Suppression of a Caribbean Fruit Fly (Anastrepha suspensa(Loew) Diptera: Tephritidae) Population through Augmented Releases of the ParasitoidDiachasmimorpha longicaudata(Ashmead) (Hymenoptera: Braconidae)

Abstract

Augmented releases of adultDiachasmimorpha longicaudata(Ashmead) to control the Caribbean fruit flyAnastrepha suspensa(Loew) were carried out in two urban Florida locations: Key Biscayne and Clewiston. In the former, 60,000 adult parasitoids/km2/week were released near host trees. Fruit fly populations during winter and much of spring appeared to be suppressed to 5–10% of levels found during a previous survey of the Key Biscayne site and a neighboring control area. Parasitism levels were difficult to quantify, but were generally higher in release areas. Sampling difficulties also create problems in demonstrating causation. The Clewiston releases were less consistent in number and size, but previous to their temporary suppression, Caribbean fruit flies were apparently also substantially suppressed. A second species of braconid,Doryctobracon areolatus(Szepligeti), common in the Clewiston area control sites, was apparently nearly eliminated from the release site. Sex ratios of wasps recovered from sampled fruit were male-biased in both release areas though the factor(s) responsible are unknown. Augmented releases ofD. longicaudatamay be particularly useful in suppressing Caribbean fruit fly populations in areas where more traditional methods such as insecticide-bait sprays and sterile male releases are impractical.