Nematode Taxa Research Articles

High-throughput sequencing of nematode communities from total soil DNA extractions

BackgroundNematodes are extremely diverse and numbers of species are predicted to be more than a million. Studies on nematode diversity are difficult and laborious using classical methods and therefore high-throughput sequencing is an attractive alternative. Primers that have been used in previous sequence-based studies are not nematode specific but also amplify other groups of organisms such as fungi and plantae, and thus require a nematode enrichment step that may introduce biases.ResultsIn this study an amplification strategy which selectively amplifies a fragment of the SSU from nematodes without the need for enrichment was developed. Using this strategy on DNA templates from a set of 22 agricultural soils, we obtained 64.4% sequences of nematode origin in total, whereas the remaining sequences were almost entirely from other metazoans. The nematode sequences were derived from a broad taxonomic range and most sequences were from nematode taxa that have previously been found to be abundant in soil such as Tylenchida, Rhabditida, Dorylaimida, Triplonchida and Araeolaimida.ConclusionsOur amplification and sequencing strategy for assessing nematode diversity was able to collect a broad diversity without prior nematode enrichment and thus the method will be highly valuable in ecological studies of nematodes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12898-014-0034-4) contains supplementary material, which is available to authorized users.

Are juveniles of the enigmatic deep-sea nematode Rhaptothyreus (Rhaptothyreida: Rhaptothyreidae) parasitic?

Rhaptothyreus is arguably the most enigmatic nematode taxon due to a combination of unusual morphological features (e.g., large feather-like amphids, vestigial mouth, trophosome, single spicule), unclear phylogenetic relationships (possible affinities with the Enoplida, Mermithida and Benthimermithida) and a distribution restricted to the deep sea. Here I provide the first record of the genus in the Western Pacific Ocean and describe new morphological features of a moulting juvenile. This specimen is characterised by features that differ markedly from the adults, the most prominent being the absence of cephalic sensillae and amphids and presence of a stylet-like structure in the buccal cavity. Similar contrasts in morphology are found between adults and juveniles of the order Benthimermithida, which is characterised by free-living adults and parasitic juveniles. Other morphological (large body size, presence of trophosome) and distributional characteristics (predominantly deep-sea distribution, juveniles rare/absent in sediments) are also common to both groups. Published records show that Rhaptothyreus is commonly found in oligotrophic environments (e.g., abyssal plain) where organisms bearing symbiotic bacteria are not typically found, which makes the presence of endosymbiotic bacteria inside the trophosome unlikely. These observations are consistent with the existence of a parasitic juvenile life stage in Rhaptothyreus.

Unraveling free-living marine nematode community structure from a biodiversity-rich tropical coastal setting based on molecular approaches

Free-living marine nematodes are ubiquitous in marine benthic ecosystems and play a key role in ecosystem processes. However limited information exists to date on free-living marine nematode community structure and diversity from biodiversity-rich tropical coastal environments. In this study, molecular tools based on the amplification, clone library generation and sequencing of the nematode 18S rRNA marker were employed to study free-living marine nematode community structure from two sites located in the Central West coast of India. Results based on the sequencing of 110 clones showed dominance of Enoplid and Chromadorid-like nematode 18S rRNA sequences, in addition to Monhysterid and Desmodorid-like sequences across study sites. Ptycholaimellus and Tripyloides-like nematode 18S rRNA sequences were abundant in clone libraries from the study sites. Based on morpho-taxonomic analysis, nineteen free-living marine nematode taxa were identified from both the study sites. Many of the identified taxa such as Ptycholaimellus sp., Tripyloides sp., and Terschellingia longicaudata were also detected in clone library sequences indicating that there was congruency between molecular and morphological approaches. At the same time, a sizeable number of sequences showed identity scores of only 87–96 % with published marine nematode 18S rRNA sequences available in databases indicating that the study sites harbour unreported species of marine nematodes. This finding was also supported by the presence of novel sub-clades based on phylogeny and OTU analysis where a sizeable number of singletons were detected. This study highlights the importance of including 18S rRNA marine nematode sequences in published nucleotide databases targeted specifically from biodiversity-rich tropical coastal regions so that it can ultimately improve our understanding of marine nematode community structure and diversity patterns, population genetics and nematode systematics.

