Study on Ophiostomatoid Fungi Associated with Bark Beetles on Pinus Silvestris L

НАУКА ЗА ГОРАТА, КН. 2, 2009 FOREST SCIENCE, No 2, 2009

STUDY ON OPHIOSTOMATOID FUNGI ASSOCIATED WITH BARK BEETLES ON PINUS SILVESTRIS L. IN MALESHEVSKA PLANINA MT.

Sonja Bencheva, Danail Doychev, Dinko Ovcharov University of Forestry – Sofia

Abstract: The aim of this study was to identify species composition of wood stain- causing fungi, as well as their association with bark beetles on Scots pine in the Maleshevska Planina Mt. D��imensions of�� perithecia�� of�� ophiostomatoid�� fungi�� isolated�� from�� adults�� or wood�� with�� gal��- leries of the bark beetles Orthotomicus longicollis, Trypodendron lineatum, Ips acuminatus and Ips sexdentatus led to identifying the isolated fungi as Ophiostoma piceaperdum. The fungi isolated from Tomicus piniperda, Hylurgops palliatus, Orthotomicus laricis and Hylastes attenuatus formed smaller-sized perithecia with considerably shorter necks. The dimensions of conidiophores of all isolated fungi had borderline values within the range for Leptographium wingfieldii; however, it is not characterized by perithecia as these developed in large numbers in the experiments. The probability all isolated fungi to be morphological variants of one and the same species should also be considered; on the whole, this species was thought to be O. piceaperdum. Key words: ophiostomatoid fungi, bark beetles, Pinus sylvestris, wood stain

INTRODUCTION

Stain or change of natural wood colour does not decrease wood durability (ЕN 844-10/1998); however, timber discolourations reduce its quality as they suggest that there might be a risk of presence of wood- destroying fungi. Therefore, a considerable part of discoloured wood is sold at a lower price. Ophiostomatoid fungi are one of the most important groups of microorganisms causing wood discolouration. Their hypha, conidiophores and perithecia produce melanin which induces darkening of wood. Taxonomically, these fungi belong to the Division Ascomycota, Class Pyrenomycetes, Orders Microascales and Ophiostomatales, and are represented mainly by the Genera Ceratocystis Ellis & Halst. and Ophiostoma Syd. & P. Syd. The most significant differences between them are (1) the inability of Ceratocystis species to grow in the presence of the antibiotic cycloheximide in contrast to Ophiostoma species, and (2) the presence of chitin and cellulose in the cell wall of Ophiostoma species; in comparison, these are not found in the Genus Ceratocystis.

101 The Genera Ceratocystis and Ophiostoma comprise more than 150 species, most of which are weak parasites or saprophytes, but they also include some dangerous tree species pathogens. The sexual stage (teleomorph) of these genera is characterized by dark coloured spherical ascocarps – bottle-shaped perithecia with mouths (ostioles) usually situated on elongated ‘necks’ (tubules of variable lengths). The dimensions, shapes and colours of ascocarps, and the shapes and sizes of ascospores are used for species differentiation. The ascospores released from the fragile asci developed in the perithecia of these fungi are enclosed in a sticky sheath which ensures their dissemination by insects. The anamorph (imperfect state) of the Genus Ceratocystis is associated mostly with the Genera Chalara (Corda) Rabenh. and Graphium Corda, and the Genus Ophiostoma – with Graphium and Leptographium Lagerb. & Melin. Species of the Genus Leptographium are among the economically most damaging fungi causing stain to felled wood and stored timber (Gibbs, 1993; Seifert, 1993; Jacob, Wingfield, 2001). They also damage stressed standing trees, mostly coniferous species, and rarely angiosperms (Jacobs, Wingfield 2001). Several species (such as L. wageneri (Goheen & F.W. Cobb) T.C. Harr.) are known as conifer root pathogens. Most species of this genus are considered Ophiostoma anamorphs (Wingfield, 1993; Jacobs, Wingfield 2001), although teleomorphs were identified for only a few species. The Genus Leptographium is characterized by dark coloured conidiophores ending with several filaments of conidiogenous cells which produce hyaline one-celled conidia enveloped in sticky mass (Wingfield, 1993; Masuya et al., 2004). This biological trait is also a characteristic fungus adaptation for spreading spores by insects, in particular by bark beetles (Jacobs, Wingfield 2001). Bark beetles (Coleoptera, Curculionidae, Scolytinae) are widespread in coniferous forests. Most conifers are affected by at least one specialized bark beetle capable of destroying a colonized tree under suitable conditions. For successful colonizing, bark beetles that attack living stems usually require hosts which are under some kind of physiological stress. The annual variability of the population size of these insects depends on the type and extent of forest-affecting stress factors such as drought, air pollution, damages by wind, snow, insects, diseases and etc., that can weaken a host. For example, Otrosina, Ferrell (1995) found out that site disturbances were the primary factor leading to blue stain of root wood of Douglas-fir (Pseudotsuga menziesii (Mirb.) caused by Leptographium fungi. They observed a large increase of the number of Hylastes species at sites where the plantations had been thinned, in contrast to adjoining unthinned plantations. A considerable part of the bark beetles’ life-cycle occurs under the bark of trees or in the wood, whereas only adults are found in the open while

