Charge Yield at Low Electric Fields: Considerations for Bipolar Integrated Circuits

Science.gov (United States)

Johnston, A. H.; Swimm, R. T.; Thorbourn, D. O.

2013-01-01

A significant reduction in total dose damage is observed when bipolar integrated circuits are irradiated at low temperature. This can be partially explained by the Onsager theory of recombination, which predicts a strong temperature dependence for charge yield under low-field conditions. Reduced damage occurs for biased as well as unbiased devices because the weak fringing field in thick bipolar oxides only affects charge yield near the Si/SiO2 interface, a relatively small fraction of the total oxide thickness. Lowering the temperature of bipolar ICs - either continuously, or for time periods when they are exposed to high radiation levels - provides an additional degree of freedom to improve total dose performance of bipolar circuits, particularly in space applications.

Free-living Marine Nematodes. Part 1 British Enoplids

African Journals Online (AJOL)

This is the first of three volumes dealing with the most abundant group of animals on the sea-bed and sea-shore, the free-living marine nematodes, and is devoted to those marine nematodes belonging to the subclass Enoplia. Separate volumes will deal with the orders Chromadorida and. Monhysterida. To most marine ...

Laboratory experiments on the infaunal activity of intertidal nematodes

NARCIS (Netherlands)

Steyaert, M.; Moodley, L.; Vanaverbeke, J.; Vandewiele, S.L.; Vincx, M.

2005-01-01

The impact of oxygen on the vertical distribution of an intertidal nematode community was investigated in a manipulation experiment with sediments collected from the Oosterschelde (The Netherlands). The vertical distribution of nematodes was examined in response to sediment inversion in perspex

Foraging behavior and virulence of some entomopathogenic nematodes

Directory of Open Access Journals (Sweden)

Manana A. Lortkipanidze

2016-06-01

Full Text Available At present the biological control as a pest control technology is becoming more desirable. Biological formulations on basis of entomopathogenic nematodes are one of the effective means for the protection of agricultural and forest plants from harmful insects. Nowadays, the use of entomopathogenic nematodes as biological control agents is a key component in IPM system. The foraging strategies of entomopathogenic nematodes (EPNs vary between species. This variation is consistent with use of different foraging strategies between ambush, cruise and intermediate to find their host insects. In order to ambush prey, some species of EPNs nictate, or raise their bodies of the soil surface so they are better poised to attach passing insects, other species adopt a cruising strategy and rarely nictate. Some species adopt an intermediate strategy between ambush and cruise. We compared in laboratory the foraging strategies of the entomopathogenic nematode species: Steinernema carpocapsae, Heterorhabditis bacteriophora and the recently described species Steinernema tbilisiensis and assessed their virulence against mealworm beetle, Tenebrio molitor L. (Coleoptera: Tenebrionidae. The tests showed that S. tbilisiensis adopts both foraging strategies.

Analysis of Gene expression in soybean (Glycine max roots in response to the root knot nematode Meloidogyne incognita using microarrays and KEGG pathways

Directory of Open Access Journals (Sweden)

Gamal El-Din Abd El Kader Y

2011-05-01

Full Text Available Abstract Background Root-knot nematodes are sedentary endoparasites that can infect more than 3000 plant species. Root-knot nematodes cause an estimated $100 billion annual loss worldwide. For successful establishment of the root-knot nematode in its host plant, it causes dramatic morphological and physiological changes in plant cells. The expression of some plant genes is altered by the nematode as it establishes its feeding site. Results We examined the expression of soybean (Glycine max genes in galls formed in roots by the root-knot nematode, Meloidogyne incognita, 12 days and 10 weeks after infection to understand the effects of infection of roots by M. incognita. Gene expression was monitored using the Affymetrix Soybean GeneChip containing 37,500 G. max probe sets. Gene expression patterns were integrated with biochemical pathways from the Kyoto Encyclopedia of Genes and Genomes using PAICE software. Genes encoding enzymes involved in carbohydrate and cell wall metabolism, cell cycle control and plant defense were altered. Conclusions A number of different soybean genes were identified that were differentially expressed which provided insights into the interaction between M. incognita and soybean and into the formation and maintenance of giant cells. Some of these genes may be candidates for broadening plants resistance to root-knot nematode through over-expression or silencing and require further examination.

Nematode community structure as a bioindicator in environmental monitoring

NARCIS (Netherlands)

Bongers, T.; Ferris, H.

1999-01-01

Four of every five multicellular animals on the planet are nematodes. They occupy any niche that provides an available source of organic carbon in marine, freshwater and terrestrial environments. Nematodes vary in sensitivity to pollutants and environmental disturbance. Recent development of indices

A rapid, sensitive, and cost-efficient assay to estimate viability of potato cyst nematodes.

Science.gov (United States)

van den Elsen, Sven; Ave, Maaike; Schoenmakers, Niels; Landeweert, Renske; Bakker, Jaap; Helder, Johannes

2012-02-01

Potato cyst nematodes (PCNs) are quarantine organisms, and they belong to the economically most relevant pathogens of potato worldwide. Methodologies to assess the viability of their cysts, which can contain 200 to 500 eggs protected by the hardened cuticle of a dead female, are either time and labor intensive or lack robustness. We present a robust and cost-efficient viability assay based on loss of membrane integrity upon death. This assay uses trehalose, a disaccharide present at a high concentration in the perivitelline fluid of PCN eggs, as a viability marker. Although this assay can detect a single viable egg, the limit of detection for regular field samples was higher, ≈10 viable eggs, due to background signals produced by other soil components. On the basis of 30 nonviable PCN samples from The Netherlands, a threshold level was defined (ΔA(trehalose) = 0.0094) below which the presence of >10 viable eggs is highly unlikely (true for ≈99.7% of the observations). This assay can easily be combined with a subsequent DNA-based species determination. The presence of trehalose is a general phenomenon among cyst nematodes; therefore, this method can probably be used for (for example) soybean, sugar beet, and cereal cyst nematodes as well.

Prevalence of Pasteuria SP. on Renfirom Nematode in a Georgia Cotton Field

Science.gov (United States)

Pasteuria species are bacterial parasites of nematodes and have been associated with suppression of root-knot, sting, and cyst nematode populations. Little is known about the Pasteuria sp. infecting the reniform nematode. While sampling a cotton field study near Cochran, GA, we found Pasteuria spo...

Latitudinal variation in nematode diversity and ecological roles along the Chinese coast.

Science.gov (United States)

Wu, Jihua; Chen, Huili; Zhang, Youzheng

2016-11-01

To test changes in the phylogenetic relatedness, niche breadth, and life-history strategies of nematodes along a latitudinal gradient. Sixteen wetland locations along the Pacific coast of China, from 20°N to 40°N. Linear regression was used to relate nematode phylogenetic relatedness (average taxonomic distinctness (AvTD) and average phylogenetic diversity [AvPD]), life-history group (based on " c - p " colonizer-persister group classification), and dietary specificity (based on guild classification of feeding selectivity) to latitude. Wetland nematode taxonomic diversity (richness and Shannon diversity indices) decreased with increasing latitude along the Chinese coast. Phylogenetic diversity indices (AvTD and AvPD) significantly increased with increasing latitude. This indicates that at lower latitudes, species within the nematode community were more closely related. With increasing latitude, the nematode relative richness and abundance decreased for selective deposit feeders but increased for nonselective deposit feeders. The proportion of general opportunists decreased with increasing latitude, but persisters showed the opposite trend. The annual temperature range and the pH of sediments were more important than vegetation type in structuring nematode communities. Nematode niche breadth was narrower at lower latitudes with respect to dietary specificity. Higher latitudes with a more variable climate favor r over K life-history strategists. Nematode communities at lower latitudes contained more closely related species.

Identification of Virulence Factors in Nematode-Trapping Fungi - Insights from Genomics, Transcriptomics and Proteomics

OpenAIRE

Andersson, Karl-Magnus

2013-01-01

Nematode-trapping fungi are soil-living organisms with the unique ability to capture and infect free-living nematodes. The interest in studying these fungi arises from their potential use as biological control agents for plant- and animal-parasitic nematodes. To enter the parasitic stage, nematode-trapping fungi develop different kinds of trapping structures. In order to understand more about the evolution of parasitism in the nematode-trapping fungi and to identify virulence factors in these...

Glutathione peroxidases of the potato cyst nematode Globodera Rostochiensis

NARCIS (Netherlands)

Jones, J.T.; Reavy, B.; Smant, G.; Prior, A.E.

2004-01-01

We report the cloning and characterisation of full-length DNAs complementary to RNA (cDNAs) encoding two glutathione peroxidases (GpXs) from a plant parasitic nematode, the potato cyst nematode (PCN) Globodera rostochiensis. One protein has a functional signal peptide that targets the protein for

The cyst nematodes Heterodera and Globodera species in Egypt

Science.gov (United States)

Information concerning the occurrence and distribution of the cyst nematodes (Heterodera spp. and Globodera spp.) in Egypt is important to assess their potential to cause economic damage to many crop plants. A nematode survey was conducted in Alexandria, El Behera and Sohag governorates during 2012-...

Glutathione peroxidases of the potato cyst nematode Globodera Rostochiensis.

Science.gov (United States)

Jones, J T; Reavy, B; Smant, G; Prior, A E

2004-01-07

We report the cloning and characterisation of full-length DNAs complementary to RNA (cDNAs) encoding two glutathione peroxidases (GpXs) from a plant parasitic nematode, the potato cyst nematode (PCN) Globodera rostochiensis. One protein has a functional signal peptide that targets the protein for secretion from animal cells while the other is predicted to be intracellular. Both genes are expressed in all parasite stages tested. The mRNA encoding the intracellular GpX is present throughout the nematode second stage juvenile and is particularly abundant in metabolically active tissues including the genital primordia. The mRNA encoding the secreted GpX is restricted to the hypodermis, the outermost cellular layer of the nematode, a location from which it is likely to be secreted to the parasite surface. Biochemical studies confirmed the secreted protein as a functional GpX and showed that, like secreted GpXs of other parasitic nematodes, it does not metabolise hydrogen peroxide but has a preference for larger hydroperoxide substrates. The intracellular protein is likely to have a role in metabolism of active oxygen species derived from internal body metabolism while the secreted protein may protect the parasite from host defences. Other functional roles for this protein are discussed.

Yield asymmetry design of magnesium alloys by integrated computational materials engineering

Energy Technology Data Exchange (ETDEWEB)

Li, Dongsheng [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Joshi, Vineet [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Khaleel, Mohammad [Qatar Foundation Research adn Development (Qatar); Ahzi, Said [Univ. of Strasbourg (France)

2013-11-01

Deformation asymmetry of magnesium alloys is an important factor on machine design in the automobile industry. Represented by the ratio of compressive yield stress (CYS) against tensile yield stress (TYS), deformation asymmetry is strongly related to texture and grain size. A polycrystalline viscoplasticity model, modified intermediate Φ-model, is used to predict the deformation behavior of magnesium alloys with different grain sizes. Validated with experimental results, integrated computational materials engineering is applied to find out the route in achieving desired asymmetry via thermomechanical processing. For example, CYS/TYS in rolled texture is smaller than 1 under different loading directions. In other textures, such as extruded texture, CYS/TYS is large along the normal direction. Starting from rolled texture, asymmetry will increase to close to 1 along the rolling direction after being compressed to a strain of 0.2. Our modified Φ-model also shows that grain refinement increases CYS/TYS. Along with texture control, grain refinement also can optimize the yield asymmetry. After the grain size decreases to a critical value, CYS/TYS reaches to 1 because CYS increases much faster than TYS. By tailoring the microstructure using texture control and grain refinement, it is achievable to optimize yield asymmetry in wrought magnesium alloys.

A model of nematode dynamics in the Westerschelde estuary

NARCIS (Netherlands)

Li, J.; Vincx, M.; Herman, P.M.J.

1996-01-01

We developed a time dynamic model to investigate the temporal dynamics of nematode community in the brackish zone of the Westerschelde Estuary. The biomass of four nematode feeding groups observed from March 1991 to February 1992 is used to calibrate the model. Using environmental data as the input,

Statistical analysis of nematode counts from interlaboratory proficiency tests

NARCIS (Netherlands)

Berg, van den W.; Hartsema, O.; Nijs, Den J.M.F.

2014-01-01

A series of proficiency tests on potato cyst nematode (PCN; n=29) and free-living stages of Meloidogyne and Pratylenchus (n=23) were investigated to determine the accuracy and precision of the nematode counts and to gain insights into possible trends and potential improvements. In each test, each

Altitudinal Barrier to the Spread of an Invasive Species: Could the Pyrenean Chain Slow the Natural Spread of the Pinewood Nematode?

Directory of Open Access Journals (Sweden)

Julien Haran

Full Text Available Mountain ranges may delimit the distribution of native species as well as constitute potential barriers to the spread of invasive species. The invasive pinewood nematode, Bursaphelenchus xylophilus, is a severe forest pest inducing pine wilt disease. It is vectored in Europe by a native long-horned beetle, Monochamus galloprovincialis. This study explored the potential of the Pyrenean chain to slow or prevent the natural spread of nematode-infested beetles from the Iberian Peninsula, where the nematode is established and is expanding its range, towards France and the rest of Europe. An analysis of the genetic structure and migration patterns of the beetle populations throughout the Pyrenean mountain range was combined with a spread model simulating the potential movements of nematode-infested beetles across it. The central part of the Pyrenees, which corresponds to the highest elevation zone, was shown to prevent gene flow between the French and Spanish populations of M. galloprovincialis on each side of the mountains. Conversely, strong admixture was detected between populations located on both sides of low elevation hills, and especially at the east and west extremities of the mountain range. Simulations of the spread of nematode-infested beetles under various thresholds of beetle survival and pine wilt disease expression gave results consistent with the variation in genetic make-up, suggesting that western and eastern hillsides may represent corridors favoring natural spread of the nematode from the Iberian Peninsula to France. Simulations also showed that temperature rise due to climate change may significantly reduce the extent of the barrier formed by highest elevations. Our results support the hypothesis that the Pyrenean chain represents a partial barrier to the natural spread of nematode-infested beetles. These results, which have to be considered together with potential human-assisted long-distance spread of the nematode, highlight

Effect of the spray application technique on the deposition of entomopathogenic nematodes in vegetables.

Science.gov (United States)

Brusselman, Eva; Beck, Bert; Pollet, Sabien; Temmerman, Femke; Spanoghe, Pieter; Moens, Maurice; Nuyttens, David

2012-03-01

The present study compared entomopathogenic nematode delivery at the base of savoy cabbage and cauliflower, at the lower side of savoy cabbage and cauliflower leaves and in leek stems and the ground deposition using a five-nozzle spray boom equipped with an ISO 08 flat fan, an air induction flat fan and Twinjet spray nozzles. Additionally, an air support system and a row application system were evaluated. Approximately 40% of the applied nematodes did not reach the foot of the cabbage plants. The use of an air support system or a row application system improved nematode deposition at the savoy cabbage base. Relative nematode deposition on the lower side of savoy cabbage leaves was 27.20%, while only 2.64% of the applied nematodes reached the lower side of cauliflower leaves. After spraying leek with a standard boom, a low relative nematode deposition (26.64%) was measured in the leek stem. Nozzle type affected the distribution of nematodes in droplet spots. Nozzle type has a minor effect on the number of entomopathogenic nematodes delivered on difficult-to-reach targets. The use of modified spray application techniques directing the spray to the target site are necessary to increase the chances of contact of entomopathogenic nematodes with their target. Copyright © 2011 Society of Chemical Industry.

'David and Goliath' of the soil food web - Flagellates that kill nematodes

DEFF Research Database (Denmark)

Strandmark, Lisa Bjørnlund; Rønn, Regin

2008-01-01

Nematodes and flagellates are important bacterial predators in soil and sediments. Generally, these organisms are considered to be competitors for bacterial food. We studied the interaction among flagellates and nematodes using axenic liquid cultures amended with heat-killed bacteria as food...... and showed for the first time that a small and common soil flagellate (Cercomonas sp.) is able to attack and kill the much larger nematode Caenorhabditis elegans. The killing process is not caused by soluble metabolites but requires direct contact between the flagellate cells and the nematode surface...... and occurs rapidly (within a few hours) at high flagellate density. At lower flagellate density, adult nematodes sometimes avoid attachment of flagellates, feed on them and become the dominant bacterial predator. Considering that bacterial feeders affect bacterial communities differently, and that one...

Effects of intact glucosinolates and products produced from glucosinolates in myrosinase-catalyzed hydrolysis on the potato cyst nematode (Globodera rostochiensis Cv. Woll).

Science.gov (United States)

Buskov, S; Serra, B; Rosa, E; Sørensen, H; Sørensen, J C

2002-02-13

The potato cyst nematode (Globodera rostochiensis cv. Woll) is responsible for large yield losses in the potato crop, and opportunities for reducing the attack of these plant nematode species are, therefore, important. This study has been devoted to the testing of the in vitro effects on the potato cyst nematode of eight glucosinolates [prop-2-enyl-, but-3-enyl-, (R)-4-methylsulfinylbut-3-enyl-, benzyl-, phenethyl-, 4-hydroxybenzyl-, (2S)-2-hydroxybut-3-enyl-, and (2R)-2-hydroxy-2-phenylethylglucosinolate] as well as the effects of the products of this myrosinase-catalyzed hydrolysis. The glucosinolates were used at three concentrations, 0.05, 0.3, and 1.0 mg/mL, in the presence or absence of the enzyme myrosinase. The effects of the compounds on the mortality were monitored every 8 h for a 72 h period. No effects were found for any of the intact glucosinolates. However, when active myrosinase was included with 1 mg/mL phenethylglucosinolate at pH 6.5, 100% mortality was observed within just 16 h. A similar effect was achieved at the same concentration of benzyl- and prop-2-enylglucosinolates in the myrosinase-containing solutions, although longer exposures were required (24 and 40 h, respectively). The main aglucone products released from the glucosinolates with pronounced effects on the nematodes were shown to be the corresponding isothiocyanates. The results suggest that mixtures of these specific glucosinolates and active myrosinase or autolysis of plant materials containing these enzymes and glucosinolates might be used to control the potato cyst nematode in the soil.

A Survey of Nematode Infection in Oreochromis niloticus (L ...

African Journals Online (AJOL)

The incidence and intensity of nematode infection was investigated in Nile tilapia Oreochromis niloticus from Lake Kyoga, Uganda and 11% of the 406 fish examined were parasitized by nematodes of the genus Contracaecum. The prevalence of these parasites was greatest in the smallest and largest size classes, but this ...

Human Intraocular Filariasis Caused by Pelecitus sp. Nematode, Brazil

Science.gov (United States)

Bain, Odile; Diniz, Daniel G.; Nascimento dos Santos, Jeannie; Pinto de Oliveira, Norimar; Frota de Almeida, Izabela Negrão; Frota de Almeida, Rafael Negrão; Frota de Almeida, Luciana Negrão; Dantas-Torres, Filipe; Sobrinho, Edmundo Frota de Almeida

2011-01-01

A male nematode was extracted from iris fibers of a man from the Brazilian Amazon region. This nematode belonged to the genus Pelecitus but was distinct from the 16 known species in this genus. Similarities with Pelecitus spp. from neotropical birds suggested an avian origin for this species. PMID:21529397

The effect of organic fertilizers on population dynamics of sugar beet cyst nematode, Heterodera schachtii 1871

Directory of Open Access Journals (Sweden)

N. Helalat

2018-01-01

population of the same treatment. And, comparison of means was done by Duncan tests. For the Greenhouse experiments, the same treated soils from each and every treatment in field were poured into the clay pots with a capacity of 5 kg of soil. At the time of harvest, the produced beets in each and every plot were weighted, and the beet samples for determining of sugar percentage and the important elements were sent to sugar factory for analyzes. The analysis of variance was performed, using SAS software and comparison method. Results and ddiscussions. The initial population of SBCN was 4.85 eggs and larvae per gram of soil, before the implication of the treatments in the field. There were 92.40 and 88.44 percent reduction in SBCN final population for the poultry manure at the rate of 40 and 20 tons per hectare, with the high significant effect, in comparison to other ones respectively. Variance analysis of Reproduction factor showed that there is a significant difference between the treatments. Poultry manure 40 t/h with 0.14 eggs and larvae per gram of soil was the lowest one in reproduction factor, with a high significant effect to other treatments and control groups. Followed by poultry manure 20 t/h, compost 015, 60 ha, poultry manure 10 t/h and compost 08, 60 t/h, in the next category with a significant effect. The results on the yield, sugar content and other indices showed significant differences between the various treatments. Poultry manure 20 and 40 t/h, with the yield of 27.55 and 26.93 t/h, in a statistical group had the maximum amount of product with a very minor difference, were the most effective treatments on the assessed factors, including final population, reproduction, multiplication rat and reduction percentage in SBCN, H. schachtii compared to other treatments and the checks. In this regard, it has been shown on other nematodes that, chicken manure has reduced the population of M. incognita, Hoplolaimus columbus and Pratylenchus penetrans in brinjal. And

Discovery of genomic intervals that underlie nematode responses to benzimidazoles.

Science.gov (United States)

Zamanian, Mostafa; Cook, Daniel E; Zdraljevic, Stefan; Brady, Shannon C; Lee, Daehan; Lee, Junho; Andersen, Erik C

2018-03-01

Parasitic nematodes impose a debilitating health and economic burden across much of the world. Nematode resistance to anthelmintic drugs threatens parasite control efforts in both human and veterinary medicine. Despite this threat, the genetic landscape of potential resistance mechanisms to these critical drugs remains largely unexplored. Here, we exploit natural variation in the model nematodes Caenorhabditis elegans and Caenorhabditis briggsae to discover quantitative trait loci (QTL) that control sensitivity to benzimidazoles widely used in human and animal medicine. High-throughput phenotyping of albendazole, fenbendazole, mebendazole, and thiabendazole responses in panels of recombinant lines led to the discovery of over 15 QTL in C. elegans and four QTL in C. briggsae associated with divergent responses to these anthelmintics. Many of these QTL are conserved across benzimidazole derivatives, but others show drug and dose specificity. We used near-isogenic lines to recapitulate and narrow the C. elegans albendazole QTL of largest effect and identified candidate variants correlated with the resistance phenotype. These QTL do not overlap with known benzimidazole target resistance genes from parasitic nematodes and present specific new leads for the discovery of novel mechanisms of nematode benzimidazole resistance. Analyses of orthologous genes reveal conservation of candidate benzimidazole resistance genes in medically important parasitic nematodes. These data provide a basis for extending these approaches to other anthelmintic drug classes and a pathway towards validating new markers for anthelmintic resistance that can be deployed to improve parasite disease control.

The gastropod shell has been co-opted to kill parasitic nematodes.

Science.gov (United States)

Rae, R

2017-07-06

Exoskeletons have evolved 18 times independently over 550 MYA and are essential for the success of the Gastropoda. The gastropod shell shows a vast array of different sizes, shapes and structures, and is made of conchiolin and calcium carbonate, which provides protection from predators and extreme environmental conditions. Here, I report that the gastropod shell has another function and has been co-opted as a defense system to encase and kill parasitic nematodes. Upon infection, cells on the inner layer of the shell adhere to the nematode cuticle, swarm over its body and fuse it to the inside of the shell. Shells of wild Cepaea nemoralis, C. hortensis and Cornu aspersum from around the U.K. are heavily infected with several nematode species including Caenorhabditis elegans. By examining conchology collections I show that nematodes are permanently fixed in shells for hundreds of years and that nematode encapsulation is a pleisomorphic trait, prevalent in both the achatinoid and non-achatinoid clades of the Stylommatophora (and slugs and shelled slugs), which diverged 90-130 MYA. Taken together, these results show that the shell also evolved to kill parasitic nematodes and this is the only example of an exoskeleton that has been co-opted as an immune system.

Soil nematode assemblages as bioindicators of radiation impact in the Chernobyl Exclusion Zone.

Science.gov (United States)

Lecomte-Pradines, C; Bonzom, J-M; Della-Vedova, C; Beaugelin-Seiller, K; Villenave, C; Gaschak, S; Coppin, F; Dubourg, N; Maksimenko, A; Adam-Guillermin, C; Garnier-Laplace, J

2014-08-15

In radioecology, the need to understand the long-term ecological effects of radioactive contamination has been emphasised. This requires that the health of field populations is evaluated and linked to an accurate estimate of received radiological dose. The aim of the present study was to assess the effects of current radioactive contamination on nematode assemblages at sites affected by the fallout from the Chernobyl accident. First, we estimated the total dose rates (TDRs) absorbed by nematodes, from measured current soil activity concentrations, Dose Conversion Coefficients (DCCs, calculated using EDEN software) and soil-to-biota concentration ratios (from the ERICA tool database). The impact of current TDRs on nematode assemblages was then evaluated. Nematodes were collected in spring 2011 from 18 forest sites in the Chernobyl Exclusion Zone (CEZ) with external gamma dose rates, measured using radiophotoluminescent dosimeters, varying from 0.2 to 22 μGy h(-1). These values were one order of magnitude below the TDRs. A majority of bacterial-, plant-, and fungal-feeding nematodes and very few of the disturbance sensitive families were identified. No statistically significant association was observed between TDR values and nematode total abundance or the Shannon diversity index (H'). The Nematode Channel Ratio (which defines the relative abundance of bacterial- versus fungal-feeding nematodes) decreased significantly with increasing TDR, suggesting that radioactive contamination may influence nematode assemblages either directly or indirectly by modifying their food resources. A greater Maturity Index (MI), usually characterising better soil quality, was associated with higher pH and TDR values. These results suggest that in the CEZ, nematode assemblages from the forest sites were slightly impacted by chronic exposure at a predicted TDR of 200 μGy h(-1). This may be imputable to a dominant proportion of pollutant resistant nematodes in all sites. This might

The Role of Cytokinin During Infection of Arabidopsis thaliana by the Cyst Nematode Heterodera schachtii.

Science.gov (United States)

Shanks, Carly M; Rice, J Hollis; Zubo, Yan; Schaller, G Eric; Hewezi, Tarek; Kieber, Joseph J

2016-01-01

Plant-parasitic cyst nematodes induce the formation of hypermetabolic feeding sites, termed syncytia, as their sole source of nutrients. The formation of the syncytium is orchestrated by the nematode, in part, by modulation of phytohormone responses, including cytokinin. In response to infection by the nematode Heterodera schachtii, cytokinin signaling is transiently induced at the site of infection and in the developing syncytium. Arabidopsis lines with reduced cytokinin sensitivity show reduced susceptibility to nematode infection, indicating that cytokinin signaling is required for optimal nematode development. Furthermore, lines with increased cytokinin sensitivity also exhibit reduced nematode susceptibility. To ascertain why cytokinin hypersensitivity reduces nematode parasitism, we examined the transcriptomes in wild type and a cytokinin-hypersensitive type-A arr Arabidopsis mutant in response to H. schachtii infection. Genes involved in the response to biotic stress and defense response were elevated in the type-A arr mutant in the absence of nematodes and were hyperinduced following H. schachtii infection, which suggests that the Arabidopsis type-A arr mutants impede nematode development because they are primed to respond to pathogen infection. These results suggest that cytokinin signaling is required for optimal H. schachtii parasitism of Arabidopsis but that elevated cytokinin signaling triggers a heightened immune response to nematode infection.

Bacterial antagonists of fungal pathogens also control root-knot nematodes by induced systemic resistance of tomato plants.

Directory of Open Access Journals (Sweden)

Mohamed Adam

Full Text Available The potential of bacterial antagonists of fungal pathogens to control the root-knot nematode Meloidogyne incognita was investigated under greenhouse conditions. Treatment of tomato seeds with several strains significantly reduced the numbers of galls and egg masses compared with the untreated control. Best performed Bacillus subtilis isolates Sb4-23, Mc5-Re2, and Mc2-Re2, which were further studied for their mode of action with regard to direct effects by bacterial metabolites or repellents, and plant mediated effects. Drenching of soil with culture supernatants significantly reduced the number of egg masses produced by M. incognita on tomato by up to 62% compared to the control without culture supernatant. Repellence of juveniles by the antagonists was shown in a linked twin-pot set-up, where a majority of juveniles penetrated roots on the side without inoculated antagonists. All tested biocontrol strains induced systemic resistance against M. incognita in tomato, as revealed in a split-root system where the bacteria and the nematodes were inoculated at spatially separated roots of the same plant. This reduced the production of egg masses by up to 51%, while inoculation of bacteria and nematodes in the same pot had only a minor additive effect on suppression of M. incognita compared to induced systemic resistance alone. Therefore, the plant mediated effect was the major reason for antagonism rather than direct mechanisms. In conclusion, the bacteria known for their antagonistic potential against fungal pathogens also suppressed M. incognita. Such "multi-purpose" bacteria might provide new options for control strategies, especially with respect to nematode-fungus disease complexes that cause synergistic yield losses.

Bacterial antagonists of fungal pathogens also control root-knot nematodes by induced systemic resistance of tomato plants.

