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1.
Bark beetle‐vectored ophiostomatoid fungi, Leptographium terebrantis, is inoculated on the roots and lower stems of stressed Pinus species during the feeding activity of bark beetle. To determine the exact host response following inoculation, it is critical to challenge the host with a realistic amount of fungal inoculum. Thus, we designed a series of stepwise experiments using L. terebrantis colonized toothpicks which focused on the inoculum transfer from the toothpicks to excised Pinus taeda stem segments and living saplings, respectively, at different inoculum densities. The toothpicks served as a substrate for fungal growth and sporulation and the inoculation showed their utility in eliciting host's response to the pathogen. The inoculated fungus caused blue‐stain and sapwood occlusions in P. taeda stems and saplings, respectively. The volume of occluded, visually damaged sapwood increased by 1.96 cm3 per radial inoculation point on average. Fungal colonized toothpicks can be used as a suitable alternative to agar discs for studying bark beetles vectored fungi and their host interactions.  相似文献   

2.
Pine decline poses a serious threat to forest sustainability in the south‐eastern United States. Complex interactions between biotic and abiotic factors are involved in the decline and include root‐feeding bark beetles and their associated fungal genera, Leptographium and Grosmannia. A study was conducted to determine the relative tolerance of loblolly pine (Pinus taeda L.) families when challenged with either Leptographium or Grosmannia species. In the first study, bare root seedlings from 23 loblolly pine families were screened with L. procerum, L. terebrantis, G. huntii and G. alacris using an artificial inoculation method. In a second study, containerized seedlings from 27 loblolly pine families were screened with G. huntii and L. terebrantis. Measured seedling responses to the inoculations included lesion length, lesion width and occlusion of vascular tissues, measured 8 weeks after inoculations. The most common host response was dark brown lesions and resinous occluded stem tissue. Seedling families had a wide range of host responses to the different Leptographium and Grosmannia species and showed that it could be possible to select the families that may be tolerant to Leptographium and Grosmannia fungal species based on these results.  相似文献   

3.
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.  相似文献   

4.
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.  相似文献   

5.
Loblolly pine decline, characterized by deteriorating root systems leading to shortening and thinning of foliage, has been observed throughout portions of the south‐eastern United States. Several root‐inhabiting ophiostomatoid fungi, including Leptographium procerum, Leptographium terebrantis, Leptographium serpens, and Grosmannia huntii are associated with lateral root damage on declining loblolly pine. Trees of various ages were inoculated in primary lateral roots during fall (2006 and 2007) and spring (2007 and 2008). All fungi caused a darkened, resin‐filled lesion on the surface of the phloem, extending into the xylem that was larger than that of controls. Only lesions associated with G. huntii infection were significantly larger in the spring season, compared with the fall. Grosmannia huntii was found to be the most virulent fungus, causing lesions that were longer, deeper and larger than all other fungal species during the spring and larger than L. terebrantis and L. procerum in the fall. Leptographium serpens was the second most virulent fungal species, causing lesions larger than L. procerum and L. terebrantis (with the exception of lesion depth) during both seasons. These tests indicate that G. huntii and L. serpens are significant root pathogens, capable of causing considerable damage, while L. terebrantis and L. procerum may be less virulent. Depending on the actions of their vectors, G. huntii and L. serpens may be responsible for significant root deterioration and tree disease.  相似文献   

6.
Ophiostomatoid fungi are carried by various bark beetles. However, very little is known about the role of these fungi in conifer roots. We studied ophiostomatoid fungi in roots of dying and dead Pinus sylvestris trees and tested the potential phytotoxicity of some isolates using a sensitive bioassay with Lepidium sativum in Poland. Fungi were identified based on their morphology and DNA sequencing. Three ophiostomatoid fungi, Leptographium procerum, Sporothrix inflata and Ophiostoma pallidulum, were isolated from the roots. The most abundant soil‐borne fungus, S. inflata, and relatively rare O. pallidulum were isolated for the first time from roots of dying and dead pine trees. The frequency of S. inflata and O. pallidulum correlated with tree decline. The fungi were isolated more frequently from roots of dead than dying trees. Sporothrix inflata and O. pallidulum slightly reduced the stem and root growth of L. sativum. Leptographium procerum reduced more significantly root than stem growth. This species reduced root elongation 32–54% after 10–17 days of incubation.  相似文献   

7.

