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The genetic and epigenetic variability in suitability of a host, Drosophila melanogaster Meigen, for the development of three parasitoid species (Leptopilina boulardi (Barbotin, Carton, and Kelmer-Pillault), Leptopilina heterotoma (Thompson), and Pachycrepoideus dubius Ashmead) was analyzed. The Drosophila population came from an oasis in central Tunisia, where it is infested by the three wasp species. The genetic variability of the host was analyzed by the technique of using isofemale lines. The host population exhibited no genetic variability in the degree of infestation except in the case of L. heterotoma. It did, however, show a high level of genetic variability concerning its suitability for development of the three parasitoids. The experimental conditions had a significant effect on infestation by two of the parasitoids (L. boulardi, L. heterotoma). The rates of successful parasitism were correlated only in the case of the two eucoilid parasitoids. Therefore, a single host genotype was not suitable for all three parasitoid species concomitantly. Under pressure from the three parasitoids, the host population maintained genetic variability of its response to parasitoid development.