Elevated temperature has stronger effects on the soil food web of a flooded paddy than does CO2

Paddy fields are valuable wetlands for both food production and conserving biodiversity. However, while global warming poses a major threat to biodiversity, evaluations on its impacts within flooded paddy fields have been very limited. Soil nematodes present an ideal model organism for this issue because they are dominant and diverse native animals within this system; moreover, they support aboveground biodiversity by serving as a food source for larger animals, and they are influential rice pests that affect our food output from paddy fields. We examined the effects of a predicted elevation in CO2 and temperature over the next 50 years on the dynamics of dominant nematode taxa and their food source, i.e., rice roots and microbes in a flooded paddy field equipped with a FACE + heater system. We hypothesized that, 1) the impact of an elevation in CO2 concentration (+200 ppm) would be dependent on the trophic level of the organisms (it would be greater on rice roots compared to microbes or nematodes), although the impact can be consistently detected on each of rice roots, microbes and nematodes, 2) the impact of an elevation in temperature (+2 °C) could affect each organism simultaneously but would be different among organisms due to possible differences in thermal optima. Within our 2-year study, only our temperature hypothesis was supported, i.e., that an elevation in temperature increased rice root biomass, if any, but consistently decreased microbial biomass and retarded reproduction in the nematode taxa, which are potential rice pests. Elevated CO2 increased rice root biomass, but did not consistently affect microbial biomass or reproduction of any type of nematode taxon. We infer that the small and inconsistent impact of elevated CO2 on both microbes and nematodes could be attributable to an insensitive growth response to an elevation in CO2 concentration by the rice variety we examined.

Developmental Plasticity, Straight from the Worm’s Mouth

Developmental plasticity in response to environmental conditions (polyphenism) plays an important role in evolutionary theory. Analyzing the nematode taxon Pristionchus, Ragsdale et al. demonstrate that a single gene underlies the nematode's ability to develop distinct mouth forms in response to environmental changes.

Release of isothiocyanates does not explain the effects of biofumigation with Indian mustard cultivars on nematode assemblages

While soil biota play an essential role in ecosystem services, the plant-pathogenic fraction may have a large, negative economic impact on food and feed production. For decades, the use of so-called fumigants (=general biocides) has been a common practice for controlling soil pathogens, including plant-parasitic nematodes. Due to their adverse environmental impact, many fumigants have been banned. Biofumigation – a possible alternative – encompasses the incorporation of mulched Brassicaceous debris into topsoil, and its mode of action is based on the conversion of glucosinolates (GSLs) into nematicidal isothiocyanates (ITCs). Contrary to the relatively well-characterized impact of biofumigation on plant-parasitic nematodes, the effects on the non-parasitic part of the community is largely unknown. We investigated the field effects of biofumigation with four Indian mustard (Brassica juncea) cultivars on both plant-parasitic and free-living nematodes. Prior to biofumigation, GSL contents of B. juncea were determined, and from this, the expected ITC concentrations in the topsoil were calculated. As positive controls, two concentrations of 2-propenyl ITC – corresponding to the average expected ITC concentration, and two times the concentration predicted for the highest producer – were directly applied to wheat (=non Brassica control) plots. Although biofumigation resulted in significant changes for most nematode taxa, none of these shifts could be attributed to the release of ITCs. Moreover, none of the two directly applied ITC concentrations resulted in effects on the nematode community distinct from the water control. We therefore conclude that the observed changes in nematode assemblages are related to intense mechanical disturbance, green manure and the absence of host plants for obligatory plant-parasitic nematodes, rather than to the release of ITCs.

