Field-open augmentative releases of D. longicaudata against C. capitata were assessed.
Parasitoids were reared on Sensitive Lethal Temperature Vienna-8 C. capitata strain.
Host emergence at the release plots was ca. 26% lower than that in the controls.
Between 16 and 75% of host mortality at the release plots was due to D. longicaudata.
Medfly biological control in Argentinean fruit-growing semi-arid areas is encouraged.