Science.gov (United States)

Adam, Mohamed; Heuer, Holger; Hallmann, Johannes

2014-01-01

The potential of bacterial antagonists of fungal pathogens to control the root-knot nematode Meloidogyne incognita was investigated under greenhouse conditions. Treatment of tomato seeds with several strains significantly reduced the numbers of galls and egg masses compared with the untreated control. Best performed Bacillus subtilis isolates Sb4-23, Mc5-Re2, and Mc2-Re2, which were further studied for their mode of action with regard to direct effects by bacterial metabolites or repellents, and plant mediated effects. Drenching of soil with culture supernatants significantly reduced the number of egg masses produced by M. incognita on tomato by up to 62% compared to the control without culture supernatant. Repellence of juveniles by the antagonists was shown in a linked twin-pot set-up, where a majority of juveniles penetrated roots on the side without inoculated antagonists. All tested biocontrol strains induced systemic resistance against M. incognita in tomato, as revealed in a split-root system where the bacteria and the nematodes were inoculated at spatially separated roots of the same plant. This reduced the production of egg masses by up to 51%, while inoculation of bacteria and nematodes in the same pot had only a minor additive effect on suppression of M. incognita compared to induced systemic resistance alone. Therefore, the plant mediated effect was the major reason for antagonism rather than direct mechanisms. In conclusion, the bacteria known for their antagonistic potential against fungal pathogens also suppressed M. incognita. Such "multi-purpose" bacteria might provide new options for control strategies, especially with respect to nematode-fungus disease complexes that cause synergistic yield losses.

Differential Selection by Nematodes on an Introduced Biocontrol Fungus vs. Indigenous Fungi in Nonsterile Soil.

Science.gov (United States)

Kim, Tae Gwan; Knudsen, Guy R

2018-03-15

Trophic interactions of introduced biocontrol fungi with soil animals can bea key determinant in the fungal proliferation and activity.This study investigated trophic interaction of an introduced biocontrol fungus with soil nematodes. The biocontrol fungus Trichoderma harzianum ThzID1-M3 and the fungivorous nematode Aphelenchoides sp. (10 per gram of soil) were added to nonsterile soil, and microbial populations were monitored for 40 days. Similar results were obtained when the experiment was duplicated. ThzID1-M3 stimulated the population growth of indigenous nematodes ( p nematodes did not increase in number and the added Aphelenchoides sp. nematodes almost disappeared by day 10. With ThzID1-M3, population growth of nematodes was rapid between 5 and 10 days after treatment. ThzID1-M3 biomass peaked on day 5, dropped at day 10, and then almost disappeared at day 20, which was not influenced by the addition of nematodes.In contrast, a large quantity of ThzID1-M3 hyphae were present in a heat-treated soil in which nematodes were eliminated.Total fungal biomass in all treatments peaked on day 5 and subsequently decreased.Addition of nematodes increased the total fungal biomass ( p nematode population growth; however, hyphae of the introduced fungus when densely localized did.The results suggest that soil fungivorous nematodes are an important constraint onhyphal proliferation of fungal agents introduced into natural soils.

Use of organic waste as biofumigant for controlling root knot nematodes (Meloidogyne spp.) on potato

Science.gov (United States)

Sari, D. I. P.; Lisnawita; Oemry, S.; Safni, I.; Lubis, K.; Tantawi, A. R.

2018-02-01

Root knot nematode (Meloidogyne spp.) is one of the important pathogens that causes big impact on potato crop yields. One of the control strategies for controlling this nematode is the use of biofumigants. Biofumigants are volatile toxic compound derived from plants, and have biocide properties against insects and plant pathogens. Organic waste such as Brassicaceae, Leguminoceae, and Solanaceae can be used as biofumigant sources. This research was conducted to determine the effectiveness of Brassicaceae, Leguminoceae, and Solanaceae as biofumigants against Meloidogyne spp. The experiment was set in a completely randomized design (CRD) with the treatments were organic wastes including Brassicaceae, Leguminoceae, and Solanaceae, both single and combinations, and 2 controls (positive and negative controls) with 3 replications. Each of the biofumigant treatments was prepared and stored for 2 weeks. Potato tubers were transplanted 15 days after germination into polybag inoculated with 1,000 Meloidogyne spp. J2s. The results showed that Brassicaceae + Solanaceae were effective in decreasing the number of galls in potato plants, however only Solanaceae improved plant growth.

Biocontrol: Bacillus penetrans and Related Parasites of Nematodes

OpenAIRE

Sayre, R. M.

1980-01-01

Bacillus penetrans Mankau, 1975, previously described as Duboscqia penetrans Thorne 1940, is a candidate agent for biocontrol of nematodes. This review considers the life stages of this bacterium: vegetative growth phase, colony fragmentation, sporogenesis, soil phase, spore attachment, and penetration into larvae of root-knot nematodes. The morphology of the microthallus colonies and the unusual external features of the spore are discussed. Taxonomic affinities with the actinomycetes, partic...

Response of Pinus ponderosa Seedlings to Stylet-Bearing Nematodes

Science.gov (United States)

Viglierchio, D. R.

1979-01-01

Of 12 stylet-bearing nematodes used for inoculations, Pratylenchus penetrans, P. brachyurus, P. vulnus, Ditylenchus destructor, Meloidogyne incognita, M. javanica, and M. hapla reproduced on Pinus ponderosa, while Xiphinema index, Aphelenchus avenae, Paratylenehus neoamblycephalus, Tylenchulus semipenetrans, and Macroposthonia xenoplax did not. P. vulnus, P. brachyurus, P. penetrans, A. avenae, D. destructor, T. semipenetrans, and P. neoamblycephalus significantly suppressed both the shoot and root wet weights of ponderosa pine seedlings obtained from stands in five different locations. X. index significantly suppressed root wet weights, M. xenoplax siguificantly suppressed shoot wet weight, and M. incognita, M. javanica, and M. hapla suppressed neither at the inoculation levels used. Injurious nematodes tended to suppress root growth more than shoot growth. Seedlings from two locations produced greater shoot growth wet weight than did seedlings from the other three locations. The more injurious nematodes tended to cause an increase in the water content of shoots. Frequency analyses of seedling population shoot-root ratios indicated that ponderosa pine seedlings could be selected for better shoot-root ratios as well as for resistance to several pathogenic nematodes. PMID:19300659

A SNARE-like protein and biotin are implicated in soybean cyst nematode virulence

Science.gov (United States)

Some phytoparasitic nematodes have the ability to infect and reproduce on plants that are normally considered resistant to nematode infection. Such nematodes are referred to as virulent and the mechanisms they use to evade or suppress host plant defenses are not well understood. Here, we report the ...

Dissecting host plant manipulation by cyst and root-knot nematodes

NARCIS (Netherlands)

Karczmarek, A.

2006-01-01

Cyst ( Globodera spp. and Heterodera spp.) and root-knot nematodes ( Meloidogyne spp.), one of the most damaging crop pests, are a perfect example of highly adapted, sophisticated root parasites. These nematodes induces specialized feeding structures (cyst

AMF-induced biocontrol against plant parasitic nematodes in Musa sp.: a systemic effect.

Science.gov (United States)

Elsen, A; Gervacio, D; Swennen, R; De Waele, D

2008-07-01

Although mycorrhizal colonization provides a bioprotectional effect against a broad range of soil-borne pathogens, including plant parasitic nematodes, the commercial use of arbuscular mycorrhizal fungi (AMF) as biocontrol agents is still in its infancy. One of the main reasons is the poor understanding of the modes of action. Most AMF mode of action studies focused on AMF-bacterial/fungal pathogens. Only few studies so far examined AMF-plant parasitic nematode interactions. Therefore, the aim of the study was to determine whether the AMF Glomus intraradices was able to incite systemic resistance in banana plants towards Radopholus similis and Pratylenchus coffeae, two plant parasitic nematodes using a split-root compartmental set-up. The AMF reduced both nematode species by more than 50%, even when the AMF and the plant parasitic nematodes were spatially separated. The results obtained demonstrate for the first time that AMF have the ability to induce systemic resistance against plant parasitic nematodes in a root system.

Variation in estuarine littoral nematode populations over three spatial scales

Science.gov (United States)

Hodda, M.

1990-04-01

The population characteristics of the nematode fauna from five replicate cores taken over four seasons at nine sites within mangroves, at three different estuaries on the south-east coast of Australia, are compared. Using cluster analysis, principal co-ordinate analysis and other statistical techniques, the variation in nematode populations is identified as arising from several sources: temperature changes between the more northerly and southerly estuaries (5%); changes in grain size and organic content of the sediment between sites (22%); changes between sites in the frequency of samples containing certain types of food, particularly associated with pools of water and surface topography (30%); stochastic changes in nematode populations within individual samples, probably caused by small scale spatial and temporal variability in food sources (35%); and seasonal changes at all the sites and estuaries (8%). The implications of this pattern of variation for the biology of the nematodes is discussed.

Multimodel Inference for the Prediction of Disease Symptoms and Yield Loss of Potato in a Two-Year Crop Rotation Experiment

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Wim Van den Berg

2012-01-01

Full Text Available The second order Akaike information criterion was used for the assessment of 139 regression models for three responses of potato test crops: (a incidence of Spongospora subterranea on the harvested tubers, (b percentage of haulms infected with Verticillium dahliae, and (c tuber yield. Six variables that are likely related to the response variables were taken into consideration: soil infestations of the fungus Verticillium dahliae and of three nematode species (Globodera pallida, Trichodoridae, and Meloidogyne spp. and, furthermore, soil pH and water soluble phosphor (P. Interactions between V. dahliae and the three nematode species were included as well. Based on multimodelling, predictors are given a weight from which one may decide about the need to include them in a prediction of crop yield. The most important predictors were soil infestation levels of V. dahliae and G. pallida and soil pH. The outcome also showed that tubers suffered more from S. subterranea for higher soil pH values. Finally, yield reduction from the presence of V. dahliae was enhanced by the presence of higher densities of G. pallida.

Biochemical and Molecular Characterization of Plant-Parasitic Nematodes

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I.M. de O. Abrantes

2004-08-01

Full Text Available Nematologists need correct species identification to carry out research, teaching, extension and other activities. Therefore, nematode taxonomy must be pursued diligently at all levels. The identification of plant-parasitic nematodes is not always easy and that of some species is especially difficult. Most of the information that nematologists use when characterizing and identifying specimens is based on morphological and morphometrical characters. Although these characters are of primary importance, in the last three decades they have been supplemented by biochemical/ molecular characters. Biochemical approaches include the separation of proteins (general proteins and isozymes by one-dimensional gel electrophoresis, isoelectric focusing, two-dimensional gel electrophoresis, and sodium dodecyl sulphate-capillary gel electrophoresis. Serology has also been found effective in the identification and quantification of nematodes, monoclonal antibodies being a more useful immunological tool than polyclonal antibodies. Identification based on the direct examination of DNA is potentially a more powerful method to characterize inter- and intra-specific variability. The development of techniques such as the polymerase chain reaction, restriction fragment length polymorphism, randomly amplified polymorphic DNA, and amplified fragment length polymorphism has increased the accuracy and speed of nematode characterization/identification. Progress continues to be made and more and more nematologists are using molecular techniques for diagnostic purposes and to assess genetic variation.

Nematode assemblages in the deep-sea benthos of the Norwegian Sea

Science.gov (United States)

Jensen, Preben

1988-07-01

The deep-sea benthos of the Norwegian Sea contains 20-204 nematodes per 10 cm 2 down to 3 cm depth at seven stations sampled between 970 and 3294 m water depth. The majority of nematodes occur in the uppermost cm. Biomass varies from 3 to 73 μg C per 10 cm 2. Individual adult weight of the most dominant species differs by a factor of almost 1000, i.e. from 3-4 ng C to 3400 ng C; however, the majority of the nematodes is small-sized. Species diversity and evenness are high at all stations and each station harbours its specific fauna with little overlap between stations. Analysis of trophic group composition suggests that microbial feeding types (deposit and epistrate feeders) prevail in the deep-sea benthos; predators and scavengers are scarce. It is concluded that the nematode assemblage at each station consists of a mosaic of many microhabitats. The small nematode body weight probably results from limited food supply and/or poor food quality.

flp-32 Ligand/receptor silencing phenocopy faster plant pathogenic nematodes.

Science.gov (United States)

Atkinson, Louise E; Stevenson, Michael; McCoy, Ciaran J; Marks, Nikki J; Fleming, Colin; Zamanian, Mostafa; Day, Tim A; Kimber, Michael J; Maule, Aaron G; Mousley, Angela

2013-02-01

Restrictions on nematicide usage underscore the need for novel control strategies for plant pathogenic nematodes such as Globodera pallida (potato cyst nematode) that impose a significant economic burden on plant cultivation activities. The nematode neuropeptide signalling system is an attractive resource for novel control targets as it plays a critical role in sensory and motor functions. The FMRFamide-like peptides (FLPs) form the largest and most diverse family of neuropeptides in invertebrates, and are structurally conserved across nematode species, highlighting the utility of the FLPergic system as a broad-spectrum control target. flp-32 is expressed widely across nematode species. This study investigates the role of flp-32 in G. pallida and shows that: (i) Gp-flp-32 encodes the peptide AMRNALVRFamide; (ii) Gp-flp-32 is expressed in the brain and ventral nerve cord of G. pallida; (iii) migration rate increases in Gp-flp-32-silenced worms; (iv) the ability of G. pallida to infect potato plant root systems is enhanced in Gp-flp-32-silenced worms; (v) a novel putative Gp-flp-32 receptor (Gp-flp-32R) is expressed in G. pallida; and, (vi) Gp-flp-32R-silenced worms also display an increase in migration rate. This work demonstrates that Gp-flp-32 plays an intrinsic role in the modulation of locomotory behaviour in G. pallida and putatively interacts with at least one novel G-protein coupled receptor (Gp-flp-32R). This is the first functional characterisation of a parasitic nematode FLP-GPCR.

Nematode spatial and ecological patterns from tropical and temperate rainforests.

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Dorota L Porazinska

Full Text Available Large scale diversity patterns are well established for terrestrial macrobiota (e.g. plants and vertebrates, but not for microscopic organisms (e.g. nematodes. Due to small size, high abundance, and extensive dispersal, microbiota are assumed to exhibit cosmopolitan distributions with no biogeographical patterns. This assumption has been extrapolated from local spatial scale studies of a few taxonomic groups utilizing morphological approaches. Recent molecularly-based studies, however, suggest something quite opposite. Nematodes are the most abundant metazoans on earth, but their diversity patterns are largely unknown. We conducted a survey of nematode diversity within three vertical strata (soil, litter, and canopy of rainforests at two contrasting latitudes in the North American meridian (temperate: the Olympic National Forest, WA, U.S.A and tropical: La Selva Biological Station, Costa Rica using standardized sampling designs and sample processing protocols. To describe nematode diversity, we applied an ecometagenetic approach using 454 pyrosequencing. We observed that: 1 nematode communities were unique without even a single common species between the two rainforests, 2 nematode communities were unique among habitats in both rainforests, 3 total species richness was 300% more in the tropical than in the temperate rainforest, 4 80% of the species in the temperate rainforest resided in the soil, whereas only 20% in the tropics, 5 more than 90% of identified species were novel. Overall, our data provided no support for cosmopolitanism at both local (habitats and large (rainforests spatial scales. In addition, our data indicated that biogeographical patterns typical of macrobiota also exist for microbiota.

Nematode Spatial and Ecological Patterns from Tropical and Temperate Rainforests

Science.gov (United States)

Porazinska, Dorota L.; Giblin-Davis, Robin M.; Powers, Thomas O.; Thomas, W. Kelley

2012-01-01

Large scale diversity patterns are well established for terrestrial macrobiota (e.g. plants and vertebrates), but not for microscopic organisms (e.g. nematodes). Due to small size, high abundance, and extensive dispersal, microbiota are assumed to exhibit cosmopolitan distributions with no biogeographical patterns. This assumption has been extrapolated from local spatial scale studies of a few taxonomic groups utilizing morphological approaches. Recent molecularly-based studies, however, suggest something quite opposite. Nematodes are the most abundant metazoans on earth, but their diversity patterns are largely unknown. We conducted a survey of nematode diversity within three vertical strata (soil, litter, and canopy) of rainforests at two contrasting latitudes in the North American meridian (temperate: the Olympic National Forest, WA, U.S.A and tropical: La Selva Biological Station, Costa Rica) using standardized sampling designs and sample processing protocols. To describe nematode diversity, we applied an ecometagenetic approach using 454 pyrosequencing. We observed that: 1) nematode communities were unique without even a single common species between the two rainforests, 2) nematode communities were unique among habitats in both rainforests, 3) total species richness was 300% more in the tropical than in the temperate rainforest, 4) 80% of the species in the temperate rainforest resided in the soil, whereas only 20% in the tropics, 5) more than 90% of identified species were novel. Overall, our data provided no support for cosmopolitanism at both local (habitats) and large (rainforests) spatial scales. In addition, our data indicated that biogeographical patterns typical of macrobiota also exist for microbiota. PMID:22984536

flp-32 Ligand/receptor silencing phenocopy faster plant pathogenic nematodes.

Directory of Open Access Journals (Sweden)

Louise E Atkinson

2013-02-01

Full Text Available Restrictions on nematicide usage underscore the need for novel control strategies for plant pathogenic nematodes such as Globodera pallida (potato cyst nematode that impose a significant economic burden on plant cultivation activities. The nematode neuropeptide signalling system is an attractive resource for novel control targets as it plays a critical role in sensory and motor functions. The FMRFamide-like peptides (FLPs form the largest and most diverse family of neuropeptides in invertebrates, and are structurally conserved across nematode species, highlighting the utility of the FLPergic system as a broad-spectrum control target. flp-32 is expressed widely across nematode species. This study investigates the role of flp-32 in G. pallida and shows that: (i Gp-flp-32 encodes the peptide AMRNALVRFamide; (ii Gp-flp-32 is expressed in the brain and ventral nerve cord of G. pallida; (iii migration rate increases in Gp-flp-32-silenced worms; (iv the ability of G. pallida to infect potato plant root systems is enhanced in Gp-flp-32-silenced worms; (v a novel putative Gp-flp-32 receptor (Gp-flp-32R is expressed in G. pallida; and, (vi Gp-flp-32R-silenced worms also display an increase in migration rate. This work demonstrates that Gp-flp-32 plays an intrinsic role in the modulation of locomotory behaviour in G. pallida and putatively interacts with at least one novel G-protein coupled receptor (Gp-flp-32R. This is the first functional characterisation of a parasitic nematode FLP-GPCR.

Communities of terrestrial nematodes after different approaches to heathland restoration

Science.gov (United States)

Radochova, Petra; Frouz, Jan

2016-04-01

Since the 20th century, the distribution of European heathlands rapidly decreased due to agricultural intensification, heavy use of artificial fertilizers or acidification (Aerts & Heil, 1993). Therefore, various attempts of heathland restoration are under way in these days. Analysis of nematode community composition can be one of the tools suitable for succession evaluation (Ferris et al., 2001). In 2011, 2013 and 2014, soil samples were collected from heathland restoration experiment (launched in 2011) where different restoration methods were applied in a 3 × 3 factorial experiment; existing heathlands were also sampled to identify the target community both in dry and wet heathland. A total of 60 samples of extracted nematodes were analysed for absolute abundance, trophic groups, and genera dominance. Various indices were calculated to describe the nematode community. We were able to prove faster development of wet heathlands towards the target community. However, because of large data variability, there was no significant difference between treatments. Development of wet and dry heathlands differed also in increased proportion of omniphagous nematodes in 2013 and predators in 2014 in dry heathlands. After three years of heathland restoration, nematode community has not yet reached parameters of the target community. References Aerts, R., Heil, G. W., 1993. Heathlands: patterns and processes in a changing environment, 1st ed, Geobotany: 20. Springer Netherlands, Dordrecht, p. 229. Ferris, H., Bongers, T., De Goede, R. G. M., 2001. A framework for soil food web diagnostics: Extension of the nematode faunal analysis oncept. Appl. Soil Ecol. 18, 13-29.

A farmer friendly and economic IPM strategy to combat root-knot nematodes infesting lentil

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Rose Rizvi

2015-12-01

Full Text Available An experiment was conducted to assess the effect of Rhizobium sp., waste tea leaves, eggshell powder, and composted cow dung manure on the root-knot nematode, Meloidogyne incognita, on lentil in Botany department AMU, Aligarh, India. When used alone, composted cow dung was better in reducing galling and nematode multiplication and improving lentil growth followed by eggshell powder, Rhizobium sp., and waste tea leaves. Significant result in the integrated management of M. incognita was obtained when Rhizobium sp. was used in combination with cow dung and eggshell powder (with or without waste tea leaves. Combined application of root nodule bacterium and organic wastes like waste tea leaves, eggshell, and cow dung may be suggested to the farmers/growers or related persons who are having great enthusiasm to establish a lentil production business. Application of these organic materials along with the root nodule bacteria may be helpful to foster soil ecosystem which has been a hot topic in the present scenario.

Benthic-pelagic coupling: effects on nematode communities along southern European continental margins.

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Ellen Pape

Full Text Available Along a west-to-east axis spanning the Galicia Bank region (Iberian margin and the Mediterranean basin, a reduction in surface primary productivity and in seafloor flux of particulate organic carbon was mirrored in the in situ organic matter quantity and quality within the underlying deep-sea sediments at different water depths (1200, 1900 and 3000 m. Nematode standing stock (abundance and biomass and genus and trophic composition were investigated to evaluate downward benthic-pelagic coupling. The longitudinal decline in seafloor particulate organic carbon flux was reflected by a reduction in benthic phytopigment concentrations and nematode standing stock. An exception was the station sampled at the Galicia Bank seamount, where despite the maximal particulate organic carbon flux estimate, we observed reduced pigment levels and nematode standing stock. The strong hydrodynamic forcing at this station was believed to be the main cause of the local decoupling between pelagic and benthic processes. Besides a longitudinal cline in nematode standing stock, we noticed a west-to-east gradient in nematode genus and feeding type composition (owing to an increasing importance of predatory/scavenging nematodes with longitude governed by potential proxies for food availability (percentage of nitrogen, organic carbon, and total organic matter. Within-station variability in generic composition was elevated in sediments with lower phytopigment concentrations. Standing stock appeared to be regulated by sedimentation rates and benthic environmental variables, whereas genus composition covaried only with benthic environmental variables. The coupling between deep-sea nematode assemblages and surface water processes evidenced in the present study suggests that it is likely that climate change will affect the composition and function of deep-sea nematodes.

Profiling nematode communities in unmanaged flowerbed and agricultural field soils in Japan by DNA barcode sequencing.

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Hisashi Morise

Full Text Available Soil nematodes play crucial roles in the soil food web and are a suitable indicator for assessing soil environments and ecosystems. Previous nematode community analyses based on nematode morphology classification have been shown to be useful for assessing various soil environments. Here we have conducted DNA barcode analysis for soil nematode community analyses in Japanese soils. We isolated nematodes from two different environmental soils of an unmanaged flowerbed and an agricultural field using the improved flotation-sieving method. Small subunit (SSU rDNA fragments were directly amplified from each of 68 (flowerbed samples and 48 (field samples isolated nematodes to determine the nucleotide sequence. Sixteen and thirteen operational taxonomic units (OTUs were obtained by multiple sequence alignment from the flowerbed and agricultural field nematodes, respectively. All 29 SSU rDNA-derived OTUs (rOTUs were further mapped onto a phylogenetic tree with 107 known nematode species. Interestingly, the two nematode communities examined were clearly distinct from each other in terms of trophic groups: Animal predators and plant feeders were markedly abundant in the flowerbed soils, in contrast, bacterial feeders were dominantly observed in the agricultural field soils. The data from the flowerbed nematodes suggests a possible food web among two different trophic nematode groups and plants (weeds in the closed soil environment. Finally, DNA sequences derived from the mitochondrial cytochrome oxidase c subunit 1 (COI gene were determined as a DNA barcode from 43 agricultural field soil nematodes. These nematodes were assigned to 13 rDNA-derived OTUs, but in the COI gene analysis were assigned to 23 COI gene-derived OTUs (cOTUs, indicating that COI gene-based barcoding may provide higher taxonomic resolution than conventional SSU rDNA-barcoding in soil nematode community analysis.

Profiling Nematode Communities in Unmanaged Flowerbed and Agricultural Field Soils in Japan by DNA Barcode Sequencing

Science.gov (United States)

Morise, Hisashi; Miyazaki, Erika; Yoshimitsu, Shoko; Eki, Toshihiko

2012-01-01

Soil nematodes play crucial roles in the soil food web and are a suitable indicator for assessing soil environments and ecosystems. Previous nematode community analyses based on nematode morphology classification have been shown to be useful for assessing various soil environments. Here we have conducted DNA barcode analysis for soil nematode community analyses in Japanese soils. We isolated nematodes from two different environmental soils of an unmanaged flowerbed and an agricultural field using the improved flotation-sieving method. Small subunit (SSU) rDNA fragments were directly amplified from each of 68 (flowerbed samples) and 48 (field samples) isolated nematodes to determine the nucleotide sequence. Sixteen and thirteen operational taxonomic units (OTUs) were obtained by multiple sequence alignment from the flowerbed and agricultural field nematodes, respectively. All 29 SSU rDNA-derived OTUs (rOTUs) were further mapped onto a phylogenetic tree with 107 known nematode species. Interestingly, the two nematode communities examined were clearly distinct from each other in terms of trophic groups: Animal predators and plant feeders were markedly abundant in the flowerbed soils, in contrast, bacterial feeders were dominantly observed in the agricultural field soils. The data from the flowerbed nematodes suggests a possible food web among two different trophic nematode groups and plants (weeds) in the closed soil environment. Finally, DNA sequences derived from the mitochondrial cytochrome oxidase c subunit 1 (COI) gene were determined as a DNA barcode from 43 agricultural field soil nematodes. These nematodes were assigned to 13 rDNA-derived OTUs, but in the COI gene analysis were assigned to 23 COI gene-derived OTUs (cOTUs), indicating that COI gene-based barcoding may provide higher taxonomic resolution than conventional SSU rDNA-barcoding in soil nematode community analysis. PMID:23284767

THE PREVALENCE OF GASTROINTESTINAL NEMATODES OF BALI CATTLE BREEDERS IN NUSA PENIDA

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Putu Agus Trisna Kusuma Antara

2017-08-01

Full Text Available Nusa Penida is a pure breeding area of bali cattle, in which the cattle are mainly kept in conventional maintenance system and potentially infected by parasite, especially gastrointestinal nematodes. This study aims were to determine the prevalence and type of gastrointestinal nematodes in bali cattle breeders in Nusa Penida. Fecal samples were taken from 50 bali cattle breeders kept in cages (simantri and another 50 samples were from cattle not kept in cage. The floating method was used for morphological examination and prevalence, the data was analyzed with descriptive analysis. The results showed, the prevalence of bovine gastrointestinal nematodes in Nusa Penida was 25%. The prevalence of nematode infection in bali cattle that kept cages was lower compared to the cattle that were not kept in cage. Strongyloides papillosus and Capillaria bovis were the gastrointestinal nematodes found in the infected cattle.

Infestation of natural populations of earthworm cocoons by rhabditid and cephalobid nematodes

DEFF Research Database (Denmark)

Kraglund, HO; Ekelund, Flemming

2002-01-01

Nematodes infested 13 of 100 earthworm cocoons from a compost pile and 17 of 197 cocoons from a permanent pasture soil. Between one and 2000 nematodes were found within the infested cocoons. All nematodes found in cocoons from the compost pile belonged to the genus Rhabditis, while Rhabditis spp....... as well as members of Cephalobidae infested earthworm cocoons in the pasture soil. In cultures established from cocoons found in the pasture soil, at least five different types of nematodes belonging to the family Cephalobidae were found. Acrobeloides nanus was found in six cocoons, Cephalobus persegnis...... was found in four and Chiloplacus minimus was found in one cocoon. We suggest that earthworm - nematode interactions may be an important pathway for the transfer of carbon in terrestrial ecosystems, and that the inclusion of these pathways may lead to a better understanding of soil food web functioning....

Molecular and genetic analyses of potato cyst nematode resistance loci

NARCIS (Netherlands)

Bakker, E.H.

2003-01-01

This thesis describes the genomic localisation and organisation of loci that harbour resistance to the potato cyst nematode species Globodera pallida and G. rostochiensis . Resistance to the potato cyst nematodes G. pallida and G. rostochiensis is an important aspect in potato breeding. To gain

Genome sequence of the metazoan plant-parasitic nematode Meloidogyne incognita

NARCIS (Netherlands)

Abad, P.; Gouzy, J.; Aury, J.M.; Tytgat, T.O.G.; Smant, G.

2008-01-01

Plant-parasitic nematodes are major agricultural pests worldwide and novel approaches to control them are sorely needed. We report the draft genome sequence of the root-knot nematode Meloidogyne incognita, a biotrophic parasite of many crops, including tomato, cotton and coffee. Most of the

Plant and soil nematodes from Lokchao Yangoupokpi Wildlife Sanctuary, Manipur, India

OpenAIRE

N. Mohilal; M. Pramodini; L. Bina

2009-01-01

In the present study soil samples were collected from Lokchao Yangoupokpi Wildlife Sanctuary to investigate about what nematode species are associated with different plant hosts. This study shows rich nematode diversity in the sanctuary.

Effect of nematodes on rhizosphere colonization by seed-applied bacteria.

Science.gov (United States)

Knox, Oliver G G; Killham, Ken; Artz, Rebekka R E; Mullins, Chris; Wilson, Michael

2004-08-01

There is much interest in the use of seed-applied bacteria for biocontrol and biofertilization, and several commercial products are available. However, many attempts to use this strategy fail because the seed-applied bacteria do not colonize the rhizosphere. Mechanisms of rhizosphere colonization may involve active bacterial movement or passive transport by percolating water or plant roots. Transport by other soil biota is likely to occur, but this area has not been well studied. We hypothesized that interactions with soil nematodes may enhance colonization. To test this hypothesis, a series of microcosm experiments was carried out using two contrasting soils maintained under well-defined physical conditions where transport by mass water flow could not occur. Seed-applied Pseudomonas fluorescens SBW25 was capable of rhizosphere colonization at matric potentials of -10 and -40 kPa in soil without nematodes, but colonization levels were substantially increased by the presence of nematodes. Our results suggest that nematodes can have an important role in rhizosphere colonization by bacteria in soil.

