Robert Jankowiak

Association of the pine-infesting Pissodes species with ophiostomatoid fungi in Poland

Bark weevils are consistently associated with various fungi. They act as effective vectors for root-rot fungi, the rust pathogen and the ophiostomatoid fungi. In comparison with bark beetles, the interaction between ophiostomatoid fungi and bark weevils has been poorly studied in Europe. This study aims to clarify the ties among ophiostomatoid fungi and their weevil vectors in Pinus sylvestris. Samples associated with three bark weevils, including Pissodes castaneus, P. piniphilus and P. pini were collected from seven pine stands in Poland. Fungi were isolated from laboratory-reared and field-collected beetles, larvae and galleries of weevils. Isolates were identified based on morphology, DNA sequence comparison for two gene regions (ITS, ß-tubulin) and phylogenetic analyses. Fourteen morphological and phylogenetic ophiostomatoid species were identified among the 1,219 isolates. These 14 species included 11 novel associations between fungi and bark weevils. The most commonly encountered fungal associates of bark Pissodes species were Leptographium procerum, Ophiostoma quercus and O. minus. The spectrum of fungal associates was similar in three bark weevil species, despite some differences between species. Except for P. castaneus, all species of bark weevil were frequently associated with ophiostomatoid fungi. Pissodes castaneus does appear to be a consistent vector of L. procerum and Sporothrix inflata while O. minus, O. quercus and O. cf. rectangulosporium were often found in association with P. piniphilus and P. pini.

Diversity of ophiostomatoid fungi associated with bark beetles (Coleoptera: Scolytidae) colonizing branches of Norway spruce (Picea abies) in southern Poland

Bark beetles (Coleoptera: Scolytidae) infesting Norway spruce trees are known to be associated with fungi, especially species of Ophiostoma sensu lato and Ceratocystis. However, very little is known about these fungi in Poland. In this study, we examined the ophiostomatoid species associated with seven species of bark beetles developing in Norway spruce (Picea abies). Fungi were isolated from the beetles and their galleries at ten sites in southern Poland. We identified a total of 2,769 fungal isolates that belong to 19 ophiostomatoid species. These 19 species included a total of 16 associations between fungi and bark beetles that had not been previously recorded. The isolated fungal species were similar to those previously reported. The species spectrum and relative abundance of fungal associates were similar in seven bark beetle species, despite some differences between species. Except for Pityophthorus pityographus, all bark beetles species were frequently associated with ophiostomatoid fungi. The most commonly encountered fungal associates of bark beetles were the following: Ophiostoma ainoae, O. bicolor, O. piceae sensu lato and Grosmannia piceiperda. The results support the hypothesis that pathogenic ophiostomatoid fungi are important for aggressive bark beetles to kill trees. The most virulent fungal associate of bark beetles, Ceratocystis polonica was most commonly associated with Ips typographus. The most frequent ophiostomatoid species isolated from the beetles and galleries of P. pityographus were O. ainoae and Graphium fimbriisporum.

Putative origins of the fungus Leptographium procerum.

Appropriate management of invasive fungi requires adequate understanding of their global diversities and movement histories. The fungus Leptographium procerum is associated with root-colonizing forest insects in pine forests throughout the world, and may have contributed to the aggressive behaviour of the red turpentine beetle (Dendroctonus valens) in the beetles invasive range in China. We used microsatellites and mating type loci to investigate the global diversity of L. procerum and the source population of L. procerum associated with D. valens in China. Clustering analyses supported the separation of the fungal data set into three genetically and geographically-distinct clusters: Europe, North America, and China. The fungus had the highest genetic diversity in Europe, followed by North America and China. Analyses using Approximate Bayesian Computation supported Europe as the most likely source of the North American and Chinese populations. Overall, the results suggested that Europe is the global centre of diversity of L. procerum. Furthermore, they suggested that L. procerum most likely arrived in China independently of D. valens and adopted this beetle as a vector after its introduction.

