Diversity patterns of fungivorous insects: comparison between glaciated vs. refugial boreal forests

Aim The aim of this study was to compare diversity patterns of insect communities associated with the wood‐decaying Fomitopsis fungi in north‐east (NE) Asia and Fennoscandia. We hypothesized that the diversity of the fungal–insect communities is greater in NE Asia, because the region was one of the largest refugia of boreal species during the last Pleistocene glaciation. Location This study was conducted in boreal forests in NE People's Republic of China, and in south‐central Finland. Methods Fruiting bodies of three Fomitopsis species were collected from the field in order to rear the insects inhabiting the fruiting bodies. Taxonomic uniqueness, diversity and food web structure of the insect assemblages were analysed using hierarchical cluster analysis, diversity indices and analyses of food web compartmentalization, respectively. Results Contrary to the expectations, the richness of families, genera and species was greater in Finland than in NE China. This applied for the overall Fomitopsis‐associated insect assemblage, as well as for the fungal species separately. The taxonomic composition at the level of families and genera was similar between the two regions. The level of monophagy was higher in Finland and the food web was divided into compartments corresponding to the two Fomitopsis species. Main conclusion The often‐suggested higher diversity in refugial areas does not apply for all taxa in boreal forests, such as fungivorous insects associated with Fomitopsis fungi.