Potential Nematode Alarm Pheromone Induces Acute Avoidance in Caenorhabditis elegans.

Science.gov (United States)

Zhou, Ying; Loeza-Cabrera, Mario; Liu, Zheng; Aleman-Meza, Boanerges; Nguyen, Julie K; Jung, Sang-Kyu; Choi, Yuna; Shou, Qingyao; Butcher, Rebecca A; Zhong, Weiwei

2017-07-01

It is crucial for animal survival to detect dangers such as predators. A good indicator of dangers is injury of conspecifics. Here we show that fluids released from injured conspecifics invoke acute avoidance in both free-living and parasitic nematodes. Caenorhabditis elegans avoids extracts from closely related nematode species but not fruit fly larvae. The worm extracts have no impact on animal lifespan, suggesting that the worm extract may function as an alarm instead of inflicting physical harm. Avoidance of the worm extract requires the function of a cGMP signaling pathway that includes the cGMP-gated channel TAX-2/TAX-4 in the amphid sensory neurons ASI and ASK. Genetic evidence indicates that the avoidance behavior is modulated by the neurotransmitters GABA and serotonin, two common targets of anxiolytic drugs. Together, these data support a model that nematodes use a nematode-specific alarm pheromone to detect conspecific injury. Copyright © 2017 by the Genetics Society of America.

Genetic identification of anisakid nematodes isolated from largehead hairtail (Trichiurus japonicus in Korea

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Jeong-Ho Kim

2016-07-01

Full Text Available Abstract Background The nematode species belonging to genus Anisakis occur at their third larval stage in numerous marine teleost fish species worldwide and known to cause accidental human infection through the ingestion of raw or undercooked fish or squids. They may also draw the attention of consumers because of the visual impact of both alive and dead worms. Therefore, the information on their geographical distribution and clear species identification is important for epidemiological survey and further prevention of human infection. Results For identification of anisakid nematodes species isolated from largehead hairtail (Trichiurus japonicus, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP analysis of internal transcribed spacers of ribosomal DNA were conducted. Mitochondrial cytochrome c oxidase subunit 2 gene was also sequenced, and phylogenetic analysis was conducted. From the largehead hairtail (n = 9, 1259 nematodes were isolated in total. Most of the nematodes were found encapsulated throughout the viscera (56.2 %, 708/1259 or moving freely in the body cavity (41.5 %, 523/1259, and only 0.3 % (4/1259 was found in the muscles. By PCR-RFLP, three different nematode species were identified. Anisakis pegreffii was the most dominantly found (98.7 %, 1243/1259 from the largehead hairtail, occupying 98.7 % (699/708 of the nematodes in the mesenteries and 98.1 % (513/523 in the body cavity. Hybrid genotype (Anisakis simplex × A. pegreffii occupied 0.5 %, and Hysterothylacium sp. occupied 0.2 % of the nematodes isolated in this study. Conclusions The largehead hairtail may not significantly contribute accidental human infection of anisakid nematode third stage larvae because most of the nematodes were found from the viscera or body cavity, which are not consumed raw. But, a high prevalence of anisakid nematode larvae in the largehead hairtail is still in concern because they may raise food safety

Using SNP markers to dissect linkage disequilibrium at a major quantitative trait locus for resistance to the potato cyst nematode Globodera pallida on potato chromosome V

NARCIS (Netherlands)

Achenbach, U.; Caldas Paulo, M.J.; Ilarionova, E.; Lübeck, J.; Strahwald, J.; Tacke, E.; Hofferbert, H.R.

2009-01-01

The damage caused by the parasitic root cyst nematode Globodera pallida is a major yield-limiting factor in potato cultivation . Breeding for resistance is facilitated by the PCR-based marker 'HC', which is diagnostic for an allele conferring high resistance against G. pallida pathotype Pa2/3 that

Connection between the decline of spruce and occurrence of animal pests, especially nematodes

Energy Technology Data Exchange (ETDEWEB)

Timans, U.

1986-12-01

In various regions of Bavaria, affected by the decline of spruce, attack by insects and especially nematodes was examined on diseased and healthy spruces. A connection between harmful forest insects and the decline of spruce did not become evident, neither over wide areas nor by examination of single trees. Attack by nematodes was examined in soil and wood samples and also in fine feeder roots of diseased and healthy trees. Plant-parasitic nematodes were not found in the wood and in feeder roots. Although root-parasitic nematodes were present in soil samples, their density was too little to account for a direct damage to spruce. They occurred likewise in samples from healthy and diseased trees. Plant-parasitic nematodes can thus be excluded as a possible causal agent for the decline of spruce.

The entomopathogenic nematode Heterorhabditis megidis: host searching behaviour, infectivity and reproduction

NARCIS (Netherlands)

Boff, M.I.C.

2001-01-01

Entomopathogenic nematodes in the families Heterorhabditidae and Steinernematidae have considerable potential as biological control agents of soil-inhabiting insect pests. Attributes making these nematodes ideal biological control agents include their broad host range, high virulence,

Daytime warming has stronger negative effects on soil nematodes than night-time warming

Science.gov (United States)

Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

2017-03-01

Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatment significantly decreased soil nematodes density, and night-time warming treatment marginally affected the density. The response of bacterivorous nematode and fungivorous nematode to experimental warming showed the same trend with the total density. Redundancy analysis revealed an opposite effect of soil moisture and soil temperature, and the most important of soil moisture and temperature in night-time among the measured environment factors, affecting soil nematode community. Our findings suggested that daily minimum temperature and warming induced drying are most important factors affecting soil nematode community under the current global asymmetric warming.

Mechanisms Involved in Nematode Control by Endophytic Fungi.

Science.gov (United States)

Schouten, Alexander

2016-08-04

Colonization of plants by particular endophytic fungi can provide plants with improved defenses toward nematodes. Evidently, such endophytes can be important in developing more sustainable agricultural practices. The mechanisms playing a role in this quantitative antagonism are poorly understood but most likely multifactorial. This knowledge gap obstructs the progress regarding the development of endophytes or endophyte-derived constituents into biocontrol agents. In part, this may be caused by the fact that endophytic fungi form a rather heterogeneous group. By combining the knowledge of the currently characterized antagonistic endophytic fungi and their effects on nematode behavior and biology with the knowledge of microbial competition and induced plant defenses, the various mechanisms by which this nematode antagonism operates or may operate are discussed. Now that new technologies are becoming available and more accessible, the currently unresolved mechanisms can be studied in greater detail than ever before.

Small-molecule pheromones and hormones controlling nematode development.

Science.gov (United States)

Butcher, Rebecca A

2017-05-17

The existence of small-molecule signals that influence development in Caenorhabditis elegans has been known for several decades, but only in recent years have the chemical structures of several of these signals been established. The identification of these signals has enabled connections to be made between these small molecules and fundamental signaling pathways in C. elegans that influence not only development but also metabolism, fertility, and lifespan. Spurred by these important discoveries and aided by recent advances in comparative metabolomics and NMR spectroscopy, the field of nematode chemistry has the potential to expand dramatically in the coming years. This Perspective will focus on small-molecule pheromones and hormones that influence developmental events in the nematode life cycle (ascarosides, dafachronic acids, and nemamides), will cover more recent work regarding the biosynthesis of these signals, and will explore how the discovery of these signals is transforming our understanding of nematode development and physiology.

Studies on improvement of tomato productivity in a large-scale greenhouse: Prediction of tomato yield based on integrated solar radiation

International Nuclear Information System (INIS)

Hisaeda, K.; Nishina, H.

2007-01-01

As there are currently many large-scale production facilities that have contracts with the large retailing companies, accurate prediction of yield is necessary. The present study developed a method to predict tomato yield accurately using the data on the outside solar radiation. The present study was conducted in a Venlo-type greenhouse (29,568 square m) at Sera Farm Co., Ltd. in Sera-cho in Hiroshima prefecture. The cultivar used for this experiment was plum tomato. The sowing took place on July 18, the planting took place on August 30, and the harvesting started on October 9, 2002. The planting density was 2.5 plants msup(-2). As the results of the analysis of correlation between the weekly tomato yield and the integrated solar radiation for the period from October 7 to July 28 (43 weeks), the highest correlation (r = 0.518) between the weekly tomato yield and the solar radiation integrated from seven to one weeks before the harvesting was observed. Further investigation by the same correlation analysis was conducted for the 25 weeks period from December 8 to May 26, during which time the effect of growing stages and air temperature were considered to be relatively small. The results showed the highest correlation (r = 0.730) between the weekly tomato yield and the solar radiation integrated from eight to one weeks before the harvesting. The tomato yield occasionally needed to be adjusted at Sera Farm. Consequently, the correlation between the three-week moving average of tomato yield and the integrated solar radiation was calculated. The results showed the highest correlation was obtained for the period from eight to one weeks before the harvesting (r = 0.860). This study therefore showed that it was possible to predict the tomato yield (y: kg.msup(-2).weeksup(-1)) using the following equation on the solar radiation integrated from eight to one weeks before the harvesting(x: MJ.msup(-2)): y = 7.50 x 10 sup(-6)x + 0.148 (rsup(2) = 0.740)

Plant and soil nematodes from Lokchao Yangoupokpi Wildlife Sanctuary, Manipur, India

Directory of Open Access Journals (Sweden)

N. Mohilal

2009-03-01

Full Text Available In the present study soil samples were collected from Lokchao Yangoupokpi Wildlife Sanctuary to investigate about what nematode species are associated with different plant hosts. This study shows rich nematode diversity in the sanctuary.

EFFECT OF SOIL FERTILITY MANAGEMENT PRACTICES ON NEMATODE DESTROYING FUNGI IN TAITA, KENYA

Directory of Open Access Journals (Sweden)

Peter M Wachira

2010-10-01

Full Text Available The effect of soil fertility management practices on nematode destroying fungi was investigated for three seasons in Taita, Kenya. The study aimed at identifying soil fertility practice that promoted nematode destroying fungi in the soil. Field experiments were established in Taita district, the treatments comprised of Mavuno fertilizer, Triple super- phosphate and calcium ammonium nitrate (TSP+CAN, cow manure and a control where no amendments were applied. This experiment was replicated in ten farms and repeated in three planting seasons. Isolation of nematode destroying fungi carried out was using the soil sprinkle technique and the isolates were identified using the key described by Cooke and Godfrey (1964. There were significant difference (P= 1.705 x 10-06 in occurrence of the nematode destroying fungi between soil fertility treatments. The highest mean (1.6 occurrence of nematode destroying fungi was recorded in soils amended with cow manure and the least (0.7 was recorded in soils from the control plots. A mean of 0.78 was recorded in soils from both TSP+CAN and Mavuno fertilizers. Plots amended with cow manure presented the highest diversity of nematodes followed by the control, then TSP+CAN and least in Mavuno with shannon indices of 0.34, 0.15, 0.13 and 0.11 respectively. Sixty percent of all the isolated nematode destroying fungi genera were from plots treated with cow manure and only twenty percent were from plots amended with the inorganic fertilizer. The control plots recorded higher number of nematode destroying fungi compared to the soils that received inorganic fertilizers.

Analysis of nematode motion using an improved light-scatter based system.

Directory of Open Access Journals (Sweden)

Chuck S Nutting

2015-02-01

Full Text Available The detailed assessment of nematode activity and viability still remains a relatively undeveloped area of biological and medical research. Computer-based approaches to assessing the motility of larger nematode stages have been developed, yet these lack the capability to detect and analyze the more subtle and important characteristics of the motion of nematodes. There is currently a need to improved methods of assessing the viability and health of parasitic worms.We describe here a system that converts the motion of nematodes through a light-scattering system into an electrical waveform, and allows for reproducible, and wholly non-subjective, assessment of alterations in motion, as well as estimation of the number of nematode worms of different forms and sizes. Here we have used Brugia sp. microfilariae (L1, infective larvae (L3 and adults, together with the free-living nematode Caenorhabditis elegans.The motion of worms in a small (200 ul volume can be detected, with the presence of immotile worms not interfering with the readings at practical levels (up to at least 500 L1 /200 ul. Alterations in the frequency of parasite movement following the application of the anti-parasitic drugs, (chloroquine and imatinib; the anti-filarial effect of the latter agent is the first demonstrated here for the first time. This system can also be used to estimate the number of parasites, and shortens the time required to estimate parasites numbers, and eliminates the need for microscopes and trained technicians to provide an estimate of microfilarial sample sizes up to 1000 parasites/ml. Alterations in the form of motion of the worms can also be depicted.This new instrument, named a "WiggleTron", offers exciting opportunities to further study nematode biology and to aid drug discovery, as well as contributing to a rapid estimate of parasite numbers in various biological samples.

Outcrossing and crossbreeding recovers deteriorated traits in laboratory cultured Steinernema carpocapsae nematodes.

Science.gov (United States)

Chaston, John M; Dillman, Adler R; Shapiro-Ilan, David I; Bilgrami, Anwar L; Gaugler, Randy; Hopper, Keith R; Adams, Byron J

2011-06-01

The nematode Steinernema carpocapsae infects and kills many pest insects in agro-ecosystems and is commonly used in biocontrol of these pests. Growth of the nematodes prior to distribution for biocontrol commonly results in deterioration of traits that are essential for nematode persistence in field applications. To better understand the mechanisms underlying trait deterioration of the efficacy of natural parasitism in entomopathogenic nematodes, we explored the maintenance of fitness related traits including reproductive capacity, heat tolerance, virulence to insects and 'tail standing' (formerly called nictation) among laboratory-cultured lines derived from natural, randomly mating populations of S. carpocapsae. Laboratory cultured nematode lines with fitness-related trait values below wild-type levels regained wild-type levels of reproductive and heat tolerance traits when outcrossed with a non-deteriorated line, while virulence and 'tail standing' did not deteriorate in our experiments. Crossbreeding two trait-deteriorated lines with each other also resulted in restoration of trait means to wild-type levels in most crossbred lines. Our results implicate inbreeding depression as the primary cause of trait deterioration in the laboratory cultured S. carpocapsae. We further suggest the possibility of creating inbred lines purged of deleterious alleles as founders in commercial nematode growth. Copyright © 2011 Australian Society for Parasitology Inc. All rights reserved.

75 FR 11111 - Pale Cyst Nematode; Update of Quarantined Areas

Science.gov (United States)

2010-03-10

...] Pale Cyst Nematode; Update of Quarantined Areas AGENCY: Animal and Plant Health Inspection Service...: Background The pale cyst nematode (PCN, Globodera pallida) is a major pest of potato crops in cool... made changes to the area in the State of Idaho that is quarantined to prevent the spread of pale cyst...

Nematodes from terrestrial and freshwater habitats in the Arctic

Science.gov (United States)

2014-01-01

Abstract We present an updated list of terrestrial and freshwater nematodes from all regions of the Arctic, for which records of properly identified nematode species are available: Svalbard, Jan Mayen, Iceland, Greenland, Nunavut, Northwest territories, Alaska, Lena River estuary, Taymyr and Severnaya Zemlya and Novaya Zemlya. The list includes 391 species belonging to 146 genera, 54 families and 10 orders of the phylum Nematoda. PMID:25197239

Nematode community structure along a central Chile margin transect influenced by the oxygen minimum zone

Science.gov (United States)

Neira, Carlos; King, Ian; Mendoza, Guillermo; Sellanes, Javier; De Ley, Paul; Levin, Lisa A.

2013-08-01

Nematodes are among the metazoans most tolerant of low-oxygen conditions and play major roles in seafloor ecosystem processes. Nematode communities were studied in sediments off Concepción, Central Chile, spanning the outer shelf within the OMZ (122 m) to the mid-lower continental slope (972 m) beneath the OMZ. The total density and biomass of nematodes (core depth 0-10 cm) ranged from 677 to 2006 ind. 10 cm-2, and 168.4 to 506.5 μg DW 10 cm-2, respectively. Among metazoan meiofaunal taxa, nematodes predominated at all sites both in terms of relative abundance (83.7-99.4%) and biomass (53.8-88.1%), followed by copepods, nauplii and polychaetes. Nematodes were represented by 33 genera distributed among 17 families, with densities greatest at low oxygen sites (122-364 m; ~2000 ind. 10 cm-2). Nematode generic and trophic diversity, and individual biomass were lowest, and Rank 1 dominance was highest, at the most oxygen-depleted site (122 m), despite the fact that the organic carbon content of the sediment was maximal at this depth. At the most oxygenated slope sites (827 and 972 m), all of Wieser's nematode feeding groups were represented. In contrast, at the lowest-oxygen site, only selective deposit (bacterial) feeders (1A) were present, indicating a reduction in trophic complexity. A large percentage of nematodes inhabited subsurface sediment layers (>1 cm). At deeper, more oxygenated sites (827 and 972 m), nematode individual biomass increased downcore, while within the OMZ, nematode biomass was low and remained relatively uniform through the sediment column. The concentration of nematodes in deeper sediment layers, the vertical distribution of the feeding groups, as well as the high nutritional quality of the deeper layers, suggest a differential resource partitioning of the food available, which may reduce interspecific competition.

[Diversity of soil nematode communities in the subalpine and alpine forests of western Sichuan, China.

Science.gov (United States)

Chen, Ya; Yang, Wan Qin; Wu, Fu Zhong; Yang, Fan; Lan, Li Ying; Liu, Yu Wei; Guo, Cai Hong; Tan, Bo

2017-10-01

In order to understand the diversity of soil nematodes in the subalpine/alpine forests of the eastern Qinghai-Tibet Plateau, soil nematodes in the primary forest, mixed forest and secondary forest of Abies faxoniana were extracted by elutriation and sugar-centrifugation method in July 2015, and the composition and structure characteristics of soil nematode communities were studied in the three forests at different altitudes. A total of 37950 soil nematodes were collected, which belonged to 20 families and 27 genera, and the mean density was 4217 ind·100 g -1 dry soil. Filenchus was the dominant genus in the primary forest, and Filenchus and Pararotylenchus in the mixed forest and secondary forest, respectively. The individual number of each dominant genus was significantly affected by forest type. All nematode individuals were classified into the four trophic groups of bacterivores, fungivores, plant-parasites and omnivore-predators. The fungivores were dominant in the primary and secondary forest and the bacterivores in the mixed forest. The number of soil nematode c-p (colonizer-persister) groups of c-p 1, c-p 2, c-p 3 and c-p 4 accounted for 6.1%, 51.1%, 30.0% and 12.7% of the total nematode abundance, respectively. The maturity index (MI), the total maturity index (∑MI) and the plant parasitic index (PPI) of soil nematodes decreased gradually with the increase of altitude. The nematode channel ratio in the mixed forest was higher than 0.5, but that in the primary forest and secondary forest was below 0.5. The forest type significantly affected the soil nematode maturity index and channel ratio, but the forest type, soil layer and their interaction had no significant effect on the diversity index. There were obvious diffe-rences in the composition, nutrient structure and energy flow channel of soil nematodes in the subalpine/alpine forests of western Sichuan, providing an important reference for understanding the function of soil nematodes in soil processes

Bioinformatic prediction of arthropod/nematode-like peptides in non-arthropod, non-nematode members of the Ecdysozoa.

Science.gov (United States)

Christie, Andrew E; Nolan, Daniel H; Garcia, Zachery A; McCoole, Matthew D; Harmon, Sarah M; Congdon-Jones, Benjamin; Ohno, Paul; Hartline, Niko; Congdon, Clare Bates; Baer, Kevin N; Lenz, Petra H

2011-02-01

The Onychophora, Priapulida and Tardigrada, along with the Arthropoda, Nematoda and several other small phyla, form the superphylum Ecdysozoa. Numerous peptidomic studies have been undertaken for both the arthropods and nematodes, resulting in the identification of many peptides from each group. In contrast, little is known about the peptides used as paracrines/hormones by species from the other ecdysozoan taxa. Here, transcriptome mining and bioinformatic peptide prediction were used to identify peptides in members of the Onychophora, Priapulida and Tardigrada, the only non-arthropod, non-nematode members of the Ecdysozoa for which there are publicly accessible expressed sequence tags (ESTs). The extant ESTs for each phylum were queried using 106 arthropod/nematode peptide precursors. Transcripts encoding calcitonin-like diuretic hormone and pigment-dispersing hormone (PDH) were identified for the onychophoran Peripatopsis sedgwicki, with transcripts encoding C-type allatostatin (C-AST) and FMRFamide-like peptide identified for the priapulid Priapulus caudatus. For the Tardigrada, transcripts encoding members of the A-type allatostatin, C-AST, insect kinin, orcokinin, PDH and tachykinin-related peptide families were identified, all but one from Hypsibius dujardini (the exception being a Milnesium tardigradum orcokinin-encoding transcript). The proteins deduced from these ESTs resulted in the prediction of 48 novel peptides, six onychophoran, eight priapulid and 34 tardigrade, which are the first described from these phyla. Copyright © 2010 Elsevier Inc. All rights reserved.

Micro-electro-fluidic grids for nematodes: a lens-less, image-sensor-less approach for on-chip tracking of nematode locomotion.

Science.gov (United States)

Liu, Peng; Martin, Richard J; Dong, Liang

2013-02-21

This paper reports on the development of a lens-less and image-sensor-less micro-electro-fluidic (MEF) approach for real-time monitoring of the locomotion of microscopic nematodes. The technology showed promise for overcoming the constraint of the limited field of view of conventional optical microscopy, with relatively low cost, good spatial resolution, and high portability. The core of the device was microelectrode grids formed by orthogonally arranging two identical arrays of microelectrode lines. The two microelectrode arrays were spaced by a microfluidic chamber containing a liquid medium of interest. As a nematode (e.g., Caenorhabditis elegans) moved inside the chamber, the invasion of part of its body into some intersection regions between the microelectrodes caused changes in the electrical resistance of these intersection regions. The worm's presence at, or absence from, a detection unit was determined by a comparison between the measured resistance variation of this unit and a pre-defined threshold resistance variation. An electronic readout circuit was designed to address all the detection units and read out their individual electrical resistances. By this means, it was possible to obtain the electrical resistance profile of the whole MEF grid, and thus, the physical pattern of the swimming nematode. We studied the influence of a worm's body on the resistance of an addressed unit. We also investigated how the full-frame scanning and readout rates of the electronic circuit and the dimensions of a detection unit posed an impact on the spatial resolution of the reconstructed images of the nematode. Other important issues, such as the manufacturing-induced initial non-uniformity of the grids and the electrotaxic behaviour of nematodes, were also studied. A drug resistance screening experiment was conducted by using the grids with a good resolution of 30 × 30 μm(2). The phenotypic differences in the locomotion behaviours (e.g., moving speed and oscillation

75 FR 54592 - Pale Cyst Nematode; Update of Quarantined Areas

Science.gov (United States)

2010-09-08

...] Pale Cyst Nematode; Update of Quarantined Areas AGENCY: Animal and Plant Health Inspection Service... made changes to the area in the State of Idaho that is quarantined to prevent the spread of pale cyst nematode. The description of the quarantined area was updated on April 26, 2010. As a result of these...

Induction of mutations for nematode resistance in tomato

International Nuclear Information System (INIS)

Alameddine, A.

1976-01-01

The objective of this work is to develop resistance to root-knot nematodes in tomato by induction, selection and utilization of the newly created resistant strains. Seeds of two varieties of tomato Lycopersicon esculentum L., namely Amcopack and Supermarmande, were subjected to various doses of gamma rays ranging from 10 Krads to 40 Krads in an effort to gain resistance to Meloidogyne incognita Chitwood, the prevalent species of nematodes in Lebanon. The variety Supermarmande seemed not to be affected by irradiation while Amcopack gained some resistance with a corresponding increase in the dose of radiation. The data suggest that in a variety like Amcopack, irradiation may stimulate resistance while in others like Supermarmande, susceptibility is not reduced with a corresponding increase of dosage. Those alterations in reaction within varieties may be due to genetic differences which allow some varieties to acquire resistance to nematodes when exposed to certain dosages, while others to suffer seriously due to sensitivity. (author)

Diversity and incidence of plant-parasitic nematodes in Belgian turf grass

NARCIS (Netherlands)

Vandenbossche, B.; Viaene, N.; Sutter, de N.; Maes, M.; Karssen, G.; Bert, W.

2011-01-01

Eleven golf courses and eight football pitches, located in Belgium, were surveyed for plant-parasitic nematodes. This revealed a remarkably high diversity: 52 different species/taxa were identified morphologically, belonging to 23 genera and nine families. Among the most prevalent nematodes on both

A survival-reproduction trade-off in entomopathogenic nematodes mediated by their bacterial symbionts.

Science.gov (United States)

Emelianoff, Vanya; Chapuis, Elodie; Le Brun, Nathalie; Chiral, Magali; Moulia, Catherine; Ferdy, Jean-Baptiste

2008-04-01

In this work, we investigate the investment of entomopathogenic Steinernema nematodes (Rhabditidae) in their symbiotic association with Xenorhabdus bacteria (Enterobacteriaceae). Their life cycle comprises two phases: (1) a free stage in the soil, where infective juveniles (IJs) of the nematode carry bacteria in a digestive vesicle and search for insect hosts, and (2) a parasitic stage into the insect where bacterial multiplication, nematode reproduction, and production of new IJs occur. Previous studies clearly showed benefits to the association for the nematode during the parasitic stage, but preliminary data suggest the existence of costs to the association for the nematode in free stage. IJs deprived from their bacteria indeed survive longer than symbiotic ones. Here we show that those bacteria-linked costs and benefits lead to a trade-off between fitness traits of the symbiotic nematodes. Indeed IJs mortality positively correlates with their parasitic success in the insect host for symbiotic IJs and not for aposymbiotic ones. Moreover mortality and parasitic success both positively correlate with the number of bacteria carried per IJ, indicating that the trade-off is induced by symbiosis. Finally, the trade-off intensity depends on parental effects and, more generally, is greater under restrictive environmental conditions.

Trophic position of soil nematodes in boreal forests as indicated by stable isotope analysis

Science.gov (United States)

Kudrin, Alexey; Tsurikov, Sergey

2016-04-01

Despite the well-developed trophic classification of soil nematodes, their position in soil food webs is still little understood. Observed deviations from the typical feeding strategy indicate that a simplified trophic classification probably does not fully reflect actual trophic interactions. Furthermore, the extent and functional significance of nematodes as prey for other soil animals remains unknown. Stable isotope analysis (SIA) is powerful tool for investigating the structure of soil food webs, but its application to the study of soil nematodes has been limited to only a few studies. We used stable isotope analysis to gain a better understanding of trophic links of several groups of soil nematodes in two boreal forests on albeluvisol. We investigated four taxonomic groups of nematodes: Mononchida, Dorylaimida, Plectidae and Tylenchidae (mostly from the genus Filenchus), that according to the conventional trophic classification represent predators, omnivores, bacterivores and root-fungal feeders, respectively. To assess the trophic position of nematodes, we used a comparison against a set of reference species including herbivorous, saprophagous and predatory macro-invertebrates, oribatid and mesostigmatid mites, and collembolans. Our results suggest that trophic position of the investigated groups of soil nematodes generally corresponds to the conventional classification. All nematodes were enriched in 13C relative to Picea abies roots and litter, and mycorrhizal fungal mycelium. Root-fungal feeders Tylenchidae had δ15N values similar to those of earthworms, enchytraeids and Entomobrya collembolans, but slightly lower δ13C values. Bacterivorous Plectidae were either equal or enriched in 15N compared with saprophagous macroinvertebrates and most mesofauna species. Omnivorous Dorylaimida and predatory Mononchida were further enriched in 15N and their isotopic signature was similar to that of predatory arthropods. These data confirm a clear separation of

Soil nematodes show a mid-elevation diversity maximum and elevational zonation on Mt. Norikura, Japan.

Science.gov (United States)

Dong, Ke; Moroenyane, Itumeleng; Tripathi, Binu; Kerfahi, Dorsaf; Takahashi, Koichi; Yamamoto, Naomichi; An, Choa; Cho, Hyunjun; Adams, Jonathan

2017-06-08

Little is known about how nematode ecology differs across elevational gradients. We investigated the soil nematode community along a ~2,200 m elevational range on Mt. Norikura, Japan, by sequencing the 18S rRNA gene. As with many other groups of organisms, nematode diversity showed a high correlation with elevation, and a maximum in mid-elevations. While elevation itself, in the context of the mid domain effect, could predict the observed unimodal pattern of soil nematode communities along the elevational gradient, mean annual temperature and soil total nitrogen concentration were the best predictors of diversity. We also found nematode community composition showed strong elevational zonation, indicating that a high degree of ecological specialization that may exist in nematodes in relation to elevation-related environmental gradients and certain nematode OTUs had ranges extending across all elevations, and these generalized OTUs made up a greater proportion of the community at high elevations - such that high elevation nematode OTUs had broader elevational ranges on average, providing an example consistent to Rapoport's elevational hypothesis. This study reveals the potential for using sequencing methods to investigate elevational gradients of small soil organisms, providing a method for rapid investigation of patterns without specialized knowledge in taxonomic identification.

Effect of Tropical Rotation Crops on Meloidogyne incognita and Other Plant-Parasitic Nematodes.