102 they are feeding to mature or looking for new sites to colonize. Insects carry sticky conidia and ascospores of ophiostomatoid fungi on their bodies (for this purpose they have special adaptations) under the bark of newly occupied trees, and these fungi make wood more favourable to insect development. Studying the species composition and the virulence of fungi associated to Tomicus piniperda L. in Poland Jankowiak (2006) identified 67 species, mostly representatives of ophiostomatoid fungi and moulds. The most common ophiostomatoid fungi were Ophiostoma minus (Hedgc.) Syd. & P. Syd. and O. piceae (Münch) Syd. & P. Syd., rarely Leptographium lundbergii Lagerb. & Melin, L. procerum (W.B. Kendr.) M.J. Wingf., L. wingfieldii M. Morelet and Graphium sp. The author concluded that the occurrence of these fungi varied considerably in the sites studied. According to the same author L. wingfieldii and O. minus were the only species capable of infesting living trees and penetrating deeper into the sapwood in contrast to other fungi which were considerably less virulent. Solheim et al. (2001) also mentioned the fact that T. piniperda may attack and kill living trees, but only when these were severely stressed. They thought that this bark beetle was also associated with blue-stain fungi L. wingfieldii and O. minus. According to Paine et al. (1997), the death of trees attacked by bark beetles was a result of dynamic interactions between beetles, ophiostomatoid fungi and the host tree, the fungi reducing tree stability against colonization by bark beetles and restricting the development of other insect species or fungi. In the course of a study on species composition and distribution of bark beetles on Scots pine trees (Pinus sylvestris L.) in Maleshevska Planina Mt. in 2004-2005 it was found out that the wood colonized by them was stained extensively. The expanding area affected by bark beetles and associated wood stain-causing fungi required closer investigation of the ophiostomatoid fungi found there. The aim of this study was to identify the species composition of wood stain-causing fungi, as well as their association with particular insect vectors.

MATERIALS AND METHODS

The study on ophiostomatoid fungi was carried out in 2006 in an expanding area characterized by wood stain disturbance in the territory of Strumyani Forestry State Enterprise. The area is located in 35 year-old Scots pine plantations situated at 820 m a. s. l. in Maleshevska Planina Mt. (South- western Bulgaria). Samples of stained wood and bark with galleries dug by bark beetles as well as adult insects found in the galleries were collected for phytopathological analyses between April and July 2006. The samples were placed in polythene

