Presence and distribution of insect-associated and entomopathogenic fungi in a temperate pine forest soil: An integrated approach

Abstract

For decades entomopathogenic fungi have garnered interest as possible alternatives to chemical pesticides. However, their ecology outside of agroecosystems demands further study. We assessed the diversity and abundance of entomopathogenic and insect-associated fungi at a loblolly pine forest in North Carolina, USA using culture-dependent and next-generation sequencing libraries. Fungi were isolated using Galleriamellonella larvae, as well as from soil dilutions plated on a selective medium. Isolates were identified using Sanger sequencing of the ITS and LSU rRNA gene regions, and represented 36 OTUs including Metarhizium, Lecanicillium, and Paecilomyces. Additionally, we assessed the chitinolytic potential of isolates and found widespread, variable ability to degrade chitin within and between genera. Phylogenetic analyses resolved several isolates to genus, with some forming clades with other insect-associated taxa, as well as with fungi associated with plant tissues. Saprophytes were widely distributed in soil, while entomopathogens were less abundant and present primarily in the top two cm of the soil. The similarity between culture-dependent and next-generation sequencing results demonstrates that both methods can be used concurrently in this system to study the ecology of entomopathogenic fungi.