Although most fungal spores are transported by wind, some remain on lamellae even after fungal fruiting bodies start to decay. This raises the question: are these remaining spores useless or instead transported by other means? In this study, we accordingly investigated whether adult dipteran insects transport fungal spores. Our examination revealed that fungal spores were present in intestines of most drosophilid adults but almost completely absent from those of other dipteran adults. At least some spores excreted by Drosophila angularis and D. brachynephros retained the capacity to germinate. Structural damage to spores that passed through the digestive tract of these two drosophilid species varied among fungal species, with a greater number of colorless spores generally damaged than colored ones. These results suggest that adult drosophilid flies, but not other dipterans, can transport fungal spores.

Muscina angustifrons (Diptera: Muscidae) is a mycophagous species exploiting a variety of fungi including ectomycorrhizal fungi. It has been reported that larvae of this species feed on sporocarps including spores and full-grown larvae leave sporocarps and pupate 0-6 cm below the soil surface. In this study, we examined whether M. angustifrons larvae have capacities to transport ectomycorrhizal fungal spores and enhance the formation of ectomycorrhiza on hostplant roots. In the present experiments, full-grown larvae usually moved horizontally 10 to 20 cm from feeding sites and burrowed underground. These wondering larvae retained ectomycorrhizal fungal spores in their intestines and excreted them after moving to underground pupation sites. Excreted spores retained germination and infection capacities to form ectomycorrhiza on hostplant roots. In the infection experiments, ectomycorrhizal fungal spores applied in the vicinity of underground host-plant roots were more effective to form ectomycorrhiza in comparison with those applied on the ground surface, suggesting that transportation of spores below the ground by M. angustifrons larvae could enhance ectomycorrhizal formation. These results suggest that M. angustifrons larvae act as a short-distance spore transporter of ectomycorrhizal fungi.

Slugs are important consumers of fungal fruiting bodies and expected to carry their spores. In this study, we examined whether slugs (Meghimatium fruhstorferi) can act as effective dispersers of spores of basidiomycetes. The microscopic observation confirmed the presence of basidiospores in feces of field‐collected slugs, and the DNA metabarcoding study revealed that Ascomycota and Basidiomycota were major fungal taxa found in the feces. In Basidiomycota, the dominant order was Agaricales followed by Trichosporonales and Hymenochaetales. The laboratory experiments using Tylopilus vinosobrunneus showed that slugs carried a large number of spores in their digestive tracts. It was also observed that Pleurotus, Armillaria, and Gymnopilus spores excreted by slugs had a higher germination capacity than control spores collected from spore prints. The field experiments showed that slugs traveled 10.3 m in 5 h at most by wandering on the ground, litter layers, wood debris, and tree trunks. These results suggest that slugs could carry spores of ectomycorrhizal, saprophytic, and wood‐decaying fungi to appropriate sites for these fungi to establish colonies.

To clarify the diversity and host associations of dipteran insects exploiting fungal fruiting bodies, we collected fruiting bodies at 18 localities in Hokuriku region, central Japan, from 2012 to 2015 and examined them for the emergence of insects. In total, 14,107 dipteran individuals belonging to 20 families emerged from fungi of 8 orders, 25 families, 49 genera and 129 species. Approximately 79% of dipteran individuals belonged to three families, Phoridae, Muscidae and Drosophilidae. The faunal similarity at the family level was relatively high between central (warm‐temperate) and northern (cool‐temperate) areas of Japan. However, the species composition of Drosophilidae was much different between central and northern Japan. The difference in the species composition was discussed in relation to the climatic conditions and fungal flora. None of the species from Drosophilidae, Phoridae, Muscidae, Mycetophilidae, Lonchaeidae and Chloropidae were specialists (they exploited more than one species of fungi), but they showed differences their fungi preference. Adults of some families, especially Drosophilidae, were frequently collected from fruiting bodies, but those of other families were seldom collected, probably reflecting differences in adult feeding ecology.