Diatom feeding across trophic guilds in tidal flat nematodes, and the importance of diatom cell size

We examine the capacity of nematodes from three feeding types (deposit feeder, epistrate feeder, predator) to utilize microphytobenthos (MPB), and assess whether diatom cell size and consumer body size are important drivers of their feeding. We analyzed natural stable isotope ratios of carbon and nitrogen in abundant nematode genera and a variety of carbon sources at an estuarine intertidal flat. All nematodes had δ13C indicating that MPB is their major carbon source. δ15N, however, demonstrated that only one deposit and one epistrate feeder genus obtained most of their carbon from direct grazing on MPB, whereas other deposit feeders and predators obtained at least part of their carbon by predation on MPB grazers. We then performed a microcosm experiment in which equal cell numbers of each of three differently sized strains of the pennate diatom Seminavis were offered as food to four, one and one genera of deposit feeders, epistrate feeders and predators, respectively. Previous studies have shown that all but the epistrate feeder ingest whole diatoms, whereas the epistrate feeder pierces cells and sucks out their contents. Most genera showed markedly higher carbon absorption from medium and large cells than from small ones. When considering the number of cells consumed, however, none of the nematodes which ingest whole cells exhibited a clear preference for any specific diatom size. The epistrate feeder was the smallest nematode taxon considered here, yet it showed a marked preference for large cells. These results highlight that the feeding mechanism is much more important than consumer size as a driver of particle size selection in nematodes grazing MPB.

Quantifying non-indigenous species in accumulated ballast slurry residuals (swish) arriving at Vancouver, British Columbia

Ballast tank “swish” samples were collected from ships following their arrival at Vancouver (British Columbia, Canada) after undergoing either a trans-oceanic or a Pacific-coastal voyage. The ballast swish consisted of a residual slurry mixture of sediment and water that remained trapped in ballast tanks following water discharge at port. The ballast tanks of 27 ships were sampled and ballast swish was found on 19 of the 27 ships. These ships were categorized according to ballast water management type: (1) Trans-oceanic=7 trans-oceanic ships undergoing ballast water exchange (BWE)>200nm from shore; (2) Coastal-exchange=7 Pacific-coastal ships traveling from ports south of Cape Blanco, Oregon undergoing coastal exchange>50nm from shore south of Cape Blanco; and (3) Coastal-no-exchange=5 Pacific-coastal ships traveling from ports north of Cape Blanco, Oregon, without undergoing BWE. Invertebrate abundance and taxa richness were directly correlated with ballast-swish turbidity suggesting that highly-productive coastal source waters and ballast tank retention processes contributed to this trend. In turn, invertebrate taxa diversity increased with increasing invertebrate abundance. A Principal Component Analysis of the trans-oceanic data revealed that length of voyage showed a strong inverse relationship with invertebrate abundance for this category. Within the coastal-exchange voyage category, voyage length and ballast water age tended to be of the same magnitude and were directly correlated with both crustacean and nematode taxa. Finally, the coastal-no-exchange PCA results revealed that voyage length and salinity were inversely related due to the high number of river ports located at the southern border of the regulatory BWE exemption zone. Coastal voyages not undergoing BWE and undertaking a direct river-to-river route should be considered risky for the introduction of non-indigenous species, if the source waters contain potentially invasive species. Non-indigenous species were found in all 3 vector pathways, with the highest number of propagules and survivability potential arising from the coastal-no-exchange zone. Ballast “swish” may act as a repository for ballast water organisms within ballast water tanks and may be retained in the tanks over several discharge cycles.

Unravelling the environmental drivers of deep-sea nematode biodiversity and its relation with carbon mineralisation along a longitudinal primary productivity gradient

Abstract. Alongside a primary productivity gradient between the Galicia Bank region in the Northeast Atlantic and the more oligotrophic eastern Mediterranean Basin, we investigated the bathymetric (1200–3000 m) and longitudinal variation in several measures for nematode taxon (Shannon–Wiener genus diversity, expected genus richness and generic evenness) and functional diversity (trophic diversity, diversity of life history strategies, biomass diversity and phylogenetic diversity). Our goals were to establish the form of the relation between diversity and productivity (measured as seafloor particulate organic carbon or POC flux), and to verify the positive and negative effect of sediment particle size diversity (SED) and the seasonality in POC flux (SVI), respectively, on diversity, as observed for other oceanographic regions and taxa. In addition, we hypothesised that higher taxon diversity is associated with higher functional diversity, which in turn stimulates nematode carbon mineralisation rates (determined from biomass-dependent respiration estimates). Taxon diversity related positively to seafloor POC flux. Phylogenetic diversity (measured as average taxonomic distinctness) was affected negatively by the magnitude and variability in POC flux, and positively by SED. The latter also showed an inverse relation with trophic diversity. Accounting for differences in total biomass between samples, we observed a positive linear relation between taxon diversity and carbon mineralisation in nematode communities. We could, however, not identify the potential mechanism through which taxon diversity may promote this ecosystem function since none of the functional diversity indices related to both diversity and nematode respiration. The present results suggest potential effects of climate change on deep-sea ecosystem functioning, but further also emphasise the need for a better understanding of nematode functions and their response to evolutionary processes.

