Nematode Taxa Research Articles

Cyber catalogue and revision of the nematode genus Enchodelus (Dorylaimida, Nordiidae).

The genus Enchodelus is an intriguing free-living dorylaimid nematode taxon. Its representatives display a distinct distributional pattern as they are mainly spread in high altitudinal enclaves of the Northern Hemisphere, being 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.The genus Enchodelus has not been recently revised; 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 the nowadays taxonomical standards. Thus, a comprehensive compilation and analysis of their literature data is indispensable to provide new insights into the taxonomy of the genus and to elucidate its evolutionary relationships. This contribution provides a cyber catalogue of all Enchodelus species, 28 in total. It compiles available information from the key European Research Infrastructures, such as TreatmentBank, Swiss Institute of Bioinformatics Literature Services (SIBiLS), the Catalogue of Life (CoL), Global Biodiversity Information Facility (GBIF), European Nucleotide Archive (ENA) and 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.Besides, type material Enchodelusvestibulifer Altherr, 1952, deposited in the Museo Cantonale di Storia Naturale di Lugano (Switzerland), is re-examined and the species is considered as incertae sedis. Further, a new species of the genus found in Caucasus, Georgia is described after its morphological and molecular study; also morphological and molecular data for E.macrodorus (de Man, 1880) Thorne, 1939, the type species of the genus, collected from Spain are provided.

Forest floor nematode communities and associated tree canopies: Is there an ecological linkage?

We searched for patterns supporting the hypothesis of compositional and functional linkage between forest floor nematode communities and dominant tree canopies, while controlling for some relevant soil and climate variables. Twenty-one forest sampling sites scattered throughout the South-Eastern Carpathian basin were selected under spruce, beech, and hornbeam-oak canopies. The relative contribution of forest canopy type to nematode assemblage differentiation was estimated through nematode taxonomic composition and feeding guild structure. The forest canopy type had a significant effect on nematode taxon/feeding guild composition and diversity at stand level. Several (diagnostic) nematode taxa and feeding guilds were positively associated with and accurately predicted the forest canopy types considered. Apart from the herbivorous nematodes, all the other trophic guilds were significantly related, in terms of their relative abundance, to the forest canopy type. Both nematode taxonomic and trophic diversity were significantly higher under beech canopy compared with its two counterparts. The highest total nematode beta diversity, either taxonomic or trophic, was attained between hornbeam-oak and spruce canopies. Nematode taxonomic and trophic beta diversity between forest canopy types were largely determined by taxon replacement and respectively, by a nested trophic structure. Overall, four concordant and two discordant patterns were revealed between nematode taxon and feeding guild composition with respect to overlying forest canopy, all underpinning the addressed ecological linkage. The present results bring evidence regarding the important contribution of the forest canopy, along with climatic variables, in driving the taxonomic and functional composition/diversity of nematode communities from the soil organic horizon.

Study on Impact of Soil Chemical Characteristics on Nematode Distribution Across Geographical Regions of Meghalaya

This study looks at the relationship between soil chemical characteristics and nematode communities in Meghalaya's agricultural landscapes. Nematodes, which are important bioindicators of soil health, were studied in connection to soil characteristics such as pH, Electrical Conductivity (EC), Organic Carbon (OC), and nutrient levels (N, P, K) in various parts of Meghalaya. The study found strong relationships between soil chemistry and the spread of various nematode taxa. Acidic soils with lower pH and higher organic carbon were shown to have higher populations of plant-parasitic nematodes such as Meloidogyne sp. and Xiphinema sp., both of which have been shown to reduce agricultural productivity. Soils with greater EC, on the other hand, have fewer of these damaging nematodes, implying that modifying soil salinity could be a viable technique for controlling nematode infestations. Furthermore, nutrient-rich soils, particularly those high in phosphorus and potassium, were associated with larger abundances of Tylenchorhynchus sp., emphasising the intricate relationship between soil fertility and nematode dynamics. The study highlights the critical impact of soil chemical characteristics in influencing nematode communities, as well as the importance of specific soil management strategies to improve crop health in Meghalaya. Farmers can use these findings to build targeted methods for controlling nematode populations, decreasing crop loss and encouraging sustainable agricultural practices in the region. This study offers useful recommendations for enhancing soil health and increasing agricultural productivity in some regions of Meghalaya's agroecosystems.

