|SIMMONS, JASON - University Of California, Davis|
|SEYBOLD, STEVEN - University Of California, Davis|
|BOSTOCK, RICHARD - University Of California, Davis|
Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2020
Publication Date: 8/8/2020
Citation: Simmons, J.D., Wallis, C.M., Seybold, S.J., Bostock, R.M. 2020. Metabolomic characterization of walnut bark and effects of methanolic extracts on walnut twig beetle feeding behavior. American Phytopathological Society Abstracts. 110:S2.17. https://doi.org/10.1094/PHYTO-110-12-S2.1.
Technical Abstract: Thousand cankers disease (TCD) affects members of the Juglandaceae, including economically important Juglans species in the U.S. and Italy. TCD is caused by the fungus Geosmithia morbida, an anamorphic species in the Bionectriaceae family, and its insect vector, Pityophthorus juglandis (walnut twig beetle, WTB). WTB adults inoculate host trees with G. morbida spores as the beetles penetrate the outer bark and form galleries within the inner bark. The fungus causes localized phloem lesions that coalesce and girdle branches. Certain walnut species (e.g., Juglans californica) appear to be more attractive to the WTB than other species (e.g., Juglans major). Volatile organic compounds (VOCs) from host trees likely influence WTB landing rates, and larger molecular weight compounds in the bark may act as feeding deterrents or stimulants. This study characterizes differences in bark metabolites between J. californica and J. major. VOC sampling of J. major and J. californica was done through solvent extraction of bark as well as sorbent collection followed by analysis with GC-MS. Analysis of larger molecular weight compounds was done by methanolic extraction of bark and quantitation using HPLC. A microfeeding assay measured differences in feeding behavior of WTB on J. californica and J. major extracts. Differences in metabolite content and WTB feeding activity between extracts were observed. This information will guide further studies into the functional role of specific compounds in the TCD pathosystem.