Host Suitability of Wild Cucurbits for Melon Fly, Dacus cucurbitae Coquillett, in Hawaii, with Notes on their Distribution and Taxonomic Status

Abstract

Previous confusion in botanical and entomological literature concerning the names of certain wild hosts of the melon fly, Dacus cucurbitae Coquillett, in Hawaii is discussed, and names currently accepted as correct are provided. The correct name for both wild and cultivated forms of bittermelon is Momordica charantia I.. Most previous references to Sicyos sp. and "Sycos" as melon fly hosts in Hawaii probably represent misidentification of Cucumis dipsaceus Ehrenberg ex Spach. Rearings from collections of fruit of wild Cucurbitaceae showed that, in addition to M. charantia, C. dipsaceus, Sicyos pachycarpus Hooker and Arnott, and Coccinia grandis (I.) Voigt can serve as hosts for D. cucurbitae. Of these, C. dipsaceus and S. pachycarpus appear to be less important, as flies apparently can only develop in immature fruit, which are available for a relatively short time before becoming hard and unsuitable. However, C. grandis is a hardy, rapid-growing, weedy vine that produces abundant fruit, which is an excellent melon fly host. This vine is a relatively recent introduction into Hawaii and is presently confined to Oahu and the Kona District of Hawaii island. However, it is spreading rapidly and is likely to become a major reservoir host for the melon fly.