キクイムシの共生菌の新機能を発見―単なる栄養源以上の役割(The ship-timber beetle’s fungal partner: more than just a food source)

ad

2025-12-03 マックス・プランク研究所

この研究では、枯木中で暮らす害虫コウチュウ「Ship-timber beetle(=Elateroides dermestoides など)」が、栄養に乏しい死木環境に適応するため、栄養豊富な共生菌「Alloascoidea hylecoeti」と強固な共生関係を持つことを示した。研究チームは菌糸体を分析し、この菌が糖やアミノ酸、脂肪酸、リン、窒素などを高濃度に蓄える「非常に栄養価の高い食物源」であることを初めて定量的に証明。加えて、この菌は木材由来のフェノール化合物を体内に取り込み、他の競合真菌の成長を抑制する化学防御機構を備えることも判明した。さらに菌は酢酸を産生して木材内を酸性環境に変えるが、他の真菌はこの環境で成長できない一方、共生菌はむしろそれを好むという。これにより、競合や分解者がひしめく過酷な木内部でも、ビートルの幼虫は安定して成長できるという。つまりこの共生は、単なる「食物提供」にとどまらず、「競合排除+安定環境維持」を通じて幼虫の生存と成長を強力に支える、生態的に深く構造化された仕組みである。

キクイムシの共生菌の新機能を発見―単なる栄養源以上の役割(The ship-timber beetle’s fungal partner: more than just a food source)
Micro-computed tomography scan of an adult shiptimper beetle (Elateroides dermestoides).© Veit Grabe and Maximilian Lehenberger, Max Planck Institute for Chemical Ecology

<関連情報>

アムブロシア甲虫の真菌共生菌は栄養価が高く、抗菌化合物で競合する真菌を抑制する Fungal symbiont of an ambrosia beetle possesses high nutrient content and suppresses competing fungi with antimicrobial compounds

Maximilian Lehenberger,Yu Pan,Stefanie Ungerer,Michael Reichelt,Daniela Pemp,Christian Paetz,Josef Lehenberger,Niklas Gentsch,Felix Feistel,Peter Gros,…
The ISME Journal  Published:20 November 2025
DOI:https://doi.org/10.1093/ismejo/wraf258

Abstract

Wood-colonizing beetles are associated with a diversity of microbes many of which are thought to act as mutualists with their beetle hosts, but the evidence is usually anecdotal. The ship-timber beetle Elateroides dermestoides, one of the few fungus-farming but non-social ambrosia beetles, is described to have a mutualistic relationship with the yeast-like fungus Alloascoidea hylecoeti. Here, we tested the hypothesis that A. hylecoeti has a high nutrient content thus allowing it to function as a valuable food source for the solitary larvae of E. dermestoides, which bore into the wood of dead trees, an extremely nutrient-poor substrate. Our analyses revealed that A. hylecoeti is rich in soluble sugars, free amino acids, ergosterol, phosphorus, and potassium compared to the other fungi measured, and also accumulates high amounts of fatty acids, B vitamins and nitrogen. We also tested whether A. hylecoeti possesses chemical mechanisms to suppress antagonistic microbes. Extracts from A. hylecoeti and chemical compounds produced or accumulated by this fungus were found to significantly inhibit the growth of potentially competing fungi. The active substances include fungal-produced monoterpenes and acetic acid, as well as phenolic compounds accumulated from host tree tissues. Moreover, sufficient acetic acid was released by A. hylecoeti to drop the medium pH to as low as 3.6, which inhibited all tested competitors, whereas the growth of A. hylecoeti was promoted. Taken together, the nutritional properties and competitive ability of A. hylecoeti may make a major contribution to the success of its insect partner, the ship-timber beetle under natural conditions.

生物環境工学
ad
ad
Follow
ad
タイトルとURLをコピーしました