Communities of metazoan parasites in seven sympatric skate species (Elasmobranchii, Rajidae) from the English Channel and Celtic Sea differing in conservation status

AbstractElasmobranch populations are in steep decline mainly due to overfishing bycatch, but parasites may accelerate the collapse of vulnerable and/or highly parasitized species. We therefore studied metazoan parasites of Rajidae from the northeast Atlantic: vulnerable Leucoraja fullonica, near‐threatened Raja brachyura, Raja clavata, Raja microocellata and Raja undulata, and least‐concerned Raja montagui and Leucoraja naevus. Overall prevalence varied from 19% for R. montagui to 100% for L. fullonica. Parasite communities differed between skate species, and prevalence and abundance were higher for L. fullonica, R. microocellata, and R. undulata. We recorded 11 parasite taxa in the study: three nematodes, six cestodes, one monogenean, and one myxosporean. Whatever the skate species, the parasite component community comprised at least two nematode taxa among Phocanema spp., Proleptus sp. and Anisakis simplex. DNA‐sequencing revealed that Phocanema azarasi and Phocanema krabbei both occurred in R. microocellata and R. undulata. Phocanema spp. was first recorded in L. fullonica, L. naevus, R. microocellata, R. montagui, and R. undulata, as Proleptus sp. in L. fullonica, and A. simplex in L. fullonica and R. clavata, Rockacestus sp. and Nybelinia sp. in R. undulata, and gill‐myxosporeans on L. fullonica, L. naevus, R. microocellata, and R. undulata. The occurrence of 16 new host–parasite associations suggests potential environmental changes. Information provided by trophically transmitted helminths confirmed an opportunistic skate diet based on crustaceans and fish. We discuss results in terms of host fitness loss, bioindicator role of parasites, and anisakiasis risk. We recommend incorporating parasitology in research to improve elasmobranch conservation.

A 2‐year, multi‐county survey of plant‐parasitic nematodes in North Carolina flue‐cured tobacco

AbstractNorth Carolina is the leading producer of flue‐cured tobacco (Nicotiana tabacum L.) in the United States. Production in the state is threatened by numerous plant‐parasitic nematodes, including Meloidogyne spp. (root‐knot), Globodera tabacum (tobacco cyst), Pratylenchus spp. (lesion), Rotylenchulus reniformis (reniform), and Tylenchorhynchus spp. (stunt) nematodes. The invasive Meloidogyne enterolobii is also a major threat as it can infect tobacco varieties carrying the Rk gene, which conditions resistance to other Meloidogyne species. To gain an updated understanding of which nematode taxa are present in tobacco production and investigate distribution of M. enterolobii in North Carolina, a 2‐year survey was conducted. From 2021 to 2022, 188 fields were sampled across 24 tobacco‐growing counties. Samples were assayed for identification and quantification of nematodes at the genus level; where Meloidogyne spp. was identified, molecular testing was used to determine the species. Data were also collected on the previous crop and tobacco variety grown. In both years, lesion, root‐knot, dagger, and stunt nematodes were found in the highest incidence among samples. In 2022, M. enterolobii was identified in a single sample each from Granville and Pitt counties; this is the first report of M. enterolobii from Granville County. Tobacco variety NC 196 and soybean were the most common variety and previous crop grown, respectively, in both years of the survey. Tobacco variety did not have an effect on nematode population density. The previous crop had a significant effect on root‐knot and spiral nematodes in 2021, and lesion and stubby root nematodes in 2022.

Historic Museum Samples Provide Evidence for a Recent Replacement of Wolbachia Types in European Drosophila melanogaster.

