Impairment of microbial and meiofaunal ecosystem functions linked to algal forest loss

Habitat loss is jeopardizing marine biodiversity. In the Mediterranean Sea, the algal forests of Cystoseira spp. form one of the most complex, productive and vulnerable shallow-water habitats. These forests are rapidly regressing with negative impact on the associated biodiversity, and potential consequences in terms of ecosystem functioning. Here, by comparing healthy Cystoseira forests and barren grounds (i.e., habitats where the macroalgal forests disappeared), we assessed the effects of habitat loss on meiofaunal and nematode biodiversity, and on some ecosystem functions (here measured in terms of prokaryotic and meiofaunal biomass). Overall, our results suggest that the loss of Cystoseira forests and the consequent barren formation is associated with the loss of meiofaunal higher taxa and a decrease of nematode biodiversity, leading to the collapse of the microbial and meiofaunal variables of ecosystem functions. We conclude that, given the very limited resilience of these ecosystems, active restoration of these vulnerable habitats is needed, in order to recover their biodiversity, ecosystem functions and associated services.

New records of plant-parasitic nematodes from Iceland

The plant-parasitic nematodes of Iceland are poorly understood. To address this, a study of the nematodes of the families Criconematidae and Hemicycliophoridae was performed in 2015. Soil samples were taken from underneath various host plants in different locations in Iceland. The identification was performed on the basis of the general morphology and subsequently confirmed by molecular markers (D2-D3 28S rDNA). The study revealed the presence of nematode specimens belonging to four species of the family Criconematidae: Criconemoides amorphus, Criconema demani, Mesocriconema xenoplax and Mesocriconema curvatum, as well as one species Hemicycliophora conida of the family Hemicycliophoridae. To our knowledge, this is the first record of the occurrence of these nematode species in Iceland. The species identified are economically important plant-parasitic nematodes of likely interest to—among others—Icelandic plant protection professionals. This report broadens our knowledge of Iceland’s nematode biodiversity; moreover, morphological analyses and molecular data may contribute to better understanding the origin of nematode species on the island of Iceland.

Nematode biodiversity assessments need vouchered databases: A BOLD reference library for plant-parasitic nematodes in the superfamily Criconematoidea

Nematodes are frequently cited as underrepresented in faunistic surveys using DNA barcoding with COI. This underrepresentation is generally attributed to a limited presence of nematodes in DNA databases which, in turn, is often ascribed to structural variability and high evolutionary rates in nematode mitochondrial genomes. Empirical evidence, however, indicates that many taxa are readily amplified with primer sets specifically targeted to different nematode families. Here we report the development of a COI reference library of 1726 specimens in the terrestrial plant parasitic nematode superfamily Criconematoidea. Specimens collected during an ecoregion survey of North America were individually photographed, measured, and PCR amplified to produce a 721 bp region of COI for taxonomic analysis. A neighbor-joining tree structured the dataset into 179 haplotype groups that generally conformed to morphospecies in traditional analysis or Barcode Index Numbers (BINs) in the BOLD system, although absent formal BIN membership due to insufficient overlap with the Folmer region of COI. Approximately one-third of the haplotype groups could be associated with previously described species. The geographic distribution of criconematid nematode species suggests a structure influenced by the major habitat types in the United States and Canada. All sequences collected in the ecoregion survey are deposited in BOLD.

Utjecaj pripravka na bazi fluopirama i tekućega pilećeg stajnjaka na nematode korijenovih kvržica (Meloidogyne spp.) u nasadu mrkve

The aim of this study was to investigate the nematocidal effect of the preparations based on fluopyram (pesticide) and liquid chicken manure (natural amendment) on the population density of the root-knot nematodes, Meloidogyne spp. in carrot crops. The field experiment was set up in four treatments: control (C), fluopyram (FLU), fluopyram and liquid chicken manure (FLU+LCM) and liquid chicken manure (LCM) by a random block design in four replicates. Population density of Meloidogyne spp. juveniles varied between the treatments, and the number of Meloidogyne spp. was significantly decreased in all treatments with fluopyram (FLU and FLU+LCM). All amended treatments (FLU, FLU+LCM, LCM) decreased galling of the roots and had a positive effect on carrot yield. The population of Meloidogyne spp. juveniles increased with the plant growth, regardless of the treatments applied. Fluopyram negatively affected the biodiversity indicating greater disturbance for the nematode community structure in the soil. It can be concluded that fluopyram and liquid chicken manure have nematicidal potential, while liquid chicken manure maintained or enhanced nematode biodiversity.