A Progress Report on the Sterile Insect Releases of the Melon Fly, Dacus cucurbitae COQUILLETT (Diptera : Tephritidae) on Kume Is., Okinawa

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Abstract
After reducing the population density of the melon fly, Dacus cucurbitae COQUILLETT, on Kume Is. with poisoned cue-lure and protein bait spryas, release of sterile flies was commenced on February 13, 1975. A total of 73, 384, 000 pupae were released from 170-200 points from February, 1975 to January, 1976, and the estimated number of sterile flies which emerged was 44, 600, 000. The ratio of marked to unmarked males (M/U) caught in monitor traps was 1.83 in March, thereafter it decreased, and in July the ratio was 0.06. During the the course fo the examination of M/U, detection of marked flies under an ultraviolet lamp became difficult due to the natural fluorescence occurred in the flies since June. When we estimate the ratio of sterile to normal males (S/N) by using FRIED's equation based on hatchability of eggs, and by the ratio of females which oviposited eggs to the total number of females collected on Kume Is. and Naha (control area), these two values agreed well and were always higher than M/U. If we adopt the estimated S/N, the ratio increased since Auguest and, in March, 1976, reached 2.1. The hatch of eggs laid by females captured on Kume Is. decreased from 91% in July, 1975 to 29% in March, 1976.