Influence of Bittermelon, Momordica charantia L. (Cucurbitaceae), on Distribution of Melon Fly, Dacus cucurbitae Coquillet (Diptera: Tephritidae) on the Island of Molokai, Hawaii

Abstract

A study of trap catches and fruit samples showed a strong relationship between the distribution and abundance of the melon fly, Dacus cucurbitae Coquillet, and the abundance of cultivated hosts and feral bittermelon (Momordica charantia I.) in west Molokai. In general, the melon fly was distributed in all inhabited areas on the island of Molokai. In uncultivated pineapple fields near Maunaloa and Hoolehua, growth and fruiting of M. charantia produced large populations of D. cucurbitae. Mean rate of infestation was 21.8 melon flies/kg of Momordica and 22.1 flies/kg of cultivated cucurbits (pumpkin and watermelon). Over 8000 fruits were collected which produced 2432 D. cucurbitae pupae but no parasitoids. The high winds on west Molokai appeared to be unfavorable for Opius fletcheri Fullaway, the principal parasitoid associated with melon fly in Hawaii, but were favorable for D. cucurbitae.