103 bags or in plastic flasks. They were kept in a refrigerator at 4-5 оС, and were processed up to 5 days after collection using the following methods: Wood samples (1-3 pieces) were placed in Petri dishes with nutrient medium. Samples collected from a particular tree were placed in one dish. Prior to that samples were surface sterilized by submersion for 1 minute in solution of distil water, 10% household bleach and 10% ethanol; immediately after that they were rinsed by submersion in distil water for 3 minutes and were dried on filter paper. Selective medium (CSMA – 2% malt extract agar with addition of 0,8g/l cycloheximide and 0,2g/l streptomycin sulphate) was used for isolation of Leptographium species (Jacobs, Wingfield, 2001; Eckhardt et al., 2002, Otrosina et al., 1999). After the wood samples had been placed in Petri dishes, they were incubated at room temperature (about 25 оС). The samples were checked for presence of ophiostomatoid fungi daily during the first 7 days, and after that – every 2 days; The insects collected from each stem were rolled without wounding on CSMA in Petri dishes which were incubated and checked in the same manner as the wood samples; If more insect specimens were available, 2 of them were placed in a test-glass with 2 mL distil water and were shaken vigorously. Three drops of 1 mL each from the solution were put in a Petri dish with CSMA. They were incubated in the same manner. About 10-40 of developed perithecia, conidiophores and conidia were measured for each isolate. The results of measurements were processed with the software program STATISTICA, version 6 (StatSoft, Inc., 2002).

RESULTS AND DISCUSSION

In the summer of 2005 the engraver beetle (Ips acuminatus Gyll.) was found to have attacked the upper part of crowns of a group of marginal trees in the observation site. Later (by the end of summer/the beginning of autumn) the six-toothed bark beetle (Ips sexdentatus Börn.) had invaded the already dried stems. In the course of the next year other species of bark beetles were observed as well: Trypodendron lineatum Ol. (into stem wood), Tomicus piniperda L., Orthotomicus laricis F., Orthotomicus longicollis Gyll., Hylurgops palliatus Gyll. (under stem bark) and Hylastes attenuatus Er. (on roots and underground part of stems). Collected samples from all bark beetles listed above were analysed on nutrient medium for presence of ophiostomatoid fungi. The identification of Leptographium species is accompanied with considerable difficulties because many of their taxonomic characteristics are misleading if considered on their own. Recent phylogenetic analyses (Zipfel et al., 2006) even indicated the need to restore the teleomorph genus

104 Grosmannia for species with anamorphs of Leptographium or Pesotum-like types. Furthermore, most Ophiostoma and Leptographium species show high degree of pleomorphism, i.e. some of them may be morphological variants of one and the same species (Six et al. 2003). Identification ought to be based on comparison with authentic cultures (Wingfield, 1993). In this study it was the lack of comparative materials that did not allow drawing definitive conclusions about the species composition of the isolated fungi. Therefore, only some morphometric (Table 1) and culture characteristics (Table 2, Fig. 1, 2, 3) will be shown below; these were found out during the analyses which narrowed the circle of hypothetical species so that more accurate identification can be achieved. The cluster analysis (Fig.4, diagram 1 and 2) of the perithecial measurements data (diameter and neck length) grouped together ophiostomatoid fungi isolated from adults or wood with galleries and adults of the bark beetles: Orthotomicus longicollis, Tripodendron lineatum, Ips acuminatus and Ips sexdentatus. On the basis of the seminal publication by Jacobs, Wingfield (2001), the average dimensions of diameter of perithecia observed (Table 1) and the association of these fungi with both the insects (see above) and the tree Pinus sylvestris, the fungi isolated from these bark beetles can be identified as Ophiostoma piceaperdum (Rumbold) Arx, O. laricis Van der Westh., Yamaoka & M.J. Wingf., O. huntii (R.C. Rob) de Hoog & R.J. Scheff. or O. wageneri. The neck length of perithecia of the isolated fungi, however, varied in a wider range than that for O. piceaperdum, O. huntii and O. wageneri, and it was closer to that of O. laricis. Comparing fungus anamorphs already grouped in one cluster by teleomorph, it was found out that the conidiophore length of the fungi isolated from I. acuminatus, Orth. longicollis and T. lineatum corresponded to these fungi as well; the cluster analysis (diagram 3) also showed that they may be one and the same species, while these from I. sexdentatus did not belong to the common cluster. The habitats reported for O. wageneri which has a limited distribution in the western USA, for O. huntii – in Canada, Australia, New Zealand and USA, and for O. laricis – in Japan (solely found on Larix kaempferi (Lamb.) Carr.) led to the identification of the isolated fungi as Ophiostoma piceaperdum, despite the longer average neck length of perithecia observed. The second cluster obtained on the basis of the cluster analysis of data of perithecial measurements comprised ophiostomatoid fungi isolated from the following bark beetles: T. piniperda, H. palliatus, Orth. laricis and Hylastes attenuatus. These fungi had smaller-sized perithecia which were close to the dimensions range for the species: O. crassivaginatum (H.D. Griffin) T.C. Harr. and O. wageneri. However, their necks were considerably shorter in comparison with these of the first group, and even with these of the two