Two new Leptographium spp. reveal an emerging complex of hardwood-infecting species in the Ophiostomatales

Species of Leptographium are generally characterized by mononematous conidiophores and are commonly associated with bark beetles and weevils. These species are responsible for sapstain and in some cases serious diseases on a range of primarily coniferous trees. In comparison with coniferous trees, the occurrence of Leptographium species on hardwood trees has been poorly studied in Europe. During a survey of ophiostomatoid fungi on various tree species in Norway and Poland, three unusual species, which fit the broader morphological description of Leptographium spp., were found in association with Scolytus ratzeburgi, Dryocoetes alni and Trypodendron domesticum on a variety of hardwoods, and from wounds on Tilia cordata. Phylogenetic analyses of sequence data for three gene regions (ITS2-LSU, β-tubulin, and TEF1-α) showed that these Leptographium species are phylogenetically closely related to each other and form a well-supported lineage that included Grosmannia grandifoliae and Leptographium pruni. The first species could be distinguished from the other Leptographium species based on conidiophores arising from spiral hyphae, chlamydospore-like structures and a hyalorhinocladiella-like synanamorph in culture. The second species differs from the previous one by having distinctly shorter conidiophores and smaller conidia. This species also produces a well-developed sporothrix-like synanamorph with denticulate conidiogenous cells. Based on these unusual morphological characteristics and distinct DNA sequences, these fungi were recognised as new taxa for which the names Leptographium trypodendri sp. nov. and L. betulae sp. nov. are provided. The third group of isolates belonged to Grosmannia grandifoliae, representing the first report of this species outside of the USA. The newly defined G. grandifoliae complex is the first species complex in Leptographium s.l. consisting of only hardwood-infecting species.

Identification of sapstain fungi from Scots pine pallets and assessment of their staining ability

Wood-staining fungi, moulds and decay fungi colonize freshly cut wood. Of these, only ophiostomatoid fungi are considered major agents of sapstain on logs and freshly sawn lumber because they can cause permanent staining and discoloration. Sapstain in pine pallets significantly reduces their market value and use in the food industry. The aim of this study was to identify the sapstaining fungi that colonize Scots pine wood used in pallet production. In addition, we evaluated the growth and stain intensity of six isolates of ophiostomatoid fungi on freshly cut Scots pine billets. Fungi were isolated from samples of Scots pine and identified based on morphology and DNA sequence comparisons for three gene regions (ITS, β-tubulin, TEF-1α). A total of 1259 isolates representing 31 fungal species were obtained from the pine samples in Poland during July and September. The isolates represented different ecological and taxonomical groups and belonged to the categories of staining fungi, decay fungi and surface moulds. The most frequently isolated fungi were ophiostomatoid fungi (14 species including an unknown Leptographium sp. and Ophiostoma sp.) and moulds (mainly Trichoderma and Mucor spp.). Of the ophiostomatoid species, Ophiostoma floccosum, O. piceae, O. piliferum and Endoconidiophora pinicola were the predominant species. The results of pine billet inoculation showed that among the six fungal species tested, E. pinicola exhibited the fastest growth in all three directions on the billets. Ophiostoma minus and O. piliferum displayed moderate growth rates in pine billets, while O. floccosum, O. piceae, and Leptographium lundbergii grew very slowly, especially in the tangential and radial directions. The information provided in this paper will help develop more effective control strategies for sapstain prevention in Scots pine.

Diversity of Ophiostomatales species associated with conifer-infesting beetles in the Western Carpathians

