In ambrosia and bark beetles–fungi interaction, volatile organic compounds (VOCs) play a central role in mediating various aspects of community dynamics of beetles and/or fungi. These functions include facilitating beetle habitat location, mate identification, and fungal partner differentiation. However, the understanding on this context remains limited, especially in the globally distributed subfamily Platypodinae, which comprises predominantly ambrosia beetles. There is a lack of chemical data on ambrosia fungi from native South American species. This study addresses this gap by characterizing VOCs from twelve fungal species associated with Megaplatypus mutatus and assessing species-specific behavioral responses during dispersal. Fungal VOCs were collected by gas chromatography–mass spectrometry combined with solid-phase microextraction and Y-olfactometry assays of males and females were performed at dispersal stage. Statistical analyses involved: non-metric multidimensional scaling multivariate plot and PermanovaPERMANOVA test, a cluster analysis through unweighted pair group method with Jaccard index, and finally, a chi-square goodness-of-fit test for beetle behavioral assays. We identified 72 VOCs from the fungal species isolated from M. mutatus galleries, exocuticle, and gut. The olfactory behavior of M. mutatus demonstrated its capacity to discriminate between volatile profiles, showing a preference for either the fungus or the control source. Our results also enhance the understanding in a chemotaxonomic context and in the behavioral responses of M. mutatus revealing the beetle's remarkable low temperature tolerance and its capability to maintain mobility and orientation toward volatile sources even after zero-degree Celsius exposure. This study presents a comprehensive insight into fungal VOC profiles, emphasizing the sources of isolation within pest associated fungi, as well as its symbiotic species from the Raffaelea genus. In conclusion, our findings suggest that Megaplatypus mutatus exhibits a general aversion to its fungal VOCs symbiont. However, a notable exception arises when the beetles are pre-exposed for 48 h to freezing conditions, highlighting the beetles' ability to withstand freezing conditions as adults and to exhibit altered responses to their fungal associates under these circumstances.

中文翻译：

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Megaplatypus mutatus 相关真菌释放的挥发性有机化合物：臭虫的化学鉴定和温度调节反应

在豚草和树皮甲虫与真菌的相互作用中，挥发性有机化合物（VOC）在调节甲虫和/或真菌群落动态的各个方面发挥着核心作用。这些功能包括促进甲虫栖息地定位、配偶识别和真菌伙伴分化。然而，对这方面的了解仍然有限，特别是在全球分布的扁足亚科（主要由豚草甲虫组成）中。缺乏南美本土物种豚草真菌的化学数据。本研究通过表征与巨型鸭嘴兽相关的 12 种真菌物种的 VOC 特征并评估传播过程中物种特异性的行为反应来解决这一差距。通过气相色谱-质谱联用固相微萃取收集真菌挥发性有机化合物，并在扩散阶段对雄性和雌性进行 Y 嗅觉测定。统计分析涉及：非度量多维标度多元图和 PermanovaPERMANOVA 检验、通过未加权配对方法与 Jaccard 指数进行的聚类分析，最后是甲虫行为分析的卡方拟合优度检验。我们从 M. mutatus 菌道、外角质层和肠道中分离出的真菌物种中鉴定出了 72 种 VOC。M. mutatus 的嗅觉行为证明了其区分挥发性成分的能力，显示出对真菌或对照源的偏好。我们的结果还增强了对化学分类学背景和 M. mutatus 行为反应的理解，揭示了甲虫显着的低温耐受性及其即使在零摄氏度暴露后也能保持对挥发性源的移动性和方向的能力。这项研究对真菌 VOC 概况进行了全面的了解，强调了与害虫相关的真菌及其来自拉斐尔属的共生物种的隔离来源。总之，我们的研究结果表明，Megaplatypus mutatus 表现出对其真菌 VOC 共生体的普遍厌恶。然而，当甲虫预先暴露在冰冻条件下 48 小时时，会出现一个值得注意的例外，这突显了甲虫作为成虫能够承受冰冻条件的能力，并在这些情况下对真菌伙伴表现出改变的反应。