Science.gov (United States)

McSorley, R; Dickson, D W

1995-12-01

In a field experiment conducted on sandy soil in Florida during the 1993 season, rotation crops of castor (Ricinus communis), velvetbean (Mucuna deeringina), 'Mississippi Silver' cowpea (Vigna unguiculata), American jointvetch (Aeschynomene americana), 'Dehapine 51' cotton (Gossypium hirsutum), and 'SX-17' sorghum-sudangrass (Sorghum bicolor x S. sudanense) were effective in maintaining low population densities (450/100 cm(3) soil) resulted after 'Clemson Spineless' okra (Hibiscus esculentus) and 'Kirby' soybean (Glycine max). Following a winter cover crop of rye (Secale cereale), densities of M. incognita following the six most effective rotation crops (1993 season) remained relatively low (crop planted in 1994, but increased by the end of the eggplant crop. The rotation crops planted during 1993 had little effect on yield of eggplant in 1994. Eggplant yield was inversely correlated with preplant densities (Pi) of Belonolaimus longicaudatus (r = -0.282; P crop cultivars were lower (P crops intended for suppression of individual Meloidogyne spp. be evaluated for their response to other nematode pests as well.

Effect of Integrated Weed Management Methods on Yield and Yield Components of Corn (Zea mays L. in Kermanshah Province, Iran

Directory of Open Access Journals (Sweden)

R. Amini

2017-08-01

Full Text Available Introduction: Corn (Zea mays L. is cultivated widely throughout the world and has the highest production among the cerealsafter rice and wheat. In Iran the total production of corn in 2013 was more than 2540000 tons. Weeds are one of the greatest limiting factors to decrease corn yield in Iran as the average yield loss due to weeds in the fields of Kermanshah in 2009 was 17.32 %. The herbicides are the main weed control method in conventional cropping systems but their application has been increased herbicide resistant weeds and environmental pollution. Integrated weed management combines all applicable including chemical and non-chemical methods to reduce the effect of weeds in the cropping systems. Thus, Weed control strategies such as tillage, mulch, cover crops and intercropping could be used for integrated weed management of corn. Previous studies showed that crop residues such as rye (Secale sereal L., wheat (Triticum aestivum L., barley (Hordeum vulgare L. and clover (Trifolium sp., cover crops and living mulch could inhibit weed germination and growth. Therefore the objective of this study was evaluating the effects of some integrated weed management treatments on weed characteristics, yield components and grain yield of corn. Materials and methods: In order to evaluate the effect of some weed management treatments on corn (Zea mays L. yield an experiment was conducted in 2014 in Ravansar, Kermanshah, Iran. This study was arranged based on randomized complete block design with 10 treatments and three replications. The weed management treatments were including 1-chemical control followed by mechanical control (application of nicosulfuron at a dose of 80 g.a.i.ha-1 + cultivator 40 days after emergence 2- chemical control followed by mechanical control (application of 2,4-D+MCPA at a dose of 675 g.a.i.ha-1 + cultivator 40 days after emergence 3- cultural control followed by mechanical control (planting hairy vetch (Vicia villosa in the fall

Effect of the Entomogenous Nematode Nemplectana carpocapsae on the Tachinid Parasite Compsilura concinnata (Diptera: Tachinidae)

Science.gov (United States)

Kaya, Harry K.

1984-01-01

The entomogenous nematode Neoaplectana carpocapsae and its associated bacterium, Xenorhabdus nematophilus, could not infect the pupal stage of the tachinid Compsilura concinnata through the puparium. N. carpocapsae had an adverse effect on 1-, 2- and 3-day-old C. concinnata larvae within the armyworm host in petri dish tests. All 1-day-old larvae treated with nematodes died in their hosts, whereas 61% and 69% of 2- and 3-day-old larvae treated with nematodes, respectively, died. However, the survivors developed to adults. Nine to thirty-seven percent of adult tachinids which emerged from nematode-treated soil (50 nematodes/cm²) were infected with N. carpocapsae. The nematode adversely affects C. concinnata directly by the frank infection of the tachinid and indirectly by causing the premature death of the host which results in tachinid death. PMID:19295866

On the track of transfer cell formation by specialized plant-parasitic nematodes.

Science.gov (United States)

Rodiuc, Natalia; Vieira, Paulo; Banora, Mohamed Youssef; de Almeida Engler, Janice

2014-01-01

Transfer cells are ubiquitous plant cells that play an important role in plant development as well as in responses to biotic and abiotic stresses. They are highly specialized and differentiated cells playing a central role in the acquisition, distribution and exchange of nutrients. Their unique structural traits are characterized by augmented ingrowths of invaginated secondary wall material, unsheathed by an amplified area of plasma membrane enriched in a suite of solute transporters. Similar morphological features can be perceived in vascular root feeding cells induced by sedentary plant-parasitic nematodes, such as root-knot and cyst nematodes, in a wide range of plant hosts. Despite their close phylogenetic relationship, these obligatory biotrophic plant pathogens engage different approaches when reprogramming root cells into giant cells or syncytia, respectively. Both nematode feeding-cells types will serve as the main source of nutrients until the end of the nematode life cycle. In both cases, these nematodes are able to remarkably maneuver and reprogram plant host cells. In this review we will discuss the structure, function and formation of these specialized multinucleate cells that act as nutrient transfer cells accumulating and synthesizing components needed for survival and successful offspring of plant-parasitic nematodes. Plant cells with transfer-like functions are also a renowned subject of interest involving still poorly understood molecular and cellular transport processes.

On the track of transfer cells formation by specialized plant-parasitic nematodes

Directory of Open Access Journals (Sweden)

Natalia eRodiuc

2014-05-01

Full Text Available Transfer cells are ubiquitous plant cells that play an important role in plant development as well as in responses to biotic and abiotic stresses. They are highly specialized and differentiated cells playing a central role in the acquisition, distribution and exchange of nutrients. Their unique structural traits are characterized by augmented ingrowths of invaginated secondary wall material, unsheathed by an amplified area of plasma membrane enriched in a suite of solute transporters. Similar morphological features can be perceived in vascular root feeding cells induced by sedentary plant-parasitic nematodes, such as root-knot and cyst nematodes, in a wide range of plant hosts. Despite their close phylogenetic relationship, these obligatory biotrophic plant pathogens engage different approaches when reprogramming root cells into giant cells or syncytia, respectively. Both nematode feeding-cells types will serve as the main source of nutrients until the end of the nematode life cycle. In both cases, these nematodes are able to remarkably maneuver and reprogram plant host cells. In this review we will discuss the structural, functional and morphogenetic characteristics function and formation of these specialized multinucleate cells that act as nutrient transfer cells to accumulate and synthesize components needed for survival and successful offspring of plant-parasitic nematodes. Plant cells with transfer-like functions are also a renowned subject of interest involving still poorly understood molecular and cellular transport processes.

Nematode pests threatening soybean production in South Africa, with reference to Meloidogyne

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Hendrika Fourie

2015-09-01

Full Text Available The area planted to soybean in South Africa has increased by 54% since the 2009 growing season, mainly as a result of the increasing demand for protein-rich food and fodder sources. Moreover, the introduction of advanced technology, namely the availability of genetically modified herbicide tolerant soybean cultivars also contributed towards increased soybean production. The omnipresence of plant-parasitic nematodes in local agricultural soils, however, poses a threat to the sustainable expansion and production of soybean and other rotation crops. Meloidogyne incognita and M. javanica are the predominant nematode pests in local soybean production areas and those where other grain-, legume- and/or vegetable crops are grown. The lack of registered nematicides for soybean locally, crop production systems that are conducive to nematode pest build-ups as well as the limited availability of genetic host plant resistance to root-knot nematode pests, complicate their management. Research aimed at various aspects related to soybean-nematode research, namely, audits of nematode assemblages associated with the crop, identification of genetic host plant resistance in soybean germplasm to M. incognita and M. javanica, the use of molecular markers that are linked to such genetic resistance traits as well as agronomic performance of pre-released cultivars that can be valuable to producers and the industry are accentuated in this review. Evaluation of synthetically-derived as well as biological-control agents are also discussed as complementary management tactics. It is important that lessons learned through extensive research on soybean-nematode interactions in South Africa be shared with researchers and industries in other countries as they might experience or expect similar problems and/or challenges.

Screening of in vitro derived mutants of banana against nematodes ...

African Journals Online (AJOL)

The rest of the mutants namely Ro Im V4 6-1-2 and Si Im V4 6-2-5 were found to be susceptible to nematodes. The resistant and moderately resistant mutants of banana could be further used in breeding programmes as well as being recognized as potential cultivars of commerce. Key words: Banana, nematode, resistance, ...

Effects of midas® on nematodes in commercial floriculture production in Florida.

Science.gov (United States)

Kokalis-Burelle, Nancy; Rosskopf, Erin N; Albano, Joseph P; Holzinger, John

2010-03-01

Cut flower producers currently have limited options for nematode control. Four field trials were conducted in 2006 and 2007 to evaluate Midas® (iodomethane:chloropicrin 50:50) for control of root-knot nematodes (Meloidogyne arenaria) on Celosia argentea var. cristata in a commercial floriculture production field in southeastern Florida. Midas (224 kg/ha) was compared to methyl bromide:chloropicrin (98:2, 224 kg/ha), and an untreated control. Treatments were evaluated for effects on Meloidogyne arenaria J2 and free-living nematodes in soil through each season, and roots at the end of each season. Plant growth and root disease were also assessed. Population levels of nematodes isolated from soil were highly variable in all trials early in the season, and generally rebounded by harvest, sometimes to higher levels in fumigant treatments than in the untreated control. Although population levels of nematodes in soil were not significantly reduced during the growing season, nematodes in roots and galling at the end of the season were consistently reduced with both methyl bromide and Midas compared to the untreated control. Symptoms of phytotoxicity were observed in Midas treatments during the first year and were attributed to Fe toxicity. Fertilization was adjusted during the second year to investigate potential fumigant/fertilizer interactions. Interactions occurred at the end of the fourth trial between methyl bromide and fertilizers with respect to root-knot nematode J2 isolated from roots and galling. Fewer J2 were isolated from roots treated with a higher level of Fe (3.05%) in the form of Fe sucrate, and galling was reduced in methyl bromide treated plots treated with this fertilizer compared to Fe EDTA. Reduced galling was also seen with Midas in Fe sucrate fertilized plots compared to Fe EDTA. This research demonstrates the difficulty of reducing high root-knot nematode population levels in soil in subtropical conditions in production fields that have been

The diversity and evolution of nematodes (Pharyngodonidae) infecting New Zealand lizards.

Science.gov (United States)

Mockett, Sarah; Bell, Trent; Poulin, Robert; Jorge, Fátima

2017-04-01

Host-parasite co-evolutionary studies can shed light on diversity and the processes that shape it. Molecular methods have proven to be an indispensable tool in this task, often uncovering unseen diversity. This study used two nuclear markers (18S rRNA and 28S rRNA) and one mitochondrial (cytochrome oxidase subunit I) marker to investigate the diversity of nematodes of the family Pharyngodonidae parasitizing New Zealand (NZ) lizards (lygosomine skinks and diplodactylid geckos) and to explore their co-evolutionary history. A Bayesian approach was used to infer phylogenetic relationships of the parasitic nematodes. Analyses revealed that nematodes parasitizing skinks, currently classified as Skrjabinodon, are more closely related to Spauligodon than to Skrjabinodon infecting NZ geckos. Genetic analyses also uncovered previously undetected diversity within NZ gecko nematodes and provided evidence for several provisionally cryptic species. We also examined the level of host-parasite phylogenetic congruence using a global-fit approach. Significant congruence was detected between gecko-Skrjabinodon phylogenies, but our results indicated that strict co-speciation is not the main co-evolutionary process shaping the associations between NZ skinks and geckos and their parasitic nematodes. However, further sampling is required to fully resolve co-phylogenetic patterns of diversification in this host-parasite system.

Functional Characterization of a Novel Class of Morantel-Sensitive Acetylcholine Receptors in Nematodes.

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Elise Courtot

2015-12-01

Full Text Available Acetylcholine receptors are pentameric ligand-gated channels involved in excitatory neuro-transmission in both vertebrates and invertebrates. In nematodes, they represent major targets for cholinergic agonist or antagonist anthelmintic drugs. Despite the large diversity of acetylcholine-receptor subunit genes present in nematodes, only a few receptor subtypes have been characterized so far. Interestingly, parasitic nematodes affecting human or animal health possess two closely related members of this gene family, acr-26 and acr-27 that are essentially absent in free-living or plant parasitic species. Using the pathogenic parasitic nematode of ruminants, Haemonchus contortus, as a model, we found that Hco-ACR-26 and Hco-ACR-27 are co-expressed in body muscle cells. We demonstrated that co-expression of Hco-ACR-26 and Hco-ACR-27 in Xenopus laevis oocytes led to the functional expression of an acetylcholine-receptor highly sensitive to the anthelmintics morantel and pyrantel. Importantly we also reported that ACR-26 and ACR-27, from the distantly related parasitic nematode of horses, Parascaris equorum, also formed a functional acetylcholine-receptor highly sensitive to these two drugs. In Caenorhabditis elegans, a free-living model nematode, we demonstrated that heterologous expression of the H. contortus and P. equorum receptors drastically increased its sensitivity to morantel and pyrantel, mirroring the pharmacological properties observed in Xenopus oocytes. Our results are the first to describe significant molecular determinants of a novel class of nematode body wall muscle AChR.

Functional Characterization of a Novel Class of Morantel-Sensitive Acetylcholine Receptors in Nematodes

Science.gov (United States)

Courtot, Elise; Charvet, Claude L.; Beech, Robin N.; Harmache, Abdallah; Wolstenholme, Adrian J.; Holden-Dye, Lindy; O’Connor, Vincent; Peineau, Nicolas; Woods, Debra J.; Neveu, Cedric

2015-01-01

Acetylcholine receptors are pentameric ligand–gated channels involved in excitatory neuro-transmission in both vertebrates and invertebrates. In nematodes, they represent major targets for cholinergic agonist or antagonist anthelmintic drugs. Despite the large diversity of acetylcholine-receptor subunit genes present in nematodes, only a few receptor subtypes have been characterized so far. Interestingly, parasitic nematodes affecting human or animal health possess two closely related members of this gene family, acr-26 and acr-27 that are essentially absent in free-living or plant parasitic species. Using the pathogenic parasitic nematode of ruminants, Haemonchus contortus, as a model, we found that Hco-ACR-26 and Hco-ACR-27 are co-expressed in body muscle cells. We demonstrated that co-expression of Hco-ACR-26 and Hco-ACR-27 in Xenopus laevis oocytes led to the functional expression of an acetylcholine-receptor highly sensitive to the anthelmintics morantel and pyrantel. Importantly we also reported that ACR-26 and ACR-27, from the distantly related parasitic nematode of horses, Parascaris equorum, also formed a functional acetylcholine-receptor highly sensitive to these two drugs. In Caenorhabditis elegans, a free-living model nematode, we demonstrated that heterologous expression of the H. contortus and P. equorum receptors drastically increased its sensitivity to morantel and pyrantel, mirroring the pharmacological properties observed in Xenopus oocytes. Our results are the first to describe significant molecular determinants of a novel class of nematode body wall muscle AChR. PMID:26625142

The effects of repeated applications of the molluscicide metaldehyde and the biocontrol nematode Phasmarhabditis hermaphrodita on molluscs, earthworms, nematodes, acarids and collembolans: a two-year study in north-west Spain.

Science.gov (United States)

Iglesias, Javier; Castillejo, José; Castro, Ramón

2003-11-01

Over two years, six consecutive field experiments were done in which the chemical molluscicide metaldehyde and the nematode biocontrol agent Phasmarhabditis hermaphrodita (Schneider) were applied at the standard field rates to replicated mini-plots successively planted with lettuce, Brussels sprouts, leaf beet and cabbage, to compare the effectiveness of different treatments in reducing slug damage to the crops. Soil samples from each plot were taken prior to the start of the experiments, and then monthly, to assess the populations of slugs, snails, earthworms, nematodes, acarids and collembolans. The experiments were done on the same site and each plot received the same treatment in the six experiments. The six treatments were: (1) untreated controls, (2) metaldehyde pellets, (3 and 4) nematodes applied to the planted area 3 days prior to planting without or with previous application of cow manure slurry, (5) nematodes applied to the area surrounding the planted area 3 days prior to planting, and (6) nematodes applied to the planted area once (only in the first of the six consecutive experiments). Only the metaldehyde treatment and the nematodes applied to the planted area at the beginning of each experiment without previous application of manure significantly reduced slug damage to the plants, and only metaldehyde reduced the number of slugs contaminating the harvested plants. The numbers of slugs, snails and earthworms in soil samples were compared among the six treatments tested: with respect to the untreated controls, the numbers of Deroceras reticulatum (Müller) were significantly affected only in the metaldehyde plots, and the numbers of Arion ater L only in the plots treated with nematodes applied to the planted area 3 days prior to planting without previous application of manure; numbers of snails (Ponentina ponentina (Morelet) and Oxychilus helveticus (Blum)) were not affected by the treatment. The total numbers of all earthworm species and of Lumbricus

Immunity to gastrointestinal nematode infections

DEFF Research Database (Denmark)

Sorobetea, D.; Svensson Frej, M.; Grencis, R.

2018-01-01

Numerous species of nematodes have evolved to inhabit the gastrointestinal tract of animals and humans, with over a billion of the world's population infected with at least one species. These large multicellular pathogens present a considerable and complex challenge to the host immune system give...

Variation in the susceptibility of Drosophila to different entomopathogenic nematodes.

Science.gov (United States)

Peña, Jennifer M; Carrillo, Mayra A; Hallem, Elissa A

2015-03-01

Entomopathogenic nematodes (EPNs) in the genera Heterorhabditis and Steinernema are lethal parasites of insects that are of interest as models for understanding parasite-host interactions and as biocontrol agents for insect pests. EPNs harbor a bacterial endosymbiont in their gut that assists in insect killing. EPNs are capable of infecting and killing a wide range of insects, yet how the nematodes and their bacterial endosymbionts interact with the insect immune system is poorly understood. Here, we develop a versatile model system for understanding the insect immune response to parasitic nematode infection that consists of seven species of EPNs as model parasites and five species of Drosophila fruit flies as model hosts. We show that the EPN Steinernema carpocapsae, which is widely used for insect control, is capable of infecting and killing D. melanogaster larvae. S. carpocapsae is associated with the bacterium Xenorhabdus nematophila, and we show that X. nematophila induces expression of a subset of antimicrobial peptide genes and suppresses the melanization response to the nematode. We further show that EPNs vary in their virulence toward D. melanogaster and that Drosophila species vary in their susceptibilities to EPN infection. Differences in virulence among different EPN-host combinations result from differences in both rates of infection and rates of postinfection survival. Our results establish a powerful model system for understanding mechanisms of host-parasite interactions and the insect immune response to parasitic nematode infection. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Modelling nematode movement using time-fractional dynamics.

Science.gov (United States)

Hapca, Simona; Crawford, John W; MacMillan, Keith; Wilson, Mike J; Young, Iain M

2007-09-07

We use a correlated random walk model in two dimensions to simulate the movement of the slug parasitic nematode Phasmarhabditis hermaphrodita in homogeneous environments. The model incorporates the observed statistical distributions of turning angle and speed derived from time-lapse studies of individual nematode trails. We identify strong temporal correlations between the turning angles and speed that preclude the case of a simple random walk in which successive steps are independent. These correlated random walks are appropriately modelled using an anomalous diffusion model, more precisely using a fractional sub-diffusion model for which the associated stochastic process is characterised by strong memory effects in the probability density function.

Association between entomopathogenic nematodes and fungi for control of Rhipicephalus microplus (Acari: Ixodidae).

Science.gov (United States)

Monteiro, Caio Márcio Oliveira; Araújo, Laryssa Xavier; Matos, Renata Silva; da Silva Golo, Patrícia; Angelo, Isabele Costa; de Souza Perinotto, Wendell Marcelo; Coelho Rodrigues, Camila Aparecida; Furlong, John; Bittencourt, Vânia Rita Elias Pinheiro; Prata, Márcia Cristina Azevedo

2013-10-01

The aim of the study was to assess the effect of the association of entomopathogenic nematodes and fungi on Rhipicephalus microplus. The nematodes used were Heterorhabditis bacteriophora HP88 and Heterorhabditis indica LPP1 and the fungi were Metarhizium anisopliae IBCB 116 and Beauveria bassiana ESALQ 986. In the groups treated with the fungi, the females were immersed for 3 min in a conidial suspension, while in the groups treated with the nematodes, the ticks were exposed to infective juveniles. To evaluate the interaction between entomopathogens, the females were first immersed in a conidial suspension and then exposed to the nematodes. The egg mass weight and hatching percentage values of the groups treated with M. anisopliae IBCB 116 and B. bassiana ESALQ 986 in the two experiments were statistically similar (p > 0.05) to the values of the control group. In the groups treated only with nematodes, there was a significant reduction (p fungus M. anisopliae IBCB 116.

Successful application of entomopathogenic nematodes for the biological control of western corn rootworm larvae in Europe – a mini review

Directory of Open Access Journals (Sweden)

Toepfer, Stefan

2014-02-01

Full Text Available 10 years of joint efforts in research and development have led to a nematode-based biological control solution for one of the most destructive maize pests, the western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae. Commercially mass-produced Heterorhabditis species of beneficial entomopathogenic nematodes are ready to use. They can be applied into the soil during sowing of maize for controlling the subsequently hatching larvae of D. virgifera virgifera thus preventing root feeding and damage to maize. Policy bodies, decision makers and farmers are advised to consider biological control as one of the alternatives to synthetic pesticides in maize production, and according to the EC Directive on the sustainable use of pesticides and implementation of integrated pest management.

Effects of interactions of auxin-producing bacteria and bacterial-feeding nematodes on regulation of peanut growths.

Science.gov (United States)

Xu, Li; Xu, Wensi; Jiang, Ying; Hu, Feng; Li, Huixin

2015-01-01

The influences of an IAA (indole-3-acetic acid)-producing bacterium (Bacillus megaterium) and two bacterial-feeding nematodes (Cephalobus sp. or Mesorhabditis sp.) on the growth of peanut (Arachis hypogaea L. cv. Haihua 1) after various durations of time were investigated in natural soils. The addition of bacteria and nematodes and incubation time all significantly affected plant growth, plant root growth, plant nutrient concentrations, soil nutrient concentrations, soil microorganisms and soil auxin concentration. The addition of nematodes caused greater increases in these indices than those of bacteria, while the addition of the combination of bacteria and nematodes caused further increases. After 42-day growth, the increases in soil respiration differed between the additions of two kinds of nematodes because of differences in their life strategies. The effects of the bacteria and nematodes on the nutrient and hormone concentrations were responsible for the increases in plant growth. These results indicate the potential for promoting plant growth via the addition of nematodes and bacteria to soil.

A SNARE-Like Protein and Biotin Are Implicated in Soybean Cyst Nematode Virulence.

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Sadia Bekal

Full Text Available Phytoparasitic nematodes that are able to infect and reproduce on plants that are considered resistant are referred to as virulent. The mechanism(s that virulent nematodes employ to evade or suppress host plant defenses are not well understood. Here we report the use of a genetic strategy (allelic imbalance analysis to associate single nucleotide polymorphisms (SNPs with nematode virulence genes in Heterodera glycines, the soybean cyst nematode (SCN. To accomplish this analysis, a custom SCN SNP array was developed and used to genotype SCN F3-derived populations grown on resistant and susceptible soybean plants. Three SNPs reproducibly showed allele imbalances between nematodes grown on resistant and susceptible plants. Two candidate SCN virulence genes that were tightly linked to the SNPs were identified. One SCN gene encoded biotin synthase (HgBioB, and the other encoded a bacterial-like protein containing a putative SNARE domain (HgSLP-1. The two genes mapped to two different linkage groups. HgBioB contained sequence polymorphisms between avirulent and virulent nematodes. However, the gene encoding HgSLP-1 had reduced copy number in virulent nematode populations and appears to produce multiple forms of the protein via intron retention and alternative splicing. We show that HgSLP-1 is an esophageal-gland protein that is secreted by the nematode during plant parasitism. Furthermore, in bacterial co-expression experiments, HgSLP-1 co-purified with the SCN resistance protein Rhg1 α-SNAP, suggesting that these two proteins physically interact. Collectively our data suggest that multiple SCN genes are involved in SCN virulence, and that HgSLP-1 may function as an avirulence protein and when absent it helps SCN evade host defenses.

Short-term effects of forest disturbances on soil nematode communities in European mountain spruce forests.

Science.gov (United States)

Čerevková, A; Renčo, M; Cagáň, L

2013-09-01

The nematode communities in spruce forests were compared with the short-term effects of forest damage, caused by windstorm, wildfire and management practices of forest soils. Soil samples were collected in June and October from 2006 to 2008 in four different sites: (1) forest unaffected by the wind (REF); (2) storm-felled forest with salvaged timber (EXT); (3) modified forest affected by timber salvage (wood removal) and forest fire (FIR); and (4) storm-felled forest where timber had been left unsalvaged (NEX). Nematode analysis showed that the dominant species in all four investigated sites were Acrobeloides nanus and Eudorylaimus silvaticus. An increase of A. nanus (35% of the total nematode abundance) in the first year in the FIR site led to the highest total abundance of nematodes compared with other sites, where nematode abundance reached the same level in the third year. In the FIR site bacterial feeders appeared to be the most representative trophic group, although in the second and third year, after disturbance, the abundance of this trophic group gradually decreased. In the NEX site, the number of nematode species, population densities and Maturity Index were similar to that recorded for the FIR site. In EXT and NEX sites, the other dominant species was the plant parasitic nematode Paratylenchus microdorus. Analyses of nematodes extracted from different forest soil samples showed that the highest number of species and diversity index for species (H'spp) were in the REF site. Differences between the nematode fauna in REF and other localities were clearly depicted by cluster analysis. The greatest Structure Index and Enrichment Index values were also in REF. In the EXT site, the number of nematode species, their abundance, H'spp and Maturity Index were not significantly different from those recorded in the reference site.

Soil Nematode Response to Biochar Addition in a Chinese Wheat Field

Institute of Scientific and Technical Information of China (English)

ZHANG Xiao-Ke; LI Qi; LIANG Wen-Ju; ZHANG Min; BAO Xue-Lian; XIE Zu-Bin

2013-01-01

While studies have focused on the use of biochar as soil amendment,little attention has been paid to its effect on soil fauna.The biochar was produced from slow pyrolysis of wheat straw in the present study.Four treatments,no addition (CK) and three rates of biochar addition at 2400 (B1),12000 (B5) and 48000 kg ha-1 (B20),were investigated to assess the effect of biochar addition to soil on nematode abundance and diversity in a microcosm trial in China.The B5 and B20 application significantly increased the total organic carbon and the C/N ratio.No significant difference in total nematode abundance was found among the treatments.The biochar addition to the soil significantly increased the abundance of fungivores,and decreased that of plant parasites.The diversity of soil nematodes was significantly increased by B1 compared to CK.Nematode trophic groups were more effectively indicative to biochar addition than total abundance.

Influence of the Sting Nematode, Belonolaimus longicaudalus, on Young Citrus Trees.

Science.gov (United States)

Kaplan, D T

1985-10-01

The sting nematode, Belonolaimus longicaudatus, was associated with poor growth of citrus in a central Florida nursery. Foliage of trees was sparse and chlorotic. Affected rootstocks included Changsha and Cleopatra mandarin orange; Flying Dragon, Rubidoux, and Jacobsen trifoliate orange; Macrophylla and Milam lemon; Palestine sweet lime; sour orange; and the hybrids - Carrizo, Morton, and Rusk citrange and Swingle citrumelo. Root symptoms included apical swelling, development of swollen terminals containing 3-5 apical meristems and hyperplastic tissue, coarse roots, and a reduction in the number of fibrous roots. Population densities as high as 392 sting nematodes per liter soil were detected, with 80% of the population occurring in the top 30 cm of soil; however, nematodes were detected to 107 cm deep. Although an ectoparasite, the nematode was closely associated with citrus root systems and was transported with bare root nursery stock. Disinfestation was accomplished by hot water treatment (49 C for 5 minutes).

Low cost production of nematodes for biological control of insect pests

Science.gov (United States)

Entomopathogenic nematodes are produced in two ways: in artificial media using liquid or solid fermentation methods (in vitro) or by mass producing insect hosts to be artificially exposed to mass infection by nematodes (in vivo). The yellow mealworm (Tenebrio molitor) is a good host for in vivo nema...

Nematodes as bioindicators of ecosystem recovery during phytoremediation of crude oil contaminated soil.

Science.gov (United States)

Savin, Mary C; Wolf, Duane C; Davis, K Jody; Gbur, Edward E; Thoma, Greg J

2015-01-01

Restoration of a weathered crude oil contaminated site undergoing phytoremediation was evaluated using nematodes as bioindicators. Samples were collected twice per year equating to spring and fall/winter. Mean annual total abundances ranged from 18-130 in the non-fertilized non-vegetated control (CTR) to 69-728 in tall fescue-ryegrass (FES) to 147-749 (100 g(-1)) in the fertilized bermudagrass-fescue (BER) treatment. Proportions of plant-parasitic (PP) and free-living (FL) nematodes were significantly impacted by treatment, but not year, with PP nematodes accounting for 27, 59, and 68% of CTR, FES, and BER communities, respectively. There was no significant year by season by treatment or treatment by year effect for total, PP, or FL nematode abundances. Diversity did not increase over time. The BER and FES treatments had more mature communities as indicated by higher plant-parasitic index (PPI) values. Phytoremediation accelerates petroleum degradation and alters the soil habitat which is reflected in the nematode community. However, low numbers and inconsistent presence of persister strategist omnivores and predators, and the lack in improvement over time in treatment effects for total and PP nematode abundances, PP and FL proportions, or PPI indicate the system is being rehabilitated but has not been restored after 69 months of phytoremediation.

