- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Risk of Introduction
- Habitat List
- Hosts/Species Affected
- Growth Stages
- List of Symptoms/Signs
- Biology and Ecology
- Means of Movement and Dispersal
- Plant Trade
- Impact Summary
- Risk and Impact Factors
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Gaps in Knowledge/Research Needs
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Ophiostoma longicollum Masuya 1998
Summary of InvasivenessTop of page
O. longicollum is a perithecial ascomycete that was isolated from the wood of dying oak [Quercus spp.] trees attacked by the wood-boring beetle, Platypus quercivorus, on the west coast of Japan. Neither the pathogenicity of the fungus, nor any definite association with the beetle as a vector, has been established. The beetle is ranked first as a Prioritized Pest for the USA (USDA/APHIS, 2010) and another fungus, shown to be vectored by the beetle, has been associated with tree mortality.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Fungi
- Phylum: Ascomycota
- Subphylum: Pezizomycotina
- Class: Sordariomycetes
- Subclass: Sordariomycetidae
- Order: Ophiostomatales
- Family: Ophiostomataceae
- Genus: Ophiostoma
- Species: Ophiostoma longicollum
Notes on Taxonomy and NomenclatureTop of page
O. longicollum was described by Masuya et al. (1998) from dying oak [Quercus spp.] trees on the west coast of Japan. The new fungus differed from other species of “ophiostomatoid” fungi reported on the same host by its ascoma and spore sizes, long neck, and other neck morphology. The species has a Sporothrix anamorph and, like other members of the genus, tolerates cycloheximide (Masuya et al., 1998). Recent molecular phylogenetic studies of Ophiostoma and Sporothrix (Aghayeva et al., 2005; Zipfel et al., 2006; Alamouti et al., 2009; Grobbelaar et al., 2009) have not considered O. longicollum.
DescriptionTop of page
Ascomata produced on 1% pablum agar or on oak wood blocks. Basal part globose to subglobose, black, 100-370 µm diameter, ornamented with unbranched, brown hyphal appendages up to 280 µm long. Neck cylindrical or tapered, straight or bent, black, 1-10 µm long, 30-60 µm wide at base, 15-50 µm and pale brown at apex. Apex truncate to obtuse, covered by a hyaline gelatinous cap. Asci evanescent, not described. Ascospores hyaline, aseptate, broadly lunate in side view, globose in end view, ellipsoid in top view, 2-3.5 x 1-1.5 µm, collecting in a yellow-orange mass at ostiole.
Conidiophores arising from surface or aerial mycelium, hyaline, septate, bearing terminal conidiogenous cells. Cells 0.5-2.0 x 0.5-5.5 µm, proliferating sympodially, slightly denticulate. Conidia holoblastic, hyaline, aseptate, ellipsoidal, slightly curved, sometimes Y-shaped, 2.0-6.0 x 0.5-2.5 µm, aggregating in slimy masses at cell tip.
Colony white to pale brown on 2% MEA (malt extract agar), growing 2.4-3.1 mm/day at 20°C (optimum). Growth is reduced by 60% with 2.5 g/L cycloheximide at 25°C. No growth at 4°C.
For additional details, see Masuya et al. (1998).
DistributionTop of page
So far the fungus is only known from Japan, but the host species (Quercus mongolica) is also native to other parts of Asia, including Korea, China, Mongolia, Siberia and Far Eastern Russia (BPI, 2009).
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
Risk of IntroductionTop of page
The risk of introduction is unknown. The pathogenicity of the species, and even whether or not its growth can stain wood, is not established. Although there was a simultaneous observation of galleries of a wood-boring beetle, and ophiostomatoid fungi are generally vectored by arthropods including such beetles, no clear association of the fungus with the beetle was demonstrated. Fungi can have either a specific association with a certain species of vector or be more generally distributed by insects. If the association is specific, and the fungus was introduced in wood or unprocessed wood products from Asia, then the beetle, Platypus quercivorus, might have to be introduced as well, in order for the fungus to pose a possible threat to American trees. On the other hand, species of the beetle genus, Platypus, do occur in North America and Europe (Davis et al., 2005).
