exhausted' sterile males. Comparison of hatchabilities of eggs laid by females first mated with normal males and secondly with virgin sterile males and those for females mated in the reverse order confirmed earlier observations whcih confirmed sperm mixing. The results also proved sperm precedence of the last male and the low competitiveness of sterile male. Mating with virgin sterile males after the normal mating reduced the hatchability of eggs while mating with 'exhausted' sterile males did not. This fact suggests that the sterile spermatozoa actually plays a role in the application of the sterile male technique for melon fly eradication.