Biology, ecology and ultrastructure of Ascobotryozyma and Botryozyma, unique commensal nematode-associated yeasts

Ascobotryozyma (anamorph Botryozyma) is an ascomycetous yeast genus characterized by its unusual morphology and ability to attach to free-living nematodes in the genus Panagrellus. Other than species descriptions for four taxa little is known about these yeasts. Investigations were carried out to determine the ecological relationship and specificity with nematodes in addition to examining basic cell structure, thallus development and sexual reproduction. Based on previous examinations of the yeast and nematode it was hypothesized the fungus did not parasitize the nematode but instead remained attached to nematodes for dispersal. Electron micrographs supported our hypotheses and revealed a specialized cell wall and mucilage that aid in attachment to the nematode cuticle. Tests to determine the ability of Ascobotryozyma and Botryozyma to attach to different nematode taxa revealed that attachment varies across taxonomic groups. Examinations of thallus cells, thallus growth, cell fusion and ascosporogenesis are presented. This study provides insight into an otherwise cryptic yeast genus.

Plant parasitic nematode relative abundance and population suppression under Chromolaena odorata (Asteraceae) fallow

An experimental investigation into the suppressive potential of the shrub Chromolaena odorata (L.) (Asteraceae) (also known as “Siam Weed” or “Jack-in-the-Bush”) fallow to the management of plant parasitic nematodes was undertaken between April 2008 and April 2010. The experiment involved comparing nematode population densities in: (i) pure planted fallow of C. odorata, (ii) a mixture of C. odorata with other weeds, and (iii) natural re-growth of weeds from the seed bank in the soil in the field with C. odorata excluded. The population densities of several nematode species were determined at the outset, and then at 6-month intervals for 24 months. The nematode taxa identified as being present prior to fallowing were Meloidogyne spp. (Heteroderidae), Pratylenchus spp. (Pratylenchidae), Helicotylenchus spp., Rotylenchulus spp. (Hoplolaimidae); Rhabditids (Rhabditidae) and Dorylaimus spp. (Dorylaimoidea). Chromolaena odorata fallow significantly reduced the population densities of Meloidogyne spp., Pratylenchus spp., and Helicotylenchus spp. after 2 years of fallow, by 77.2%, 75.3% and 81.3% respectively. Under natural re-growth, reduction in populations of Meloidogyne spp., Pratylenchus spp., and Helicotylenchus spp. ranged between 0.12% and 17%. Densities of non-parasitic species (Rhabditids and Dorylaimus spp.) significantly increased under both C. odorata + natural re-growth fallow. However, a 16% increase in the population density of Rotylenchulus spp. was observed under C. odorata fallow in contrast to a significant (54.1%) reduction observed under the natural re-growth fallow. Bush fallow with C. odorata may become part of an integrated management practice in the management of nematode pests in crop production by indigenous farmers in south-western Nigeria.

