The aim of this study was to assess diversity and composition of fungal communities in damaged and undamaged shoots of Norway spruce (Picea abies) following recent invasion of the spruce bud scale (Physokermes piceae) in Lithuania. Sampling was done in July 2013 and included 50 random lateral shoots from 10 random trees in each of five visually undamaged and five damaged 40-50 years-old pure stands of P. abies. DNA was isolated from 500 individual shoots, subjected to amplification of the internal transcribed spacer of fungal ribosomal DNA (ITS rDNA), barcoded and sequenced. Clustering of 149426 high-quality sequences resulted in 1193 non-singleton contigs of which 1039 (87.1%) were fungal. In total, there were 893 fungal taxa in damaged shoots and 608 taxa in undamaged shoots (p<0.0001). Furthermore, 431 (41.5%) fungal taxa were exclusively in damaged shoots, 146 (14.0%) were exclusively in undamaged shoots and 462 (44.5%) were common to both types of samples. Correspondence analysis showed that study sites representing damaged and undamaged shoots were separated from each other, indicating that in these fungal communities were largely different, and therefore heavily affected by P. piceae. In conclusion, the results demonstrated that invasive alien tree pests may have a profound effect on fungal mycobiota associated with the phyllosphere of P. abies, and therefore, in addition to their direct negative effect owing physical damage of the tissue, they may also indirectly determine health, sustainability and ultimately distribution of the forest tree species.Keywords: forest health, pathogens, pest insects, climate change, fungal community Introduction Norway spruce (Picea abies) is one of the dominant tree species distributed in a larger part of the north temperate and boreal forests of Europe, and therefore is of tremendous socioeconomic importance [33]. It appears that the climate has been the major determinant of the distributional limits of the tree species and these limits track climate change so closely that even short-term climatic variation can lead to significant range adjustments with consequences for practical forestry and society [39]. The recent observations suggest that the range limit of P. abies has begun to change more rapidly than in the past, and a further projection predicts its range expansion in the north and much greater contraction in the south of the present limit [3]. Climate change can affect forests directly (storms, droughts, high