Evolution of Polydnavirus Genes in Microgastrine Braconid Parasitoid Wasps

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ABSTRACTPI: WhitfieldProposal: DEB 9873748University of Arkansas Of the parasitoid wasps important in attacking and regulating populations of caterpillars, perhaps the most familiar and numerically dominant are wasps belonging to the microgastroid complex. This complex of braconid wasps comprises eight subfamilies, several of which have already been demonstrated to carry hereditary polydnaviruses which compromise host Immune systems, and none of which have been shown not to carry the viruses. Since these viruses are crucial to the wasp/caterpillar parasitic relationship, they are of considerable evolutionary, physiological and economic interest. Phylogenetic analysis of braconid wasps based on comparative morphology and on 16S and 28S rRNA sequence data indicates that the microgastroids form a monophyletic lineage probably dating back at least 60 million years. Preliminary results of phylogenetic analysis of 16S and NADH1 DNA sequence data, from wasps in the genus Cotesia, and of the genes EP1 and Crv1 from the viruses they carry, suggest that the phylogeny of the polydnaviruses mirrors that of their wasp carriers, at least within this group. This project will more fully address whether this expected parallel phylogeny really exists by obtaining DNA sequences from the 16S, NADH1 and CO1 genes in the genomes of a further 25 species of microgastrines, and comparing the phylogeny obtained from these to that estimated from the EP1 and CrV1 genes of the viruses they carry. The results will have important implications for the use of phylogeny to predict aspects of the host-parasitoid relationship in this large, economically important group of wasps.