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ARS Home » Pacific West Area » Hilo, Hawaii » Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center » Tropical Plant Genetic Resources and Disease Research » Research » Publications at this Location » Publication #422014
Research Project: Conservation, Management, and Genetic Improvement of Tropical and Subtropical Fruit, Nut, and Beverage Crop Germplasm for the Pacific Region

Location: Tropical Plant Genetic Resources and Disease Research

Title: The in vitro and in vivo fungal volatile organic compounds associated with rapid 'Ohi'a death and the response of Xyleborine ambrosia beetles to those compounds

Author
item ROY, KYLLE - Us Forest Service (FS)
item BRILL, EVA - Former ARS Employee
item MIKROS, DAN - University Of Hawaii
item TOBIN, KELSEY - Purdue University
item JUZWIK, JENNIFER - Us Forest Service (FS)
item McNellis, Brandon
item JACOBS, DOUG - Purdue University
item Keith, Lisa
item Cha, Dong
item GINZEL, MATTHEW - Purdue University

Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2025
Publication Date: 5/27/2025
Citation: Roy, K., Brill, E., Mikros, D., Tobin, K., Juzwik, J., Mcnellis, B.E., Jacobs, D., Keith, L.M., Cha, D.H., Ginzel, M. 2025. The in vitro and in vivo fungal volatile organic compounds associated with rapid 'Ohi'a death and the response of Xyleborine ambrosia beetles to those compounds. Journal of Chemical Ecology. 51. Article 59. https://doi.org/10.1007/s10886-025-01606-1.
DOI: https://doi.org/10.1007/s10886-025-01606-1

Interpretive Summary: Rapid ‘ohi'a death (ROD) caused by two fungal pathogens, Ceratocystis lukuohia and Ceratocystis huliohia fungi, is devastating 'ohi'a (Metrosideros polymorpha), the keystone tree species of Hawai'i. The objectives of this study were to identify fungal volatile organic compounds (VOCs) associated with the ROD pathosystem and characterize the behavioral response of the ROD-associated beetles to the VOCs.

Technical Abstract: Rapid ‘ohi'a death (ROD) is caused by Ceratocystis lukuohia and Ceratocystis huliohia fungi and is devastating 'ohi'a (Metrosideros polymorpha), the keystone tree species of Hawai'i. Ceratocystidae fungi produce fungal volatile organic compounds and sticky sexual spores, suggesting they are adapted for insect dispersal. In this study, we explored chemical signaling between the causal agents of the ROD disease complex and their ambrosia beetle (Coleoptera: Curculiondiae: Scolytidae) vectors. Four species of ambrosia beetles (Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, and Xyleborus perforans) are vectors of the ROD pathogens and also spread them indirectly through contaminated frass. In order to further understand the extent to which semiochemicals mediate relationships between agents of the ROD pathosystem, we identified the fungal volatile organic compounds (VOCs) both in vitro and in vivo. We then tested the response of the ROD-associated ambrosia beetles to the fungi using still-air olfactometer assays. Similar fruity and banana-like fusel alcohols and acetates were produced from C. lukuohia and C. huliohia in culture and when colonizing ‘ohi'a seedlings. We detected fungal VOCs one day post-inoculation, nine days before symptom onset. Xyleborus affinis had positive arrestment responses towards both C. lukuohia and C. huliohia, while X. ferrugineus responded to C. lukuohia and X. perforans to C. huliohia. These findings support the hypothesis of a coevolutionary history between Ceratocystis fungi and insects.