Trematodes enhance the development of the nematode-trapping fungus Arthrobotrys (Duddingtonia) flagrans.

Science.gov (United States)

Arias, María Sol; Suárez, José; Cazapal-Monteiro, Cristiana Filipa; Francisco, Iván; López-Arellano, María Eugenia; Piñeiro, Pablo; Suárez, José Luis; Sánchez-Andrade, Rita; Mendoza de Gives, Pedro; Paz-Silva, Adolfo

2013-01-01

The capability of helminth (nematode and trematode) parasites in stimulating nematode trap and chlamydospore development of the nematophagous fungus Arthrobotrys (formerly Duddingtonia) flagrans was explored. Dead adult specimens of trematodes (the liver fluke Fasciola hepatica and the rumen fluke Calicophoron daubneyi) and nematodes (the ascarid Parascaris equorum and the strongylid Oesophagostomum spp.), as well as their secretory products, were placed onto corn meal agar plates concurrently inoculated with A. flagrans. Trapping organs were observed after 5 d and chlamydospores after 16 d, including in the control plates in the absence of parasitic stimulus. However, our data shows that both nematodes and trematodes increase trap and chlamydospore production compared with controls. We show for the first time that significantly higher numbers of traps and chlamydospores were observed in the cultures coinoculated with adult trematodes. We conclude that both the traps and chlamydospores formation are not only related to nematode-specific stimuli. The addition of secretory products of the trematode C. daubneyi to culture medium has potential for use in the large scale production of chlamydospores. Copyright © 2013 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Nematode grazing promotes bacterial community dynamics in soil at the aggregate level.

Science.gov (United States)

Jiang, Yuji; Liu, Manqiang; Zhang, Jiabao; Chen, Yan; Chen, Xiaoyun; Chen, Lijun; Li, Huixin; Zhang, Xue-Xian; Sun, Bo

2017-12-01

Nematode predation has important roles in determining bacterial community composition and dynamics, but the extent of the effects remains largely rudimentary, particularly in natural environment settings. Here, we investigated the complex microbial-microfaunal interactions in the rhizosphere of maize grown in red soils, which were derived from four long-term fertilization regimes. Root-free rhizosphere soil samples were separated into three aggregate fractions whereby the abundance and community composition were examined for nematode and total bacterial communities. A functional group of alkaline phosphomonoesterase (ALP) producing bacteria was included to test the hypothesis that nematode grazing may significantly affect specific bacteria-mediated ecological functions, that is, organic phosphate cycling in soil. Results of correlation analysis, structural equation modeling and interaction networks combined with laboratory microcosm experiments consistently indicated that bacterivorous nematodes enhanced bacterial diversity, and the abundance of bacterivores was positively correlated with bacterial biomass, including ALP-producing bacterial abundance. Significantly, such effects were more pronounced in large macroaggregates than in microaggregates. There was a positive correlation between the most dominant bacterivores Protorhabditis and the ALP-producing keystone 'species' Mesorhizobium. Taken together, these findings implicate important roles of nematodes in stimulating bacterial dynamics in a spatially dependent manner.

The Transcriptome of Nacobbus aberrans Reveals Insights into the Evolution of Sedentary Endoparasitism in Plant-Parasitic Nematodes

Science.gov (United States)

Eves-van den Akker, Sebastian; Lilley, Catherine J.; Danchin, Etienne G. J.; Rancurel, Corinne; Cock, Peter J. A.; Urwin, Peter E.; Jones, John T.

2014-01-01

Within the phylum Nematoda, plant-parasitism is hypothesized to have arisen independently on at least four occasions. The most economically damaging plant-parasitic nematode species, and consequently the most widely studied, are those that feed as they migrate destructively through host roots causing necrotic lesions (migratory endoparasites) and those that modify host root tissue to create a nutrient sink from which they feed (sedentary endoparasites). The false root-knot nematode Nacobbus aberrans is the only known species to have both migratory endoparasitic and sedentary endoparasitic stages within its life cycle. Moreover, its sedentary stage appears to have characteristics of both the root-knot and the cyst nematodes. We present the first large-scale genetic resource of any false-root knot nematode species. We use RNAseq to describe relative abundance changes in all expressed genes across the life cycle to provide interesting insights into the biology of this nematode as it transitions between modes of parasitism. A multigene phylogenetic analysis of N. aberrans with respect to plant-parasitic nematodes of all groups confirms its proximity to both cyst and root-knot nematodes. We present a transcriptome-wide analysis of both lateral gene transfer events and the effector complement. Comparing parasitism genes of typical root-knot and cyst nematodes to those of N. aberrans has revealed interesting similarities. Importantly, genes that were believed to be either cyst nematode, or root-knot nematode, “specific” have both been identified in N. aberrans. Our results provide insights into the characteristics of a common ancestor and the evolution of sedentary endoparasitism of plants by nematodes. PMID:25123114

Control of Root-Knot Nematodes on Tomato by the Endoparasitic Fungus Meria coniospora

OpenAIRE

Jansson, Hans-Börje; Jeyaprakash, A.; Zuckerman, Bert M.

1985-01-01

The endoparasitic nematophagous fungus Meria coniospora reduced root-knot nematode galling on tomatoes in greenhouse pot trials. The fungus was introduced to pots by addition of conidia at several inoculum levels directly to the soil or addition of nematodes infected with M. coniospora to the soil; both methods reduced root galling by root-knot nematodes. These studies represent a part of a recently initiated effort to evaluate the potential of endoparasitic nematophagous fungi for biocontrol...

Development of a nematode offspring counting assay for rapid and simple soil toxicity assessment.

Science.gov (United States)

Kim, Shin Woong; Moon, Jongmin; Jeong, Seung-Woo; An, Youn-Joo

2018-05-01

Since the introduction of standardized nematode toxicity assays by the American Society for Testing and Materials (ASTM) and International Organization for Standardization (ISO), many studies have reported their use. Given that the currently used standardized nematode toxicity assays have certain limitations, in this study, we examined the use of a novel nematode offspring counting assay for evaluating soil ecotoxicity based on a previous soil-agar isolation method used to recover live adult nematodes. In this new assay, adult Caenorhabditis elegans were exposed to soil using a standardized toxicity assay procedure, and the resulting offspring in test soils attracted by a microbial food source in agar plates were counted. This method differs from previously used assays in terms of its endpoint, namely, the number of nematode offspring. The applicability of the bioassay was demonstrated using metal-spiked soils, which revealed metal concentration-dependent responses, and with 36 field soil samples characterized by different physicochemical properties and containing various metals. Principal component analysis revealed that texture fraction (clay, sand, and silt) and electrical conductivity values were the main factors influencing the nematode offspring counting assay, and these findings warrant further investigation. The nematode offspring counting assay is a rapid and simple process that can provide multi-directional toxicity assessment when used in conjunction with other standard methods. Copyright © 2018 Elsevier Ltd. All rights reserved.

Windstorms as mediator of soil nematode community changes: Evidence from European spruce forest

Directory of Open Access Journals (Sweden)

Renčo M.

2017-03-01

Full Text Available Nematode communities in a Norway spruce forest in High Tatra National Park, Slovakia were monitored for the period of several years (2006 and 2013. Unfortunately, in May 2014 natural windstorm damaged the forest. This disastrous event, together with preliminary obtained results allowed us to compare the direct impact of windstorm damage of forest habitat on soil nematode assemblages. The forest destruction by windstorm had a significant effect on the total nematode abundance, the abundance of omnivores and herbivores, as well as the nematode species diversity. The most dominant species, representing 55 % of the total nematode fauna, in the plot studied were Acrobeloides nanus followed by Malenchus exiguus, Filenchus vulgaris, Plectus communis, Plectus parvus and Tylencholaimus mirabilis. The abundance of bacterivorous signifi cantly increased after the windstorm, meanwhile the abundance of omnivores, fungivores, and herbivores ectoparasites and epidermal/root hair feeders showed an opposite trend. Of the evaluative indicators, Shannon species diversity (H’spp, maturity index (MI, maturity index 2-5 (MI2-5, sigma maturity index (ΣMI, enrichment index (EI and structure index (SI decreased significantly after windstorm. The EI and SI indexes characterized soil ecosystems before windstorm (2006 - 2013 as maturing with low or moderate disturbance, but soil ecosystems shortly after the windstorm (2014 were degraded and nutrient depleted. This also corresponded with graphical display of metabolic footprints characteristics of soil food web. Overall, the nematode communities differed significantly before and after forest damage. These results suggest the role of nematode communities as indicators of environment condition quality or its disruption.

The suppression of tomato defence response genes upon potato cyst nematode infection indicates a key regulatory role of miRNAs.

Science.gov (United States)

Święcicka, Magdalena; Skowron, Waldemar; Cieszyński, Piotr; Dąbrowska-Bronk, Joanna; Matuszkiewicz, Mateusz; Filipecki, Marcin; Koter, Marek Daniel

2017-04-01

Potato cyst nematode Globodera rostochiensis is an obligate parasite of solanaceous plants, triggering metabolic and morphological changes in roots which may result in substantial crop yield losses. Previously, we used the cDNA-AFLP to study the transcriptional dynamics in nematode infected tomato roots. Now, we present the rescreening of already published, upregulated transcript-derived fragment dataset using the most current tomato transcriptome sequences. Our reanalysis allowed to add 54 novel genes to 135, already found as upregulated in tomato roots upon G. rostochiensis infection (in total - 189). We also created completely new catalogue of downregulated sequences leading to the discovery of 76 novel genes. Functional classification of candidates showed that the 'wound, stress and defence response' category was enriched in the downregulated genes. We confirmed the transcriptional dynamics of six genes by qRT-PCR. To place our results in a broader context, we compared the tomato data with Arabidopsis thaliana, revealing similar proportions of upregulated and downregulated genes as well as similar enrichment of defence related transcripts in the downregulated group. Since transcript suppression is quite common in plant-nematode interactions, we assessed the possibility of miRNA-mediated inverse correlation on several tomato sequences belonging to NB-LRR and receptor-like kinase families. The qRT-PCR of miRNAs and putative target transcripts showed an opposite expression pattern in 9 cases. These results together with in silico analyses of potential miRNA targeting to the full repertoire of tomato R-genes show that miRNA mediated gene suppression may be a key regulatory mechanism during nematode parasitism. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Sampling Error in Relation to Cyst Nematode Population Density Estimation in Small Field Plots.

Science.gov (United States)

Župunski, Vesna; Jevtić, Radivoje; Jokić, Vesna Spasić; Župunski, Ljubica; Lalošević, Mirjana; Ćirić, Mihajlo; Ćurčić, Živko

2017-06-01

Cyst nematodes are serious plant-parasitic pests which could cause severe yield losses and extensive damage. Since there is still very little information about error of population density estimation in small field plots, this study contributes to the broad issue of population density assessment. It was shown that there was no significant difference between cyst counts of five or seven bulk samples taken per each 1-m 2 plot, if average cyst count per examined plot exceeds 75 cysts per 100 g of soil. Goodness of fit of data to probability distribution tested with χ 2 test confirmed a negative binomial distribution of cyst counts for 21 out of 23 plots. The recommended measure of sampling precision of 17% expressed through coefficient of variation ( cv ) was achieved if the plots of 1 m 2 contaminated with more than 90 cysts per 100 g of soil were sampled with 10-core bulk samples taken in five repetitions. If plots were contaminated with less than 75 cysts per 100 g of soil, 10-core bulk samples taken in seven repetitions gave cv higher than 23%. This study indicates that more attention should be paid on estimation of sampling error in experimental field plots to ensure more reliable estimation of population density of cyst nematodes.

Characterizing Ancylostoma caninum transcriptome and exploring nematode parasitic adaptation

Directory of Open Access Journals (Sweden)

Hawdon John

2010-05-01

Full Text Available Abstract Background Hookworm infection is one of the most important neglected diseases in developing countries, with approximately 1 billion people infected worldwide. To better understand hookworm biology and nematode parasitism, the present study generated a near complete transcriptome of the canine hookworm Ancylostoma caninum to a very high coverage using high throughput technology, and compared it to those of the free-living nematode Caenorhabditis elegans and the parasite Brugia malayi. Results The generated transcripts from four developmental stages, infective L3, serum stimulated L3, adult male and adult female, covered 93% of the A. caninum transcriptome. The broad diversity among nematode transcriptomes was confirmed, and an impact of parasitic adaptation on transcriptome diversity was inferred. Intra-population analysis showed that A. caninum has higher coding sequence diversity than humans. Examining the developmental expression profiles of A. caninum revealed major transitions in gene expression from larval stages to adult. Adult males expressed the highest number of selectively expressed genes, but adult female expressed the highest number of selective parasitism-related genes. Genes related to parasitism adaptation and A. caninum specific genes exhibited more expression selectivity while those conserved in nematodes tend to be consistently expressed. Parasitism related genes were expressed more selectively in adult male and female worms. The comprehensive analysis of digital expression profiles along with transcriptome comparisons enabled identification of a set of parasitism genes encoding secretory proteins in animal parasitic nematode. Conclusions This study validated the usage of deep sequencing for gene expression profiling. Parasitic adaptation of the canine hookworm is related to its diversity and developmental dynamics. This comprehensive comparative genomic and expression study substantially improves our understanding of

78 FR 1713 - Golden Nematode; Removal of Regulated Areas in Livingston and Steuben Counties, NY

Science.gov (United States)

2013-01-09

...-0079] Golden Nematode; Removal of Regulated Areas in Livingston and Steuben Counties, NY AGENCY: Animal... are amending the golden nematode regulations by removing areas in Livingston and Steuben Counties in... areas in these two counties are free of golden nematode, and we have determined that regulation of these...

Nematicidal effect of rhizobacteria on plant-parasitic nematodes associated with vineyards.

Science.gov (United States)

Aballay, E; Prodan, S; Zamorano, A; Castaneda-Alvarez, C

2017-07-01

The action of metabolites and exoenzymes from rhizobacteria on different plant-parasitic nematodes has an influence on the nematicidal efficacy of the microbe. Seven rhizobacteria, divided into two bacterial groups, were evaluated in vitro for nematicidal activity on Meloidogyne ethiopica and Xiphinema index. The direct effect of their filtrates on egg hatching and juveniles of M. ethiopica as well as mobile stages of X. index was evaluated during a 72-h period. The production of four exoenzymes and two metabolites associated with nematode mortality was investigated. Molecular characterization of three isolates was performed, and the physiological profiles and lipase activity of all isolates were obtained using the BIOLOG EcoPlate system. While chitinase and collagenase were measured using the BIOLOG MT2 plate system, protease, hydrogen cyanide and hydrogen sulphide were directly determined in Petri dishes. Nematode mobile stages exposure to the bacterial filtrate revealed a nematicidal effect up to 93.7% on X. Index and up to 83.3% on M. ethiopica. The control of egg hatching varied between 35 and 85%. A positive correlation was found between the mortality of both nematode mobile stages and the concerted activities of the bacterial enzymes as well as the level of the volatile metabolites. The nematicidal effect of rhizobacteria strains varies by nematode genera and among the developmental stages evaluated.

In vivo effects of Sainfoin (Onobrychis viciifolia) on parasitic nematodes in calves

DEFF Research Database (Denmark)

Desrues, Oliver; Pena-Espinoza, Miguel Angel; Hansen, T.V.A.

Sainfoin (Onobrychis viciifolia) is a fodder legume containing condensed tannins known to improve protein self-sufficiency, animal health and environment. In addition, anthelmintic effects have been demonstrated in vitro against cattle nematodes, and in vivo against nematodes of small ruminants...

Effective and specific in planta RNAi in cyst nematodes: expression interference of four parasitism genes reduces parasitic success.

Science.gov (United States)

Sindhu, Anoop S; Maier, Tom R; Mitchum, Melissa G; Hussey, Richard S; Davis, Eric L; Baum, Thomas J

2009-01-01

Cyst nematodes are highly evolved sedentary plant endoparasites that use parasitism proteins injected through the stylet into host tissues to successfully parasitize plants. These secretory proteins likely are essential for parasitism as they are involved in a variety of parasitic events leading to the establishment of specialized feeding cells required by the nematode to obtain nourishment. With the advent of RNA interference (RNAi) technology and the demonstration of host-induced gene silencing in parasites, a new strategy to control pests and pathogens has become available, particularly in root-knot nematodes. Plant host-induced silencing of cyst nematode genes so far has had only limited success but similarly should disrupt the parasitic cycle and render the host plant resistant. Additional in planta RNAi data for cyst nematodes are being provided by targeting four parasitism genes through host-induced RNAi gene silencing in transgenic Arabidopsis thaliana, which is a host for the sugar beet cyst nematode Heterodera schachtii. Here it is reported that mRNA abundances of targeted nematode genes were specifically reduced in nematodes feeding on plants expressing corresponding RNAi constructs. Furthermore, this host-induced RNAi of all four nematode parasitism genes led to a reduction in the number of mature nematode females. Although no complete resistance was observed, the reduction of developing females ranged from 23% to 64% in different RNAi lines. These observations demonstrate the relevance of the targeted parasitism genes during the nematode life cycle and, potentially more importantly, suggest that a viable level of resistance in crop plants may be accomplished in the future using this technology against cyst nematodes.

The feeding tube of cyst nematodes: characterisation of protein exclusion.

Directory of Open Access Journals (Sweden)

Sebastian Eves-van den Akker

Full Text Available Plant parasitic nematodes comprise several groups; the most economically damaging of these are the sedentary endoparasites. Sedentary endoparasitic nematodes are obligate biotrophs and modify host root tissue, using a suite of effector proteins, to create a feeding site that is their sole source of nutrition. They feed by withdrawing host cell assimilate from the feeding site though a structure known as the feeding tube. The function, composition and molecular characteristics of feeding tubes are poorly characterised. It is hypothesised that the feeding tube facilitates uptake of host cell assimilate by acting as a molecular sieve. Several studies, using molecular mass as the sole indicator of protein size, have given contradictory results about the exclusion limits of the cyst nematode feeding tube. In this study we propose a method to predict protein size, based on protein database coordinates in silico. We tested the validity of these predictions using travelling wave ion mobility spectrometry--mass spectrometry, where predictions and measured values were within approximately 6%. We used the predictions, coupled with mass spectrometry, analytical ultracentrifugation and protein electrophoresis, to resolve previous conflicts and define the exclusion characteristics of the cyst nematode feeding tube. Heterogeneity was tested in the liquid, solid and gas phase to provide a comprehensive evaluation of three proteins of particular interest to feeding tube size exclusion, GFP, mRFP and Dual PI. The data and procedures described here could be applied to the design of plant expressed defence compounds intended for uptake into cyst nematodes. We also highlight the need to assess protein heterogeneity when creating novel fusion proteins.

The feeding tube of cyst nematodes: characterisation of protein exclusion.

Science.gov (United States)

Eves-van den Akker, Sebastian; Lilley, Catherine J; Ault, James R; Ashcroft, Alison E; Jones, John T; Urwin, Peter E

2014-01-01

Plant parasitic nematodes comprise several groups; the most economically damaging of these are the sedentary endoparasites. Sedentary endoparasitic nematodes are obligate biotrophs and modify host root tissue, using a suite of effector proteins, to create a feeding site that is their sole source of nutrition. They feed by withdrawing host cell assimilate from the feeding site though a structure known as the feeding tube. The function, composition and molecular characteristics of feeding tubes are poorly characterised. It is hypothesised that the feeding tube facilitates uptake of host cell assimilate by acting as a molecular sieve. Several studies, using molecular mass as the sole indicator of protein size, have given contradictory results about the exclusion limits of the cyst nematode feeding tube. In this study we propose a method to predict protein size, based on protein database coordinates in silico. We tested the validity of these predictions using travelling wave ion mobility spectrometry--mass spectrometry, where predictions and measured values were within approximately 6%. We used the predictions, coupled with mass spectrometry, analytical ultracentrifugation and protein electrophoresis, to resolve previous conflicts and define the exclusion characteristics of the cyst nematode feeding tube. Heterogeneity was tested in the liquid, solid and gas phase to provide a comprehensive evaluation of three proteins of particular interest to feeding tube size exclusion, GFP, mRFP and Dual PI. The data and procedures described here could be applied to the design of plant expressed defence compounds intended for uptake into cyst nematodes. We also highlight the need to assess protein heterogeneity when creating novel fusion proteins.

Functionality of resistance gene Hero, which controls plant root-infecting potato cyst nematodes, in leaves of tomato.

Science.gov (United States)

Poch, H L Cabrera; López, R H Manzanilla; Kanyuka, K

2006-07-01

The expression of host genomes is modified locally by root endoparasitic nematode secretions to induce the development of complex cellular structures referred as feeding sites. In compatible interactions, the feeding sites provide the environment and nutrients for the completion of the nematode's life cycle, whereas in an incompatible (resistant) interaction, the host immune system triggers a plant cell death programme, often in the form of a hypersensitive reaction, which restricts nematode reproduction. These processes have been studied in great detail in organ tissues normally infected by these nematodes: the roots. Here we show that host leaves can support a similar set of programmed developmental events in the potato cyst nematode Globodera rostochiensis life cycle that are typical of the root-invading nematodes. We also show that a gene-for-gene type specific disease resistance that is effective against potato cyst nematodes (PCN) in roots also operates in leaves: the expression of the resistance (R) gene Hero and members of its gene family in leaves correlates with the elicitation of a hypersensitive response only during the incompatible interaction. These findings, and the ability to isolate RNA from relevant parasitic stages of the nematode, may have significant implications for the identification of nematode factors involved in incompatible interactions.

Rhizosphere Microbiomes Modulated by Pre-crops Assisted Plants in Defense Against Plant-Parasitic Nematodes

Directory of Open Access Journals (Sweden)

Ahmed Elhady

2018-06-01

Full Text Available Plant-parasitic nematodes cause considerable damage to crop plants. The rhizosphere microbiome can affect invasion and reproductive success of plant-parasitic nematodes, thus affecting plant damage. In this study, we investigated how the transplanted rhizosphere microbiome from different crops affect plant-parasitic nematodes on soybean or tomato, and whether the plant’s own microbiome from the rhizosphere protects it better than the microbiome from fallow soil. Soybean plants growing in sterilized substrate were inoculated with the microbiome extracted from the rhizosphere of soybean, maize, or tomato. Controls were inoculated with extracts from bulk soil, or not inoculated. After the microbiome was established, the root lesion nematode Pratylenchus penetrans was added. Root invasion of P. penetrans was significantly reduced on soybean plants inoculated with the microbiome from maize or soybean compared to tomato or bulk soil, or the uninoculated control. In the analogous experiment with tomato plants inoculated with either P. penetrans or the root knot nematode Meloidogyne incognita, the rhizosphere microbiomes of maize and tomato reduced root invasion by P. penetrans and M. incognita compared to microbiomes from soybean or bulk soil. Reproduction of M. incognita on tomato followed the same trend, and it was best suppressed by the tomato rhizosphere microbiome. In split-root experiments with soybean and tomato plants, a systemic effect of the inoculated rhizosphere microbiomes on root invasion of P. penetrans was shown. Furthermore, some transplanted microbiomes slightly enhanced plant growth compared to uninoculated plants. The microbiomes from maize rhizosphere and bulk soil increased the fresh weights of roots and shoots of soybean plants, and microbiomes from soybean rhizosphere and bulk soil increased the fresh weights of roots and shoots of tomato plants. Nematode invasion did not affect plant growth in these short-term experiments. In

Viability and Virulence of Entomopathogenic Nematodes Exposed to Ultraviolet Radiation.

Science.gov (United States)

Shapiro-Ilan, David I; Hazir, Selcuk; Lete, Luis

2015-09-01

Entomopathogenic nematodes (EPNs) can be highly effective biocontrol agents, but their efficacy can be reduced due to exposure to environmental stress such as from ultraviolet (UV) radiation. Our objectives were to 1) compare UV tolerance among a broad array of EPN species, and 2) investigate the relationship between reduced nematode viability (after exposure to UV) and virulence. Nematodes exposed to a UV radiation (254 nm) for 10 or 20 min were assessed separately for viability (survival) and virulence to Galleria mellonella. We compared 9 different EPN species and 15 strains: Heterorhabditis bacteriophora (Baine, fl11, Oswego, and Vs strains), H. floridensis (332), H. georgiana (Kesha), H. indica (HOM1), H. megidis (UK211), Steinernema carpocapsae (All, Cxrd, DD136, and Sal strains), S. feltiae (SN), S. rarum (17C&E), and S. riobrave (355). In viability assessments, steinernematids, particularly strains of S. carpocapsae, generally exhibited superior UV tolerance compared with the heterorhabditids. However, some heterorhabditids tended to be more tolerant than others, e.g., H. megidis and H. bacteriophora (Baine) were most susceptible and H. bacteriophora (Vs) was the only heterorhabditid that did not exhibit a significant effect after 10 min of exposure. All heterorhabditids experienced reduced viability after 20 min exposure though several S. carpocapsae strains did not. In total, after 10 or 20 min exposure, the viability of seven nematode strains did not differ from their non-UV exposed controls. In virulence assays, steinernematids (particularly S. carpocapsae strains) also tended to exhibit higher UV tolerance. However, in contrast to the viability measurements, all nematodes experienced a reduction in virulence relative to their controls. Correlation analysis revealed that viability among nematode strains is not necessarily related to virulence. In conclusion, our results indicate that the impact of UV varies substantially among EPNs, and viability alone

Evolutionary history of nematodes associated with sweat bees.

Science.gov (United States)

McFrederick, Quinn S; Taylor, Douglas R

2013-03-01

Organisms that live in close association with other organisms make up a large part of the world's diversity. One driver of this diversity is the evolution of host-species specificity, which can occur via reproductive isolation following a host-switch or, given the correct circumstances, via cospeciation. In this study, we explored the diversity and evolutionary history of Acrostichus nematodes that are associated with halictid bees in North America. First, we conducted surveys of bees in Virginia, and found six halictid species that host Acrostichus. To test the hypothesis of cospeciation, we constructed phylogenetic hypotheses of Acrostichus based on three genes. We found Acrostichus puri and Acrostichus halicti to be species complexes comprising cryptic, host-specific species. Although several nodes in the host and symbiont phylogenies were congruent and tests for cospeciation were significant, the host's biogeography, the apparent patchiness of the association across the host's phylogeny, and the amount of evolution in the nematode sequence suggested a mixture of cospeciation, host switching, and extinction events instead of strict cospeciation. Cospeciation can explain the relationships between Ac. puri and its augochlorine hosts, but colonization of Halictus hosts is more likely than cospeciation. The nematodes are vertically transmitted, but sexual transmission is also likely. Both of these transmission modes may explain host-species specificity and congruent bee and nematode phylogenies. Additionally, all halictid hosts come from eusocial or socially polymorphic lineages, suggesting that sociality may be a factor in the suitability of hosts for Acrostichus. Copyright © 2012 Elsevier Inc. All rights reserved.

78 FR 27856 - Golden Nematode; Removal of Regulated Areas in Livingston and Steuben Counties, NY

Science.gov (United States)

2013-05-13

.... APHIS-2012-0079] Golden Nematode; Removal of Regulated Areas in Livingston and Steuben Counties, NY... nematode regulations by removing areas in Livingston and Steuben Counties in New York from the list of... nematode, and we determined that regulation of these areas was no longer necessary. As a result of that...

The transcriptome of Nacobbus aberrans reveals insights into the evolution of sedentary endoparasitism in plant-parasitic nematodes.

Science.gov (United States)

Eves-van den Akker, Sebastian; Lilley, Catherine J; Danchin, Etienne G J; Rancurel, Corinne; Cock, Peter J A; Urwin, Peter E; Jones, John T

2014-08-13

Within the phylum Nematoda, plant-parasitism is hypothesized to have arisen independently on at least four occasions. The most economically damaging plant-parasitic nematode species, and consequently the most widely studied, are those that feed as they migrate destructively through host roots causing necrotic lesions (migratory endoparasites) and those that modify host root tissue to create a nutrient sink from which they feed (sedentary endoparasites). The false root-knot nematode Nacobbus aberrans is the only known species to have both migratory endoparasitic and sedentary endoparasitic stages within its life cycle. Moreover, its sedentary stage appears to have characteristics of both the root-knot and the cyst nematodes. We present the first large-scale genetic resource of any false-root knot nematode species. We use RNAseq to describe relative abundance changes in all expressed genes across the life cycle to provide interesting insights into the biology of this nematode as it transitions between modes of parasitism. A multigene phylogenetic analysis of N. aberrans with respect to plant-parasitic nematodes of all groups confirms its proximity to both cyst and root-knot nematodes. We present a transcriptome-wide analysis of both lateral gene transfer events and the effector complement. Comparing parasitism genes of typical root-knot and cyst nematodes to those of N. aberrans has revealed interesting similarities. Importantly, genes that were believed to be either cyst nematode, or root-knot nematode, "specific" have both been identified in N. aberrans. Our results provide insights into the characteristics of a common ancestor and the evolution of sedentary endoparasitism of plants by nematodes. © The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Functional analysis of pathogenicity proteins of the potato cyst nematode Globodera rostochiensis using RNAi.