Effect of forest and field habitat features on abundance of genera in nematode assemblages

Abundances of nematode genera were examined in several forest and field habitats located in close proximity in Florida, USA. Effects of selected habitat features were also evaluated, such as tree type, management and presence of litter, grasses or invasive species. Of 37 common taxa evaluated, ten were more abundant in forest and ten in field habitats. Several genera includingAcrobeloides,AphelenchoidesandMesocriconemawere common in all habitats. Light management, consisting of mowing of grasses, negatively affected 19 taxa. More genera appeared adapted to closed forest over open forest, and most of these were more common in plots with oak trees or oak litter than in plots with pine. Numbers ofParatylenchus,PlectusandXiphinemawere further increased by the presence of herbaceous plants on the forest floor. When invasive elephantgrass (Pennisetum purpureum) was included in plots with other grasses, numbers of eight genera that typically were common in grass plots were further increased.Alaimus,CervidellusandWilsonemawere negatively affected by the invasive elephantgrass. Most of the nine genera in guild Ba2 were more abundant in either forest (Acrobeles,Cervidellus,Plectus,Wilsonema) or grass (Eucephalobus,Zeldia) habitats, whileAcrobeloideswas common and two genera were rare in all habitats. The effects of habitats and habitat features on many different nematode taxa add to our growing knowledge of the ecological habits of free-living nematodes.

The Response of Soil Nematode Community to Nitrogen, Water, and Grazing History in the Inner Mongolian Steppe, China

Nutrient nitrogen and water availability are co-limiting factors for grassland productivity in the Inner Mongolian steppe. The objective of this study was to evaluate the interactive effects of water and nitrogen (N) addition on soil abiotic factors and soil nematode community composition. A 3-year experiment with addition of water (with and without irrigation simulating wet year precipitation) and nitrogen (0, 25, and 50 kg N ha−1) was conducted at two sites in Inner Mongolia with histories of heavy grazing (HG) and moderate grazing (MG). The results showed that HG had several lower nematode ecological indicators; namely, the Simpson index (P < 0.01), maturity index (MI, including free-living nematodes), and plant parasite index (PPI, including plant-parasitic nematodes). In addition, HG had a lower proportion of omnivores–predators and higher proportion of bacterivores (P < 0.01), with reduced soil moisture, total nitrogen and total carbon (C), and increased C/N ratio. A relatively low addition of N did not influence soil total carbon and total nitrogen and had only a slight effect on the composition and structure of the soil nematode community. Water addition increased the proportion of plant parasites, reduced the proportion of bacterivores and omnivores–predators and increased the soil total carbon and total nitrogen. Redundancy analysis revealed that grazing history alone explained more variation in nematode taxon composition (17.4%, P < 0.01) and PPI (35.6%, P < 0.01) and MI (17.5%, P < 0.01) and Simpson index (10.5%, P < 0.01). Water addition explained more variation in the nematode feeding group (24.4%, P < 0.01), total nematodes (7.9%, P < 0.01) and PPI (78.7%, P < 0.01). Nitrogen addition explained variation in the nematode taxon composition (6.2%, P < 0.01). These results suggested that HG caused soil degradation, and water addition facilitated plant parasites and enhanced soil properties, whereas application of small amounts of nitrogen to N-limited semiarid grasslands did not induce clear changes in this system in the short term.

Population dynamics of Meloidogyne incognita on black pepper plants in two agro-ecological regions in Vietnam

The objective of our study was to examine the effect of local environmental conditions, especially air temperature and rainfall, in two agro-ecological regions in Vietnam on the population dynamics of Meloidogyne incognita on black pepper plants and on percentage root galling. The two study sites were situated in Cam Lo, Quang Tri province (North Central Coast) and Buon Ma Thuot, Dac Lac province (Central Highlands). At the study sites, 13 plant-parasitic nematode taxa belonging to 12 genera were identified. Ten of these taxa were present in both study sites. Helicotylenchus certus, Hemicriconemoides cocophilus and Pratylenchus coffeae were only found in Buon Ma Thuot. Based on nematode population densities, M. incognita was the most abundant taxon present. Rainfall and air temperature differed significantly between the two study sites. The most important climatic difference was rainfall: in Buon Ma Thuot, the rainy season lasted 2 months longer and the monthly rainfall during the rainy season was much higher compared to Cam Lo. Although this difference resulted in some differences in the population dynamics of M. incognita in the soil and roots of the black pepper variety Vinh Linh, the highest root population densities were observed in both study sites during the first half of the dry season. In Cam Lo, the highest percentage root galling was observed during the first half of the dry season. In Buon Ma Thuot, the highest percentage root galling was observed towards the end of the rainy season. Estimating the population densities if M. incognita to decide on the application of a management strategy should be done during the first half of the dry season.