Habitat ListTop of page
|Terrestrial ‑ Natural / Semi-natural||Natural forests||Present, no further details||Harmful (pest or invasive)|
Hosts/Species AffectedTop of page
Only Quercus mongolica was identified as a host in Japan (Masuya et al., 1998). In current taxonomy, this species includes both Quercus mongolica var. grosseserrata and Quercus mongolica subsp. crispula (BPI, 2009).
Growth StagesTop of page Vegetative growing stage
SymptomsTop of page
The symptoms of the declining oaks [Quercus spp.] from which the fungus was isolated, have not been described. Mass mortality of oaks on the western coast of Japan has been reported to be preceded by wilting in early summer, followed by reddening of the leaves (Kinuura, 1994; Ito et al., 2003), but this has been associated with the fungus, Raffaelea quercivora (Ito et al., 2003).
List of Symptoms/SignsTop of page
|Leaves / wilting|
|Whole plant / plant dead; dieback|
Biology and EcologyTop of page
The biology of O. longicollum may be expected to be similar to that of other ophiostomatoid fungi. Carried by arthropods to trees, the fungus would grow in beetle galleries, producing conidia that may serve for local dispersal or as spermatia in mating between strains. Ascomata then develop in the galleries and the ascospores collecting in a sticky mass at the apex of the neck become attached to the bodies of arthropods and are carried to new trees (Malloch and Blackwell, 1993).
The fungus was isolated from sapwood containing the galleries of the beetle, Platypus quercivorus (Masuya et al., 1998), but no definite interaction with the beetle was established. The ambrosia fungus, Raffaelea quercivora, has a close association with the same beetle. It has been isolated from the beetle’s body surfaces and mycangia, and appears to be vectored by it (Kinuura, 2002; Kubono and Ito, 2002).
ClimateTop of page
|Cf - Warm temperate climate, wet all year||Preferred||Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year|
|Df - Continental climate, wet all year||Preferred||Continental climate, wet all year (Warm average temp. > 10°C, coldest month < 0°C, wet all year)|
Means of Movement and DispersalTop of page
In related fungi, conidia are considered likely to serve the function of local dispersal in the tree (Malloch and Blackwell, 1993). If they were produced in functioning xylem, they could be carried to the roots and through them to other trees in natural root grafting, as occurs for Ophiostoma ulmi (Sinclair and Lyon, 2005).
The fungus is likely to have one or more arthropod vectors. Malloch and Blackwell (1993) report that all species in the ophiostomatoid groups are disseminated by arthropods. Association with galleries of the beetle, Platypus quercivorus, was observed by Masuya et al. (1998). Other Ophiostoma species occurring in Abies (Yamaoka et al., 2004) and Pinus densiflora (Masuya et al., 2009) appear to have associations with one or more species of bark beetle. Accidental Introduction Logs, unprocessed wood or wood bearing bark imported from eastern Asia, could carry the fungus and/or an infested insect vector.
Logs, unprocessed wood or wood bearing bark imported from eastern Asia, could carry the fungus and/or an infested insect vector.
Plant TradeTop of page
|Plant parts liable to carry the pest in trade/transport||Pest stages||Borne internally||Borne externally||Visibility of pest or symptoms|
|Stems (above ground)/Shoots/Trunks/Branches||fruiting bodies; hyphae; spores||Yes||Pest or symptoms not visible to the naked eye but usually visible under light microscope|
|Plant parts not known to carry the pest in trade/transport|
|Fruits (inc. pods)|
|Growing medium accompanying plants|
|True seeds (inc. grain)|
Impact SummaryTop of page
ImpactTop of page
No impact of this species has been reported, but the possible beetle vector, Platypus quercivorus, is already a Prioritized Pest for USDA/APHIS (2010) based on its potential economic and environmental damage (Davis et al., 2005). Separation of damage due to O. longicollum from that which is associated with the fungus Raffaelea quercivora (Ito et al., 1998; 2003; Kubono and Ito, 2002), which is known to be vectored by the beetle (Kinuura, 2002), may be difficult.
Risk and Impact FactorsTop of page Invasiveness
- Reproduces asexually
- Host damage
- Negatively impacts forestry
- Difficult to identify/detect as a commodity contaminant
- Difficult to identify/detect in the field
DiagnosisTop of page
A simple and rapid PCR protocol for the identification of other Ophiostoma species in wood, which might be adapted for O. longicollum, was developed by Kim et al. (1999). There are no sequences of any DNA region for this species deposited in GenBank (as of January, 2010), but sequences for other species in the genus are available for comparison (NCBI, 2010).
