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Keywords:

  • Basidiomycetes;
  • Cerambycidae;
  • decay fungi;
  • host volatiles;
  • priority effects;
  • saproxylic beetles;
  • sesquiterpene

Abstract

  1. Two experiments were conducted to investigate the role of basidiomycetes and volatiles in the ecology of saproxylic Coleoptera. Volatile organic compounds (VOCs) were sampled from beech (Fagus sylvatica) logs experimentally inoculated with the basidiomycetes Stereum hirsutum, Coriolus versicolor, Phanerochaete velutina, Hypholoma fasiculare, Bjerkandera adusta both singly and in various combinations. Volatile emissions were found to be in accordance with amounts detectable to insects suggesting that in a natural decay situation, saproxylic volatiles are readily available as insect semiochemicals.
  2. Furthermore, fungal community structure was found to significantly affect the volatile profile of decaying wood, with specific VOCs associated with particular fungal treatments. Thus, volatiles of fungal origin are a strong potential source of semiochemicals for those insects utilising the saproxylic habitat and their natural enemies.
  3. Beetles were reared from logs inoculated with the same basidiomycete treatments as described earlier and a total of 604 individuals comprising 84 species were obtained. Eleven species (Cis boleti, C. micans, Dacne bipustulata, Latridius consimilis, Mycetophagus atomarius, M. quadripustulatus, Octotemnus glabriculus, Platystomus albinos, Ptilinus pectinicornis, Stictoleptura scutellata, Tomoxia bucephala) exhibited significant associations with one or more fungal treatments.
  4. Explanations are provided for the various beetle–fungus associations observed. The data set is notable for the presence of various wood boring species that tend to be absent in experiments where volatiles from fungi are presented in isolation.
  5. Coarse woody debris (CWD) and its interaction with fungi CWD, are shown to give off VOCs of varying degrees of specificity. These VOCs are potential semiochemicals for saproxylic insects and may mediate fungus/CWD-specific interactions. We conclude that future work in this direction would be profitable.