105 1 3 3. 2.00 0.268 0.233 0.305 0.828 0.491 1.132 0.124 0.094 0.147 0.008 0.006 0.011 0.004 0.003 0.005 lineatum Trypodendron Trypodendron 6 00 3 1. 2. 0.083 0.047 0.134 0.130 0.057 0.235 0.344 0.132 0.684 0.006 0.004 0.007 0.003 0.002 0.003 Tomicus Tomicus piniperda 0 2 3 . 4.2 2 0.213 0.137 0.261 0.895 0.445 1.370 0.159 0.092 0.214 0.011 0.006 0.014 0.005 0.003 0.008 longicollis Orthotomicus 8 33 . 8 0 2 2. 0.115 0.072 0.131 0.317 0.577 0.251 0.052 0.486 0.007 0.005 0.010 0.003 0.003 0.004 laricis Orthotomicus 88 3 0.9 1. 0.089 0.062 0.124 0.081 0.045 0.120 0.285 0.142 0.569 0.015 0.004 0.021 0.008 0.002 0.017 palliatus Hylurgops

Table 1 6 00 3 . 3. 2 0.100 0.080 0.115 0.356 0.295 0.413 0.161 0.067 0.382 0.008 0.004 0.013 0.004 0.003 0.007 Hylastes attenuatus 5 67 . 7 4 Ips 1. 0.233 0.136 0.405 1.055 0.655 1.676 0.358 0.072 0.850 0.005 0.002 0.006 0.003 0.002 0.003 sexdentatus (length l and width w) of the isolates studied bark beetles 0 4 4.6 Ips 2.5 0.199 0.135 0.287 0.918 0.336 1.850 0.228 0.084 0.426 0.005 0.004 0.008 0.002 0.001 0.004 acuminatus l l d w l/d l/w min min min min min max max max max max length

number

phores

Perithecia Conidia

- �� onidio C Average, minimum and maximum dimensions (mm) of perithecia (diameter d neck length l), conidiophores (length) conidia solates I Isolates of bark beetle:

106

- and with

there

)

F medium

mycelium

were also were occasional media

media

. Two months and (Fig. 2-

nutrient was higher than higher was masses )

nutrient H

nutrient On day 20 day On

). the

the H mycelium had developed

conidial in

(fig. 1- (fig.

s conidiophores conidiophores , slimy brown (Fig. 2- (Fig. - . On day 20 the samples

sample and

masses the

greyish hyphae, many

conidial placing the placing

onidiophores . medium ) on it and on wood on and it on

F slimy

nutrient were necks had already formed had formed around formed had

(Fig. 1-

in conidiophores

Two months after months Two . . There were slimy conidial masses around the wood samples Characteristics of the isolates many with occasional serpentine Table 2 ), hyphae The number of perithecia per unit area in wood in area unit per perithecia of number The H adult . conidial masses at places. C places. at masses conidial and

