Immunogenetic aspects of the cellular immune response of Drosophila against parasitoids

Host-parasite relationships represent integrating adaptations of considerab le complexity involving the host's immune capacity to both recognize and de stroy the parasite, and the latter's ability to successfully invade the hos t and to circumvent its immune response. Compatibility in Drosophila-parasi tic wasp (parasitoid) associations has been shown to have a genetic basis, and to be both species and strain specific. Studies using resistant and sus ceptible strains of Drosophila melanogaster infected with virulent and avir ulent strains of the wasp Leptopilina boulardi demonstrate that the success of the host cellular immune response depends on the genetic status of both host and parasitoid. Immunological, physiological, biochemical, and geneti c data form the bases of a two-component model proposed here to account for the observed specificity and complexity of two coevolved adaptations, host nonself recognition and parasitoid virulence.