Arthropod OTUs in fruit bodies of wood decay fungi

Biological communities within living organisms are structured by their
host’s traits. How host traits affect biodiversity and community
composition is poorly explored for some associations, such as arthropods
within fungal fruit bodies. Using DNA metabarcoding, we revealed the
arthropod communities in living fruit bodies of eleven wood-decay fungi
from boreal forests and investigated how they were affected by different
fungal traits. Arthropod diversity was higher in fruit bodies with a
larger surface area-to-volume ratio, suggesting that colonisation is
crucial to maintain arthropod populations. Diversity was not higher in
long-lived fruit bodies, most likely because these fungi invest in
physical or chemical defences against arthropods. Arthropod community
composition was structured by all measured host traits, namely fruit body
size, thickness, surface area, morphology and toughness. Notably, we
identified a community gradient where soft and short-lived fruit bodies
harboured more true flies, while tougher and long-lived fruit bodies had
more oribatid mites and beetles, which might reflect different development
times of the arthropods. Ultimately, close to 75% of the arthropods were
specific to one or two fungal hosts. Besides revealing surprisingly
diverse and host-specific arthropod communities within fungal fruit
bodies, our study provided insight on how host traits structure
communities.