(fig. 3- (fig. slimy

in nutrient medium there in wood

thick black

There were conidiophores, slimy conidial masses, and perithecia with long necks. There . fused

sample �� black; there was poorly developed white aerial mycelium in patches, and there were many con many were there and patches, in mycelium aerial white developed poorly was there black; but with masses

after placing poorly developed greyish-brown mycelium greyish-brown developed poorly

loose, on wood samples where perithecia with long onidiophores conidial placing the occasional perithecia with medium-long necks

poorly developed white aerial mycelium aerial white developed poorly day 7 On with found completely was idiophores (some of which in clusters) fused in slimy conidial masses, and large groups of perithecia with long necks (Fig. 1-С). Formation of coloured mycelium in nutrient medium started on day 2. On day 14 the medium was completely covered by dark greyish-brown mycelium; there were conidiophores, slimy conidial masses, and perithecia with long necks. The number of perithecia per unit area in wood (Fig. 1-D) was higher than that medium. 7 day On hyphae serpentine occasional was still after necks medium-long with perithecia that in medium. Formation of coloured mycelium in nutrient medium started on day 2. On day 14 the medium was covered by dark brown to greyish-black mycelium slimy was were Morphobiological characteristics of the isolates ophiostomatoid fungi associated with studied bark beetles palliatus

attenuatus

Isolates of bark beetle Ips acuminatus Ips sexdentatus Hylastes Hylurgops

107

, ) on G - ( 3 (Fig. greyish-brown slimy conidial slimy

with long necks hyphae

and black; the mycelium had clumps of conidiophores in

perithecia without necks there were many were there were and

), among which there were clumps were there which among ),

brownish- without necks ) G - A – - 2 2 (Fig. (Fig. mycelium had serpentine had mycelium there were conidiophores and perithecia with hyphae. There

. masses )

wood samples; in the medium dark , and

G ) B - the 2 medium. On day 14 the medium was covered by greyish- by covered was medium the 14 day On medium.

conidial

(Fig. 1- the nutrient medium was (Fig. with serpentine nutrient slimy

masses, conidiophores

in and ).

Characteristics of the isolates B conidiophores (singly and in clusters, with yellowish slimy substance on substance slimy yellowish with clusters, in and (singly conidiophores On day 20 Table 2 Continued . ) many There were many single conidiophores (some of which in clusters) fused in had formed around . (Fig. 1-

clumps of slimy hyphae masses,

mycelium

with , slimy conidial masses and different types of perithecia aerial conidial )

E - 2 in the wood samples slimy white

. ) E (Fig. these had medium-long necks On day 2 mycelium had started developing started had mycelium 2 day On conidiophores many with mycelium brown after months Two wood. on formed had necks without perithecia undersized many necks; short with perithecia of the black, completely was medium nutrient the samples the placing were there top) and many perithecia with medium-long necks On day 7 mycelium had formed wood dense thin grayish-brown slimy conidial masses at places, and perithecia with very long necks (Fig. 1-A). Formation of coloured mycelium in nutrient medium started on day 2. On day 14 by vigorously developed dark the brown mycelium medium was covered clusters (Fig. 1- 14 day On 2. day on started medium nutrient in mycelium coloured of Formation masses and small conidiophores in the medium long necks lineatum laricis longicollis

piniperda

Isolates of bark beetle Orthotomicus Orthotomicus Tomicus Trypodendron

108 Fig. 1. Perithecia of ophiostomatoid fungi associated with studied bark beetles

109 Fig. 2. Conidiophores of ophiostomatoid fungi associated with studied bark beetles

Fig. 3. Serpentine hyphae

110 species above. It was quite probable that this was one and the same fungus, but, at this stage of the study, no definitive identification could be made. O. wageneri forms much longer conidiophores, whereas O. crassivaginatum has shorter ones than those measured in the samples that led to their exclusion as potential species. Considering the average conidiophore length, all isolates had borderline values within the range for Leptographium wingfieldii. However, almost all isolates formed perithecia not reported for this fungus. Furthermore, serpentine hyphae found in many of the obtained isolates (Table 2) were not typical of it. A typical morphological feature of mycelium of isolates from the bark beetles H. attenuatus, Orth. laricis, T. piniperda and H. palliatus is the presence of occasional serpentine hyphae (Table 2, Fig. 4). These hyphae are a distinctive trait of the fungus O. serpens (Goid.) Arx, as is the formation of rhizoids at the base of conidiophores. No rhizoids were found in the observed isolates. Serpentine hyphae, even though not as distinct, were also reported in O. huntii and O. wageneri (Wingfield 1993). Therefore, it is possible these isolates to be identified as O. piceaperdum whose colonies were reported to have such hyphae as a characteristic trait (Jacobs & Wingfield 2001), or that there was a failure to observe rhizoids in O. serpens.

