Kolarík Miroslav, Kostovcík Martin, Pazoutová Sylvie
Institute of Microbiology AS CR, Vídenská 1083, 142 20 Praha 4, Czech Republic.
Mycol Res. 2007 Nov;111(Pt 11):1298-310. doi: 10.1016/j.mycres.2007.06.010. Epub 2007 Jun 29.
Geosmithia spp. (Ascomycota: Hypocreales) are dry-spored fungi that occur in galleries built by many phloeophagous bark beetles. This study mapped the diversity, host spectrum and area of distribution of Geosmithia spp. occurring in galleries of bark beetle species with a Mediterranean distribution. Eighty-six wood samples of 19 tree species infested by 18 subcortical insect species were collected from across the Mediterranean Basin during the years 2003-2006. Geosmithia spp. were found in 82 samples of angiosperms and two host trees from the family Juniperaceae infested by 14 bark beetles and the bostrichid Scobicia pustulata, suggesting that the association of Geosmithia and phloeophagous bark beetles is very widespread in the Mediterranean. Geosmithia isolates were sorted into 13 operational taxonomic units (OTUs) based on their phenotype similarity and phylogeny of their ITS regions of rDNA (ITS1-5.8S-ITS2). The OTUs represent five known species (G. flava, G. langdonii, G. lavendula, G. pallida, G. putterillii) and seven undescribed taxa. Most of the bark beetles were associated with on average 1-2.5 OTUs per sample. G. lavendula, considered very uncommon in nature, was found as a common associate of bark beetles. Six out of 13 OTUs were found to be distributed in the Mediterranean but not in neighbouring areas of temperate Europe suggesting that Geosmithia spp. have a geographically limited distribution, probably due to their dependency on the geographically limited area of their vectors. The proportion of generalists and specialists among Geosmithia spp. was smaller compared with data from temperate Europe. A possible explanation is the effective dispersal of Geosmithia by polyphagous bostrichids across the niches defined by mutually exclusive bark beetles.
地丝霉属（子囊菌门：肉座菌目）是一种干孢子真菌，存在于许多蛀食韧皮部的小蠹虫所建造的虫道中。本研究绘制了在地中海分布的小蠹虫物种虫道中出现的地丝霉属的多样性、寄主谱和分布区域。在2003年至2006年期间，从地中海盆地各地收集了19种树种的86个木材样本，这些样本受到18种皮层下昆虫物种的侵害。在地丝霉属中，发现其存在于82个被子植物样本以及来自柏科的两棵寄主树中，这些样本受到14种小蠹虫和长蠹科的脓疱材小蠹的侵害，这表明地丝霉属与蛀食韧皮部的小蠹虫之间的关联在地中海地区非常普遍。根据其表型相似性和核糖体DNA的ITS区域（ITS1 - 5.8S - ITS2）的系统发育，地丝霉分离株被分为13个操作分类单元（OTU）。这些OTU代表了5个已知物种（黄地丝霉、兰氏地丝霉、薰衣草地丝霉、苍白地丝霉、普氏地丝霉）和7个未描述的分类单元。大多数小蠹虫每个样本平均与1 - 2.5个OTU相关联。薰衣草地丝霉在自然界中被认为非常罕见，但却被发现是小蠹虫的常见伴生菌。13个OTU中有6个被发现分布在地中海地区，但在欧洲温带的邻近地区却没有，这表明地丝霉属的分布在地理上受到限制，可能是由于它们依赖于其传播媒介在地理上有限的分布区域。与来自欧洲温带的数据相比，地丝霉属中泛化种和特化种的比例较小。一个可能的解释是多食性长蠹科有效地传播了地丝霉，使其跨越了由相互排斥的小蠹虫所定义的生态位。
