Presence and Distribution of Insect-Associated and Entomopathogenic Fungi in a Temperate Pine Forest Soil: an Integrated Approach

This study assessed differences in the diversity and abundance of entomopathogenic and insect-associated fungi at a loblolly pine research forest in North Carolina, USA using culture-dependent sampling methods and next generation sequencing libraries. Fungi were baited using Galleria mellonella larvae, and soil samples were diluted and placed on a selective medium containing cycloheximide, chloramphenicol, and thiabendazole. Isolates from both methods were identified using Sanger sequencing of the ITS and LSU rRNA gene regions. These isolates represented three phyla—Ascomycota, Basidiomycota and Mucoromycota—and a total of 36 unique OTUs, including known entomopathogenic fungi such as Metarhizium, Lecanicillium and Paecilomyces. Entomopathogenic and other insect-associated fungi are responsible for the breakdown and availability of large molecular weight polysaccharides such as chitin, and as such we conducted a simple enzyme assay to assess the ability of isolates to degrade chitin. Isolates showed a widespread ability to degrade chitin, although considerable variation existed in chitinolytic activity within and between genera. Phylogenetic analyses of the Hypocreales, Mucorales, and Mortierellales resolved several isolates at the genus level, with some showing close phylogenetic placement with taxa including fungi associated with plant tissues and other insect-associated fungi. Saprophytic fungi including Mucor and Mortierella were widely distributed in soils, while ent...
Source: Fungal Biology - Category: Biology Source Type: research