The importance of scale and spatial variables for the fungivorous beetle Bolitophagus reticulatus (Coleoptera, Tenebrionidae) in a fragmented forest landscape

Effects of isolation, habitat size and several microhabitat variables on pr esence/ absence of the monophagous Bolitophagus reticulatus (L.) (Coleopter a, Tenebrionidae) were investigated in 58 forest fragments in an agricultur al landscape (15 km(2)) in south-eastern Norway. All potential habitats of the beetle, dead Fomes fomentarius (L.) Kicks basidiocarps (n = 587), were collected from trees (n = 185) within the study area. The basidiocarps were dissected and the number of B. reticulatus specimens (larvae, pupae and ad ults) counted. The material was analysed at four distinguishable spatial sc ales: basidiocarp-, tree-, tree-group- and forest island level. Different p atterns of beetle presence emerged at the different scales. Increasing habi tat size and decreasing degree of isolation increased the probability of B. reticulatus presence at three (basidiocarp-, tree- and forest island level ) and one (tree level) scales, respectively, whilst no such trends were fou nd at the fourth level (tree-group level). Increasing insolation and thereb y higher ambient temperatures, indicated by several microhabitat variables, improved the probability of beetle presence amongst the trees. The number of beetle specimens correlated positively with an increase in the habitat s ize at the tree level.