Recovery of associated fungal DNA from ambrosia beetle museum specimens (Curculionidae: Scolytinae: Xyleborini)

Ambrosia beetles are a polyphyletic group characterized by their obligate associations with various fungi. The beetles inoculated the fungi into trees from special spore carrying organs in the beetles’ exoskeleton, called mycangia. The fungi grow through the beetle-bored galleries and are consumed throughout the life-cycle of the beetles. 34 Asian xyleborine (Coleoptera: Curculionidae: Scolytinae) species have been introduced to the US through trade in the last ~30 years. Most are of little interest to the public, however, some of the beetle-transported fungi are pathogenic to trees, such as Xyleborus glabratus, which inoculate and kill many SE US Lauraceae trees with their associated fungal pathogen, Raffaeeae lauricola. Currently, only 28 fungi have been identified within a subset of ~1300 xyleborine ambrosia beetles. Generation of pure fungal cultures sampled from live beetles has hampered the progress of identifying associated fungi. In this study, a novel approach for identifying associated fungi with beetles is proposed. Using anchored hybrid enrichment accompanied with Illumina sequencing, we surveyed a diversity of xyleborine museum specimens for the Fusarium AF9 fungal lineage. Previously unknown fungal sequences from several xyleborines were successfully recovered. This described method would allow previously collected museum specimens to be used in identification of understudied fungal lineages.