Wolbachia is one of the most common bacterial endosymbionts, which is frequently found in numerous arthropods and nematode taxa. Wolbachia infections can have a strong influence on the evolutionary dynamics of their hosts since these bacteria are reproductive manipulators that affect the fitness and life history of their host species for their own benefit. Host-symbiont interactions with Wolbachia are perhaps best studied in the model organism Drosophila melanogaster, which is naturally infected with at least 5 different variants among which wMel and wMelCS are the most frequent ones. Comparisons of infection types between natural flies and long-term lab stocks have previously indicated that wMelCS represents the ancestral type, which was only very recently replaced by the nowadays dominant wMel in most natural populations. In this study, we took advantage of recently sequenced museum specimens of D. melanogaster that have been collected 90 to 200 yr ago in Northern Europe to test this hypothesis. Our comparison to contemporary Wolbachia samples provides compelling support for the replacement hypothesis. Our analyses show that sequencing data from historic museum specimens and their bycatch are an emerging and unprecedented resource to address fundamental questions about evolutionary dynamics in host-symbiont interactions. However, we also identified contamination with DNA from crickets that resulted in co-contamination with cricket-specific Wolbachia in several samples. These results underpin the need for rigorous quality assessments of museomic data sets to account for contamination as a source of error that may strongly influence biological interpretations if it remains undetected.

Nematodes Infecting the Shield Frog <i>Adelophryne baturitensis</i> in Rainforest Enclaves of Brazilian Semiarid

Parasitological studies provide important information about host biology. However, most anuran species in mountain environments have their helminth fauna understudied. In the present study, we aimed to inventory the endoparasites associated with the shield frog Adelophryne baturitensis from an altitudinal rainforest enclave in the Brazilian semiarid region. We found 57 specimens from five nematode taxa. Perhaps, the high nematode infection on this mountain frog might be related to the host’s direct life cycle where they do not need water ponds to lay eggs and reach tadpole development. Trematodes and other endoparasite taxa are commonly reported in water-dependent frogs. Although shield frogs seem to be myrmecophagous, more studies are still needed to investigate how their feeding habits might influence parasitological infection. Our study is an important contribution to understanding the parasite-host ecological relationship in minute frogs.

The nematode assemblages of a lake ecosystem (Lake Korugöl Natural Park, Düzce, West Black Sea Cost of Türkiye): ecology and biodiversity patterns with first reports of 10 genera to the Türkiye nematofauna

This research was conducted to reveal the soil nematode fauna of Korugöl, Düzce and to contribute to the nematode diversity of the Western Black Sea Region of Türkiye. Field studies within the scope of the study were implemented in 2021. As a result of the study, 29 families, 45 genera and 46 nematode taxa were identified. 10 nematode taxon, namely Aporcelinus, Baladorylaimus, Dorylaimoides, Euteratocephalus, Labronemella, Laimydorus, Lindseyus, Metateratocephalus, Paractinolaimus and Tripylella are the first report for Türkiye's nematofauna. Classification of nematodes according to their feeding types were: 27.27% bacterivorous nematodes, 2.10% fungivoresnematodes, 1.51% herbivorous nematodes, 16.35% predator nematodes and 52.77% omnivorous nematodes.

Integrated characterisation of Daubaylia burnupiae n. sp. (Nematoda: Daubayliidae) from a freshwater gastropod in South Africa, with comments on the biology of Daubaylia spp.

Gastropod-nematode associations are underreported worldwide. In the present study, juvenile and adult nematodes were found in the freshwater gastropod Burnupia stenochorias (Melvill & Ponsonby, 1903), from the Vaal River, South Africa. The nematodes were confirmed to belong to the genus Daubaylia chitwood & chitwood, 1934 (Daubayliidae). This is the first report of Daubaylia from a snail belonging to the family Burnupiidae, and the first report of this nematode taxon in southern Africa. Like D. pearsoni and D. malayanum from Australia and Malaysia respectively, adult females of the current species possess multiple well-developed eggs in the uteri, with larvae developing in utero. Morphological and molecular characteristics showed that the nematodes are distinct from all the described species of Daubaylia. Thus, they are considered a new species, Daubaylia burnupiae n. sp. The species differs from its congeners based on spicule shape, the short tail of the male, an anal cuticular knob-like protrusion on the female, and oesophagi with short isthmi and short glandular basal bulbs in both sexes. Three club-shaped pharyngeal lobes, extending slightly above the surface of the cephalic lips in both sexes and a pre-cloacal median papilla on the male were described using scanning electron microscopy, the first of such observations for the daubayliids. Genetic analyses showed that partial sequences of D. burnupiae n. sp. differed from species for which genetic data are available, by at least 26 and 9 base pair differences for 28S and 18S rDNA, respectively. Our results show that low prevalence and abundance of nematodes in the snails, corresponded with increased pollution in the river. We suspect that exposure to pollutants reduces the viability of the infective gravid female nematode during transmission. Therefore, the nematode is a potential bioindicator for aquatic pollution.

