Ophiostomatoid Fungi Associated with the Four-Eyed Fir Bark Beetle on the Territory of Russia

Abstract

The study is aimed at investigation of ophiostomatoid fungi, associated with the four-eyed fir bark beetle (Polygraphus proximus Blandford, Coleoptera, Curculionidae)—an invasive pest of Siberian fir Abies sibirica. In the Russian Far East, eight fungal species are associated with this bark beetle. All of these fungi (except Leptographium taigense and Grosmannia europhioides) were brought by P. proximus to its secondary range (Southern Siberia and Moscow oblast). In the secondary range, a complex of ophiostomatoid fungi connected with P. proximus consists mainly of the Far Eastern species adapted to new habitats. Phytopathogenic activity of the fungi associated with bark beetle was studied. G. aoshimae and Ophiostoma nikkoense demonstrated high phytopathogenic activity after inoculation into phloem of Siberian fir. The culture of G. aoshimae and O. subalpinum produced extensive necroses in stems of Siberian larch Larix sibirica. In general, G. aoshimae is the main fungal associate of P. proximus, considering the frequency and stability of its occurrence in samples, as well as its aggressiveness toward coniferous species of Southern Siberia. It demonstrated high aggressiveness toward Siberian fir and Siberian larch; Scots pine Pinus sylvestris is also susceptible to this fungus. Siberian spruce Picea obovata and Siberian pine Pinus sibirica are resistant. There is a high possibility of P. proximus mycobiota enrichment with a complex of fungi connected with fir sawyer beetle Monochamus urussovi Fisch., an aboriginal pest of fir in Siberia.