Insect-Fungus Interactions in Dead Wood Systems

Abstract

Tree hollows are fascinating microcosms that host a rich saproxylic insect assemblage. One of the most peculiar characteristics of this habitat is that both biotic and abiotic factors affect the evolution of the cavity making each unique and able to host a specialized fauna. Tree hollows are patchy habitats that provide a stable abiotic environment and long-lasting resources to a complex assembly of species from different trophic guilds (xylophagous, xylomycetophagous, saproxylophagous, saprophagous, predators, etc.), where species interactions seem to be an important piece of the puzzle of tree hollow diversity. Fourteen orders of insects and more than 800 species have been reported from tree hollows (primarily from Europe), with Coleoptera being the most diverse, followed by Diptera. However, knowledge of tree hollow insects and their requirements is still very asymmetric both geographically and taxonomically. Forest reduction and fragmentation, climatic change, forestry and the abandonment of cultural practices are causing a decrease in tree hollow availability in natural and seminatural habitats, threatening the survival of the species that depend exclusively on them. Conservation and retention of hollowed trees has crucial importance for forest diversity maintenance worldwide; thus, actions should be urgently adopted.