Bark beetles (Coleoptera: Curculionidae, Scolytinae) are commonly recognised as important agents of tree mortality in coniferous forests of the Western Carpathians. They, together with weevils, are consistently associated with ophiostomatoid fungi. Information regarding conifer beetle-associated fungi in the Western Carpathians remains incomplete and unreliable, particularly with respect to fir-infesting bark beetles. This study aims to clarify associations between fungi in the genera Graphilbum, Leptographium, Ophiostoma and Sporothrix (Ophiostomatales) and their beetle vectors in Norway spruce (Picea abies), European larch (Larix decidua) and silver fir (Abies alba). Samples associated with 20 bark beetle species and weevils were collected from nine stands in Poland and the Czech Republic. Fungi were isolated from adult beetles and galleries. Isolates were identified based on morphology, DNA sequence comparisons for four gene regions (ITS, LSU, ß-tubulin, TEF 1-α) and phylogenetic analyses. In total, 46 distinct taxa were identified, including 25 known and 21 currently unknown species. Several associations between fungi and subcortical insects were recorded for the first time. In addition, O. borealis and O. quercus were detected from A. alba for the first time. The composition of the fungal communities varied among the studied tree species and to a lesser degree among the beetle species. The spruce-infesting bark beetles were commonly associated with species of Leptographium s. l. and Ophiostoma s. str.; the larch-infesting bark beetles were often associated with Ophiostoma s. str. and Sporothrix, while the fir-infesting bark beetles were commonly associated with Ophiostoma s. str. and Graphilbum. The most commonly encountered fungal associates of the examined insects were (a) Grosmannia cucullata, G. piceiperda, Grosmannia sp. 1, Ophiostoma macroclavatum and O. piceae with the spruce-infesting bark beetles; (b) O. pseudocatenulatum and Sporothrix sp. 1 with the larch-infesting bark beetles; and (c) O. piceae, Ophiostoma sp. 2 and Graphilbum sp. 2 with the fir-infesting bark beetles. The differences in fungal associates among the bark beetle species occurring on P. abies, L. decidua and A. alba could be linked to the different habitats that these beetles occupy.

A preliminary study on the pathogenicity of three blue-stain fungi associated with Tetropium spp. to Norway spruce in Poland

Wstępne badania nad patogenicznością trzech grzybów siniznowych związanych z Tetropium spp. na świerku pospolitym w Polsce A preliminary study on the pathogenicity of three blue-stain fungi associated with Tetropium spp. to Norway spruce in Poland To evaluate pathogenicity of some fungi associated with Tetropium spp. (Coleoptera: Cerambycidae): Grosmannia piceiperda, Grosmannia penicillata and Ophiostoma tetropii the inoculation of Norway spruce (Picea abies) trees experiment was performed. The inoculation densities were 400 and 800 points/m2 in a 60 cm wide band at breast height. The effects of inoculation were examined 23 weeks after treatment. Two trees inoculated with G. piceiperda were dying at harvest. Inoculation with G. piceiperda produced significantly greater phloem and sapwood lesions in comparison with other fungi and control. Moreover, the percentage of occluded sapwood was also highest following G. piceiperda inoculations at 800 points/m2. Ophiostoma tetropii, however, produced more occlusions than G. piceiperda at 400 points/m2. These preliminary results suggest that G. piceiperda is pathogenic and may contribute to the mortality of spruces infested by Tetropium beetles.

Three new Leptographium spp. (Ophiostomatales) infecting hardwood trees in Norway and Poland

Species of Leptographium are characterized by mononematous or synnematous conidiophores and are commonly associated with different arthropods. Some of them also produce a sexual state characterised by globose ascomata with elongated necks. Compared to investigations on coniferous trees, the occurrence of Leptographium species on hardwood trees has been poorly studied in Europe. During a survey of ophiostomatoid fungi on various hardwood tree species in Norway and Poland, three unusual species, which fit in the broader morphological description of Leptographium spp., were found in association with Trypodendron domesticum, Trypodendron signatum and Dryocoetes alni, and from wounds on a variety of hardwoods. Phylogenetic analyses of sequence data for six different loci (ITS1–5.8 S–ITS2, ITS2-LSU, ACT, β-tubulin, CAL, and TEF-1α) showed that these Leptographium species are phylogenetically closely related to the species of the Grosmannia olivacea complex. The first species forms a well-supported lineage that includes Ophiostoma brevicolle, while the two other new taxa resided in a separate lineage; possibly affiliated with Grosmannia francke-grosmanniae. All the new species produce perithecia with necks terminating in ostiolar hyphae and orange-section shaped ascospores with cucullate, gelatinous sheaths. These species also produce dark olivaceous mononematous asexual states in culture. In addition, two of the newly described species have a second type of conidiophore with a short and non-pigmented stipe. The new Leptographium species can be easily distinguished from each other by their appearance and growth in culture. Based on novel morphological characters and distinct DNA sequences, these fungi were recognised as new taxa for which the names Leptographium tardum sp. nov., Leptographium vulnerum sp. nov., and Leptographium flavum sp. nov. are provided.