Effect of gut passage by two highland rodents on spore activity and mycorrhiza formation of two species of ectomycorrhizal fungi (Laccaria trichodermophora and Suillus tomentosus)

Research on mycophagy has focused mainly on fungi with hypogeous fruiting bodies, while studies on epigeous fruiting bodies are rare. We evaluated spore activity and capacity to establish mycorrhizal associations for the ectomycorrhizal fungi Laccaria trichodermophora Mueller and Suillus tomentosus (Kauffman) Singer, Snell and Dick (both of which produce epigeous fruiting bodies) after being consumed by the mice Peromyscus alstoni Merrian and Peromyscus maniculatus Wagner. Passage through the digestive tract of both rodent species reduced spore activity of S. tomentosus but increased spore activity of L. trichodermophora. In contrast, passage through the digestive tract of P. alstoni increased the percentage of mycorrhiza formation by S. tomentosus, whereas mycorrhiza formation by L. trichodermophora decreased following gut passage in either species of mice. These results show that the studied rodent species have differential effects on mycorrhiza formation by two species of fungi with epigeous fruiting bodies and may play a significant role in maintaining mycorrhizal communities and healthy forest ecosystems in central Mexico. Key words: epigeous fruiting bodies, Laccaria, Peromyscus, Pinus, Suillus. La recherche en mycophagie porte surtout sur les champignons formant des fructifications hypogees, alors que les etudes chez les especes a fructification epigees restent rares. Les auteurs ont evalue l'activite et la capacite des spores a etablir des associations mycorhiziennes chez les champignons ectomycorhiziens Laccaria trichodermophora Mueller et Suillus tomentosus (Kauffman) Singer, Snell and Dick (tous deux produisant des fructification epigees), apres avoir ete consommees par les souris Peromyscus alstoni Merrian and Peromyscus maniculatus Wagner. Le passage a travers le tractus digestif des deux especes de rongeurs reduit l'activite des spores du S. tomentosus, mais augmente l'activite sporale du L. trichodermophora. Au contraire, le passage a travers le tractus digestif du P. alstoni augmente le nombre de mycorhizes formees par le S. tomentosus, alors que la formation de mycorhizes par le L. trichodermophora diminue suite au passage dans l'une ou l'autre des souris. Ces resultats montrent que chez les souris etudiees, les especes de rongeur exercent des effets differents sur la formation des mycorhizes par les deux especes de champignons formant des fructification epigees, et pourraient jouer un role significatif dans le maintien en sante des communautes mycorhiziennes et des ecosysteme forestiers du centre du Mexique. Mots-cles : fructifications epigees, Laccaria, Peromyscus, Pinus, Suillus. [Traduit par la Redaction]
Introduction Mycophagy, where an animal consumes fungal mycelia, fruiting bodies, or spores, is a widespread eating habit in terrestrial ecosystems (Lawrence 1989). There are many cases of mycophagous invertebrate animals; [...]