Morphological and Molecular Diagnosis of Anisakid Nematode Larvae from Cutlassfish (Trichiurus lepturus) off the Coast of Rio de Janeiro, Brazil

Anisakid nematode larvae from Trichiurus lepturus off coast of Rio de Janeiro were studied using light, laser confocal and scanning electron microscopy, in addition to a molecular approach. Mitochondrial cytochrome c-oxidase subunit 2 (mtDNA cox-2), partial 28S (LSU) and internal transcribed spacers (ITS-1, 5.8S, ITS-2) of ribosomal DNA were amplified using the polymerase chain reaction and sequenced to evaluate the phylogenetic relationships between the nematode taxa. The morphological and genetic profiles confirmed that, of the 1,030 larvae collected from the 64 fish examined, 398 were analysed, of which 361 were Hysterothylacium sp. and 37 were Anisakis typica. Larvae of Hysterothylacium sp. were not identified to the species level due to the absence of similar sequences for adult parasites; however, the ITS sequence clustered in the phylogenetic tree with sequences of H. deardorffoverstreetorum, whereas an mtDNA cox-2 and LSU concatenated phylogenetic analysis demonstrated the presence of two clades, both of them under the same name as the larval H. deardorffoverstreetorum. Data on the occurrence of parasites during the winter and summer months were compared using the t-test. The greatest prevalence and intensity of infection were recorded for larval Hysterothylacium, with a prevalence of 51.56% and an intensity of up to 55 parasites per fish. The larval Anisakis exhibit a higher abundance and intensity of infection in the winter months, and those of Hysterothylacium during the summer. However, the t-test indicated no significant differences between the abundance and intensity of infection recorded during the months of collection for either of these larval nematodes. All sequences generated in this study were deposited in GenBank.

Ecology of the dorylaimid omnivore genera Aporcelaimellus, Eudorylaimus and Mesodorylaimus

Eudorylaimus, Aporcelaimellus and Mesodorylaimus are dominant members of the omnivorous nematode fauna in Florida, USA. Ecological studies that included numerical data on these genera were reviewed to determine key aspects of their ecology and behaviour. These three genera were also the dominant omnivores in many parts of Europe and often occurred together. Multiple species within genera may be present in samples as well. Although results varied with habitat, these omnivores were present in nearly all stages of succession but often reached their greatest numbers in later stages of succession such as old-growth forests. They also showed remarkable adaptation to extreme environments, including Antarctic habitats, dune sands and temperate sites without vegetation. They were found in a variety of soil types but limited by soil pH &lt; 4.0. Compared with other nematode taxa, they were among the genera most sensitive to moisture levels in sandy soils and to pollution by heavy metals. Some reports also indicated adverse impacts from inorganic fertilisers and other agrichemicals. Much remains unknown about the ecology of these common nematodes, which are widely distributed in soil ecosystems.

Nematode biodiversity in a semi-arid pasture under different grazing regimes

The study was conducted to explore the influence of over-grazing and ungrazing on nematode biodiversity in a semi-arid region pasture, in AdA±yaman, Turkey, in 2008. Soil samples were taken in mid spring from a pasture that was previously divided into two sites, one is protected by fencing and the second is open to grazing, freely. Nematodes were extracted and allocated to trophic groups and both sites were compared regarding their abundance and diversity. A total of 19 nematode taxa were found in the study area. Plant parasitic nematodes 9 genera, bacterivores 6 genera, fungivores 3 genera, and predators and omnivores were represented by 1 order. Rotylenchus, Tylenchus, Pratylenchus and Paratylenchus were the abundant genera in plant parasitic group; Acrobeloides and Cervidellus were the abundant genera in bacterivore group; Aphelenchoides and Ditylenchus were the abundant genera in fungivore group. Nematode diversity and abundance were greatly affected by the vegetation status depending on the grazing pattern. Diversity and abundance parameters were lower under the over-grazed site. The study suggested that there was a tight connection between vegetation cover of the ecosystem and soil biodiversity beneath it. Key words: Nematode biodiversity, pasture, trophic groups, grazing.