Fig. 4. Cluster analysis of measurements data

111 CONCLUSIONS

The colonization of bark beetles on Scots pine in the area under observation was started by Ips acuminatus, immediately followed on the newly dried stems by Ips sexdentatus. Later Trypodendron lineatum, Tomicus piniperda, Orthotomicus laricis, Orthotomicus longicollis and Hylurgops palliatus were observed on the same stems, and Hylastes attenuatus – on the roots, i.e. each of these bark beetles was a probable vector of fungi which had caused the stain of wood observed. That was confirmed for all species during the test isolations. On the basis of the results obtained after conducting laboratory analyses the following summary can be made: Dimensions of perithecia (diameter and neck length) and conidiophore lengths of ophiostomatoid fungi isolated from adults or wood of Pinus sylvestris with galleries of the bark beetles Orthotomicus longicollis, Trypodendron lineatum, Ips acuminatus and Ips sexdentatus led to identifying the isolated fungi as Ophiostoma piceaperdum, despite the observed longer average neck length of perithecia in all of them, and the wide variation of conidiophore lengths of I. sexdentatus. The ophiostomatoid fungi isolated from the bark beetles Tomicus piniperda, Hylurgops palliatus, Orthotomicus laricis and Hylastes attenuatus formed smaller-sized perithecia with considerably shorter necks in comparison with the above mentioned group. A typical morphological feature of mycelium of these fungi is the presence of occasional serpentine hyphae which are a distinctive trait of the fungus O. serpens. However, the observed isolates did not exhibit the typical fungal rhizoids at the base of conidiophores. The dimensions of conidiophores of all isolated fungi had borderline values within the range for Leptographium wingfieldii; however, serpentine hyphae are not typical for this species, nor is it characterized by perithecia as these developed in large numbers in the experiments. The probability all isolated fungi to be morphological variants of one and the same species should also be considered; on the whole, this species was thought to be O. piceaperdum. Finally, further studies are required in order to more precisely establish the species composition of the representative of the family Ophiostomataceae associated with the observed bark beetles as well as to assess the impact of particular fungi on insect development, and on the damages caused by these bark beetles.

Acknowledgements: The study is part of the research conducted under VU-AN-01/05 grant financed by the Ministry of Education and Science of Bulgaria. Kind thanks go to Ms. Bilyana Ovcharova (University of Forestry) for proofreading the paper.