Detection and InspectionTop of page
The fungus was detected originally by its growth on wood blocks from insect-infested oak [Quercus spp.] trees. The symptoms of the declining oaks were not described. Mass mortality of oaks on the western coast of Japan is reported to be preceded by wilting and has been associated with the presence of the ambrosia beetle, Platypus quercivorus (Kinuura, 2002; Ito et al., 2003).
Similarities to Other Species/ConditionsTop of page
Masuya et al. (1998) noted that 17 species of Ophiostoma were reported from oak [Quercus spp.] at that time and none closely resembled O. longicollum except Ophiostoma grandicarpum [Ceratocystis grandicarpa]. The Japanese species differs from that European species, known from Quercus robur, in having a smaller ascomata and smaller ascospores and in producing a gelatinous cap on the ostiole (Masuya et al., 1998). It differs from a more recently described European species on oak, Ophiostoma dentifundum, in that the newer fungus has conidia that are longer and of a different shape, and also bears ostiolar hairs on the ascoma (Aghayeva et al., 2005). The ascospores are quite similar. The neck of the ascomata of O. dentifundum is long, but is not reported to reach 10 mm. Three species of related fungi were previously reported from the same variety of Quercusmongolica in Japan (Masuya et al., 1998). Both Ophiostoma piceae and Ophiostoma pluriannulatum [Ceratocystis pluriannulata] occur worldwide on both conifers [Pinopsida] and broadleaved trees, including oaks. The former species has a Pesotum anamorph (Zipfel et al., 2006; Grobbelaar et al., 2009); the latter resembles O. longicollum in having a Sporothrix anamorph (Upadhyay, 1981; Benade et al., 1998). Ascomata of both are reported to bear ostiolar hairs, which are lacking in the Japanese species. The third species, Ceratocystis moniliformis, is also of worldwide distribution, but has a Chalara-like anamorph and, despite the convergent morphology of the sexual form, is placed in a different order, the Microascales (Paulin and Harrington, 2000; Alamoutui et al., 2009). In any case, the identifications made in 1961 of these species occurring in Japan are currently considered uncertain (Masuya et al., 2009).
Three species of related fungi were previously reported from the same variety of Quercusmongolica in Japan (Masuya et al., 1998). Both Ophiostoma piceae and Ophiostoma pluriannulatum [Ceratocystis pluriannulata] occur worldwide on both conifers [Pinopsida] and broadleaved trees, including oaks. The former species has a Pesotum anamorph (Zipfel et al., 2006; Grobbelaar et al., 2009); the latter resembles O. longicollum in having a Sporothrix anamorph (Upadhyay, 1981; Benade et al., 1998). Ascomata of both are reported to bear ostiolar hairs, which are lacking in the Japanese species. The third species, Ceratocystis moniliformis, is also of worldwide distribution, but has a Chalara-like anamorph and, despite the convergent morphology of the sexual form, is placed in a different order, the Microascales (Paulin and Harrington, 2000; Alamoutui et al., 2009). In any case, the identifications made in 1961 of these species occurring in Japan are currently considered uncertain (Masuya et al., 2009).
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.
Existing measures that prohibit logs, lumber, wood products or other materials that could carry fungi or insects (Davis et al., 2005; CFIA, 2006) should be maintained against importations of Quercus mongolica.
Not enough is known about the biology of O. longicollum to require or permit the design of suitable control measures. If an arthropod vector is in fact involved in its transmission outside of the tree, the strategy of controlling the vector is likely to be most feasible.
Gaps in Knowledge/Research NeedsTop of page
DNA sequences from this species are needed for comparison with those of other Ophiostoma species. Tests of pathogenicity and virulence to Quercus mongolica and some assessment of the potential host range of O. longicollum should determine whether the fungus is a threat as an introduced species. If the fungus does appear likely to be invasive, its distribution in the known host across Asia should be surveyed. The nature of the association, if any, with Platypus quercivorus or other wood-boring beetles infesting Japanese oaks should be clarified. Although the primary control against this type of fungus, as for any tree pathogen or insect pest of trees, must be control of the entry of trees and wood materials from the infested areas. Development of a PCR protocol or other rapid test for the species in wood is desirable.
