Kaufman Michael G, Chen Shicheng, Walker Edward D
Department of Entomology, Michigan State University, East Lansing, MI 48824, USA.
Microb Ecol. 2008 May;55(4):673-84. doi: 10.1007/s00248-007-9310-6.
Larvae of the eastern tree hole mosquito, Ochlerotatus triseriatus (Say), and related container-breeding species are known to feed upon substrate-associated microorganisms. Although the importance of these microbial resources to larval growth has been established, almost nothing is known about the taxonomic composition and dynamics of these critical microbial food sources. We examined bacterial and fungal community compositional changes on oak leaves tethered in natural tree hole habitats of O. triseriatus. We eliminated larvae experimentally in a subset of the tree holes and examined 16S rDNA gene sequences for bacteria and ergosterol concentrations and 18S rRNA gene sequences for fungi collected from leaf material subsamples. Leaf ergosterol content varied significantly with time, but not treatment. Principal component analysis (PCA) was used to compare microbial taxonomic patterns found in leaves incubated with or without larvae present, and we found that larval presence affected both bacterial and fungal groups, either from loosely attached or strongly adherent categories. Bacterial communities generally grouped more tightly when larvae were present, and class level taxa proportions changed when larvae were present, suggesting selection by larval feeding or activities for particular taxa such as members of the Bacteroidetes, Alphaproteobacteria, and Betaproteobacteria classes. Fungal taxa composite scores also separated along PC axes related to the presence of larvae and indicated larval feeding effects on several higher taxonomic groups, including Saccharomycetes, Dothideomycetes, and Chytridiomycota. These results support the hypothesis that larval mosquito feeding and activities altered microbial communities associated with substrate surfaces, potentially leading to decreased food value of the resource and affecting decomposition of particulate matter in the system.
东方树洞蚊（Ochlerotatus triseriatus (Say)）的幼虫以及相关的容器孳生蚊种已知以与基质相关的微生物为食。尽管这些微生物资源对幼虫生长的重要性已得到证实，但对于这些关键微生物食物来源的分类组成和动态变化却几乎一无所知。我们研究了系于三带喙库蚊自然树洞栖息地的橡树叶上细菌和真菌群落组成的变化。我们通过实验消除了一部分树洞中的幼虫，并检测了从叶片材料子样本中收集的细菌的16S rDNA基因序列、真菌的麦角固醇浓度以及18S rRNA基因序列。叶片麦角固醇含量随时间有显著变化，但不受处理影响。主成分分析（PCA）用于比较有或无幼虫存在时叶片中发现的微生物分类模式，我们发现幼虫的存在影响了细菌和真菌类群，无论是松散附着的还是紧密附着的类别。当有幼虫存在时，细菌群落通常聚类更紧密，且幼虫存在时类水平分类单元比例发生变化，这表明幼虫的取食或活动对特定分类单元有选择作用，如拟杆菌门、α-变形菌纲和β-变形菌纲的成员。真菌分类单元综合得分也沿着与幼虫存在相关的主成分轴分离，表明幼虫取食对几个较高分类类群有影响，包括酵母菌纲、座囊菌纲和壶菌门。这些结果支持了这样的假设，即幼虫蚊的取食和活动改变了与基质表面相关的微生物群落，可能导致资源的食物价值降低，并影响系统中颗粒物的分解。