112 References

Eckhardt, L., J. Jones, N. Hess, E. Carter. 2002. Leptographium Species a Component of Loblolly Pine Decline. FHM Posters 2002. Gibbs, J.N. 1993. The biology of ophiostomatoid fungi causing sapstain in trees and freshly cut logs. In: Wingfield, M.J., Seifert, K.A., Webber, J.F. (Eds.). Ceratocystis and Ophiostoma: taxonomy, ecology, and pathogenicity. St. Paul, Minnesota, APS Press., 141–152. Jacobs, K., M.J. Wingfield. 2001. Leptographium species, tree pathogens, insect associates, and agents of blue-stain. St. Paul, Minnesota: APS Press. 207. Jankowiak, R. 2006. Fungi associated with Tomicus piniperda in Poland and assessment of their virulence using Scots pine seedlings. – Annals of Forest Science, 63, 7, 801-808. Masuya, H., M. J. Wingfield, T. Kubono, Y. Ichihara. 2004. Leptographium pruni, sp. nov. from bark beetle-infested Prunus jamasakura in Japan. – Mycologia, 96 (3), 548-557. Otrosina, W. J., D. Bannwart, R. W. Roncadori. 1999. Root-infecting fungi associated with a decline of longleaf pine in the southeastern United States. – Plant and Soil, 217, 145- 150. Otrosina, W. J., Ferrell, G. T. 1995. Root diseases: primary agents and secondary consequences of disturbance. In: Eskew L. (comp.). Forest health through silviculture: proceedings of the 1995 National Silviculture Workshop, Mescalero, New Mexico, May 8-11, 1995. Gen. Tech. Rep. RM-GTR-267. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station, 87-92. Paine, T. D., K. F. Raffa, T. C. Harrington, 1997. Interactions Among Scolytid Bark Beetles, Their Associated Fungi, and Live Host Conifers. – Annual Review of Entomology, 42, 179–206. Paulin-Mahady, A. E., T. C. Harrington, D. McNew. 2002. Phylogenetic and taxonomic evaluation of Chalara, Chalaropsis, and Thielaviopsis anamorphs associated with Ceratocystis. – Mycologia, 94, 62-72. Seifert, K. A. 1993. Sapstain of commercial lumber by species of Ophiostoma and Ceratocystis. In: Wingfield M. J., Seifert K. A., Webber J. F. (Eds.). Ceratocystis and Ophiostoma, taxonomy, ecology, and pathogenicity. St. Paul, Minnesota: APS Press., 141–151. Six, D. L., T. C. Harrington, J. Steime, D. McNew, T. D. Paine. 2003. Genetic relationships among Leptographium terebrantis and the mycangial fungi of three western Dendroctonus bark beetles. – Mycologia, 95 (5), 781–792. Solheim, H., P. Krokene, B. Lаngstrоm. 2001. Effects of growth and virulence of associated blue-stain fungi on host colonization behaviour of the pine shoot beetles Tomicus minor and T. piniperda. – Plant Pathology, 50 (1), 111–116. Wingfield, M. J. 1993. Leptographium species as anamorphs of Ophiostoma: progress in establishing acceptable generic and species concepts. In: Wingfield M. J., Seifert K. A., Webber J. F. [eds]. Ceratocystis and Ophiostoma: taxonomy, ecology, and pathogenicity. St. Paul, Minnesota: APS Press, 40-48. Zipfel, R. D., de Beer W., Jacobs K., Wingfield B. D., Wingfield M. J. 2006. Multi-gene phylogenies define Ceratocystiopsis and Grosmannia distinct from Ophiostoma. – Studies in Mycology, 55, 75–97.

113 Проучване на офиостоматоидните гъби, свързани с корояди По PINUS SILVESTRIS L. в малешевска Планина

С. Бенчева, Д. Дойчев, Д. Овчаров Лесотехнически университет – София

(р езюме)

Целта на проучването бе да се определи видовия състав на гъбите, причиняващи оцветяване на дървесината, както и връзката им с короядите по белия бор (Pinus sylvestris L.) в Малешевска планина. Размерите на перитециите при офиостоматоидните гъби, изолирани от имаго или дървесина с ходове на видовете Orthotomicus longicollis, Trypodendron lineatum, Ips acuminatus и Ips sexdentatus ни насочват да определим изолираните гъби като Ophiostoma piceaperdum. При гъбитe, изолирани от Tomicus piniperda, Hylurgops palliatus, Orthotomicus laricis и Hylastes attenuatus се формираха по-дребни перитеции със значително по-къси шийки. Размерите на коремиите при всички проучвани видове гъби се включват в граничните стойности за Leptographium wingfieldii, за която обаче не се описват перитеции, каквито се развиха масово при нашите експерименти. Не изключваме вероятността всички изолирани гъби да са морфологични варианти на един и същ вид, като предположенията ни са насочени като цяло към O. piceaperdum. ключови думи: офиостоматоидни гъби, корояди, Pinus sylvestris, оцветяване на дървесината.

E-mail: [email protected]

114