ReferencesTop of page
Aghayeva DN; Wingfield MJ; Kirisits T; Wingfield BD, 2005. Ophiostoma dentifundum sp. nov. from oak in Europe, characterized using molecular phylogenetic data and morphology. Mycological Research, 109(10):1127-1136.
Alamouti SM; Tsui CKM; Breuil C, 2009. Multigene phylogeny of filamentous ambrosia fungi associated with ambrosia and bark beetles. Fungal Biology, 113(8):822-835. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7XMR-4W0WJDG-1&_user=3325428&_coverDate=08%2F31%2F2009&_rdoc=4&_fmt=high&_orig=browse&_srch=doc-info(%23toc%2329677%232009%23998869991%231393084%23FLA%23display%23Volume)&_cdi=29677&_sort=d&_docanchor=&_ct=14&_acct=C000050221&_version=1&_urlVersion=0&_userid=3325428&md5=8dd0522d4edb135d2ff1a0d44c5403e0
BPI (US National Fungus Collections), 2009. Fungal Databases - Specimens. Beltsville, USA: Systematic Mycology and Microbiology Laboratory, Agricultural Research Service, USDA. www.nt.ars-grin.gov/fungaldatabases/specimens/specimens.cfm
CFIA, 2006. Exotic forest insect guidebook 2006. Exotic forest insect guidebook 2006. Ottawa, Canada: Canadian Food Inspection Agency, unpaginated. http://www.inspection.gc.ca/english/plaveg/pestrava/exot/introe.shtml
Davis EE; French RS; Venette RC, 2005. Mini risk assessment ambrosia beetle: Platypus quercivorus Murayama. Mini risk assessment ambrosia beetle: Platypus quercivorus Murayama., USA: Animal and Plant Health Inspection Service, US Department of Agriculture, unpaginated. http://www.aphis.usda.gov/plant_health/plant_pest_info/pest_detection/downloads/pra/pquercivoruspra.pdf
Grobbelaar JW; Aghayeva DN; Beer ZWde; Bloomer P; Wingfield MJ; Wingfield BD, 2009. Delimitation of Ophiostoma quercus and its synonyms using multiple gene phylogenies. Mycological Progress, 8(3):221-236. http://www.springerlink.com/content/en830689115w4125/?p=3cbb8352446f4a8282bf1c1412c3babd&pi=6
Kinuura H, 2002. Relative dominance of the mold fungus, Raffaelea sp., in the mycangium and proventriculus in relation to adult stages of the oak platypodid beetle, Platypus quercivorus (Coleoptera; Platypodidae). Journal of Forest Research, 7:7-12.
Malloch D; Blackwell M, 1993. Dispersal biology of the ophiostmatoid fungi. Ceratocystis and phiostoma. Taxonomy, ecology and pathogenicity [ed. by Wingfield, M. J.\Seifert, K. A.\Webber, J. F.]. St Paul, Minnesota, USA: American Phytopathological Society Press, 195-206.
Masuya H; Yamaoka Y; Kaneko S; Yamaura Y, 2009. Ophiostomatoid fungi isolated from Japanese red pine and their relationships with bark beetles. Mycoscience, 50(3):212-223. http://www.springerlink.com/content/6h631840v7726884/fulltext.pdf
NCBI, 2010. Entrez cross-database search engine. Entrez cross-database search engine. Bethesda, Maryland, USA: National Center for Biotechnology Information, U.S. National Library of Medicine, unpaginated. http://www.ncbi.nlm.nih.gov/sites/gquery
USDA/APHIS, 2010. Analytic hierarchy process Prioritized Pest List for FY 2010. Analytic hierarchy process Prioritized Pest List for FY 2010., USA: Animal and Plant Health Inspection Service, US Department of Agriculture, unpaginated. http://www.aphis.usda.gov/plant_health/plant_pest_info/pest_detection/downloads/survey/survey-2010/2010%20Appendix%20D.pdf
Yamaoka Y; Masuya H; Ohtaka N; Goto H; Kaneko S; Kuroda Y, 2004. Ophiostoma species associated with bark beetles infesting three Abies species in Nikko, Japan. Journal of Forest Research, 9(1):67-74. http://www.springerlink.com/content/8qhcy8tgntqb4fwa/?p=d52e3bc6615845db91455a5617585bf1&pi=8
ContributorsTop of page
02/01/10 Original text by:
Distribution MapsTop of page
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