Fungos associados a Platypus cylindrus (Coleoptera: platypodidae) e sua relação com o declinio do montado

Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de AgronomiaThe ambrosia beetle Platypus cylindrus establishes symbiotic relationships with fungi. P. cylindrus may act as a vector for the dispersal of phytopathogenic fungi in the Mediterranean cork oak stands. The aim of this study was to identify the fungi associated with P. cylindrus in Portugal and to understand the role and potential impacts on cork oak stands of both insect and fungi. A complex of fungi was found in association with the insect, namely species of cosmopolitan genera whose exact role in the interaction still remains under discussion. Biscogniauxia mediterranea, the causal agent of charcoal canker disease was also found associated with P. cylindrus which contributes to disease spread in cork oak stands. A total of fourteen representative isolates belonging to Ophiostomatales where selected. Fungal strains were morphologically and molecularly characterized. Three rDNA contiguous regions SSU, ITS and LSU, were profiled for each strain and contrasted with pre-existent Ophiostomatales species worldwide. In addition, pathogenicity tests were conducted. A new Ophiostoma species, with Hyalorhinocladiella anamorph, and a Raffaelea species closely related to R. canadensis were noticed for the first time and in association with the ambrosia beetle. Molecular evidence suggests that a different phylogenetic lineage of Ophiostomatales exists in Portugal. R. montetyi was found to be the primary ambrosia fungus of P. cylindrus. The pathogenicity of R. montetyi towards cork oak seedlings was confirmed and its role as a cork oak declining agent determine