Fruit Fly Parasites and Their Activities in Hawaii

Intensive studies were made of the progress and status of the several entomophagous insects released in Hawaii to combat the Oriental fruit fly, Dacus dorsalis Hendel, the melon fly, Dacus cucurbitae Coquillett, and the Mediterranean fruit fly, Ceratitis capitata (Wiedemann).These studies were deemed essential to the effective development of the cooperative biological control program which was initiated in 1948.A total of 32 entomophagous species and varieties were released between 1947 and 1952 to supplement those which have been estab lished here for many years (table l).Thirteen of the recently-introduced species were recovered but only three, Opius longkaudatus (Ashmead)4, 0. vandenboschi Fullaway, and 0. oophilus Fullaway, became widespread and abundant.This paper presents an account of the progress of the recently released ento mophagous insects which attack tephritid fruit flies, together with information about the status of those parasites which were present before the establishment of D. dorsalis. Procedure and MethodsSince all the parasites complete their development in and emerge from fruit fly puparia, their progress was followed by determining the parasite emergence from samples of puparia formed from maggots obtained from field collected fruits.Furthermore, since practically all the parasites attack and lay their eggs either in the eggs or maggots of the fruit flies, this made it practical to either remove the maggots from the fruits or recover the full grown maggots on emergence from the fruits.Most of the data obtained on the progress of the parasites were derived from fruits in the manner described below, however, field 1 Published with the approval of the Director of the Hawaii Agricultural Experiment Station as Technical Paper No. 318. 2 Now Associate Entomologist, University of California, Citrus Experiment Station. 3 The authors are grateful to the many individuals in the Entomology Department of the University of Hawaii and those associated with the several cooperating agencies who have aided in this study.4 Fullaway (1953) described 4 varieties of Opius longkaudatus (Ashmead).The variety malaiaensis is the only one of the 4 that became numerous and unless stated otherwise, subse quent references to 0. longkaudatus in this paper are to that variety.