Context

Ophiostomatoid fungi can severely affect the health and economic value of Norway spruce trees (Picea abies). Although the diversity of ophiostomatoid species and their associations with insects have been well-investigated in central and northern Europe, little is known about the conditions in south-eastern Europe.

Aim

This study aims to study the assemblages of ophiostomatoid fungi associated with three bark beetle species (Ips typographus, Ips amitinus, and Pityogenes chalcographus) that infect Norway spruce in Slovenia.

Methods

Bark beetles were sampled in four phytogeographic regions in Slovenia. The fungi found on the bark beetles were identified based on morphology, DNA sequence comparisons of ITS regions and phylogenetic analysis. The species compositions of the fungal associates of the three insect species were compared and the pairwise associations of the occurrence of the fungal species were analysed.

Results

Thirteen different species were found. The most commonly encountered fungal associates of the beetles were Ophiostoma bicolor, Ophiostoma brunneo-ciliatum, Grosmannia piceiperda, Ophiostoma ainoae, Ceratocystiopsis minuta, and Grosmannia penicillata. The composition of the fungal associates differed among the bark beetle species, but not among the phytogeographic regions.

Conclusions

This study confirms that ophiostomatoid species are common associates of the investigated bark beetle species. Many ophiostomatoid species have strong host associations. I. typographus and P. chalcographus can act as effective vectors for O. bicolor, O. ainoae, G. piceiperda and O. brunneo-ciliatum, whereas I. amitinus often carries G. piceiperda and C. minuta in Slovenian forests.  相似文献   

8.
Bursaphelenchus tusciae is reported for the first time in Tunisia and North Africa, associated with the insect Hylurgus ligniperda Fabricius (Coleoptera: Curculionidae: Scolytinae). Nematode identification was based on restriction fragment length polymorphism analysis and sequencing of the internal transcribed spacer (ITS) regions of ribosomal DNA. Phylogenetic analysis revealed that Tunisian B. tusciae clusters together with two other B. tusciae isolates forming a separate group close to B. hildegardae and B. eggersi. As H. ligniperda is among maritime pine scolytids pests in Tunisia and is widely distributed in North Africa, this study is an important contribution to the knowledge of Bursaphelenchus species associated with bark beetles of pine forests in Tunisia and North Africa.  相似文献   

9.
Pine plantations in Argentinian Patagonia cover ca. 95,000 ha in Chubut, Río Negro and Neuquén provinces. Exotic bark beetles (Orthotomicus laricis, Hylastes ater and Hylurgus ligniperda) commonly occur in freshly cut logs, stumps and slash. These beetles are vectors of “ophiostomatoid” fungi which include primary tree pathogens as well as important agents of blue stain. The aim of this study was to identify these beetle‐associated fungi. Sawing mills and pine plantations were surveyed three consecutive years. Fungal isolates from stained logs, processed wood and insect galleries were identified based on morphological and DNA sequence comparisons of ITS and β‐tubulin gene regions. Two Grosmannia, one Graphilbum and three Ophiostoma species were identified. Ophiostoma piliferum and O. peregrinum sp. nov. were the most frequently isolated taxa. O. peregrinum occurred in all provinces, colonizing different conifer species and, interestingly, also the native broadleaved species Nothofagus dombeyi. Pine plantation forestry in southern South America includes Argentina, Brazil, Chile, Paraguay and Uruguay. Emerging data from Argentina, Chile and Uruguay revealed some coincidences between these countries, but also several differences, probably, as a result of multiple introduction events.  相似文献   

