Geosmithia species associated with fir-infesting beetles in Poland

Geosmithia species (Ascomycota: Hypocreales) are common ectosymbionts of scolytine bark and ambrosia beetles that feed on coniferous and deciduous trees in different forest ecosystems. Geosmithia morbida is the canker pathogen that causes extensive mortality of Juglans nigra. Because little is known regarding the Geosmithia species on European silver fir (Abies alba), we have investigated the diversity and abundance of these fungi associated with insects infesting European silver fir in Poland. Samples associated with eight beetle species were collected from three fir forests. Fungi were isolated from beetles and galleries. Isolates were identified based on morphological characteristics, DNA sequence comparison for three gene regions (ITS, ßT, TEF1-α), and phylogenetic analyses. Geosmithia was detected in 33% of the total 531 beetle samples obtained from A. alba. Two undescribed species of Geosmithia were distinguished, Geosmithia sp. 9 and Geosmithia sp. 16. Associations of Pityokteines spp. with Geosmithia fungi were recorded for the first time. Pityokteines vorontzowi and Pityophthorus pityographus appear to be regular vectors for Geosmithia sp. 9 and Geosmithia sp. 16, respectively. Pityokteines curvidens and Cryphalus piceae were associated with Geosmitha sp. 9 at lower frequencies.