A study on the ecology of melon fly.
Lee H. S.
Author Affiliation: Fengshan Tropical Horticultural Experiment Station, Taiwan Agricultural Research Institute.
Plant Protection Bulletin, Taiwan 14 : 175-182
Abstract : Laboratory and field studies were carried out in Taiwan in 1969-72 on the ecology of Dacus cucurbitae Coq., an important pest of cucurbits. All stages of the Tephritid were present in the field in southern areas throughout the year. Population size was greatest during June-July when crops of watermelon and muskmelon [Cucumis melo] in riverine areas and rice-fields were fruiting, decreased sharply during the rainy season in August-September, gradually increased again during October-February when watermelon and cucumber were being grown in riverine areas and rice-fields, and finally decreased during March-May when the spring watermelon crop was immature. As judged by the number of pupae/100 g fruit of eight kinds of field-grown cucurbits, the fly preferred muskmelon, oriental pickling melon [Cucumis cocomon] and bitter cucumber [Citrullus colocynthis] the most; it apparently preferred to oviposit in certain kinds of cucurbits and younger fruits because the skins were smoother and softer. Collections in traps baited with male attractant (98% anisylacetone [4-(p-methoxyphenyl)-2-butanone] and 2% technical dichlorvos (DDVP)) and hung under different types of trees showed that the flies were commonest on guava, some Citrus species and mango; the adults fed on honeydew produced by aphids and mealybugs on these trees and migrated to cucurbits only for oviposition. Pruning guava trees in January was found to eliminate the fly. Trap collections showed that when the temperature at 9 a.m. was below 20 deg C, from then until noon was the period of greatest male activity, followed by the period from noon to 3 p.m. When it was 21-25 deg C, 9 a.m. to noon was still the period of greatest activity, followed by the period from dawn to 9 a.m. When it was above 25 deg C, the period from dawn to 9 a.m. was the period of greatest activity, followed by 9 a.m.-noon.