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Commensal Associations


Insects have a wide range of associations with the fungi. However, in some cases, the association, while essential for the fungus appears to have no consequence for the insect host. The taxon Laboulbeniales are widely thought to have a commensal relationship with their insect hosts.

The Commensal Laboulbeniales

Members of the Laboulbeniales, a large group of Ascomycota, are found attached to many different insects. The association appears to be highly specialised, in that each fungal taxon appears to be specific to a small group of insects. The fungi colonise the surface of insects, forming a haustorium within the cuticle of the outer surface of the insect. The fungi apparently derive all their nutrition from the host. However, they do not appear to damage their host. The fungi are obligate commensals: attempts to culture the fungi have so far failed.


The Trichomycetes

Endoparasites of Insects

Members of the Trichomycetes are obligately associated with the internal cuticles, mostly the hindgut, of insects and many other Arthropods. We know very little about these associations. Some argue that the fungus is not a parasite as the fungus does not reduce nutrient supply to the host. Thus these fungi might be commensals too.

The distinction between parasites and commensal is difficult to define. Clearly, by accessing organic energy from a host, a fungus may be described as parasitic. As the fungi do not appear to harm their host then they may also be commensal. The entire group remain to be examined more closely, as both the insect hosts and their fungal associations remain poorly understood.



Lawrence JF and Milner RJ. (1996). Associations between Arthropods and Fungi. Fungi of Australia, Vol 1B, 137 – 202.


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