Science.gov (United States)

Chen, Qing; Rehman, S; Smant, G; Jones, John T

2005-07-01

RNA interference (RNAi) has been used widely as a tool for examining gene function and a method that allows its use with plant-parasitic nematodes recently has been described. Here, we use a modified method to analyze the function of secreted beta-1,4, endoglucanases of the potato cyst nematode Globodera rostochiensis, the first in vivo functional analysis of a pathogenicity protein of a plant-parasitic nematode. Knockout of the beta-1,4, endoglucanases reduced the ability of the nematodes to invade roots. We also use RNAi to show that gr-ams-1, a secreted protein of the main sense organs (the amphids), is essential for host location.

Superoxide Dismutase as a Tool for the Mulacular Identification of Plant Parasitic Nematodes

Directory of Open Access Journals (Sweden)

S. Molinari

2004-08-01

Full Text Available Superoxide dismutase (SOD is a constitutive family of enzymes produced by all aerobic organisms. Varying amounts of SOD activity have been found at all life stages of the most diffused plant parasitic nematodes. SOD is important to aerobic metabolism and parasitism of nematodes in that it catalyzes the first step of the neutralization of the highly toxic superoxide anion (O2 •-, which is largely produced in plant-nematode incompatible reactions. SOD has also been shown to be a significant tool to diagnose root-knot, cyst-, and longidorid nematodes. A high SOD polymorphism has been revealed by Native-Page on gradient polyacrylamide gels for Meloidogyne spp. and by isoelectrofocusing for Globodera, Xiphinema and Longidorus spp. The sensitivity of such procedures has been improved by using the PhastSystem (Amersham Biosciences, Piscata, NJ, USA, an automated equipment for electrophoresis. An accurate discrimination of species of all the nematode genera tested has been achieved and an attempt was made to group populations of the Xiphinema americanum-group and to detect Globodera rostochiensis and G. pallida pathotypes.

Prevalence of intestinal nematodes in alcoholic patients

Directory of Open Access Journals (Sweden)

Zago-Gomes Maria P.

2002-01-01

Full Text Available We report the results of a retrospective study on the frequency of intestinal nematodes among 198 alcoholic and 440 nonalcoholic patients at the University Hospital Cassiano Antonio Moraes in Vitória, ES, Brazil. The control sample included 194 nonalcoholic patients matched according to age, sex and neighborhood and a random sample of 296 adults admitted at the same hospital. Stool examination by sedimentation method (three samples was performed in all patients. There was a significantly higher frequency of intestinal nematodes in alcoholics than in controls (35.3% and 19.2%, respectively, due to a higher frequency of Strongyloides stercoralis (21.7% and 4.1%, respectively. Disregarding this parasite, the frequency of the other nematodes was similar in both groups. The higher frequency of S. stercoralis infection in alcoholics could be explained by immune modulation and/or by some alteration in corticosteroid metabolism induced by chronic ethanol ingestion. Corticosteroid metabolites would mimic the worm ecdisteroids, that would in turn increase the fecundity of females in duodenum and survival of larvae. Consequently, the higher frequency of Strongyloides larvae in stool of alcoholics does not necessarily reflect an increased frequency of infection rate, but only an increased chance to present a positive stool examination using sedimentation methods.

Lymphatic dwelling filarioid nematodes in reindeer Rangifer tarandus tarandus, (cervidae) in Finland, identified as Rumenfilaria andersoni Lankester & Snider, 1982 (nematoda: Onchocercidae: Splendidofilariinae).

Science.gov (United States)

Laaksonen, S; Saari, S; Nikander, S; Oksanen, A; Bain, O

2010-03-01

A filarioid nematode inhabiting the lymphatic vessels of the subserosal rumen and mesenteries associated with a high prevalence of its microfilariae in peripheral blood was observed in Finnish reindeer (Rangifer tarandus tarandus) in 2004 and 2006. Adult specimens were collected by dissecting lymphatic vessels from slaughtered animals, where some of the nematodes were seen through the wall of the dilated vessels as thin white winding threads obscuring the vessel. The morphology of adult worms and microfilaria is described based on light and scanning electron microscopy. These filariae belong to the subfamily Splendidofilariinae of the Onchocercidae and resemble Rumenfilaria andersoni, recovered from different host and localization, the ruminal veins of Alces alces in Canada. Comparison of paratypes of this species revealed only minor differences which were not sufficient to separate the filarioid parasitic in R. tarandus in Finland and we identify the nematode as R. andersoni. However, the findings suggest two different parasite populations. The finalizing of this taxonomic question in the future requires an integrated approach, in which the DNA-based and morphological identifications are consistent.

Lymphatic dwelling filarioid nematodes in reindeer Rangifer tarandus tarandus, (Cervidae in Finland, identified as Rumenfilaria andersoni Lankester & Snider, 1982 (Nematoda: Onchocercidae: Splendidofilariinae

Directory of Open Access Journals (Sweden)

Laaksonen S.

2010-03-01

Full Text Available A filarioid nematode inhabiting the lymphatic vessels of the subserosal rumen and mesenteries associated with a high prevalence of its microfilariae in peripheral blood was observed in Finnish reindeer (Rangifer tarandus tarandus in 2004 and 2006. Adult specimens were collected by dissecting lymphatic vessels from slaughtered animals, where some of the nematodes were seen through the wall of the dilated vessels as thin white winding threads obscuring the vessel. The morphology of adult worms and microfilaria is described based on light and scanning electron microscopy. These filariae belong to the subfamily Splendidofilariinae of the Onchocercidae and resemble Rumenfilaria andersoni, recovered from different host and localization, the ruminal veins of Alces alces in Canada. Comparison of paratypes of this species revealed only minor differences which were not sufficient to separate the filarioid parasitic in R. tarandus in Finland and we identify the nematode as R. andersoni. However, the findings suggest two different parasite populations. The finalizing of this taxonomic question in the future requires an integrated approach, in which the DNAbased and morphological identifications are consistent.

Pasteuria spp.: Systematics and Phylogeny of These Bacterial Parasites of Phytopathogenic Nematodes.

Science.gov (United States)

Preston, J F; Dickson, D W; Maruniak, J E; Nong, G; Brito, J A; Schmidt, L M; Giblin-Davis, R M

2003-06-01

Pasteuria spp. include endospore-forming bacterial pathogens of cladoceran crustaceans and plant-parasitic nematodes. Propagation of these nematode pathogens requires attachment of soilborne endospores to nematode hosts, infection, growth, sporulation, and release of endospores to repeat the cycle of infection and propagation. The ability of these bacteria to suppress the levels of plant-parasitic nematodes in the field has made them particularly promising candidates for biocontrol of nematode diseases of plants. Genes encoding 16S ribosomal RNA have been sequenced for the cladoceran (water flea) parasite and type species, Pasteuria ramosa, and for Pasteuria spp. isolated from root-knot (Meloidogyne arenaria race 1 and Meloidogyne sp.), soybean cyst (Heterodera glycines), and sting (Belonolaimus longicaudatus) nematodes. These have provided a phylogenetic basis for their designation to a distinct clade within the family Alicyclobacillaceae of the gram-positive endospore-forming bacteria. Two apparent biotypes of P. penetrans demonstrating a host preference for different Meloidogyne spp. showed identical 16S rDNA sequences, suggesting host-recognition evolves within a given species. The sequences of genes encoding sporulation transcription factors, sigE and sigF, from P. penetrans biotype P-20 show different phylogenetic relationships to other endospore-forming bacteria, supporting their application to further discriminate Pasteuria spp. and biotypes. Distribution of an adhesin-associated epitope on polypeptides from different Pasteuria isolates provides an immunochemical approach to differentiate species and biotypes with specific host preferences. Application of bioinformatics to genomic data, as well as further characterization of the biochemical basis for host recognition, will facilitate development of Pasteuria spp. as benign alternatives to chemical nematicides.

Findings of Entomopathogenic Nematodes (Rhabditida, Steinernematidae in Nature Reserves in Ukraine

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Yakovlev Ye. B.

2014-07-01

Full Text Available Findings of Entomopathogenic Nematodes (Rhabditida, Steinernematidae in Nature Reserves in-Ukraine. Yakovlev, Ye. B., Kharchenko, V. A., Mráček, Z. — Five strains of Steinernema Travassos, 1927 were isolated by live baiting method with last instar larvae of Tenebrio molitor Linnaeus, 1758 from the reserves of some central and southern oblasts of Ukraine and the Crimean AR. Entomopathogenic nematodes were recovered from 5 of 196 (2.6 % soil samples collected in 2010. Isolated nematodes were identified using a combination of molecular (ITS1-5.8S-ITS2 rDNA gene sequencing and morphological techniques. Four of the isolated strains were recognized as S. feltiae (Filipjev, 1934, one as S. arenarium (Artyukhovsky, 1967.

Survival and Movement of Insect Parasitic Nematodes in Poultry Manure and Their Infectivity Against Musca domestica

OpenAIRE

Georgis, Ramon; Mullens, Bradley A.; Meyer, Jeffery A.

1987-01-01

Survival, infectivity, and movement of three insect parasitic nematodes (Steinernema feltiae All strain, S. bibionis SN strain, and Heterorhabditis heliothidis NC strain) in poultry manure were tested under laboratory conditions. The majority (70-100%) of the nematodes died within 18 hours after exposure to the manure. Nematodes exposed to manure slurry for 6 hours killed at least 95% of the house fly larvae, Musca domestica, but nematodes exposed for 12 hours achieved less than 40% larval mo...

Soil nematode community under the non-native trees in the Botanic Garden of Petrozavodsk State University

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Sushchuk Anna

2016-12-01

Full Text Available The particularities of soil nematode communities of the rhizosphere of non-native trees were studied in the Botanic Garden of Petrozavodsk State University (Republic of Karelia. Taxonomic diversity, abundance, community structure and ecological indices derived from nematode fauna analysis were used as the evaluation parameters. Nematode fauna included 51 genera, 6 of them were plant parasitic. The dominant eco-trophic group in the nematode community structure of coniferous trees was bacterial feeders; fungal feeders in most cases were observed in the second numbers. The contribution of bacterial feeders was decreased and plant parasites were increased in eco-trophic structure of nematode communities of deciduous trees in compared with coniferous trees. Analysis of ecological indices showed that the state of soil nematode communities reflects complex, structured (stable soil food web in the biocenoses with deciduous trees, and degraded (basal food web – under coniferous trees.

Nematodes as sentinels of heavy metals and organic toxicants in the soil

NARCIS (Netherlands)

Ekschmitt, K.; Korthals, G.W.

2006-01-01

Field and laboratory research has repeatedly shown that free-living soil nematodes differ in their sensitivity to soil pollution. In this paper, we analyze whether nematode genera proved sensitive or tolerant toward heavy metals and organic pollutants in six long-term field experiments. We discuss

Nematóides do Brasil. Parte V: nematóides de mamíferos Brazillan nematodes. Part V: nematodes of mammals

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Joaquim Júlio Vicente

1997-01-01

Full Text Available A survey of nematode species parasitizing Brazilian mammals is presented, with enough data to provide their specific identification. The tirst section refers to the survey ofthe species, related to 21 superfamilies, 45 families, 160 genera and 495 species that are illustrated and measurement tables are given. The second section is concerned to the catalogue ofhost mammals which includes 34 families, 176 species and their respective parasite nematodes. The identification of these helminths is achieved by means of keys to the superfamilies, families and genera. Specific determination is induced through the figures and tables as above mentioned.

Effect of tillage and crop residue management on nematode densities on corn.

Science.gov (United States)

McSorley, R; Gallaher, R N

1994-12-01

Effects of winter cover crop management on nematode densities associated with a subsequent corn (Zea mays) crop were examined in five sites in north Florida. Two sites had received winter cover crops of lupine (Lupinus angustifolius), and one site each had rye (Secale cereale), hairy vetch (Vicia villosa), and crimson clover (Trifolium incarnatum). In each site, five different management regimes were compared: 1) conventional tillage after the cover crop was removed for forage; 2) conventional tillage with the cover crop retained as green manure; 3) no-till with the cover crop mowed and used as a mulch; 4) no-till with the cover crop removed as forage; and 5) fallow. Sites were sampled at corn planting and harvest for estimates of initial (Pi) and final (Pf) nematode population densities, respectively. Whether the cover crop was removed as forage or retained as green manure or mulch had no effect (P > 0.10) on population densities of any plant-parasitic nematode before or after corn at any site. Differences between conventional-till and no-till treatments were significant (P cover crop residues had little consistent effect on nematodes, and these practices should be considered based on agronomic benefits rather than for nematode management.

Resistance and Resistant Reaction of Gossypium arboreum to the Reniform, Nematode, Rotylenchulus reniformis

Science.gov (United States)

Carter, William W.

1981-01-01

Gossypium arboreum 'Nanking CB 1402' possessed a high level of resistance to Rotylenchulus reniformis. Within 16 h, the nematode penetrated roots of resistant and susceptible cottons equally. After 36 h, significantly fewer nematodes were found in resistant roots. Larvae fed in either an endodermal or pericyclic cell and had no specificity for root tissue of a particular age. In roots of resistant G. arboreum '1402,' wall breakdown of pericyclic cells was evident after 3 d, endodermal and cortical cells collapsed, and the hypertrophied pericyclic cells disintegrated within 12 d. Cell walls immediately adjacent to the nematode's head were thickened and more safranin positive in resistant than in susceptible cotton cultivars. Several other cultivars of G. arboreum were also resistant to R. reniformis, based on nematode fecundity and percent egg reduction. PMID:19300777

A parasitic nematode releases cytokinin that controls cell division and orchestrates feeding site formation in host plants.

Science.gov (United States)

Siddique, Shahid; Radakovic, Zoran S; De La Torre, Carola M; Chronis, Demosthenis; Novák, Ondřej; Ramireddy, Eswarayya; Holbein, Julia; Matera, Christiane; Hütten, Marion; Gutbrod, Philipp; Anjam, Muhammad Shahzad; Rozanska, Elzbieta; Habash, Samer; Elashry, Abdelnaser; Sobczak, Miroslaw; Kakimoto, Tatsuo; Strnad, Miroslav; Schmülling, Thomas; Mitchum, Melissa G; Grundler, Florian M W

2015-10-13

Sedentary plant-parasitic cyst nematodes are biotrophs that cause significant losses in agriculture. Parasitism is based on modifications of host root cells that lead to the formation of a hypermetabolic feeding site (a syncytium) from which nematodes withdraw nutrients. The host cell cycle is activated in an initial cell selected by the nematode for feeding, followed by activation of neighboring cells and subsequent expansion of feeding site through fusion of hundreds of cells. It is generally assumed that nematodes manipulate production and signaling of the plant hormone cytokinin to activate cell division. In fact, nematodes have been shown to produce cytokinin in vitro; however, whether the hormone is secreted into host plants and plays a role in parasitism remained unknown. Here, we analyzed the spatiotemporal activation of cytokinin signaling during interaction between the cyst nematode, Heterodera schachtii, and Arabidopsis using cytokinin-responsive promoter:reporter lines. Our results showed that cytokinin signaling is activated not only in the syncytium but also in neighboring cells to be incorporated into syncytium. An analysis of nematode infection on mutants that are deficient in cytokinin or cytokinin signaling revealed a significant decrease in susceptibility of these plants to nematodes. Further, we identified a cytokinin-synthesizing isopentenyltransferase gene in H. schachtii and show that silencing of this gene in nematodes leads to a significant decrease in virulence due to a reduced expansion of feeding sites. Our findings demonstrate the ability of a plant-parasitic nematode to synthesize a functional plant hormone to manipulate the host system and establish a long-term parasitic interaction.

Some aspects of fracture assessment diagrams, plastic zone size corrections and contour integrals in post-yield fracture mechanics

International Nuclear Information System (INIS)

Ainsworth, R.A.

1981-03-01

The CEGB failure assessment route is briefly described and is shown to be consistent with a plastic zone size correction method. Modifications to the assessment route which have recently been suggested for describing the effects of thermal and residual stresses are examined. It is shown that the plastic zone size correction method may be used to include local thermal and residual stresses in the assessment route in a simple manner. The assessment route is compared with finite-element solutions for a thermal stress problem and with strip-yield model solutions for a residual stress problem. In using finite-element solutions there are different contour integral methods available for calculating a post-yield fracture parameter. The J-integral of Rice and the J*-integral of Blackburn are examined and compared and the appropriate parameter is identified. (author)

Population Genetics of Hirsutella rhossiliensis, a Dominant Parasite of Cyst Nematode Juveniles on a Continental Scale.

Science.gov (United States)

Wang, Niuniu; Zhang, Yongjie; Jiang, Xianzhi; Shu, Chi; Hamid, M Imran; Hussain, Muzammil; Chen, Senyu; Xu, Jianping; Xiang, Meichun; Liu, Xingzhong

2016-11-01

Hirsutella rhossiliensis is a parasite of juvenile nematodes, effective against a diversity of plant-parasitic nematodes. Its global distribution on various nematode hosts and its genetic variation for several geographic regions have been reported, while the global population genetic structure and factors underlying patterns of genetic variation of H. rhossiliensis are unclear. In this study, 87 H. rhossiliensis strains from five nematode species (Globodera sp., Criconemella xenoplax, Rotylenchus robustus, Heterodera schachtii, and Heterodera glycines) in Europe, the United States, and China were investigated by multilocus sequence analyses. A total of 280 variable sites (frequency, 0.6%) at eight loci and six clustering in high accordance with geographic populations or host nematode-associated populations were identified. Although H. rhossiliensis is currently recognized as an asexual fungus, recombination events were frequently detected. In addition, significant genetic isolation by geography and nematode hosts was revealed. Overall, our analyses showed that recombination, geographic isolation, and nematode host adaptation have played significant roles in the evolutionary history of H. rhossiliensis IMPORTANCE: H. rhossiliensis has great potential for use as a biocontrol agent to control nematodes in a sustainable manner as an endoparasitic fungus. Therefore, this study has important implications for the use of H. rhossiliensis as a biocontrol agent and provides interesting insights into the biology of this species. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Nematode Infections Are Risk Factors for Staphylococcal Infection in Children

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Sandra F Moreira-Silva

2002-04-01

Full Text Available Nematode infection may be a risk factor for pyogenic liver abscess in children and we hypothesized that the immunomodulation induced by those parasites would be a risk factor for any staphylococcal infection in children. The present study was designed to compare, within the same hospital, the frequency of intestinal nematodes and Toxocara infection in children with and without staphylococcal infections. From October 1997 to February 1998, 80 children with staphylococcal infection and 110 children with other diseases were submitted to fecal examination, serology for Toxocara sp., evaluation of plasma immunoglobulin levels, and eosinophil counts. Mean age, gender distribution, birthplace, and socioeconomic conditions did not differ significantly between the two groups. Frequency of intestinal nematodes and positive serology for Toxocara, were remarkably higher in children with staphylococcal infections than in the non-staphylococcal group. There was a significant correlation between intestinal nematodes or Toxocara infection and staphylococcal infection in children, reinforced by higher eosinophil counts and higher IgE levels in these children than in the control group. One possible explanation for this association would be the enhancement of bacterial infection by the immunomodulation induced by helminth infections, due to strong activation of the Th2 subset of lymphocytes by antigens from larvae and adult worms.

Limiting opportunities for cheating stabilizes virulence in insect parasitic nematodes.

Science.gov (United States)

Shapiro-Ilan, David; Raymond, Ben

2016-03-01

Cooperative secretion of virulence factors by pathogens can lead to social conflict when cheating mutants exploit collective secretion, but do not contribute to it. If cheats outcompete cooperators within hosts, this can cause loss of virulence. Insect parasitic nematodes are important biocontrol tools that secrete a range of significant virulence factors. Critically, effective nematodes are hard to maintain without live passage, which can lead to virulence attenuation. Using experimental evolution, we tested whether social cheating might explain unstable virulence in the nematode Heterorhabditis floridensis by manipulating relatedness via multiplicity of infection (MOI), and the scale of competition. Passage at high MOI, which should reduce relatedness, led to loss of fitness: virulence and reproductive rate declined together and all eight independent lines suffered premature extinction. As theory predicts, relatedness treatments had more impact under stronger global competition. In contrast, low MOI passage led to more stable virulence and increased reproduction. Moreover, low MOI lineages showed a trade-off between virulence and reproduction, particularly for lines under stronger between-host competition. Overall, this study indicates that evolution of virulence theory is valuable for the culture of biocontrol agents: effective nematodes can be improved and maintained if passage methods mitigate possible social conflicts.

Mitochondrial genome diversity in dagger and needle nematodes (Nematoda: Longidoridae).

Science.gov (United States)

Palomares-Rius, J E; Cantalapiedra-Navarrete, C; Archidona-Yuste, A; Blok, V C; Castillo, P

2017-02-02

Dagger and needle nematodes included in the family Longidoridae (viz. Longidorus, Paralongidorus, and Xiphinema) are highly polyphagous plant-parasitic nematodes in wild and cultivated plants and some of them are plant-virus vectors (nepovirus). The mitochondrial (mt) genomes of the dagger and needle nematodes, Xiphinema rivesi, Xiphinema pachtaicum, Longidorus vineacola and Paralongidorus litoralis were sequenced in this study. The four circular mt genomes have an estimated size of 12.6, 12.5, 13.5 and 12.7 kb, respectively. Up to date, the mt genome of X. pachtaicum is the smallest genome found in Nematoda. The four mt genomes contain 12 protein-coding genes (viz. cox1-3, nad1-6, nad4L, atp6 and cob) and two ribosomal RNA genes (rrnL and rrnS), but the atp8 gene was not detected. These mt genomes showed a gene arrangement very different within the Longidoridae species sequenced, with the exception of very closely related species (X. americanum and X. rivesi). The sizes of non-coding regions in the Longidoridae nematodes were very small and were present in a few places in the mt genome. Phylogenetic analysis of all coding genes showed a closer relationship between Longidorus and Paralongidorus and different phylogenetic possibilities for the three Xiphinema species.

Exploitation of FTA cartridges for the sampling, long-term storage, and DNA-based analyses of plant-parasitic nematodes.

Science.gov (United States)

Marek, Martin; Zouhar, Miloslav; Douda, Ondřej; Maňasová, Marie; Ryšánek, Pavel

2014-03-01

The use of DNA-based analyses in molecular plant nematology research has dramatically increased over recent decades. Therefore, the development and adaptation of simple, robust, and cost-effective DNA purification procedures are required to address these contemporary challenges. The solid-phase-based approach developed by Flinders Technology Associates (FTA) has been shown to be a powerful technology for the preparation of DNA from different biological materials, including blood, saliva, plant tissues, and various human and plant microbial pathogens. In this work, we demonstrate, for the first time, that this FTA-based technology is a valuable, low-cost, and time-saving approach for the sampling, long-term archiving, and molecular analysis of plant-parasitic nematodes. Despite the complex structure and anatomical organization of the multicellular bodies of nematodes, we report the successful and reliable DNA-based analysis of nematode high-copy and low-copy genes using the FTA technology. This was achieved by applying nematodes to the FTA cards either in the form of a suspension of individuals, as intact or pestle-crushed nematodes, or by the direct mechanical printing of nematode-infested plant tissues. We further demonstrate that the FTA method is also suitable for the so-called "one-nematode-assay", in which the target DNA is typically analyzed from a single individual nematode. More surprisingly, a time-course experiment showed that nematode DNA can be detected specifically in the FTA-captured samples many years after initial sampling occurs. Collectively, our data clearly demonstrate the applicability and the robustness of this FTA-based approach for molecular research and diagnostics concerning phytonematodes; this research includes economically important species such as the stem nematode (Ditylenchus dipsaci), the sugar beet nematode (Heterodera schachtii), and the Northern root-knot nematode (Meloidogyne hapla).

PATHOGENICITY, DEVELOPMENT AND REPRODUCTION OF THE ENTOMOPATHOGENIC NEMATODE Steinernema sp., IN MEALWORM Tenebrio molitor

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Yuliantoro Baliadi

2011-10-01

Full Text Available The pathogenicity, development and reproduction of Steinernema sp., isolate Skpr-20/Str, were studied using Tenebrio molitor. Results revealed that pathogenicity, development and reproduction were significantly influenced by nematode doses. Although the number of invading IJs increased with increasing dose, percentage penetration declined. The IJs reached adulthood within 3 days. Females laid eggs from day 4-7. All eggs remaining inside uterus develop inside the maternal body. The first female bearing endotokia matricida was observed on day 5. In a sand-based assay, nematode was more pathogenic at lower dose instead of higher ones, where optimum dose was 80 nematodes per larva and average number of progeny per female was 5438. Under crowded conditions, development proceeds to IJ stage instead of the J3. The average length and width decreased with increasing of nematode doses. The IJ produced in cadavers infested with 640 nematodes per larva was significantly smaller (492 ± 6.4 µm than offspring from other doses. The number of days which nematodes first emerged from the cadavers decreased with increasing dose. IJ first emerged at the average of 10-13 days at high IJ densities. It is concluded that the wide experimental characteristic of EPNs is also true for Steinernema sp., isolate Skpr-20/Str.

United States Department of Agriculture-Agricultural Research Service research programs on microbes for management of plant-parasitic nematodes.

Science.gov (United States)

Meyer, Susan L F

2003-01-01

Restrictions on the use of conventional nematicides have increased the need for new methods of managing plant-parasitic nematodes. Consequently, nematode-antagonistic microbes, and active compounds produced by such organisms, are being explored as potential additions to management practices. Programs in this area at the USDA Agricultural Research Service investigate applied biocontrol agents, naturally occurring beneficial soil microbes and natural compounds. Specific research topics include use of plant growth-promoting rhizobacteria and cultural practices for management of root-knot and ring nematodes, determination of management strategies that enhance activity of naturally occurring Pasteuria species (bacterial obligate parasites of nematodes), studies on interactions between biocontrol bacteria and bacterial-feeding nematodes, and screening of microbes for compounds active against plant-parasitic nematodes. Some studies involve biocontrol agents that are active against nematodes and soil-borne plant-pathogenic fungi, or combinations of beneficial bacteria and fungi, to manage a spectrum of plant diseases or to increase efficacy over a broader range of environmental conditions. Effective methods or agents identified in the research programs are investigated as additions to existing management systems for plant-parasitic nematodes.

Damage-associated responses of the host contribute to defence against cyst nematodes but not root-knot nematodes

NARCIS (Netherlands)

Shah, Syed Jehangir; Anjam, Muhammad Shahzad; Mendy, Badou; Anwer, Muhammad Arslan; Habash, Samer S.; Lozano-Torres, Jose L.; Grundler, Florian M.W.; Siddique, Shahid

2017-01-01

When nematodes invade and subsequently migrate within plant roots, they generate cell wall fragments (in the form of oligogalacturonides; OGs) that can act as damage-associated molecular patterns and activate host defence responses. However, the molecular mechanisms mediating damage responses in

Optimization of a host diet for in vivo production of entomopathogenic nematodes

Science.gov (United States)

In previous studies, we developed an improved diet for Tenebrio molitor, a host that is used for in vivo nematode production, and we demonstrated that single insect diet components (e.g., lipids and proteins) can have a positive or negative impact on entomopathogenic nematode fitness and quality. I...

Feeding and the rhodopsin family g-protein coupled receptors in nematodes and arthropods.

Science.gov (United States)

Cardoso, João C R; Félix, Rute C; Fonseca, Vera G; Power, Deborah M

2012-01-01

In vertebrates, receptors of the rhodopsin G-protein coupled superfamily (GPCRs) play an important role in the regulation of feeding and energy homeostasis and are activated by peptide hormones produced in the brain-gut axis. These peptides regulate appetite and energy expenditure by promoting or inhibiting food intake. Sequence and function homologs of human GPCRs involved in feeding exist in the nematode roundworm, Caenorhabditis elegans (C. elegans), and the arthropod fruit fly, Drosophila melanogaster (D. melanogaster), suggesting that the mechanisms that regulate food intake emerged early and have been conserved during metazoan radiation. Nematodes and arthropods are the most diverse and successful animal phyla on Earth. They can survive in a vast diversity of environments and have acquired distinct life styles and feeding strategies. The aim of the present review is to investigate if this diversity has affected the evolution of invertebrate GPCRs. Homologs of the C. elegans and D. melanogaster rhodopsin receptors were characterized in the genome of other nematodes and arthropods and receptor evolution compared. With the exception of bombesin receptors (BBR) that are absent from nematodes, a similar gene complement was found. In arthropods, rhodopsin GPCR evolution is characterized by species-specific gene duplications and deletions and in nematodes by gene expansions in species with a free-living stage and gene deletions in representatives of obligate parasitic taxa. Based upon variation in GPCR gene number and potentially divergent functions within phyla we hypothesize that life style and feeding diversity practiced by nematodes and arthropods was one factor that contributed to rhodopsin GPCR gene evolution. Understanding how the regulation of food intake has evolved in invertebrates will contribute to the development of novel drugs to control nematodes and arthropods and the pests and diseases that use them as vectors.