New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand

Relatively little is known about the taxonomy and ecology of deep-sea nematode species inhabiting cold seep habitats. The available data show that cold seep nematode communities are typically characterized by low diversity and are often dominated by a single species, although no nematode taxon appears to have a strong association with methane seepage. In July 2019, a research voyage to New Zealand’s Hikurangi Margin provided an opportunity to characterize the nematode species communities of New Zealand cold seeps, which had not been investigated until now. Here, six new species and two new nematode genera of the class Chromadorea are described from macrofauna cores obtained at three seep sites (Mungaroa, Glendhu, and Uruti South) on Hikurangi Margin from 1227 to 2077 m depth. The species described here represent a wide range of feeding groups, ranging from deposit feeders (Linhomoeus pycnocricus sp. nov., Deraionema barbatum gen. et sp. nov.) to microvores (Aulostomonema abyssum gen. et sp. nov., Aegialoalaimus magnus sp. nov.) and epigrowth feeders (Desmodora parapilosa sp. nov.). The diet of Siphonolaimus curtisensillus sp. nov., which is characterized by an unusual stylet-like feeding apparatus, remains to be determined, however the presence of several different feeding modes in the species described here indicates that a range of food sources are exploited by macrofaunal nematodes at the study sites. Desmodora, Linhomoeus, and Aegialoalaimus have been reported from cold seep habitats previously, however no records of Siphonolaimus from cold seeps could be found in the literature. Aulostomonema gen. nov. does not appear to have a close association with seeps, whilst Deraionema gen. nov. appears to be restricted to the centre of the seep sites where methane seepage is likely strongest. Ongoing work on the ecology and distribution of nematode communities at the Hikurangi Margin seep sites will help determine spatial patterns in abundance and species distributions in more detail, including the identification of any species/taxa with affinities with methane seepage.

A Survey of Plant Parasitic Nematodes of Soybeans in Delaware and Maryland 2019 to 2021

Soybean cyst nematode (SCN; Heterodera glycines) is the most yield-limiting pathogen of soybean across Delaware and eastern shore Maryland. To update nematode distribution and population data, a 3-year survey of nematode soil samples was conducted from 2019 to 2021. Soybean fields across Delaware and nine Maryland counties were sampled from August through October in each year. In total, 311 soil samples were collected, including 222 predictive samples and 89 diagnostic samples. Across all samples, nine nematode taxa were identified. SCN (53%), root-knot nematode (RKN; Meloidogyne incognita, 18%), and lesion nematode ( Pratylenchus spp., 57%) were the most notable populations of economic concern. Among positive samples, populations were above the economic threshold for 66% of samples with SCN; 39% of samples with RKN; and 14% of samples with lesion nematode. Results from this survey highlight the continued challenge of SCN in the region and that other nematode taxa like RKN and lesion should be monitored. Many fields have multiple nematode genera present, and interactions are poorly understood.

Impacts of the first deep-sea seafloor massive sulfide mining excavation tests on benthic communities

Japan undertook the first ever tests of deep-sea seafloor massive sulfide (SMS) excavation in 2017 in the Okinawa Trough. This study examines infauna from several nearby stations before and up to 3 yr after disturbance. Distance from excavation, current direction, seafloor topography, and modeled and observed deposition were used to classify the level of impact of each station. Metal concentrations were analyzed, as were nanofauna (2-32 µm), meiofauna (32-300 µm), and macrofauna (>300 µm). Elevated Cd, Pb, Hg, Zn, Fe, and Cu were confirmed as indicators of sedimentation from the SMS extraction. Benthic communities appeared altered by the disturbance test, with different size classes showing different levels of response and recovery. Nanofaunal and meiofaunal abundances appeared to take several weeks to show impacts from the disturbance and may have returned to pre-test levels within 1 yr, but changes to nematode community structure persisted longer. In contrast, macrofaunal abundances and diversity appeared to decrease immediately, and possibly remained depressed compared to pre-test levels at impacted sites at least 3 yr later. In addition, meiofaunal nematode:copepod ratio and macrofaunal percent composition of polychaetes, along with several nematode taxa, may serve as useful bioindicators of SMS mining. The small scale of disturbance requires caution when extrapolating to full-scale mining, but these results suggest current direction and topography greatly influence the extent of mining impacts; in addition, several metals may be useful for identifying the mining footprint. Biological results indicate that larger macroinfauna may be less resistant and resilient to mining impacts than smaller meiofauna and impacts from even small-scale mining activities may persist for at least 3 yr.