10.
The pine shoot beetle, Tomicus piniperda, is a secondary colonizer of pines and other conifers. Although it is necessary to understand interactions of this insect with other organisms, few studies have focused on its fungal associates. This study focused on the effect of geographical distance on the occurrence of fungi carried by the beetle. Adult beetles were collected from Scots pine (Pinus sylvestris) in North (Rovaniemi) and South (Hyytiälä) Finland. The mycota was isolated and identified using a combination of morphological and molecular data. The results revealed a great diversity of fungal taxa isolated from T. piniperda, with a total of 3073 isolates representing 20 taxonomic units. The most frequently isolated fungi in the bark beetles from North Finland were Beauveria bassiana, Kuraishia sp., whereas Penicillium velutinum was mostly observed in the insects from South Finland. Ophiostoma canum and Ophiostoma minus were also isolated from the beetles from both North and South Finland. The number of fungi isolates per insect was 2.58 in the North and 3.74 in the South, respectively. Significant differences were found between South and North Finland in fungal taxa isolated from the beetles. The highest richness and diversity of the fungal taxa was observed in the South. However, the overall fungal diversity index analysis revealed that the mycobiota was under-sampled which suggests that a proportion of the fungal species may have remained undetected.  相似文献   

11.
To investigate the fungal flora associated with the spruce bark beetle Ips typographus in an endemic area, beetles were collected during the flight period in six locations in Tr?ndelag, Norway. The beetles were inoculated into fresh Norway spruce logs, and the frequency of different species was monitored by fungal isolation from bark and wood. The most common species were Ophiostoma bicolor, O. penicillatum, O. polonicum and a previously undescribed Graphium species, the same species which were the most important associates of I. Typographus in an epidemic area in southeastern Norway. The frequency of the primary invader, O. polonicum, was, however, lower in Tr?ndelag, which may indicate that this species is less frequent in endemic areas than in epidemic areas.  相似文献   

12.
Relationships between tree mortality and bark beetle infestation onAbies veitchii at the wave-regenerated forest in Mt. Asahi, Okuchichibu area were investigated. Most of the firs with green needles and newly developed current year’s shoots in the dieback zone were heavily infested by bark beetles before the death of the trees. After heavy infestation of beetles, about half of the infested firs died within the year, and the other half died in the next year. When the species composition of bark beetles and associated ophiostomatoid fungi were investigated in Mt. Asahi and also at a typical wave-regenerated forest in Mt. Shimagare, Yatsugatake area,Cryphalus montanus andC. piceae were dominant beetle species for Mt. Asahi and Mt. Shimagare, respectively.Ophiostoma subalpinum andO. europhioides were dominant fungal species at both wave-generated forests. BecauseO. subalpinum was detected more frequently from deeper areas of sapwood thanO. europhioides, it was suggested that the fungal species may accelerate the death of stressed firs in wave-regenerated forests. Contribution No. 169, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba.  相似文献   

13.
Ophiostoma species were isolated from bark beetles and Abies mariesii, A. veitchii and A. homolepis attacked by the beetles in Nikko, Tochigi, central Honshu, Japan. One to two Ophiostoma species were frequently isolated from each species of bark beetle. Ophiostoma subalpinum was the most common associate of Cryphalus montanus. Ophiostoma sp. B as well as O. subalpinum was a common fungus associated with Polygraphus proximus. Ophiostoma europhioides was isolated from Dryocoetes hectographus and D. autographus as one of the common associates. Ophiostoma sp. J and Ophiostoma sp. S were frequently isolated from D. autographus and D. striatus, respectively. These fungi seem to have specific relationships with particular bark beetles. Ophiostoma sp. B, Ophiostoma sp. J and Ophiostoma sp. S have unique morphological characteristics and appear to be new species. Five trees of A. veitchii, approximately 43 years old, were inoculated with five Ophiostoma species to assess the relative virulence of the fungi. Ophiostoma subalpinum, Ophiostoma sp. B, and O. europhioides had relatively higher virulence than the other species studied.  相似文献   

14.
The association between Tomicus destruens and fungi of the genus Leptographium was studied in Pinus pinea and P. pinaster forests in Tuscany, central Italy. Fungi were isolated from adult beetles and from pine tissues from infested trees. On average, Leptographium spp. were associated with 18% of beetles in breeding galleries, 35% of emergent brood beetles and 18% of beetles undergoing maturation feeding in pine twigs. The fungal species most frequently identified were Leptographium wingfieldii and L. lundbergii while L. guttulatum and L. serpens were also found.  相似文献   

