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The efficacy of the semiochemical repellent verbenone to reduce ambrosia beetle attack on healthy and Ceratocystis-infested ‘ōhiʻa trees

Trees, Forests and People
By: , , , , , and 
https://doi.org/10.1016/j.tfp.2024.100735

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Abstract

The Ceratocystis fungal disease complex, rapid ʻōhiʻa death (ROD), has killed over one million ʻōhiʻa (Metrosideros polymorpha), the keystone tree species of Hawaiʻi. The causal fungi can be spread by invasive ambrosia beetles (Coleoptera: Curculionidae) through fungal inoculum found on their bodies and in the frass they produce. Thus, there is a critical need to manage beetle attack on ʻōhiʻa trees to curtail subsequent pathogen spread and disease development. In this experiment at Waiākea Forest Reserve, we tested the potential of the semiochemical repellent, verbenone, in a commercial formulation, to protect healthy and ROD-affected ʻōhiʻa from ambrosia beetle attack in each of the 2022 and 2023 field seasons. Landing rates of ambrosia beetles on healthy and diseased trees were quantified over 16 weeks each year, using sticky traps on ethanol-baited trees that also received either a low (72 g) or high (108 g) dose of verbenone or untreated controls. In addition, we used gas-chromatography mass-spectrometry (GC–MS) to measure verbenone emission over 16 weeks in 2022. We found that the low dose of verbenone is the most effective and economical application to reduce beetle landing on healthy ʻōhiʻa trees and the high dose may be needed to reduce attraction to diseased ʻōhiʻa. Despite a large decrease in verbenone emission levels by week eight, the low dose effectively reduced beetle captures on healthy trees for 14 weeks and the high dose reduced landing rates on diseased trees for 10–14 weeks. Our results indicate verbenone may significantly lower ambrosia beetle attack on ʻōhiʻa, and thus, lead to reduction in the spread of ROD.

    Suggested Citation

    Roy, K., Mikros, D., Cha, D., Dunkle, E., Juzwik, J., and Ginzel, M.D., 2024, The efficacy of the semiochemical repellent verbenone to reduce ambrosia beetle attack on healthy and Ceratocystis-infested ‘ōhiʻa trees: Trees, Forests and People, v. 18, 100735, 9 p., https://doi.org/10.1016/j.tfp.2024.100735.

    Study Area

    Publication type Article
    Publication Subtype Journal Article
    Title The efficacy of the semiochemical repellent verbenone to reduce ambrosia beetle attack on healthy and Ceratocystis-infested ‘ōhiʻa trees
    Series title Trees, Forests and People
    DOI 10.1016/j.tfp.2024.100735
    Volume 18
    Year Published 2024
    Language English
    Publisher Elsevier
    Contributing office(s) Pacific Island Ecosystems Research Center
    Description 100735, 9 p.
    Country United States
    State Hawaii
    Other Geospatial Island of Hawaii, Wai¯akea Forest Reserve
    Additional publication details