Transcriptomic analysis of the mycangium from the ambrosia beetle Xylosandrus germanus (Coleoptera: Curculionidae)

Wednesday, November 16, 2022

4:18 PM – 4:30 PM PT

Location: Vancouver Convention Centre, Meeting Room 217/218/219

Presenting Author(s)

Christopher M. Ranger

Research Entomologist
USDA-ARS
Wooster, Ohio

Co-Author(s)

Nisha Patwa

Post-Doctoral Research Associate
USDA-ARS
Wooster, Ohio

Co-Author(s)

JP

Jelmer W Poelstra

The Ohio State University
Wooster, Ohio
ML

Maximilian Lehenberger

Max Planck Institute for Chemical Ecology
Jena, Thuringen, Germany
MR

Michael E. Reding

Research Entomologist
USDA-ARS
Wooster, Ohio
PB

Peter H. Biedermann

Professor
University of Freiburg
Würzburg, Baden-Wurttemberg, Germany

The ambrosia beetle Xylosandrus germanus is a wood-boring insect that infests horticultural trees. Like other ambrosia beetles, X. germanus cultivates its nutritional fungal symbiont, Ambrosiella grosmanniae, within galleries of infested host trees. In turn, A. grosmanniae relies on X. germanus for dispersal and propagation. Female X. germanus uses a specialized pouch-like structure (i.e., mycangium) to maintain and transport spores of A. grosmanniae. Freshly-molted adults within their natal galleries possess a deflated mycangium without a fungal mass while adults dispersing from their natal galleries possess a mycangium that is partially or fully inflated with spores of A. grosmanniae. Previous studies suggest that cells within the outer layer of the mycangium secrete metabolites that stimulate the growth of ambrosia beetle fungal mutualists and perhaps inhibit antagonistic fungi. To improve our understanding how the mycangium selectively supports mutualist growth, we used RNAseq to assemble an X. germanus transcriptome and analyze gene expression patterns in three tissue types: deflated mycangium + scutellum, inflated mycangium + scutellum, and inflated mycangium. We validated the expression level of 20 genes, including genes specific to insect-fungal symbioses. Validation of the selected genes could provide key insights into the mechanism by which the mycangium of X. germanus facilitates the in vivo proliferation of its nutritional fungal symbiont.