Rapid 'Ōhi'a Death (ROD) is a deadly disease that is threatening the native Hawaiian keystone tree species, 'ōhi'a lehua (Metrosideros polymorpha Gaudich). Ambrosia beetles (Curculionidae: Scolytinae) and their frass are hypothesized to play a major role in the spread of ROD, although their ecological niches and frass production within trees and across the landscape are not well understood. We characterized the beetle communities and associated frass production from bolts (tree stem sections) representative of entire individual 'ōhi'a trees from multiple locations across Hawai'i Island by rearing beetles and testing their frass for viable ROD-causing fungi. Additionally, we estimated frass production for three beetle species by weighing their frass over time. We found that Xyleborinus saxesenii (Ratzburg), Xyleborus affinis Eichhoff, Xyleborus ferrugineus (Fabricius), Xyleborus perforans (Wollaston), and Xyleborus simillimus Perkins were commonly found on ROD-infected 'ōhi'a and each produced frass containing viable Ceratocystis propagules. The Hawai'i Island endemic beetle and the only native ambrosia beetle associated with 'ōhi'a, X. simillimus, was limited to high elevations and appeared to utilize similar tree heights or niche dimensions as the invasive X. ferrugineus. Viable Ceratocystis propagules expelled in frass were found throughout entire tree bole sections as high as 13 m. Additionally, we found that X. ferrugineus produced over 4× more frass than X. simillimus. Our results indicate the ambrosia beetle community and their frass play an important role in the ROD pathosystem. This information may help with the development and implementation of management strategies to control the spread of the disease.

中文翻译：

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Ambrosia Beetle (Coleoptera: Curculionidae) 群落和草皮生产在 ʻŌhiʻa (Myrtales: Myrtaceae) 感染 Ceratocystis (Microascales: Ceratocystidaceae) 真菌导致 ʻŌhiʻa 快速死亡

Rapid 'Ōhi'a Death (ROD) 是一种致命的疾病，威胁着夏威夷本土的关键树种 'ōhi'a lehua (Metrosideros polymorpha Gaudich)。Ambrosia beetles (Curculionidae: Scolytinae) 和它们的 frass 被假设在 ROD 的传播中起主要作用，尽管它们的生态位和树内和整个景观中的 frass 生产尚不清楚。我们通过饲养甲虫并测试它们的 frass 中可行的 ROD 真菌，对代表整个夏威夷岛多个地点的整个 'ōhi'a 树的螺栓（树茎部分）的甲虫群落和相关的 fras 生产进行了表征。此外，我们通过随时间称重三种甲虫的草料来估计它们的草料产量。我们发现 Xyleborinus saxesenii (Ratzburg), Xyleborus affinis Eichhoff、Xyleborus ferrugineus (Fabricius)、Xyleborus perforans (Wollaston) 和 Xyleborus simillimus Perkins 普遍存在于 ROD 感染的 'ōhi'a 上，每一种都产生含有可行 Ceratocystis 繁殖体的 frass。夏威夷岛地方性甲虫和唯一与 'ōhi'a、X. simillimus 相关的本地龙舌兰甲虫仅限于高海拔地区，并且似乎利用与入侵的 X. ferrugineus 相似的树高或生态位尺寸。在高达 13 m 的整个树干部分都发现了在 frass 中排出的有活力的角囊藻繁殖体。此外，我们发现 X. ferrugineus 比 X. simillimus 产生 4 倍以上的杂质。我们的研究结果表明，豚草甲虫群落及其 frass 在 ROD 病理系统中起着重要作用。