First use of soil nematode communities as bioindicator of radiation impact in the Chernobyl exclusion zone

Energy Technology Data Exchange (ETDEWEB)

Lecomte, C.; Bonzom, J.M.; Adam-Guillermin, C. [Institute for Radioprotection and Nuclear Safety, IRSN/PRP-ENV/SERIS, LECO (France); Della-Vedova, C. [Magelis, Cadenet (France); Beaugelin-Seiller, K. [Institute for Radioprotection and Nuclear Safety, IRSN/PRP-ENV/SERIS, LM2E (France); Gaschak, S. [Chernobyl Center for Nuclear safety, Radioactive waste and Radioecology, International Radioecology Laboratory (Ukraine); Coppin, F. [Institute for Radioprotection and Nuclear Safety, IRSN/PRP-ENV/SERIS, L2BT (France); Garnier-Laplace, J. [Institute for Radioprotection and Nuclear Safety, IRSN/PRP-ENV/SERIS (France)

2014-07-01

The aim of the study was to assess the effects of former radioactive contamination on the structure of the nematode community in sites affected by the fallout from the Chernobyl accident that occurred on 26, April 1986. Nematodes were collected in spring 2011 from 18 forest sites of the Chernobyl Exclusion Zone (CEZ). The external gamma dose rates, measured from radiophotoluminescent dosimeters (RPL) varied from 0.2 to 22 μGy h{sup -1} between sites. In parallel, the Total dose rates (TDR) absorbed by nematodes were predicted from measured soil activity concentrations, Dose Conversion Coefficients (DCC, calculated by the EDEN software) and Soil-to-biota concentration ratios (from the ERICA tool database). Results showed that TDR were one order of magnitude above the external gamma dose rate measured from RPL. This is mainly due to the contribution of alpha ({sup 241}Am,{sup 238,239,240}Pu) and beta ({sup 90}Sr, and {sup 137}Cs) emitters in the external dose rate. The small size (in the order of mm) of nematodes promoted a high energy deposition throughout the organisms without fading, giving more weight to external dose rate induced by alpha-and beta-emitters, relatively to gamma-emitters. Analysis of the nematode community showed a majority of bacterial-, plant-, and fungal- feeder nematodes and almost none of the disturbance sensitive families whatever the level of radioactive contamination. Multiple regression analysis was used to establish relationships between ecological features (nematodes abundance and family diversity, indices of ecosystem structure and function) to the environmental characteristics (TDR and soil physico-chemical properties). No evidence was found that nematode total abundance and family diversity were impaired by the radiological contamination. However, the Nematode Channel Ratio (defining the relative abundance of bacterial- versus fungal-feeding nematodes) decreased significantly with increasing TDR suggesting that the radioactive

Excretory/secretory products of anisakid nematodes

DEFF Research Database (Denmark)

Mehrdana, Foojan; Buchmann, Kurt

2017-01-01

Parasites from the family Anisakidae are widely distributed in marine fish populations worldwide and mainly nematodes of the three genera Anisakis, Pseudoterranova and Contracaecum have attracted attention due to their pathogenicity in humans. Their life cycles include invertebrates and fish as i...

Nematode and arthropod genomes provide new insights into the evolution of class 2 B1 GPCRs.

Science.gov (United States)

Cardoso, João C R; Félix, Rute C; Power, Deborah M

2014-01-01

Nematodes and arthropods are the most speciose animal groups and possess Class 2 B1 G-protein coupled receptors (GPCRs). Existing models of invertebrate Class 2 B1 GPCR evolution are mainly centered on Caenorhabditis elegans and Drosophila melanogaster and a few other nematode and arthropod representatives. The present study reevaluates the evolution of metazoan Class 2 B1 GPCRs and orthologues by exploring the receptors in several nematode and arthropod genomes and comparing them to the human receptors. Three novel receptor phylogenetic clusters were identified and designated cluster A, cluster B and PDF-R-related cluster. Clusters A and B were identified in several nematode and arthropod genomes but were absent from D. melanogaster and Culicidae genomes, whereas the majority of the members of the PDF-R-related cluster were from nematodes. Cluster A receptors were nematode and arthropod-specific but shared a conserved gene environment with human receptor loci. Cluster B members were orthologous to human GCGR, PTHR and Secretin members with which they probably shared a common origin. PDF-R and PDF-R related clusters were present in representatives of both nematodes and arthropods. The results of comparative analysis of GPCR evolution and diversity in protostomes confirm previous notions that C. elegans and D. melanogaster genomes are not good representatives of nematode and arthropod phyla. We hypothesize that at least four ancestral Class 2 B1 genes emerged early in the metazoan radiation, which after the protostome-deuterostome split underwent distinct selective pressures that resulted in duplication and deletion events that originated the current Class 2 B1 GPCRs in nematode and arthropod genomes.

Three Nematode Species Recovered from Terrestrial Snakes in Republic of Korea.

Science.gov (United States)

Choe, Seongjun; Lim, Junsik; Kim, Hyun; Kim, Youngjun; Kim, Heejong; Lee, Dongmin; Park, Hansol; Jeon, Hyeong-Kyu; Eom, Keeseon S

2016-04-01

The majority of parasitological studies of terrestrial snakes in Korea have focused on zoonotic parasites. However, in the present study, we describe 3 unrecorded nematode species recovered from 5 species of snakes (n=6) in Korea. The examined snakes, all confiscated from illegal hunters, were donated by the Chungnam Wild Animal Rescue Center and Korean Broadcasting System in July 2014 and February 2015. Light and scanning electron microscopies on the shapes of spicules that are either bent or straight (kalicephalids) and the presence of the intestinal cecum (ophidascarids) figured out 3 nematodes; Kalicephalus brachycephalus Maplestone, 1931, Kalicephalus sinensis Hsü, 1934, and Ophidascaris excavata Hsü and Hoeppli, 1934. These 3 species of nematode faunas are recorded for the first time in Korea.

First report of the root-knot nematode Meloidogyne ethiopica on tomato in Slovenia

NARCIS (Netherlands)

Sirca, S.; Urek, G.; Karssen, G.

2004-01-01

The root-knot nematode Meloidogyne ethiopica Whitehead originally described from Tanzania is also distributed in South Africa, Zimbabwe, and Ethiopia (3). Although this species is a relatively unknown root-knot nematode, M. ethiopica parasitizes several economical important crops, such as tomato,

A Plant-Feeding Nematode Indirectly Increases the Fitness of an Aphid

Directory of Open Access Journals (Sweden)

Grace A. Hoysted

2017-11-01

Full Text Available Plants suffer multiple, simultaneous assaults from above and below ground. In the laboratory, pests and/or pathogen attack are commonly studied on an individual basis. The molecular response of the plant to attack from multiple organisms and the interaction of different defense pathways is unclear. The inducible systemic responses of the potato (Solanum tuberosum L. host plant were analyzed to characterize the plant-mediated indirect interactions between a sedentary, endoparasitic nematode (Globodera pallida, and a phloem-sucking herbivore (Myzus persicae. The reproductive success of M. persicae was greater on potato plants pre-infected with G. pallida compared to control plants. Salicylic acid (SA increased systemically in the leaves of potato plants following nematode and aphid infection singly with a corresponding increase in expression of SA-mediated marker genes. An increase in jasmonic acid associated with aphid infection was suppressed when plants were co-infected with nematodes. Our data suggests a positive, asymmetric interaction between a sedentary endoparasitic nematode and a sap-sucking insect. The systemic response of the potato plant following infection with G. pallida indirectly influences the performance of M. persicae. This work reveals additional secondary benefits of controlling individual crop pests.

Use of mixed cultures of biocontrol agents to control sheep nematodes.

Science.gov (United States)

Baloyi, M A; Laing, M D; Yobo, K S

2012-03-23

Biological control is a promising non-chemical approach for the control of gastrointestinal nematodes of sheep. Use of combinations of biocontrol agents have been reported to be an effective method to increase the efficacy of biological control effects. In this study, combinations of either two Bacillus thuringiensis (Bt) or Clonostachys rosea (C. rosea) isolates and Bt+C. rosea isolates were evaluated in vitro in microtitre plates for their biocontrol activity on sheep nematodes. The Baermann technique was used to extract the surviving L3 larval stages of intestinal nematodes and counted under a dissecting microscope to determine the larval counts. Results indicate that there was a significant reduction of nematode counts due to combination of biocontrol agents (Pnematodes counts by 72.8%, 64% and 29.8%. The results revealed a control level of 57% when C. rosea isolates P3+P8 were combined. Combination of Bt and C. rosea isolates B10+P8 caused the greatest mortality of 76.7%. Most combinations were antagonistic, with only a few combinations showing an additive effect. None were synergistic. The isolate combinations were more effective than when isolates were used alone. Copyright © 2011 Elsevier B.V. All rights reserved.

[Controlling effect of antagonist bioorganic fertilizer on tomato root-knot nematode].

Science.gov (United States)

Zhu, Zhen; Chen, Fang; Xiao, Tong-jian; Wang, Xiao-hui; Ran, Wei; Yang, Xing-ming; Shen, Qi-rong

2011-04-01

Indoor in vitro culture experiment and greenhouse pot experiment were conducted to evaluate the capabilities of three bacterial strains XZ-173 (Bacillus amyloliquefaciens), SL-25 (B. gibsonii), and KS-62 (Paenibacillus polymyxa) that can hydrolyze collagen protein in controlling tomato root-knot nematode. In the in vitro culture experiment, suspensions of XZ-173, SL-25, and KS-62 induced a mortality rate of 75.9%, 66.7%, and 50.0% to the second-stage junior nematode within 24 h, and decreased the egg hatching rate to 17.8%, 28.9% and 37.6% after 7-day incubation, respectively, in contrast to the 17.4% mortality rate and 53.6% egg hatching rate in the control (sterilized water). In the greenhouse pot experiment, the bioorganic fertilizer mixed with equal parts of fermented XZ-173, SL-25, and KS-62 gained the best result, with the root-knot nematode population in rhizosphere soil decreased by 84.0% as compared with the control. The bioorganic fertilizer also decreased the numbers of galls and eggs on tomato roots significantly, and increased the underground and aboveground biomass of tomato. Therefore, antagonist bioorganic fertilizer has promising potential in controlling root-knot nematode.

Application of PCR-DGGE method for identification of nematode communities in pepper growing soil

OpenAIRE

Nguyen, Thi Phuong; Ha, Duy Ngo; Nguyen, Huu Hung; Duong, Duc Hieu

2017-01-01

Soil nematodes play an important role in indication for assessing soil environments and ecosystems. Previous studies of nematode community analyses based on molecular identification have shown to be useful for assessing soil environments. Here we applied PCR-DGGE method for molecular analysis of five soil nematode communities (designed as S1 to S5) collected from four provinces in Southeastern Vietnam (Binh Duong, Ba Ria Vung Tau, Binh Phuoc and Dong Nai) based on SSU gene. By sequencing DNA ...

Natural product synthesis: Making nematodes nervous

Science.gov (United States)

Snyder, Scott A.

2011-06-01

A highly inventive route for the synthesis of a key substance that stimulates potato cyst nematodes to hatch has been developed. This discovery has potential to impact food supplies, as treatment of crops with this compound could alleviate the devastating effect of these parasites.

Evaluation of Clonostachys rosea for Control of Plant-Parasitic Nematodes in Soil and in Roots of Carrot and Wheat.

Science.gov (United States)

Iqbal, Mudassir; Dubey, Mukesh; McEwan, Kerstin; Menzel, Uwe; Franko, Mikael Andersson; Viketoft, Maria; Jensen, Dan Funck; Karlsson, Magnus

2018-01-01

Biological control is a promising approach to reduce plant diseases caused by nematodes. We tested the effect of the fungus Clonostachys rosea strain IK726 inoculation on nematode community composition in a naturally nematode infested soil in a pot experiment, and the effect of C. rosea on plant health. The numbers of plant-parasitic nematode genera extracted from soil and plant roots decreased by 40 to 73% when C. rosea was applied, while genera of nonparasitic nematodes were not affected. Soil inoculation of C. rosea increased fresh shoot weight and shoot length of wheat plants by 20 and 24%, respectively, while only shoot dry weight increased by 48% in carrots. Light microscopy of in vitro C. rosea-nematode interactions did not reveal evidence of direct parasitism. However, culture filtrates of C. rosea growing in potato dextrose broth, malt extract broth and synthetic nutrient broth exhibited toxicity toward nematodes and immobilized 57, 62, and 100% of the nematodes, respectively, within 48 h. This study demonstrates that C. rosea can control plant-parasitic nematodes and thereby improve plant growth. The most likely mechanism responsible for the antagonism is antibiosis through production of nematicidal compounds, rather than direct parasitism.

Identification and characterisation of a hyper-variable apoplastic effector gene family of the potato cyst nematodes.

Science.gov (United States)

Eves-van den Akker, Sebastian; Lilley, Catherine J; Jones, John T; Urwin, Peter E

2014-09-01

Sedentary endoparasitic nematodes are obligate biotrophs that modify host root tissues, using a suite of effector proteins to create and maintain a feeding site that is their sole source of nutrition. Using assumptions about the characteristics of genes involved in plant-nematode biotrophic interactions to inform the identification strategy, we provide a description and characterisation of a novel group of hyper-variable extracellular effectors termed HYP, from the potato cyst nematode Globodera pallida. HYP effectors comprise a large gene family, with a modular structure, and have unparalleled diversity between individuals of the same population: no two nematodes tested had the same genetic complement of HYP effectors. Individuals vary in the number, size, and type of effector subfamilies. HYP effectors are expressed throughout the biotrophic stages in large secretory cells associated with the amphids of parasitic stage nematodes as confirmed by in situ hybridisation. The encoded proteins are secreted into the host roots where they are detectable by immunochemistry in the apoplasm, between the anterior end of the nematode and the feeding site. We have identified HYP effectors in three genera of plant parasitic nematodes capable of infecting a broad range of mono- and dicotyledon crop species. In planta RNAi targeted to all members of the effector family causes a reduction in successful parasitism.

Molecular diversity of fungal phylotypes co-amplified alongside nematodes from coastal and deep-sea marine environments.

Directory of Open Access Journals (Sweden)

Punyasloke Bhadury

Full Text Available Nematodes and fungi are both ubiquitous in marine environments, yet few studies have investigated relationships between these two groups. Microbial species share many well-documented interactions with both free-living and parasitic nematode species, and limited data from previous studies have suggested ecological associations between fungi and nematodes in benthic marine habitats. This study aimed to further document the taxonomy and distribution of fungal taxa often co-amplified from nematode specimens. A total of 15 fungal 18S rRNA phylotypes were isolated from nematode specimens representing both deep-sea and shallow water habitats; all fungal isolates displayed high pairwise sequence identities with published data in Genbank (99-100% and unpublished high-throughput 454 environmental datasets (>95%. BLAST matches indicate marine fungal sequences amplified in this study broadly represent taxa within the phyla Ascomycota and Basidiomycota, and several phylotypes showed robust groupings with known taxa in phylogenetic topologies. In addition, some fungal phylotypes appeared to be present in disparate geographic habitats, suggesting cosmopolitan distributions or closely related species complexes in at least some marine fungi. The present study was only able to isolate fungal DNA from a restricted set of nematode taxa; further work is needed to fully investigate the taxonomic scope and function of nematode-fungal interactions.

Earthworms and Plant Residues Modify Nematodes in Tropical Cropping Soils (Madagascar): A Mesocosm Experiment

International Nuclear Information System (INIS)

Villenave, C.; Kichenin, E.; Djigal, D.; Blanchart, E.; Rabary, B.; Djigal, D.

2010-01-01

Free-living nematodes present several characteristics that have led to their use as bio indicators of soil quality. Analyzing the structure of nematofauna is a pertinent way to understand soil biological processes. Earthworms play an important role in soil biological functioning and organic matter dynamics. Their effects on soil nematofauna have seldom been studied. We studied the effect of the tropical endogeic earthworm, Pontoscolex corethrurus, on nematode community structure in a 5-month field mesocosm experiment conducted in Madagascar. Ten different treatments with or without earthworms and with or without organic residues (rice, soybean) were compared. Organic residues were applied on the soil surface or mixed with the soil. The abundance of nematodes (bacterial and fungal feeders) was higher in presence of P. corethrurus than in their absence. The type of plant residues as well as their localisation had significant effects on the abundance and composition of soil nematodes. The analysis of nematode community structure showed that earthworm activity led to an overall activation of the microbial compartment without specific stimulation of the bacterial or fungal compartment.

Earthworms and Plant Residues Modify Nematodes in Tropical Cropping Soils (Madagascar: A Mesocosm Experiment

Directory of Open Access Journals (Sweden)

Cécile Villenave

2010-01-01

Full Text Available Free-living nematodes present several characteristics that have led to their use as bioindicators of soil quality. Analyzing the structure of nematofauna is a pertinent way to understand soil biological processes. Earthworms play an important role in soil biological functioning and organic matter dynamics. Their effects on soil nematofauna have seldom been studied. We studied the effect of the tropical endogeic earthworm, Pontoscolex corethrurus, on nematode community structure in a 5-month field mesocosm experiment conducted in Madagascar. Ten different treatments with or without earthworms and with or without organic residues (rice, soybean were compared. Organic residues were applied on the soil surface or mixed with the soil. The abundance of nematodes (bacterial and fungal feeders was higher in presence of P. corethrurus than in their absence. The type of plant residues as well as their localisation had significant effects on the abundance and composition of soil nematodes. The analysis of nematode community structure showed that earthworm activity led to an overall activation of the microbial compartment without specific stimulation of the bacterial or fungal compartment.

Entomopathogenic nematodes in the European biocontrol market.

Science.gov (United States)

Ehlers, R U

2003-01-01

In Europe total revenues in the biocontrol market have reached approximately 200 million Euros. The sector with the highest turn-over is the market for beneficial invertebrates with a 55% share, followed by microbial agents with approximately 25%. Annual growth rates of up to 20% have been estimated. Besides microbial plant protection products that are currently in the process of re-registration, several microbial products have been registered or are in the process of registration, following the EU directive 91/414. Entomopathogenic nematodes (EPN) are exceptionally safe biocontrol agents. Until today, they are exempted from registration in most European countries, the reason why SMEs were able to offer economically reasonable nematode-based products. The development of technology for mass production in liquid media significantly reduced the product costs and accelerated the introduction of nematode products in tree nurseries, ornamentals, strawberries, mushrooms, citrus and turf. Progress in storage and formulation technology has resulted in high quality products which are more resistant to environmental extremes occurring during transportation to the user. The cooperation between science, industry and extension within the EU COST Action 819 has supported the development of quality control methods. Today four companies produce EPN in liquid culture, offering 8 different nematode species. Problems with soil insects are increasing. Grubs, like Melolontha melolontha and other scarabaeidae cause damage in orchards and turf. Since the introduction of the Western Corn Rootworm Diabrotica virgifera into Serbia in 1992, this pests as spread all over the Balkan Region and has reached Italy, France and Austria. These soil insect pests are potential targets for EPN. The development of insecticide resistance has opened another sector for EPN. Novel adjuvants used to improve formulation of EPN have enabled the foliar application against Western Flower Thrips and Plutella

Investigation on the infection mechanism of the fungus Clonostachys rosea against nematodes using the green fluorescent protein.

Science.gov (United States)

Zhang, Lin; Yang, Jinkui; Niu, Qiuhong; Zhao, Xuna; Ye, Fengping; Liang, Lianming; Zhang, Ke-Qin

2008-04-01

The fungus Clonostachys rosea (syn. Gliocladium roseum) is a potential biocontrol agent. It can suppress the sporulation of the plant pathogenic fungus Botrytis cinerea and kill pathogenic nematodes, but the process of nematode pathogenesis is poorly understood. To help understand the underlying mechanism, we constructed recombinant strains containing a plasmid with both the enhanced green fluorescent protein gene egfp and the hygromycin resistance gene hph. Expression of the green fluorescent protein (GFP) was monitored using fluorescence microscopy. Our observations reveal that the pathogenesis started from the adherence of conidia to nematode cuticle for germination, followed by the penetration of germ tubes into the nematode body and subsequent death and degradation of the nematodes. These are the first findings on the infection process of the fungal pathogen marked with GFP, and the developed method can become an important tool for studying the molecular mechanisms of nematode infection by C. rosea.

Exploring the host parasitism of the migratory plant-parasitic nematode Ditylenchus destuctor by expressed sequence tags analysis.

Directory of Open Access Journals (Sweden)

Huan Peng

Full Text Available The potato rot nematode, Ditylenchus destructor, is a very destructive nematode pest on many agriculturally important crops worldwide, but the molecular characterization of its parasitism of plant has been limited. The effectors involved in nematode parasitism of plant for several sedentary endo-parasitic nematodes such as Heterodera glycines, Globodera rostochiensis and Meloidogyne incognita have been identified and extensively studied over the past two decades. Ditylenchus destructor, as a migratory plant parasitic nematode, has different feeding behavior, life cycle and host response. Comparing the transcriptome and parasitome among different types of plant-parasitic nematodes is the way to understand more fully the parasitic mechanism of plant nematodes. We undertook the approach of sequencing expressed sequence tags (ESTs derived from a mixed stage cDNA library of D. destructor. This is the first study of D. destructor ESTs. A total of 9800 ESTs were grouped into 5008 clusters including 3606 singletons and 1402 multi-member contigs, representing a catalog of D. destructor genes. Implementing a bioinformatics' workflow, we found 1391 clusters have no match in the available gene database; 31 clusters only have similarities to genes identified from D. africanus, the most closely related species to D. destructor; 1991 clusters were annotated using Gene Ontology (GO; 1550 clusters were assigned enzyme commission (EC numbers; and 1211 clusters were mapped to 181 KEGG biochemical pathways. 22 ESTs had similarities to reported nematode effectors. Interestedly, most of the effectors identified in this study are involved in host cell wall degradation or modification, such as 1,4-beta-glucanse, 1,3-beta-glucanse, pectate lyase, chitinases and expansin, or host defense suppression such as calreticulin, annexin and venom allergen-like protein. This result implies that the migratory plant-parasitic nematode D. destructor secrets similar effectors to

Morphological and morphometric features of nematode-cysts in Gymnotus inaequilabiatus liver in the Brazilian Pantanal

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Gizela Melina Galindo

2017-08-01

Full Text Available Abstract The aim of this study was to determine the morphometric measures and morphological aspects of nematode-cysts in Gymnotus inaequilabiatus, and the presence of melanomacrophage centers (MMCs associated with the periphery of cysts and in the liver parenchyma. Adult specimens, 34 female (123.1 ± 43.9g and 45 male (135.5 ± 43.4g, from Paraguay River, Corumbá, Brazil, were used. The number of nematode-cysts was determined in 79 livers and 25 of them randomly selected for histopathological analysis and morphometric measures of nematode-cysts (mean diameter, thickness of collagen layer, and cyst-wall layer. The percentage of cysts with MMCs on the periphery and density in the liver parenchyma was estimated. The average number of macroscopic cysts was of 48.7 ± 2.78. Granulomatous reaction was observed surrounding the cysts. Diameter, collagen layer and cyst-wall measurements were 293.0 ± 75.18 (µm, 17.72 ± 6.01 (µm and 12.21 ± 9.51 (µm, respectively. The number of nematode-cysts was correlated with hepatosomatic index, (r=0.26, P<0.05. Collagen layer was correlated with cyst diameter (r=0.62, P<0.01. Pericystic and parenchymatous MMCs were moderately (r=0.48 and highly (r=0.90 correlated with nematode-cysts number. Morphological characteristics of hepatic tissue and cysts-nematodes measures suggest that G. inaequilabiatus acts as a paratenic host to nematodes in the larval stage.

Population dynamics of host-specific root-feeding cyst nematode and resource quantity in the root zone of a clonal grass

NARCIS (Netherlands)

Stoel, C.D.; Duyts, H.; Putten, van der W.H.

2006-01-01

Recent studies have suggested that root-feeding nematodes influence plant community dynamics, but few studies have investigated the population dynamics of the nematodes. In coastal foredunes, feeding-specialist cyst nematodes (Heterodera spp.) are dominant in the soil nematode community and

Discrimination of plant-parasitic nematodes from complex soil communities using ecometagenetics.

Science.gov (United States)

Porazinska, Dorota L; Morgan, Matthew J; Gaspar, John M; Court, Leon N; Hardy, Christopher M; Hodda, Mike

2014-07-01

Many plant pathogens are microscopic, cryptic, and difficult to diagnose. The new approach of ecometagenetics, involving ultrasequencing, bioinformatics, and biostatistics, has the potential to improve diagnoses of plant pathogens such as nematodes from the complex mixtures found in many agricultural and biosecurity situations. We tested this approach on a gradient of complexity ranging from a few individuals from a few species of known nematode pathogens in a relatively defined substrate to a complex and poorly known suite of nematode pathogens in a complex forest soil, including its associated biota of unknown protists, fungi, and other microscopic eukaryotes. We added three known but contrasting species (Pratylenchus neglectus, the closely related P. thornei, and Heterodera avenae) to half the set of substrates, leaving the other half without them. We then tested whether all nematode pathogens-known and unknown, indigenous, and experimentally added-were detected consistently present or absent. We always detected the Pratylenchus spp. correctly and with the number of sequence reads proportional to the numbers added. However, a single cyst of H. avenae was only identified approximately half the time it was present. Other plant-parasitic nematodes and nematodes from other trophic groups were detected well but other eukaryotes were detected less consistently. DNA sampling errors or informatic errors or both were involved in misidentification of H. avenae; however, the proportions of each varied in the different bioinformatic pipelines and with different parameters used. To a large extent, false-positive and false-negative errors were complementary: pipelines and parameters with the highest false-positive rates had the lowest false-negative rates and vice versa. Sources of error identified included assumptions in the bioinformatic pipelines, slight differences in primer regions, the number of sequence reads regarded as the minimum threshold for inclusion in analysis

Comparison of three methods for gastrointestinal nematode diagnosis determination in grazing dairy cattle in relation to milk production.

Science.gov (United States)

Mejía, M E; Perri, A F; Licoff, N; Miglierina, M M; Cseh, S; Ornstein, A M; Becu-Villalobos, D; Lacau-Mengido, I M

2011-12-29

Development of resistance to anthelmintic drugs has motivated the search for diagnostic methods to identify animals for targeted selective treatments. We compared three methods for the diagnosis of nematode infection in relation to milk production in a fully grazing dairy herd of 150 cows in the humid Pampa (Argentina). Animals had feces, blood and milk sampled during the first postpartum month for EPG, pepsinogen and anti-Ostertagia antibody determination, respectively. With the results obtained two groups of cows, divided in high and low parasite burden, were conformed for each method, and milk production was then compared between groups. When cows were separated by the EPG method (EPG=0 (N=106) vs. EPG>0 (N=44)) a difference of nearly 800 l of milk per cow per lactation was found (P 1000) or by anti-Ostertagia (ODR ≤ 0.5 vs. ODR > 0.5) results did not differ. Interestingly, proportion of cows in each group differed between methods (P<0.0001), and the anti-Ostertagia method yielded significantly more cows in the high index group compared to results using the EPG or Pepsinogen method. No correlations were found between parasite indexes determined by the different methods. High parasite burden estimation found may be ascribed to the production system, fully grazing all year round, and to the sampling time, at the beginning of lactation with cows in negative energy balance and depressed immunity. The fact that the cows were born and reared outside, on pasture with continuous nematode larvae exposure, may also account for the results obtained. In conclusion, EPG counting during the first postpartum month may be a useful tool for the diagnosis of production impairment induced by high nematode burden in adult grazing dairy cows. The anthelmintic treatment of only the EPG-positive recently calved cows would improve milk production, while reducing selective pressure on nematode population for the development of resistance. Copyright © 2011 Elsevier B.V. All rights

RNA interference in plant parasitic nematodes

African Journals Online (AJOL)

STORAGESEVER

2008-08-04

Aug 4, 2008 ... grower preference or by government restrictions to limit the environmental ... risks associated with chemical control and (c) the pro- vision of ... certain model organisms. The first ... reproductive system (Lilley et al., 2005b), sperm (Urwin .... interference of dual oxidase in the plant nematode Meloidogyne.

A new look into the small-scale dispersal of free-living marine nematodes

Directory of Open Access Journals (Sweden)

Micheli C Thomas

2011-08-01

Full Text Available We tested experimentally the hypothesis that prevailing locomotion/feeding strategies and body morphology may lead to more active dispersal of free-living marine nematodes, besides passive transport. Neutral Red was applied to the sediment inside cores and the red plume formed during the flood tide was divided into near, middle, and distant zones. At 0.5 m and 1 m from the stained cores, sampling nets were suspended 5 and 10 cm above the sediment-water interface. Dispersion behaviors were defined as a function of a the numbers of stained recaptured nematodes in comparison to their mean densities in the sediment, b movement in the sediment or swimming in the water column, and c body morphology. Tidal currents with average velocities of 9 cm/s resuspended the numerically dominant nematode taxa Sabatieria sp., Terschellingia longicaudata de Man, 1907, Metachromadora sp. and Viscosia sp. The recapture of stained nematodes as far as 2 m from the original stained cores showed that, despite their small body size, they can disperse through relatively large distances, either passively or actively, via the water column during a single tidal event. Recapture patterns in the sediment and in the water column indicate that nematode dispersal is directly influenced by their body morphology and swimming ability, and indirectly by their feeding strategies, which ultimately define their position in the sediment column. Besides stressing the role played by passive transport in the water column, our experiment additionally showed that mobility and feeding strategies also need to be considered as determinant of short-scale nematode dispersal.

