Nematodes Consume Four Species of a Common, Wood-Decay Fungus

Since nitrogen is in short supply in wood yet relatively plentiful in the bodies of nematodes, wood-decay fungi have been thought to be nematophagous. In an earlier study, we confirmed the nematophagy of two species of wood-decay fungi (Pleurotus ostreatus and P. pulmonarius), although we also found nematode species that could turn the tables and consume Pleurotus. In this study, we tested interactions between nematode species and Fomitopsis, another genus of common wood-decay fungi. Four geographically distinct isolates, or provenances, within each of four species (i.e., the European F. pinicola and three North American species: F. ochracea, F. schrenkii, and F. mounceae) were confronted with a total of twenty nematode species (twenty-four strains) in four experiments. Nematophagy was observed much less frequently in Fomitopsis than in Pleurotus: only 31 of the 516 interactions (6%), overall, resulted in nematophagy by a Fomitopsis isolate, whereas with Pleurotus, the result was 16 of 28 (57%). In contrast, all 20 species of nematode here were capable of mycophagy and dominated interactions with all isolates of Fomitopsis overall. Clearly, not all wood-decay fungi are as strongly nematophagous as the Pleurotus species. Perhaps arboreal nematodes even tend towards mycophagy, given the limiting nitrogen in wood.

Automated summary

Wood-decay fungi have been traditionally thought to be nematophagous due to the limited nitrogen supply in wood. However, this study found that nematophagy was much less common in Fomitopsis fungi compared to Pleurotus fungi. Instead, all 20 nematode species tested in the study were capable of mycophagy and dominated interactions with Fomitopsis fungi. These findings suggest that not all wood-decay fungi exhibit strong nematophagous behavior and that arboreal nematodes may prefer mycophagy due to the limited nitrogen in wood.