Suppression of growth of a brown rot fungus, Gloeophyllum trabeum, by Formosan subterranean termites (Isoptera: Rhinotermitidae)

Although a brown rot fungus, Gloeophyllum trabeum (Pers.) Murrill, has been shown to be attractive and beneficial to subterranean termites, including Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), no research has been conducted to determine whether the association is mutualistic. We first investigated whether the fungus could be spread by C. formosanus, because this would represent an obvious benefit to the fungus. We found that Formosan subterranean termites did not spread G. trabeum, rather they suppressed its growth. To further investigate this phenomenon, wood chips were inoculated with G. trabeum, and fungal growth was measured in treatments with termites or without termites (controls). A significant suppression of fungus growth was found only in treatments where termites were present. This antagonistic interaction between the termites and fungus was further investigated by placing wood chips from the termite treatments on potato dextrose yeast agar medium to determine G. trabeum survivorship. Although G. trabeum did not grow, many green-spored fungi developed, including Aspergillus flavus Link and Trichoderma spp. We hypothesize that these green-spored fungi are carried by termites and that they may play a role in suppressing the growth of G. trabeum.