Community patterns of soil bacteria and nematodes in relation to geographic distance

Ecosystems consist of aboveground and belowground subsystems and the structure of their communities is known to change with distance. However, most of this knowledge originates from visible, aboveground components, whereas relatively little is known about how soil community structure varies with distance and if this variability depends on the group of organisms considered. In the present study, we analyzed 30 grasslands from three neighboring chalk hill ridges in southern UK to determine the effect of geographic distance (1–198 km) on the similarity of bacterial communities and of nematode communities in the soil. We found that for both groups, community similarity decayed with distance and that this spatial pattern was not related to changes either in plant community composition or soil chemistry. Site history may have contributed to the observed pattern in the case of nematodes, since the distance effect depended on the presence of different nematode taxa at one of the hill ridges. On the other hand, site-related differences in bacterial community composition alone could not explain the spatial turnover, suggesting that other factors, such as biotic gradients and local dispersal processes that we did not include in our analysis, may be involved in the observed pattern. We conclude that, independently of the variety of causal factors that may be involved, the decay in similarity with geographic distance is a characteristic feature of both communities of soil bacteria and nematodes.

Does meatiness of pigs depend on the level of gastro-intestinal parasites infection?

The aim of the present paper was to determine an influence of the presence and a level of intestine parasites infection on the quality of pork carcass expressed by the content of meat in carcass (meatiness) in pigs. The experimental part of the study was conducted on pigs farm produced in a closed cycle. The population in the study included 120 fattening pigs maintained in two keeping systems: group I – 60 individuals kept on slatted floor, and group II – 60 individuals kept on deep litter. All the experimental animals were treated in the same manner. The analysed fatteners were slaughtered in Meat Processing Plant when their body mass reached 110 kg, and the post-slaughter assessment was conducted according to the EUROP classification of pigs carcass using the Ultra-Fom 300 device. The study concerning the internal parasites were conducted basing on coproscopic quantitative McMaster method. As a results, the eggs of three nematode taxa were isolated and identified: Oesophagostomum spp., Ascaris suum and Strongyloides ransomi. Overall prevalence of infection of fatteners kept on litter was lower (25% ± 11.2) as compared to those kept on slatted floor (38.3% ± 12.6), however the differences were not statistically significant ( χ 2 = 2.465; df = 1; P = 0.116). The mean value of meatiness for pigs free from parasites was 53.68, while in the case of infected pigs the meatiness was statistically lower and was 52.12 ( t = 2.35; P = 0.02). The analysed pigs were classified into three categories and conducted analysis of an influence of parasites on meatiness demonstrate the relationship that is statistically significant. The analysis of correlation between meatiness and an average number of helminth eggs also demonstrated the negative, statistically significant, relationship ( F = 5.52; P = 0.020), i.e. in fatteners with higher EPG value the meatiness was lower.

Cutidiplogaster manati n. gen., n. sp. (Nematoda: Diplogastridae) from skin lesions of a West Indian manatee (Sirenia) from the Okinawa Churaumi Aquarium

AbstractA new species of the nematode taxon Diplogastridae is described on morphology and additional molecular data. The new species cannot be grouped in any of the currently accepted diplogastrid genera. Therefore, we introduce the new genus Cutidiplogaster n. gen. along with the description of our new species Cutidiplogaster manati n. gen., n. sp. Cutidiplogaster manati n. gen., n. sp. was isolated from skin lesions of manatees, Trichechus manatus manatus, kept in Okinawa Churaumi Aquarium, Japan. The specimens were found anchored with their extraordinarily long tails to the small, thick epidermal bumps within thread algae that form part of the epizoic community on the manatee skin. Cutidiplogaster manati n. gen., n. sp. is characterised by the tube-shaped and finely annulated postdental part of the stegostom that makes it distinct from all other Diplogastridae so far known, and the coiled long tail that makes it unique in comparison with all known diplogastrids. On the basis of detail in stoma morphology in C. manati n. gen., n. sp., we discuss implications in homologising diplogastrid mouthparts and their evolution.