Technical Abstract: Domestication of olive fruit, Olea europaea L., produced a better host for olive fruit fly, Bactrocera oleae (Gmelin), than wild olives, but fruit domestication reduced natural enemy efficiency. Important factors for selection of natural enemies for control of olive fruit fly include climate matching, alternate host risk assessments, rearing methods, and association of host and local natural enemy fauna. Molecular studies help distinguish original areas of evolution of the host, identify natural enemies, and separate sibling species and geographic strains. Host mortality may result from biological control or abiotic factors including high temperature related to natural enemy-free space. Studies of the association between natural enemies and the olive fruit fly contributes to the understanding of successful biocontrol.