Fungi associated with Tomicus piniperda in Poland and assessment of their virulence using Scots pine seedlings

The species composition and virulence of fungi associated with Tomicus piniperda were studied at eight locations in Poland. The fungi were isolated from phloem and sapwood samples taken from insect galleries and then identified. The virulence of the most common ophiostomatoid species was evaluated through inoculations using two-year-old Scots pine seedlings. A great diversity of fungi were found associated with T. piniperda, including 4 837 cultures and 67 species. The most important groups of fungi were the ophiostomatoids and moulds, including mainly Penicillium, Trichoderma and Mucor species. Among ophiostomatoid fungi, Ophiostoma minus and O. piceae dominated, with a frequency of occurrence of 32.4 and 11.5% of inspected galleries, respectively. Occasionally isolated species included Leptographium lundbergii, L. procerum, L. wingfieldii, Graphium pycnocephalum and Graphium sp. 'W'. In general, the frequency of the ophiostomatoid species was highly variable among locations. Leptographium wingfieldii and O. minus, were the only species capable of killing whole plants and penetrated deeper into the sapwood than other species (87-100% mortality during the 11 week incubation period). Other fungi, including O. piliferum, O. piceae and L. procerum, were considerably less virulent.