ABSTRACT The West Indian fruit fly, Anastrepha obliqua (Macquart), infests numerous fruit species, particularly Anacardiaceae and most importantly mango (Mangifera indica L.). Widespread in the Neotropics, it was first reported in Hispaniola nearly 70 years ago. Continental populations are attacked by the opiine braconid parasitoids Utetes anastrephae (Viereck) and Doryctobracon areolatus (Szepligeti). Largely sympatric, the two species co-exist through microhabitat specializations based on different ovipositor lengths and asymmetries in larval competitive abilities during multiparasitism. Utetes anastrephae, but not D. areolatus, is apparently native to the Dominican Republic. Since the two parasitoids share an evolutionary history over a substantial portion of their distributions it was proposed that 1) D. areolatus would find the Dominican environment suitable, as does U. anastrephae; and 2) that there would be no negative interactions when the two species were reunited and overall parasitism would inc...