Genetic disruption of Arabidopsis secondary metabolite synthesis leads to microbiome-mediated modulation of nematode invasion.

In-depth understanding of metabolite-mediated plant-nematode interactions can guide us towards novel nematode management strategies. To improve our understanding of the effects of secondary metabolites on soil nematode communities, we grew Arabidopsis thaliana genetically altered in glucosinolate, camalexin, or flavonoid synthesis pathways, and analyzed their root-associated nematode communities using metabarcoding. To test for any modulating effects of the associated microbiota on the nematode responses, we characterized the bacterial and fungal communities. Finally, as a proxy of microbiome-modulating effects on nematode invasion, we isolated the root-associated microbiomes from the mutants and tested their effect on the ability of the plant parasitic nematode Meloidogyne incognita to penetrate tomato roots. Most mutants had altered relative abundances of several nematode taxa with stronger effects on the plant parasitic Meloidogyne hapla than on other root feeding taxa. This probably reflects that M. hapla invades and remains embedded within root tissues and is thus intimately associated with the host. When transferred to tomato, microbiomes from the flavonoid over-producing pap1-D enhanced M. incognita root-invasion, whereas microbiomes from flavonoid-deficient mutants reduced invasion. This suggests microbiome-mediated effect of flavonoids on Meloidogyne infectivity plausibly mediated by the alteration of the abundances of specific microbial taxa in the transferred microbiomes, although we could not conclusively pinpoint such causative microbial taxa.

Impact of Super-High Density Olive Orchard Management System on Soil Free-Living and Plant-Parasitic Nematodes in Central and South Italy.

Simple SummarySuper-high density olive orchards are spreading in Italy to reduce production costs and increase yields per hectare. The objective of this study was to assess the orchards’ effect on the soil nematode community in five sites located in the main Italian olive cultivation areas compared to the adjacent traditional olive orchard system. Super-high density olive orchard management combined with conventional tillage and mineral fertilization decreased total organic carbon compared to traditional management. The soil nematode community was affected by the depletion of organic matter, especially for plant-parasitic nematodes, which increased. Moreover, this investigation evidenced that the Super-high density olive orchard management system could change the soil plant-parasitic nematode composition of olive orchards. In fact, the families Telotylenchidae, Paratylenchidae, Meloidogynidae, and Criconematidae were favored in the Super-high density olive orchard system, while Longidoridae, Heteroderidae, and Pratylenchidae were disadvantaged. However, conservative and sustainable soil management might maintain or improve the soil nematode community functionality and reduce plant-parasitic nematodes.The soil nematode community plays an important role in ecosystem services. The objective of this study was to assess the effect of Super-high density (SHD) olive orchards on the nematode community in five sites with different soils, climates, and cultivars. At each site, the SHD management system was compared to the adjacent olive orchard traditional (TRAD) system, in which the same soil management and phytosanitary measures were applied. Soil management was assessed by total organic carbon content (TOC), while the soil nematode community was evaluated using the nematode taxa abundances and soil nematode indicators. TOC was significantly decreased in the SHD olive orchard system compared to TRAD in the sites characterized by conventional tillage and mineral fertilization. The two-way ANOSIM analysis on nematode abundance showed no difference between the two olive management methods, instead showing only a significant difference per site mainly due to variabilities in plant-parasitic nematode assemblage. However, a negative impact of SHD management was evident in environments stressed by summer droughts and conventional tillage: the ratio of obligate plant-parasites to bacterivores and fungivores (Pp/(B+F)) was significantly higher in SHD than in the TRAD olive orchard system, and the prey-to-predator θ mass ratio showed the lowest values in the sites under organic fertilization or green manure. The canonical correspondence analysis showed that the free-living nematodes were only slightly affected by SHD olive orchards; instead, the presence of plant-parasitic nematodes families such as Telotylenchidae, Paratylenchidae, Meloidogynidae, and Criconematidae was favored, in comparison to Longidoridae, Heteroderidae, and Pratylenchidae.

