Structure of insect communities inhabiting old-growth forest specialist bracket fungi

1. This paper describes the structure of the insect communities inhabiting two old-growth forest specialist bracket fungi, Amylocystis lapponica and Fomitopsis rosea. To study the consequences of old-growth forest fragmentation on community structure, non-fragmented and fragmented forest areas in eastern and southern Finland were compared. 2. Both fungal species are inhabited by more than 50 insect species. The most abundant species in the A. lapponica community is a melandryid beetle Hallomenus sp., and in the F. rosea community a tineid moth Agnathosia mendicella. The occurrence of several nationally or globally rare species underscores the importance of specific insect microhabitats, such as the specialist fungi A. lapponica and F. rosea, for the persistence of specialised insects in old-growth forests. 3. The species composition in both fungal species differs greatly from each other. The food webs are characterised by one numerically dominant host-specific primary fungivore, which implies that fungivorous species inhabiting bracket fungi may be more specialised on a particular host than is generally thought. 4. The community structure was the same in the highly fragmented and in the non-fragmented study areas, probably because fragmentation has occurred relatively recently.