Insect-Associated Fungi and Blue
Bark beetles, horntails, ambrosia
Raffaelea, Leptographium and others
Ophiostoma species are common associates of bark beetles (Harrington,
1993a, 1993b, 2005, Paine et al. 1997), but they are also important
as stain fungi. Much of the blue stain in conifer timber is caused
by species of Ophiostoma and their anamorphs, especially
Graphium and Leptographium.
A study on the Ophiostoma piceae complex
was completed (Harrington et al. 2001), and a manuscript on the
Ophiostoma species found in New Zealand was published (Thwaites
et al. 2005).
We (Six et al. 2003) also looked at the genetically
similar but morphologically distinct Leptographium terebrantis,
which is associated with a number of pine bark beetles, and its
more insect-specialized relatives Ophiostoma clavigerum
and L. pyrinum.
The evolution of basidiomycetes associated
with bark beetles was recently examined (Hsiau and Harrington
2003), and a review of the evolution and ecology of mycophagus
bark beetles and their fungal symbionts has just been published
We also studied the Amylostereum species
associated with horntails (Tabata et al. 2000).
Graduate student Sujin Kim studied insects associated with two introduced beetles in California (Kim et al. 2011).
Laurel wilt, caused by Raffaelea
Another on-going study is the new laurel wilt
pathogen that was introduced with the Asian ambrosia beetle, Xyleborus
glabratus, to the Coastal Plains of the southeastern USA.
This work is conducted with Stephen Fraedrich and others (Fraedrich
et al., 2008, 2011, 2014; Harrington et al. 2008, 2010, 2011; Harrington and Fraedrich, 201). I have a separate page on my work on with laurel wilt, and the Laurel Wilt Task Force has much more information.
here for a listing of all publications on Ophiostoma, Leptographium
and insect-associated Fungi
- Three genera of Ceratocystidaceae are ambrosia beetles symbionts (pdf of manuscript form).
- Xyleborus glabratus and Raffaelea lauricola on Cinnamomum camphora (pdf of manuscript).
- Ambrosiella roeperi sp. nov. is the mycangial symbiont of Xylosandrus crassiusculus (pdf of manuscript).
- Wickerhamomyces arborarius, sp. nov., a novel ascomycetous yeast species found in arboreal habitats (pdf of manuscript).
- Exotic pathogens or shifts in climate? Luarel wilt and bur oak blight. (pdf of manuscript).
- Raffaelea lauricola, on sassafras in Alabama. (http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-09-12-0866-PDN)
- Isolations from Xyleborus glabratus in Taiwan and Japan (pdf of manuscript).
- Laurel wilt in two rare plant species, pondberry and pondspice (pdf of manuscript).
- Raffaelea lauricola on sassafras in Mississippi. (link to note).
- Leptographium tereforme sp. nov. and other Ophiostomatales from Hylurgus ligniperda (pdf of manuscript) .
- Quantification of propagules of the laurel wilt fungus fromXyleborus glabratus (pdf of manuscript).
- Revision of the genera Raffaelea and Ambrosiella, and Raffaelea spp. from Xyleborus glabratus (pdf of manuscript)
- Recovery plan for laurel wilt on redbay. (pdf of report).
- Formal description
of the causal agent of laurel wilt, Raffaelea lauricola
(pdf file of manuscript)
- The first
full description of laurel wilt and its association with Xyleborus
glabradus (pdf file of manuscript)
- Short note
on laurel wilt on redbay caused by a fungal symbiont of Xyleborus
glabratus (pdf file of manuscript)
novo-ulmi and Scolytus schevyrewi (pdf
- Ecology and evolution of mycophagous
bark beetles and their fungal partners. (pdf
of manuscript) (purchase from Oxford
- Survey of potential sapstain fungi
on Pinus radiata in New Zealand. (pdf
file of manuscript).
- Epitypification of Ophiostoma galeiforme
and phylogeny of species in the O. galeiforme complex (pdf file
- Comparison of Ophiostoma clavigerum
with Leptographium terebrantis and L. pyrinum
- Phylogeny of the Ophiostoma stenocerasSporothrix
- Phylogenetics and adaptations of basidiomycetous
fungi fed upon by bark beetles.(pdf of manuscript)
- Species delimitation and host specialization
of Ceratocystis laricicola and C. polonica (pdf file of manuscript).
- Phylogeny and taxonomy of the Ophiostoma
piceae complex and the Dutch elm disease fungi. (pdf of manuscript)
- Molecular phylogeny of species in
the genera Amylostereum and Echinodontium. (pdf of manuscript)
- Association between Hpothenemus
hampei (Coleoptera: Scolytidae) and Fusarium solani (Moniliales:
- Leptographium engelmannii, a synonym of L. abietinum, and description
of L. hughesii sp. nov.
- Ceratocystiopsis brevicomi sp.
nov., a mycangial fungus from
Dendroctonus brevicomis. (pdf of manuscript)
- Cycloheximide sensitivity in Ceratocystis and tolerance in Ophiostoma (pdf of manuscript)
- Interactions among scolytid bark beetles,
their associated fungi, and live host conifers.
- And others . . .
From generalist bark beetle associate:
FIGS. 19. Leptographium pyrinum and L.
terebrantis. 13. L. pyrinum. 1, 2. Conidiophores.
3. Conidia. 13 from strain C833. 49. L. terebrantis.
4, 5. Conidiophores. 6. Conidia. 7, 8. Conidiophores. 9. Conidia.
46 from strain C680. 79 from strain C25. Scale bars:
1 = 100 µm; 2, 7 = 50 µm; 3, 6, 9 = 10 µm;
4, 5, 8 = 25 µm
Compare the morphology of these genetically
related species, especially the long, clavate conidia of Ophiostoma
clavigerum (Figs. 10-16), which appear to be more suitable
for grazing by its bark beetle symbionts (Dendroctonus ponderosae
and D. jeffreyi), which are mycophagus for at least part
of their life cycle. We believe O. clavigeum evolved from
a more generalist species, perhaps Leptographium terebrantis
(Figs. 4-9), which has been associated with many unrelated bark
beetle species. Note that cultures of O. clavigerum can
degenerate and form conidia and conidiophores (Figs. 13-16) more
typical of L. terebrantis.
Six et al. 2003
To ambrosia for mycophagus bark beetles:
FIGS. 1016. Ophiostoma clavigerum. 10, 11.
Conidiophores. 12. Clavate conidia. 13, 14. Conidiophores. 15.
Clavate conidia. 16. Conidia. 1012 from strain C187. 1316
from strain C813. Scale bars: 10, 13 = 50 µm; 11, 14, 15
= 25 µm.