Nematodes in the Pine Forests of Northern and Central Greece.

Simple SummaryPine wood nematode Bursaphelenchus xylophilus is the agent of pine wilt disease and one of the most important forest tree pathogens worldwide, transmitted through beetles of the Monochamus genus. As an invasive species, it has spread beyond its natural range by human activity mainly wood trade. The devastating impact it has on pine forests has led to severe environmental and economic damages in its introduced countries. The wide distribution of Monochamus spp. beetles in many parts of the world along with favourable climatic conditions, which are both important factors for the establishment of pine wilt disease, have raised awareness over its continuous expansion. Therefore, in an attempt to control and even inhibit its further spread and consequently its severely adverse impacts, appropriate measures have already been taken and implemented from countries across the globe.In the context of plants or plant products protection by harmful organisms, measures have been taken by EU countries in order to prevent their introduction and establishment into the EU, and also limit their expansion in case they do enter. Such a case is Bursaphelenchus xylophilus (Parasitaphelenchidae, Nematoda), already recorded in Portugal and Spain. So, Member States should take all the appropriate steps in order to monitor and confine if necessary susceptible plants and/or plant products. Such measures include annual surveys even in countries where pine wilt disease does not occur yet. Therefore, national survey programs are widely established, sampling and examining samples from pine trees showing suspicious symptoms that could potentially be attributed to B. xylophilus. In this direction, such a network has also been established in Greece collecting and examining wood samples nationwide. In total, 123 wood samples were collected from conifer trees of Northern and Central Greece. Though B. xylophilus was absent from all samples examined, four other Bursaphelenchus species were identified. In addition, other nematode taxa were also recorded, including several phytophagous, microbivorous as well as predatory nematode species. This highlights the fact that besides preventing the introduction of B. xylophilus in Greece, national survey programs can significantly contribute to and enhance our knowledge of the indigenous nematode species.

Insights into the functional expansion of the astacin peptidase family in parasitic helminths

Helminths secrete a plethora of proteins involved in parasitism-related processes such as tissue penetration, migration, feeding and immunoregulation. Astacins, a family of zinc metalloproteases belonging to the peptidase family M12, are one of the most abundantly represented protein families in the secretomes of helminths. Despite their involvement in virulence, very few studies have addressed the role of this loosely defined protein group in parasitic helminths. Herein, we have analysed the predicted proteomes from 154 helminth species and confirmed the expansion of the astacin family in several nematode taxa. The astacin domain associated with up to 110 other domains into 145 unique domain architectures, where CUB and ShK constitute the principal and nearly independent bi-domain frameworks. The presence of co-existing domains suggests promiscuous adaptable functions to several roles. These activities could be related either to substrate specificity or to higher-order functions, such as anti-angiogenesis and immunomodulation, where the astacin domain would play an accessory role. Furthermore, some phylogenetically restricted mutations in the astacin domain affected residues located at the active cleft and binding sub-pockets, suggesting adaptation to different substrate specificities. Altogether, these findings suggest the astacin domain is a highly adaptable module that fulfils multiple proteolytic needs of the parasitic lifestyle. This study contributes to the understanding of helminth-secreted astacins and, ultimately, provides the foundation to guide future investigations about the role of this diverse family of proteins in host–parasite interactions.

Diversity and distribution of plant-parasitic nematodes associated with watermelon, in northwest Morocco

Watermelon (Citrullus lanatus) fields in northwest Morocco’s Molay Bousselham region were surveyed to study the distribution and occurrence of plant-parasitic nematodes. Eighteen nematode taxa were identified in soil and root samples collected from 24 watermelon plots. The most common plant-parasitic nematodes (PPN) identified were Meloidogyne (M. javanica, M. incognita, M. arenaria and M. hapla), Pratylenchus (P. penetrans, P. thornei, and P. fallax), Tylenchus, Helicotylenchus, Xiphinema and Ditylenchus genera. The diversity patterns of PPN were thoroughly assessed via calculating diversity indices. High species richness was recorded while significant differences were observed between the main locations based on the Shannon–Wiener index (H’) and the Evenness (J). This description of PPN assemblages associated with watermelon fields in northwest Morocco provides fundamental information to design suitable nematode management strategies to reduce yield loss and benefit our food security.

