Tag: nematodes

Cyber catalogue and revision of the nematode genus Enchodelus 

All available information on Enchodelus species is brought together. This will contribute to a more complete assessment of species diversity and distribution.

Guest blog post by Milka Elshishka and Vlada Peneva

The order Dorylaimida is the most diverse nematode group, with over 2640 valid species and more than 260 valid genera, with new taxa being described each year. They are the richest nematode order in number of species in natural soils. Dorylaims are often regarded as good environmental bio-indicators since the number of species/specimens drastically decreases following any significant disturbance in their habitat.

In our study, published in the Biodiversity Data Journal, we examined one intriguing free-living dorylaimid nematode taxon: the genus Enchodelus which is considered to have conservation value. The genus currently includes 28 species, which display a distinct distributional pattern, being spread mainly in high altitudinal enclaves of the Northern Hemisphere (with the exception of E. brasiliensis, only known to occur in Brazil). Its representatives are often associated with mosses and cliff vegetation. Although their feeding habits have not been studied with experimental protocols, it is traditionally assumed that they are omnivorous.

Distribution of Enchodelus species

The genus Enchodelus has not been recently revised; the descriptions of many ‘old species’ (that have been described long ago and have not been reported since their original discovery) are of poor quality, hardly discoverable, and do not conform to today’s taxonomical standards.

An Enchodelus species.

Actually, information available from databases often is limited to some of the species and usually incomplete as relevant data are missing. Consequently, a comprehensive compilation and analysis of literature data is indispensable to reach new insights into the taxonomy of the genus and to elucidate its evolutionary relationships.

Our work provides a cyber catalogue of Enchodelus species, where all available data for the species are accessible and collected in one place, which will greatly facilitate future research. It compiles available information from key European Research Infrastructures, such as TreatmentBank, the Swiss Institute of Bioinformatics Literature Services (SIBiLS), the Catalogue of Life (CoL), the Global Biodiversity Information Facility (GBIF), the European Nucleotide Archive (ENA) and the Biodiversity Literature Repository (BLR). Data about their distribution (geographical records and habitats) are incorporated too and all brought together. It is completed with discussion and notes for some species, along with information on species distributions and microhabitats.

Here, all available information on Enchodelus species is brought together. This will contribute to a more complete assessment of species diversity and distribution and support further biogeographical and ecological research.

The type species Enchodelus macrodorus is the most widely spread and reported Enchodelus species. It is a typical member of Palearctic nematode fauna, recorded in a myriad of countries and habitats and very sporadically recorded in Nearctic and Indomalayan enclaves. In our study we add new morphological and molecular data for this species collected from Spain.

Enchodelus macrodorus from Spain.

Additionally, type material of Enchodelus vestibulifer, belonging to Edmond Altherr’s collection, deposited at the Museo Cantonale di Storia Naturale di Lugano (Switzerland), is re-examined.

Enchodelus vestibulifer

This species was described by the Swiss nematologist Edmond Altherr in 1952 on the basis of a single female from Switzerland and no later record of it exists. The re-examination of this material revealed that several relevant traits are not compatible with those characterising the genus Enchodelus and we considered it as incertae sedis.

In our study we also present one new species, Enchodelus enguriensis. It was collected from moss on stone (Tortellasquarrosa) in Caucasus, Georgia (Samegrelo-Zemo Svaneti Region, Bogreshi, Enguri River, Tower of Love). The description of the new species was supported by a comprehensive phylogenetic analysis based on D2-D3 of 28S rRNA. When naming the new taxon, we selected the name of the place from which the material was collected, namely the River Enguri; it was recovered from the stone next to the Tower of Love on the bank of the river.

Enchodelus enguriensis

We are grateful for the support the BiCIKL project, Grant No 101007492.

Research article:

Elshishka M, Mladenov A, Altash S, Álvarez-Ortega S, Peña-Santiago R, Peneva V (2024) Cyber catalogue and revision of the nematode genus Enchodelus (Dorylaimida, Nordiidae). Biodiversity Data Journal 12: e126315. https://doi.org/10.3897/BDJ.12.e126315

Survival of soil organisms is a wake-up call for biosecurity

Tiny creatures in soil that attack plants have shown the ability to survive for at least three years stored in dry conditions in a recent AgResearch study, giving new insights into the biosecurity threats posed by passenger travel and trade between countries. The research article is published in the open access journal Neobiota.

The findings of the study also add to the discussions about how best to detect these creatures, called nematodes, before they cross borders and potentially reduce yields of important crops and pasture.

Nematodes are very small worm-like organisms. They can be extremely hardy and can have both beneficial and detrimental impacts. The harmful ones, the plant parasitic nematodes (PPN) include species that attack plants reducing their growth and survival.

In the study, funded by AgResearch via the Better Border Biosecurity collaboration, soil collected from a native forest and an organic orchard was stored separately in cupboards at room temperature for a period of 36 months.

Samples were then taken at regular intervals to see if any nematodes could be recovered from the soil and, if they could, whether they were able to infect plant hosts.

“In the study we used different methods to detect nematodes — including a water misting technique to draw them out of the soil, and a baiting method — where we grew white clover and ryegrass plants in pots containing a soil sample,” explain the authors.

“One of the PPN we looked at was the root lesion nematode. What we found was that lesion nematodes were able to successfully invade the roots of ryegrass even after 36 months,” says AgResearch nematologist Lee Aalders.

“They were also able to produce offspring at 13 months. Interestingly, no PPN were recovered from soil stored beyond the 13th month using the three-day misting technique.”

This means that given the right conditions, PPN in soil, which is carried on sea freight, footwear or used machinery, and protected from sun or extreme heat, will survive if they end up near a suitable host plant. This is a result that may not be detected using an extraction test like misting.

For quarantine officials around the world, this result is an important find, as it reinforces the risk associated with soil that, even though it may look sterile, unwanted nematodes may be present and undetected until paired with a suitable host plant.

“In the context of biosecurity, we think that the development of a generic test for plant parasitic nematodes – based around a molecular based bioassay — would enhance the probability of detection of PPNs and, therefore, prevent unwanted incursions beyond the border.”

Earlier this year, another AgResearch study into the survival rates of various transported soil organisms and published in Neobiota concluded that biosecurity risks from soil organisms are to increase with declining transport duration and increasing protection from environmental extremes.

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Original source:

Aalders LT, McNeill MR, Bell NL, Cameron C (2017) Plant parasitic nematode survival and detection to inform biosecurity risk assessment. NeoBiota 36: 1-16. https://doi.org/10.3897/neobiota.36.11418