Mycorrhizal fungi and invertebrates: Impacts on Tuber melanosporum ascospore dispersal and lifecycle by isopod mycophagy

Abstract

The icon ectomycorrhizal (EcM) species, Tuber melanosporum, requires mycophagy for ascospore dispersal. Isopods are often found within fruitbodies and to explore why, Oniscus asellus were presented with T. melanosporum as a food source. Fruitbodies were consumed at a rate of 4.0 mg per isopod, over 24 h. Most of the recovered faecal pellets contained ascospores after 12 h. Gut-transit inflicted little mechanical damage to ascospores, and the majority were still contained with an ascus 30 h post feeding. Further, ascospores were observed in faecal pellets 18 days after consumption. Combined, the results suggest a previously overlooked role for isopods in EcM spore dispersal. The impacts for EcM ecology and the role of isopods in Tuber spp. lifecycles, including mating type distribution, is discussed alongside the emerging threat of climate change and how such knowledge can inform management by custodians of relevant habitat types.