Soil Nematode identification service and training in the new normal

Nematodes constitute one of the key components of soil ecosystems, and further studies are needed to explore the roles of each nematode taxon in soil ecosystems. Nematode communities can serve as bioindicator of soil health. However, the two points necessitate accurate identification of existing nematode taxa which in Indonesia is challenging due to the insufficient skill of workers and lack of identification service. The present study was aimed to explore the prospect of online nematode identification training and service as a solution to the above problem. A video conference with 38 participants was held during which still and video images of nematodes examined under a microscope were shared. The results showed that most participants reported clear images with minimum delay, although a smaller percentage had problems related to unstable internet connection. Therefore, the present study suggested the possibility of online nematode identification training and service. In this paper some procedures and setups are proposed for implementing such services, emphasizing on online activities during New Normal and beyond. Fully online or blended deliveries are proposed with increasing nematode handling skill development but also increasing need of access to laboratory facilities. The blended program is extensible to the post-pandemic state or new normal schemes of such activities have been proposed. The present paper also argues that Indonesia needs to build center(s) of nematode collection employing specialist taxonomists who can identify nematodes and are competent in providing identification services.

Molecular phylogenetic relationships of Metastrongylus nematodes with emphasis on specimens from domestic pigs in Vietnam.

Lungworms of the genus Metastrongylus are parasitic nematodes in the respiratory tract of swine. Although they infect both wild boars and domestic pigs, studies on Metastrongylus infections in wild boars in Europe, the Americas and Africa are numerous, while those in domestic pigs are few. There are several studies analysing the molecular phylogenetic relationships of few individual Metastrongylus species with other nematode taxa, but there are no studies on the phylogenetic relationships of species within the genus Metastrongylus. In Southeast Asia, reports on swine lungworms are extremely scarce and do not include any nucleotide sequence data. Therefore, the aim of the present study is to survey Metastrongylus infection in domestic pigs raised in Dien Bien Province, Northern Vietnam, and to analyse the molecular phylogenetic relationships of Metastrongylus species. Based on morphological and molecular data, we identified two species: Metastrongylus apri and Metastrongylus pudendotectus. The prevalence of the former species was found to be significantly higher than the latter one (24.1% vs. 2.3%). We observed pigs exhibiting a coinfection with the two lungworm species or a single infection with only M. apri. However, we did not observe any pigs being infected with just M. pudendotectus. Vietnamese Metastrongylus specimens showed slight morphological and molecular differences compared to those from other countries. The molecular analyses revealed a close genetic relationship between M. apri and Metastrongylus salmi, while both these species were far distant from M. pudendotectus. The present study highlights the needs for further studies to clarify the morphological features and ecological and phylogenetic relationships of Metastrongylus species at the global scale.

Experimental selection of Marylynnia puncticaudata (Cyatholaimidae, Nematoda) and effects of organic enrichment.

Meiobenthic nematodes are well-known bioindicators in aquatic ecosystem health programs. However, the explored taxa are still limited and practically devoted to the community level. The present study provided a new method of experimental isolation of a species from a pristine nematofauna. In our method, the nematofauna faced two types of sediment, namely, the leaves of Posidonia oceanica and shells of Mytilus galloprovincialis, under controlled laboratory conditions, and several changes in species composition occurred through gradual selection of the most adaptable nematode taxa to the new environments, which were previously defaunated. We used the selected nematode taxon, Marylynnia puncticaudata (Cyatholaimidae), to examine the possible effects of organic enrichment, and the results clearly showed that the body size of the nematodes significantly increased and they became fat when after enrichment using a powder made of marine agar (1200mgl-1) and cuticles of Crangon crangon (900mgl-1), but their relative body growth showed no discernible changes.