Dispersal patterns of a saproxylic beetle, Osmoderma eremita, in Mediterranean woodlands

Dispersal patterns of a beetle inhabiting tree hollows, Osmoderma eremita (Scopoli, 1763) (Coleoptera: Cetoniidae), were studied in a cork oak (Quercus suber) woodland in central Italy, the southernmost part of its distribution range. During 2years, we used radio telemetry to monitor dispersal of 39 free-ranging individuals (16 males, 23 females). Telemetered beetles spent their lifetime not only inside hollow trees but also in other habitats, such as above or under the ground surface. Beetles were more active at the beginning of the season. Eighty-one per cent of the males and 69% of the females conducted dispersals during their lifetime. The dispersal distance over individuals' lifetime did not differ between sexes. The longest dispersal was conducted by a female that moved 1504m. Thirty-nine per cent of dispersing individuals reached distances farther than 250m. Both dispersal rate and range are higher than what has been found in Northern Europe. The population size per tree is low, most of the adults leave their natal tree, and a high predation rate (at least 28%) was observed among dispersing beetles. Therefore, to balance the local extinction risk from single trees, a high density of hollow trees is probably required. It is desirable that suitable trees are concentrated at a spatial scale of a few hundred metres.