15.
In addition to Hymenoscyphus fraxineus, two fungi identified as Diaporthe eres aff. and Fusarium sambucinum aff. were also isolated from necrotic bark lesions on declining one‐year‐old Fraxinus excelsior in a forest stand in Montenegro. To examine their involvement in ash decline, a pathogenicity test was performed using under bark inoculations on one‐year‐old Fraxinus excelsior. Hymenoscyphus fraxineus was included as comparison. All three fungal species proved highly pathogenic towards one‐year‐old seedlings although lesion sizes differed significantly between the different species. Hymenoscyphus fraxineus was most aggressive, followed by F. sambucinum aff., while D. eres aff. caused the smallest lesions. This study demonstrates for the first time the ability of isolates in the D. eres and F. sambucinum species complexes to cause decline on one‐year‐old common ash seedlings.  相似文献   

16.
Oak (Quercus robur) powdery mildew is a common and damaging fungal disease. In a local survey at Reading, UK, oak powdery mildew was common on trees of all height classes but was most common on trees of 3–9 m. A variety of other fungal species were commonly found growing in association with oak powdery mildew colonies. The abundance of such fungi was estimated through stratified sample surveys for 2.5 years. The taxa most commonly associated with oak powdery mildew were Acremonium sp., Trichoderma sp., Ampelomyces/Phoma sp. and Leptosphaerulina australis. Nearly 90% of mildew colonies were associated with L. australis, which is not generally considered as a mycoparasite or antagonist, in contrast with the other three fungi. Abundance varied between June and October surveys. Acremonium sp. abundance was greater in summer samplings, whereas L. australis and Trichoderma sp. abundances were greater in autumn samplings. Ampelomyces/Phoma sp. was never observed in the absence of powdery mildew. Relationships between the mildew‐associated fungi and oak powdery mildew appeared curved and differed significantly between sampling years. L. australis was positively correlated with the other three associated fungi studied when powdery mildew was also present . The variety and high population densities of the mildew‐associated fungi suggest that they may be important in determining the final density of oak mildew and the damage caused by it.  相似文献   

17.
Pathogenic fungi can survive and develop in living plants, often causing diseases in the host. Some theories speculate that pathogenic ophiostomatoid fungi provide benefits to its vectors – bark beetles – by overcoming the tree's defence mechanisms. This study reports the results of an experiment in south‐eastern Europe in which mature and seedling Norway spruce trees were artificially inoculated with various ophiostomatoid fungi. The aim of the experiment was to determine the relative virulence of ophiostomatoid fungi by assessing the ability of the fungi to stimulate host tree defence mechanisms through inoculation experiments. Experiments were performed by inoculation of Picea abies in seedling and mature trees. The following fungi were used in low‐density and seedling inoculations: Ophiostoma ainoae, O. brunneo‐ciliatum, Grosmannia cucullata and an unidentified Leptographium sp., O. bicolor, O. fuscum, O. piceae, G. penicillata and G. piceiperda. Endoconidiophora polonica was used in mass and seedling inoculations. Various characteristics such as host vitality, blue stain, lesion and resin outflow were measured before and after the trees were felled. E. polonica caused blue stain, induced large lesions and killed some of the mature trees and seedlings, confirming earlier reports that it is a strong wound pathogen. Only E. polonica, Leptographium sp. and O. ainoae caused blue stains in the sapwood of inoculated seedlings. In low‐density inoculations, G. piceiperda induced intense necrosis and had higher values for all the characteristics monitored. Some of the other ophiostomatoid fungi showed a moderate level of pathogenicity. Fungi with the capacity to stimulate a host defence mechanism could play a role in the establishment of bark beetle populations.  相似文献   

