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Morphological and molecular identification of ophiostomatoid fungi associated with spruce-attacking bark beetles of the genus Ips De Geer Alamouti, Sepideh Massoumi

Abstract

The work described in this thesis contributes to the description and identification of the ophiostomatoid fungi carried by the bark beetles (Coleoptera: Curculionidae: Scolytinae) of the genus Ips De Geer, infesting spruce species (Picea spp.) in North America. The work covers three research subjects. First, the composition and the frequency of the fungi isolated from adult Ips perturbatus collected from the spruce logs in northern British Columbia and the Yukon Territory are reported. As well, the fungal associates of /. tridens, and two other beetle species belonging to the genera Dryocoetes and Polygraphus, are described. Second, the morphological characteristics of the associated fungi with their micrographs are presented. Third, the molecular characteristics of the associated fungi, including their phylogenetic and taxonomic positions, based on sequence analyses of the nuclear rDNA and partial P-tubulin genes, are reported. A number of fungi, including Leptographium sp. 1, Hyalorhinocladiella sp. 2, Ophiostoma bicolor and O. manitobense, were consistently isolated from /. perturbatus adults, while others, i.e. L. abietinum, seemed to be rather sporadic or ubiquitous associates. Similar patterns were observed for the fungal associates of the other beetle species. For /. perturbatus and /. tridens, the most frequent associates were Leptographium sp. 1 and O. abiocarpum, respectively. These fungi appeared to have a specific association with their beetle host. These results were supported by phylogenetic data, which also suggested that the fungal association with the beetle vector might involve co-evolution. Fourteen morphological and phylogenetic species were recognized among the ophiostomatoid fungi isolated from the bark beetles. Five species were identified as O. bicolor, O. manitobense, O. abiocarpum, O. piceaperdum and L. abietinum, one species was regarded as O. cucullatum-like, and eight fungi were recognized as undescribed species of the genus Ophiostoma and the anamorph genera Leptographium, Hyalorhinocladiella, Ambrosiella and Graphium. Overall, the phylogenic placement of the recognized species within the subclades correlated well with their morphological characteristics.

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