The endoparasitoid Asobara citri avoids Drosophila melanogaster immune defenses, thanks to immune suppressive effects. We investigated whether this parasitoid could also circumvent the immune reaction of D. simulans, a sibling species of D. melanogaster. The rates of infestation, successful parasitism, total encapsulation and mortality were measured after complete development of both D. melanogaster and D. simulans larvae parasitized by A. cirri. Results showed that the parasitoids were almost never encapsulated in D. melanogaster larvae, while 45 % were encapsulated in D. simulans. A. citri induced a targeted disruption of the hematopoietic organs and a decrease of the hemocytes load in host larvae of both species. Despite such disruptive immune effects most D. simulans larvae succeeded in encapsulating A. citri eggs. probably thanks to their ability to immediately mount a capsule after infestation. This work brings some insight into the diversity of the immune potentials evolved by Drosophila species towards parasitoids. [copyright] 2004 Elsevier Ltd. All rights reserved Drosophila melanogaster (Drosophilidae) : Host Drosophila simulans (Drosophilidae) : Host Asobara citri (Braconidae) : Parasite Circulatory system; Haemolymph; Life cycle and development; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Immunology and repair mechanisms; Tissue reactions Asobara citri; Development; Dipteran hosts; Host circumvention of endoparasitoid immunosuppressive effects; comparative study; Drosophila melanogaster & Drosophila simulans Drosophila melanogaster; Drosophila simulans; Haemocytes; Development; Hymenopteran parasites; Host circumvention of endoparasitoid immunosuppressive effects; comparative study; Asobara citri; Immune like reactions; Encapsulation none2005