18.
Phytopathogenic fungi associated with the bark beetles Tomicus piniperda and Orthotomicus erosus were isolated in various pine forests of Tunisia. Tomicus piniperda and its galleries yielded Leptographium wingfieldii, Ophiostoma minus, and Ophiostoma ips. Ophiostoma minus was the most frequent species associated with T. piniperda, in both the attacking and the emerging beetles. It was collected from most investigated forests, whereas O. ips and L. wingfieldii were obtained only from forests located in Central and Northern Tunisia. Frequencies of association with T. piniperda were always low, reaching 11.1% only once, for O. ips. Ophiostoma ips was the only blue stain fungus associated with O. erosus and its galleries. It was found in all the localities, but at a low and variable frequency, exceeding 15% very rarely. The virulence of 16 fungal isolates was tested by single inoculations into Pinus halepensis (Aleppo pine) at two localities. Differences were detected among species; L. wingfieldii was the most virulent and O. minus the least virulent species in terms of phloem reaction zone formation and fungal growth in the phloem. In a separate experiment, mass inoculations (400 and 800 inoculations per m2 of bole on 1‐m high belts) were performed with two isolates of L. wingfieldii on Aleppo pine and on Pinus brutia (Brutia pine). Three months later, measurements of sapwood status (% of conductive transversal section) and of its specific hydraulic conductivity, as well as of the phloem reaction zone lengths, did not show any isolate or density effect. At these experimental sites, Brutia pines appeared significantly more susceptible than Aleppo pines.  相似文献   

19.
Dutch Elm Disease (DED) is a vascular wilt disease of Ulmus species (elms) incited in North America primarily by the exotic fungus Ophiostoma novo‐ulmi. The pathogen is transmitted via root grafts and elm bark beetle vectors, including the native North American elm bark beetle, Hylurgopinus rufipes and the exotic smaller European elm bark beetle, Scolytus multistriatus. The banded elm bark beetle, Scolytus schevyrewi, is an exotic Asian bark beetle that is now apparently the dominant elm bark beetle in the Rocky Mountain region of the USA. It is not known if S. schevyrewi will have an equivalent vector competence or if management recommendations need to be updated. Thus the study objectives were to: (i) determine the type and size of wounds made by adult S. schevyrewi on branches of Ulmus americana and (ii) determine if adult S. schevyrewi can transfer the pathogen to American elms during maturation feeding. To determine the DED vectoring capability of S. schevyrewi, newly emerged adults were infested with spores of Ophiostoma novo‐ulmi and then placed with either in‐vivo or in‐vitro branches of American elm trees. The inoculation of trees via feeding wounds was successful 30% of the time for in‐vivo trials and 33% for in‐vitro trials. Although the infection rate of DED has declined in Colorado over the past 10 years, the disease is still present in urban elms. While it appears that S. schevyrewi is another vector of the DED pathogens, it appears that S. schevyrewi is no more efficient than S. multistriatus. Thus, management programs that remove elm bark beetle breeding sites, rapidly remove DED‐infected elms and include the planting of DED‐resistant elms should continue to be effective management tactics.  相似文献   

20.
Conifer bark beetles are often associated with fungal complexes whose components have different ecological roles. Some associated species are nutritionally obligate fungi, serving as nourishment to the larvae, whereas others are pathogenic blue-stain fungi known to be involved in the interaction with host defenses. In this study we characterized the local and systemic defense responses of Scots pine (Pinus sylvestris L.) against Ophiostoma brunneo-ciliatum Math. (a blue-stain pathogen) and Hyalorhinocladiella macrospora (Franke-Grosm.) Harr. (a nutritional fungus). These fungi are the principal associates of the pine engraver beetle, Ips acuminatus (Gyll.). Host responses were studied following inoculation with the fungi, singly and as a fungal complex, and by identifying and quantifying terpenoids, phenolic compounds and lignin. Although the length of the necrotic lesions differed between control (wound) and fungal treatments, only two compounds (pinosylvin monomethyl ether and (+)-α-pinene) were significantly affected by the presence of the fungi, indicating that Scots pine has a generic, rather than specific, induced response. The fact that both nutritional and blue-stain fungi triggered comparable induced defense responses suggests that even a non-pathogenic fungus may participate in exhausting host plant defenses, indirectly assisting in the beetle establishment process. Our findings contribute to the further development of current theory on the role of associated fungal complexes in bark beetle ecology.  相似文献   

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