Abstract

Beetles living in tree hollows can feed on a wealth of substrates-e.g. the rotten wood surrounding the cavity, leaf humus falling into the hole, and larval frass accumulating in the cavity. In this paper, we examine the role of these main substrates in Finnish tree hollows in the female preference and larval growth of the hermit beetle Osmoderma barnabita. We rear larvae on diets consisting of wood material (as affected by brown-rot), leaf humus, and larval frass, in varying proportions. To pinpoint the effects of microbes, we contrast larval growth on sterilized versus unsterilized larval frass, and on pure mycelia of the cavity-creating fungus Laetiporus sulphureus. Finally, to relate larval performance to female preference, we examine female choice among the three main substrates used in the larval rearings. We found that the presence of one substrate modifies the influence of another, with larval growth and survival being highest on pure leaf humus. Microbes came with both positive and negative impacts on larval performance, as larvae grew quicker on unsterilized than on sterilized larval frass, but were also struck by higher mortality. On pure fungal mycelia, larvae neither grew nor survived. Female preference reflected larval performance, with leaf humus being preferred over other resources. Overall, our study suggests that organisms inhabiting tree holes may be dependent on subsidies entering the cavity from outside, and that ovipositing females may specifically respond to the presence of such subsidies. Thus, the quality of a microhabitat may depend on what enters it from outside.

Keywords

Osmoderma; wood mould; ecosystem engineer; optimal oviposition; preference-performance hypothesis

Published in

Oecologia
2016, Volume: 182, number: 1, pages: 163-175
Publisher: SPRINGER

SLU Authors

• Roslin, Tomas

  • Department of Ecology, Swedish University of Agricultural Sciences
    
  • University of Helsinki

UKÄ Subject classification

Ecology


Publication identifier

DOI: https://doi.org/10.1007/s00442-016-3661-y

Permanent link to this page (URI)

https://res.slu.se/id/publ/78454