Insect-Associated Fungi and Blue Stain Fungi

Bark beetles, horntails, ambrosia beetles

Ophiostoma, Raffaelea, Leptographium and others

Laurel wilt, caused by Raffaelea lauricola, and other ambrosia beetle associations

Most of our work on Ophiostomatales and other associates of Scolytidae has been on the laurel wilt pathogen, which 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, 2018; Harrington et al. 2008, 2010, 2011; Harrington and Fraedrich, 2011; Wuest et al. 2017). I have a separate page on my work on with laurel wilt.

Click here for a listing of all publications on Ophiostoma, Leptographium and insect-associated Fungi

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.