Is current irrigation sustainable in the United States? An integrated assessment of climate change impact on water resources and irrigated crop yields

Science.gov (United States)

Blanc, Elodie; Caron, Justin; Fant, Charles; Monier, Erwan

2017-08-01

While climate change impacts on crop yields has been extensively studied, estimating the impact of water shortages on irrigated crop yields is challenging because the water resources management system is complex. To investigate this issue, we integrate a crop yield reduction module and a water resources model into the MIT Integrated Global System Modeling framework, an integrated assessment model linking a global economic model to an Earth system model. We assess the effects of climate and socioeconomic changes on water availability for irrigation in the U.S. as well as subsequent impacts on crop yields by 2050, while accounting for climate change projection uncertainty. We find that climate and socioeconomic changes will increase water shortages and strongly reduce irrigated yields for specific crops (i.e., cotton and forage), or in specific regions (i.e., the Southwest) where irrigation is not sustainable. Crop modeling studies that do not represent changes in irrigation availability can thus be misleading. Yet, since the most water-stressed basins represent a relatively small share of U.S. irrigated areas, the overall reduction in U.S. crop yields is small. The response of crop yields to climate change and water stress also suggests that some level of adaptation will be feasible, like relocating croplands to regions with sustainable irrigation or switching to less irrigation intensive crops. Finally, additional simulations show that greenhouse gas (GHG) mitigation can alleviate the effect of water stress on irrigated crop yields, enough to offset the reduced CO2 fertilization effect compared to an unconstrained GHG emission scenario.

Controlling tulip stem nematodes in tulip bulbs by a hot water treatment

NARCIS (Netherlands)

Dam, van M.F.N.

2013-01-01

A hot water treatment (HWT) protocol is needed to control tulip stem nematode (TSN) in tulip bulbs. A HWT above approximately 45°C in tulips is assumed to be harmful to the bulbs. Experience with HWT to destroy stem nematodes in daffodils shows that the required temperature for this is 4 hours at

Nematodes Relevance in Soil Quality Management and their Significance as Biomarkers in Aquatic Substrates: Review.

Science.gov (United States)

Akpheokhai, Leonard I; Oribhabor, Blessing J

2016-01-01

The interaction of man with the ecosystem is a major factor causing environmental pollution and its attendant consequences such as climate change in our world today. Patents relating to nematodes' relevance in soil quality management and their significance as biomarkers in aquatic substrates were reviewed. Nematodes are useful in rapid, easy and inexpensive method for testing the toxicity of substance (e.g. aquatic substrates). This review paper sets out to examine and discuss the issue of soil pollution, functions of nematodes in soil and aquatic substrates as well as bio-indicators in soil health management in terrestrial ecology. The information used were on the basis of secondary sources from previous research. It is abundantly clear that the population dynamics of plant parasitic or free-living nematodes have useful potentials as biomonitor for soil health and other forms of environmental contamination through agricultural activities, industrial pollution and oil spillage, and the analysis of nematode community structure could be used as complementary information obtained from conventional soil testing approaches.

Changes in plant species richness induce functional shifts in soil nematode communities in experimental grassland.

Directory of Open Access Journals (Sweden)

Nico Eisenhauer

Full Text Available Changes in plant diversity may induce distinct changes in soil food web structure and accompanying soil feedbacks to plants. However, knowledge of the long-term consequences of plant community simplification for soil animal food webs and functioning is scarce. Nematodes, the most abundant and diverse soil Metazoa, represent the complexity of soil food webs as they comprise all major trophic groups and allow calculation of a number of functional indices.We studied the functional composition of nematode communities three and five years after establishment of a grassland plant diversity experiment (Jena Experiment. In response to plant community simplification common nematode species disappeared and pronounced functional shifts in community structure occurred. The relevance of the fungal energy channel was higher in spring 2007 than in autumn 2005, particularly in species-rich plant assemblages. This resulted in a significant positive relationship between plant species richness and the ratio of fungal-to-bacterial feeders. Moreover, the density of predators increased significantly with plant diversity after five years, pointing to increased soil food web complexity in species-rich plant assemblages. Remarkably, in complex plant communities the nematode community shifted in favour of microbivores and predators, thereby reducing the relative abundance of plant feeders after five years.The results suggest that species-poor plant assemblages may suffer from nematode communities detrimental to plants, whereas species-rich plant assemblages support a higher proportion of microbivorous nematodes stimulating nutrient cycling and hence plant performance; i.e. effects of nematodes on plants may switch from negative to positive. Overall, food web complexity is likely to decrease in response to plant community simplification and results of this study suggest that this results mainly from the loss of common species which likely alter plant-nematode interactions.

'Candidatus pasteuria usgae' sp. nov., an obligate endoparasite of the phytoparasitic nematode Belonolaimus longicaudatus.

Science.gov (United States)

Giblin-Davis, R M; Williams, D S; Bekal, S; Dickson, D W; Brito, J A; Becker, J O; Preston, J F

2003-01-01

Taxonomically relevant characteristics of a fastidiously Gram-positive, obligately endoparasitic prokaryote (strain S-1) that uses the phytoparasitic sting nematode Belonolaimus longicaudatus as its host are reviewed. 16S rDNA sequence similarity (> or = 93%) confirms its congeneric ranking with other Pasteuria species and strains from nematodes and cladocerans and corroborates morphological, morphometric and host range evidence suggesting a novel taxon. The 16S rDNA sequence of strain S-1 has greatest similarity (96%) to the 16S rDNA sequences of both Pasteuria penetrans from root-knot nematodes (Meloidogyne species) and the recently reported strain of Pasteuria isolated from the soybean cyst nematode Heterodera glycines. Because the obligately endoparasitic nature of prokaryotes in the genus Pasteuria prevents isolation of definitive type strains, strain S-1 is proposed as 'Candidatus Pasteuria usgae' sp. nov.

Further Screening of Entomopathogenic Fungi and Nematodes as Control Agents for Drosophila suzukii.

Science.gov (United States)

Cuthbertson, Andrew G S; Audsley, Neil

2016-06-09

Drosophila suzukii populations remain low in the UK. To date, there have been no reports of widespread damage. Previous research demonstrated that various species of entomopathogenic fungi and nematodes could potentially suppress D. suzukii population development under laboratory trials. However, none of the given species was concluded to be specifically efficient in suppressing D. suzukii. Therefore, there is a need to screen further species to determine their efficacy. The following entomopathogenic agents were evaluated for their potential to act as control agents for D. suzukii: Metarhizium anisopliae; Isaria fumosorosea; a non-commercial coded fungal product (Coded B); Steinernema feltiae, S. carpocapsae, S. kraussei and Heterorhabditis bacteriophora. The fungi were screened for efficacy against the fly on fruit while the nematodes were evaluated for the potential to be applied as soil drenches targeting larvae and pupal life-stages. All three fungi species screened reduced D. suzukii populations developing from infested berries. Isaria fumosorosea significantly (p nematodes significantly reduced adult emergence from pupal cases compared to the water control. Larvae proved more susceptible to nematode infection. Heterorhabditis bacteriophora proved the best from the four nematodes investigated; readily emerging from punctured larvae and causing 95% mortality. The potential of the entomopathogens to suppress D. suzukii populations is discussed.

Nematodes enhance plant growth and nutrient uptake under C and N-rich conditions

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Gebremikael, Mesfin T.; Steel, Hanne; Buchan, David; Bert, Wim; de Neve, Stefaan

2016-09-01

The role of soil fauna in crucial ecosystem services such as nutrient cycling remains poorly quantified, mainly because of the overly reductionistic approach adopted in most experimental studies. Given that increasing nitrogen inputs in various ecosystems influence the structure and functioning of soil microbes and the activity of fauna, we aimed to quantify the role of the entire soil nematode community in nutrient mineralization in an experimental set-up emulating nutrient-rich field conditions and accounting for crucial interactions amongst the soil microbial communities and plants. To this end, we reconstructed a complex soil foodweb in mesocosms that comprised largely undisturbed native microflora and the entire nematode community added into defaunated soil, planted with Lolium perenne as a model plant, and amended with fresh grass-clover residues. We determined N and P availability and plant uptake, plant biomass and abundance and structure of the microbial and nematode communities during a three-month incubation. The presence of nematodes significantly increased plant biomass production (+9%), net N (+25%) and net P (+23%) availability compared to their absence, demonstrating that nematodes link below- and above-ground processes, primarily through increasing nutrient availability. The experimental set-up presented allows to realistically quantify the crucial ecosystem services provided by the soil biota.

Molecular contest between potato and the potato cyst nematode Globodera pallida: modulation of Gpa2-mediated resistance

NARCIS (Netherlands)

Koropacka, K.B.

2010-01-01

Gpa2 recognition specificity
Among all the multicellular animals, nematodes are the most numerous. In soil, a high variety
of free living nematodes feeding on bacteria can be found as well as species that parasitize
insects, animals or plants. The potato cyst nematode (PCN)

Differentiation of bacterial feeding nematodes in soil ecological studies by means of arbitrarily primed PCR

Science.gov (United States)

Van Der Knaap, Esther; Rodriguez, Russell J.; Freckman, Diana W.

1993-01-01

Arbitrarily-primed polymerase chain reaction (ap-PCR) was used to differentiate closely related bacterial-feeding nematodes of the genera: Caenorhabditis, Acrobeloides, Cephalobus and Zeldia. Average percentage similarity of bands generated by ap-PCR with seven different primers between 14 isolates of Caenorhabditis elegans was ⪢ 90%, whereas between C. elegans, C. briggsae and C. remanei similarity was nematode populations were also obtained from ap-PCR analysis of single worms. Due to the difficulty of identification of soil nematodes, the ap-PCR offers potential as a rapid and reliable technique to assess biodiversity. Ap-PCR will make it feasible, for the first time, to study the ecological interactions of unique nematode genotypes in soil habitats.

Seasonal prevalence of gastrointestinal nematode parasites of sheep in Northern region of Nile Delta, Egypt.

Science.gov (United States)

Khalafalla, Reda E; Elseify, Mahmoud A; Elbahy, Nasr M

2011-02-01

Over 1 year, from January to December 1999, a total of 173 slaughtered sheep at Al-Mahala abattoir were examined for presence of nematode parasites. Eighteen sheep (10.4%) were infected with eight different species of nematodes. The prevalence rates of detected nematode parasites were; Haemonchus contortus (3.5%), Haemonchus placei (1.7%), Trichuris ovis (5.8%), Parabronema skrjabini (2.9%), Ostertagia trifurcata (1.2%), Chabertia ovina (0.6%) and Strongyloides papillosus (0.6%), and Graphidiops species (2.9%). The seasonal prevalence of the infection with the nematode parasites was studied and the highest rate was during autumn (15.2%) followed by summer (11.1%) and winter (9.4%) while the lowest rate was during spring (5.6%).

Morphological and morphometric features of nematode-cysts in Gymnotus inaequilabiatus liver in the Brazilian Pantanal.

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Galindo, Gizela Melina; Rodrigues, Robson Andrade; Marcondes, Sandriely Fernanda; Soares, Priscilla; Tavares, Luiz Eduardo Roland; Fernandes, Carlos Eurico

2017-01-01

The aim of this study was to determine the morphometric measures and morphological aspects of nematode-cysts in Gymnotus inaequilabiatus, and the presence of melanomacrophage centers (MMCs) associated with the periphery of cysts and in the liver parenchyma. Adult specimens, 34 female (123.1 ± 43.9g) and 45 male (135.5 ± 43.4g), from Paraguay River, Corumbá, Brazil, were used. The number of nematode-cysts was determined in 79 livers and 25 of them randomly selected for histopathological analysis and morphometric measures of nematode-cysts (mean diameter, thickness of collagen layer, and cyst-wall layer). The percentage of cysts with MMCs on the periphery and density in the liver parenchyma was estimated. The average number of macroscopic cysts was of 48.7 ± 2.78. Granulomatous reaction was observed surrounding the cysts. Diameter, collagen layer and cyst-wall measurements were 293.0 ± 75.18 (µm), 17.72 ± 6.01 (µm) and 12.21 ± 9.51 (µm), respectively. The number of nematode-cysts was correlated with hepatosomatic index, (r=0.26, Pcyst diameter (r=0.62, Pnematode-cysts number. Morphological characteristics of hepatic tissue and cysts-nematodes measures suggest that G. inaequilabiatus acts as a paratenic host to nematodes in the larval stage.

Nematode suppression and growth stimulation in corn plants (Zea mays L.) irrigated with domestic effluent.

Science.gov (United States)

Barros, Kenia Kelly; do Nascimento, Clístenes Williams Araújo; Florencio, Lourdinha

2012-01-01

Treated wastewater has great potential for agricultural use due to its concentrations of nutrients and organic matter, which are capable of improving soil characteristics. Additionally, effluents can induce suppression of plant diseases caused by soil pathogens. This study evaluates the effect of irrigation with effluent in a UASB reactor on maize (Zea mays L.) development and on suppression of the diseases caused by nematodes of the genus Meloidogyne. Twelve lysimeters of 1 m(3) each were arranged in a completely randomized design, with four treatments and three replicates. The following treatments were used: T1 (W+I), irrigation with water and infestation with nematodes; T2 (W+I+NPK), irrigation with water, infestation with nematodes and fertilization with nitrogen (N), phosphorus (P) and potassium (K); T3 (E+I), irrigation with effluent and infestation with nematodes; and T4 (E+I+P), irrigation with effluent, infestation with nematodes and fertilization with phosphorus. The plants irrigated with the effluent plus the phosphorus fertilizer had better growth and productivity and were more resistant to the disease symptoms caused by the nematodes. The suppression levels may have been due to the higher levels of Zn and NO(3)(-) found in the leaf tissue of the plants irrigated with the effluent and phosphorus fertilizer.

Comparative Genomics and Transcriptomics Analyses Reveal Divergent Lifestyle Features of Nematode Endoparasitic Fungus Hirsutella minnesotensis

Science.gov (United States)

Lai, Yiling; Liu, Keke; Zhang, Xinyu; Zhang, Xiaoling; Li, Kuan; Wang, Niuniu; Shu, Chi; Wu, Yunpeng; Wang, Chengshu; Bushley, Kathryn E.; Xiang, Meichun; Liu, Xingzhong

2014-01-01

Hirsutella minnesotensis [Ophiocordycipitaceae (Hypocreales, Ascomycota)] is a dominant endoparasitic fungus by using conidia that adhere to and penetrate the secondary stage juveniles of soybean cyst nematode. Its genome was de novo sequenced and compared with five entomopathogenic fungi in the Hypocreales and three nematode-trapping fungi in the Orbiliales (Ascomycota). The genome of H. minnesotensis is 51.4 Mb and encodes 12,702 genes enriched with transposable elements up to 32%. Phylogenomic analysis revealed that H. minnesotensis was diverged from entomopathogenic fungi in Hypocreales. Genome of H. minnesotensis is similar to those of entomopathogenic fungi to have fewer genes encoding lectins for adhesion and glycoside hydrolases for cellulose degradation, but is different from those of nematode-trapping fungi to possess more genes for protein degradation, signal transduction, and secondary metabolism. Those results indicate that H. minnesotensis has evolved different mechanism for nematode endoparasitism compared with nematode-trapping fungi. Transcriptomics analyses for the time-scale parasitism revealed the upregulations of lectins, secreted proteases and the genes for biosynthesis of secondary metabolites that could be putatively involved in host surface adhesion, cuticle degradation, and host manipulation. Genome and transcriptome analyses provided comprehensive understanding of the evolution and lifestyle of nematode endoparasitism. PMID:25359922

Origanum vulgare (Lamiaceae OVICIDAL POTENTIAL ON GASTROINTESTINAL NEMATODES OF CATTLE

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Luciana Laitano Dias de Castro

2013-12-01

Full Text Available Due to anthelmintic resistance in nematodes, several research studies have been developed seeking control alternatives to these parasites. This study evaluated the in vitro action of Origanum vulgare on gastrointestinal nematode eggs of cattle. In order to evaluate the ability to inhibit egg hatch, different dried leaves extracts of this plant were tested, such as dye, hydroalcoholic and aqueous extracts at concentrations varying from 0.62 to 80 mg/mL. Each assay was accompanied by control containing levamisole hydrochloride (0.2 mg/mL, distilled water and 70 ºGL grain alcohol at the same concentration of the extracts. Test results showed that the different O. vulgare extracts inhibited egg hatch of cattle gastrointestinal nematodes at a percentage that varied from 8.8 to 100%; dye and hydroalcoholic extract were the most promising inhibitors. In view of this ovicidal property, O. vulgare may be an important source of viable antiparasitic compounds for nematodiosis control in ruminants.

Nematodes from Achatina fulica Bowdich, 1822 (Mollusca: Gastropoda in Argentina

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Valente R.

2016-03-01

Full Text Available The aim of this study is to describe the nematode cysts and larvae found in Achatina fulica, the giant African snail, in the northeast of Argentina. A total of 373 snails were collected from the cities of Puerto Iguazú and Corrientes. Cysts (N= 2958 containing nematodes identified as L3 Strongyluris sp. were found in the mantle cavity of 87 snails from Puerto Iguazú City (Prevalence 23 %; Mean Intensity= 34; Mean Abundance= 8. The shell size correlated with prevalence, mean intensity and mean abundance (p < 0.05 indicating that there is an exposure-infection constant rather than an accidental one. In other hand, the absence of infection in the smallest shell size suggests a threshold of size to be infected. Taking into account that there exist records of A. fulica infected by nematodes of medical and veterinary importance such as Angiostrongylus and Aelurostrongylus in some Brazilian states near Puerto Iguazú, we emphasize the need for snail surveillance.

Root-lesion nematodes suppress cabbage aphid population development by reducing aphid daily reproduction

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W. H. Gera eHol

2016-02-01

Full Text Available Empirical studies have shown that belowground feeding herbivores can affect the performance of aboveground herbivores in different ways. Often the critical life-history parameters underlying the observed performance effects remain unexplored. In order to better understand the cause for the observed effects on aboveground herbivores, these ecological mechanisms must be better understood. In this study we combined empirical experiments with a modelling approach to analyse the effect of two root feeding endoparasitic nematodes with different feeding strategies on the population growth of the aboveground feeding specialist aphid Brevicoryne brassicae on Brassica nigra. The aim was to test whether emerging differences in life history characteristics (days until reproduction, daily reproduction would be sufficient to explain observed differences in aphid population development on plants with and without two species of nematodes. Aphid numbers were lower on plants with Pratylenchus penetrans in comparison to aphid numbers on plants with Meloidogyne spp. A dedicated experiment showed that aphid daily reproduction was lower on plants with P. penetrans (3.08 offspring per female per day in comparison to both uninfested plants and plants with Meloidogyne spp. (3.50 offspring per female per day. The species-specific reduction of aphid reproduction appeared independent of changes in amino acids, soluble sugars or the glucosinolate sinigrin in the phloem. An individual-based model revealed that relatively small differences in reproduction rate per female were sufficient to yield a similar difference in aphid populations as was found in the empirical experiments.

Identification and characterisation of a hyper-variable apoplastic effector gene family of the potato cyst nematodes.

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Sebastian Eves-van den Akker

2014-09-01

Full Text Available Sedentary endoparasitic nematodes are obligate biotrophs that modify host root tissues, using a suite of effector proteins to create and maintain a feeding site that is their sole source of nutrition. Using assumptions about the characteristics of genes involved in plant-nematode biotrophic interactions to inform the identification strategy, we provide a description and characterisation of a novel group of hyper-variable extracellular effectors termed HYP, from the potato cyst nematode Globodera pallida. HYP effectors comprise a large gene family, with a modular structure, and have unparalleled diversity between individuals of the same population: no two nematodes tested had the same genetic complement of HYP effectors. Individuals vary in the number, size, and type of effector subfamilies. HYP effectors are expressed throughout the biotrophic stages in large secretory cells associated with the amphids of parasitic stage nematodes as confirmed by in situ hybridisation. The encoded proteins are secreted into the host roots where they are detectable by immunochemistry in the apoplasm, between the anterior end of the nematode and the feeding site. We have identified HYP effectors in three genera of plant parasitic nematodes capable of infecting a broad range of mono- and dicotyledon crop species. In planta RNAi targeted to all members of the effector family causes a reduction in successful parasitism.

Tracing organic matter sources of estuarine tidal flat nematodes with stable carbon isotopes

NARCIS (Netherlands)

Moens, T.; Luyten, C.; Middelburg, J.J.; Herman, P.M.J.; Vincx, M.

2002-01-01

The present study explores the use of stable carbon isotopes to trace organic matter sources of intertidal nematodes in the Schelde estuary (SW Netherlands). Stable carbon isotope signatures of nematodes from a saltmarsh and 4 tidal flat stations were determined in spring and winter situations, and

Controlling Aphelenchoides subtenuis nematodes with a hot water treatment in Crocus and Allium

NARCIS (Netherlands)

Leeuwen, van P.J.; Trompert, J.P.T.

2011-01-01

Several bulbous crops like Crocus, Allium and some species of Tulipa and Narcissus can be infected with the nematode Aphelenchoides subtenuis. The nematodes cause retarded growth, poor or no flowering and eventually death of the bulbs and corms. A hot water treatment after lifting the bulbs has

The genome and life-stage specific transcriptomes of Globodera pallida elucidate key aspects of plant parasitism by a cyst nematode.

Science.gov (United States)

Cotton, James A; Lilley, Catherine J; Jones, Laura M; Kikuchi, Taisei; Reid, Adam J; Thorpe, Peter; Tsai, Isheng J; Beasley, Helen; Blok, Vivian; Cock, Peter J A; Eves-van den Akker, Sebastian; Holroyd, Nancy; Hunt, Martin; Mantelin, Sophie; Naghra, Hardeep; Pain, Arnab; Palomares-Rius, Juan E; Zarowiecki, Magdalena; Berriman, Matthew; Jones, John T; Urwin, Peter E

2014-03-03

Globodera pallida is a devastating pathogen of potato crops, making it one of the most economically important plant parasitic nematodes. It is also an important model for the biology of cyst nematodes. Cyst nematodes and root-knot nematodes are the two most important plant parasitic nematode groups and together represent a global threat to food security. We present the complete genome sequence of G. pallida, together with transcriptomic data from most of the nematode life cycle, particularly focusing on the life cycle stages involved in root invasion and establishment of the biotrophic feeding site. Despite the relatively close phylogenetic relationship with root-knot nematodes, we describe a very different gene family content between the two groups and in particular extensive differences in the repertoire of effectors, including an enormous expansion of the SPRY domain protein family in G. pallida, which includes the SPRYSEC family of effectors. This highlights the distinct biology of cyst nematodes compared to the root-knot nematodes that were, until now, the only sedentary plant parasitic nematodes for which genome information was available. We also present in-depth descriptions of the repertoires of other genes likely to be important in understanding the unique biology of cyst nematodes and of potential drug targets and other targets for their control. The data and analyses we present will be central in exploiting post-genomic approaches in the development of much-needed novel strategies for the control of G. pallida and related pathogens.

Drechslerella stenobrocha genome illustrates the mechanism of constricting rings and the origin of nematode predation in fungi

Science.gov (United States)

2014-01-01

Background Nematode-trapping fungi are a unique group of organisms that can capture nematodes using sophisticated trapping structures. The genome of Drechslerella stenobrocha, a constricting-ring-forming fungus, has been sequenced and reported, and provided new insights into the evolutionary origins of nematode predation in fungi, the trapping mechanisms, and the dual lifestyles of saprophagy and predation. Results The genome of the fungus Drechslerella stenobrocha, which mechanically traps nematodes using a constricting ring, was sequenced. The genome was 29.02 Mb in size and was found rare instances of transposons and repeat induced point mutations, than that of Arthrobotrys oligospora. The functional proteins involved in nematode-infection, such as chitinases, subtilisins, and adhesive proteins, underwent a significant expansion in the A. oligospora genome, while there were fewer lectin genes that mediate fungus-nematode recognition in the D. stenobrocha genome. The carbohydrate-degrading enzyme catalogs in both species were similar to those of efficient cellulolytic fungi, suggesting a saprophytic origin of nematode-trapping fungi. In D. stenobrocha, the down-regulation of saprophytic enzyme genes and the up-regulation of infection-related genes during the capture of nematodes indicated a transition between dual life strategies of saprophagy and predation. The transcriptional profiles also indicated that trap formation was related to the protein kinase C (PKC) signal pathway and regulated by Zn(2)–C6 type transcription factors. Conclusions The genome of D. stenobrocha provides support for the hypothesis that nematode trapping fungi evolved from saprophytic fungi in a high carbon and low nitrogen environment. It reveals the transition between saprophagy and predation of these fungi and also proves new insights into the mechanisms of mechanical trapping. PMID:24507587

Identification of a bacteria-like ferrochelatase in Strongyloides venezuelensis, an animal parasitic nematode.

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Eiji Nagayasu

Full Text Available Heme is an essential molecule for vast majority of organisms serving as a prosthetic group for various hemoproteins. Although most organisms synthesize heme from 5-aminolevulinic acid through a conserved heme biosynthetic pathway composed of seven consecutive enzymatic reactions, nematodes are known to be natural heme auxotrophs. The completely sequenced Caenorhabditis elegans genome, for example, lacks all seven genes for heme biosynthesis. However, genome/transcriptome sequencing of Strongyloides venezuelensis, an important model nematode species for studying human strongyloidiasis, indicated the presence of a gene for ferrochelatase (FeCH, which catalyzes the terminal step of heme biosynthesis, whereas the other six heme biosynthesis genes are apparently missing. Phylogenetic analyses indicated that nematode FeCH genes, including that of S. venezuelensis (SvFeCH have a fundamentally different evolutionally origin from the FeCH genes of non-nematode metazoa. Although all non-nematode metazoan FeCH genes appear to be inherited vertically from an ancestral opisthokont, nematode FeCH may have been acquired from an alpha-proteobacterium, horizontally. The identified SvFeCH sequence was found to function as FeCH as expected based on both in vitro chelatase assays using recombinant SvFeCH and in vivo complementation experiments using an FeCH-deficient strain of Escherichia coli. Messenger RNA expression levels during the S. venezuelensis lifecycle were examined by real-time RT-PCR. SvFeCH mRNA was expressed at all the stages examined with a marked reduction at the infective third-stage larvae. Our study demonstrates the presence of a bacteria-like FeCH gene in the S. venezuelensis genome. It appeared that S. venezuelensis and some other animal parasitic nematodes reacquired the once-lost FeCH gene. Although the underlying evolutionary pressures that necessitated this reacquisition remain to be investigated, it is interesting that the presence of Fe

Interspecific competition between entomopathogenic nematodes (Steinernema is modified by their bacterial symbionts (Xenorhabdus

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Pages Sylvie

2006-09-01

Full Text Available Abstract Background Symbioses between invertebrates and prokaryotes are biological systems of particular interest in order to study the evolution of mutualism. The symbioses between the entomopathogenic nematodes Steinernema and their bacterial symbiont Xenorhabdus are very tractable model systems. Previous studies demonstrated (i a highly specialized relationship between each strain of nematodes and its naturally associated bacterial strain and (ii that mutualism plays a role in several important life history traits of each partner such as access to insect host resources, dispersal and protection against various biotic and abiotic factors. The goal of the present study was to address the question of the impact of Xenorhabdus symbionts on the progression and outcome of interspecific competition between individuals belonging to different Steinernema species. For this, we monitored experimental interspecific competition between (i two nematode species: S. carpocapsae and S. scapterisci and (ii their respective symbionts: X. nematophila and X. innexi within an experimental insect-host (Galleria mellonella. Three conditions of competition between nematodes were tested: (i infection of insects with aposymbiotic IJs (i.e. without symbiont of both species (ii infection of insects with aposymbiotic IJs of both species in presence of variable proportion of their two Xenorhabdus symbionts and (iii infection of insects with symbiotic IJs (i.e. naturally associated with their symbionts of both species. Results We found that both the progression and the outcome of interspecific competition between entomopathogenic nematodes were influenced by their bacterial symbionts. Thus, the results obtained with aposymbiotic nematodes were totally opposite to those obtained with symbiotic nematodes. Moreover, the experimental introduction of different ratios of Xenorhabdus symbionts in the insect-host during competition between Steinernema modified the proportion of

Assaying environmental nickel toxicity using model nematodes

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Rudel, David; Douglas, Chandler; Huffnagle, Ian; Besser, John M.; Ingersoll, Christopher G.

2013-01-01

Although nickel exposure results in allergic reactions, respiratory conditions, and cancer in humans and rodents, the ramifications of excess nickel in the environment for animal and human health remain largely undescribed. Nickel and other cationic metals travel through waterways and bind to soils and sediments. To evaluate the potential toxic effects of nickel at environmental contaminant levels (8.9-7,600 µg Ni/g dry weight of sediment and 50-800 µg NiCl2/L of water), we conducted assays using two cosmopolitan nematodes, Caenorhabditis elegans and Pristionchus pacificus. We assayed the effects of both sediment-bound and aqueous nickel upon animal growth, developmental survival, lifespan, and fecundity. Uncontaminated sediments were collected from sites in the Midwestern United States and spiked with a range of nickel concentrations. We found that nickel-spiked sediment substantially impairs both survival from larval to adult stages and adult longevity in a concentration-dependent manner. Further, while aqueous nickel showed no adverse effects on either survivorship or longevity, we observed a significant decrease in fecundity, indicating that aqueous nickel could have a negative impact on nematode physiology. Intriguingly, C. elegansand P. pacificus exhibit similar, but not identical, responses to nickel exposure. Moreover, P. pacificus could be tested successfully in sediments inhospitable to C. elegans. Our results add to a growing body of literature documenting the impact of nickel on animal physiology, and suggest that environmental toxicological studies could gain an advantage by widening their repertoire of nematode species.

Feeding and the rhodopsin family G-Protein Coupled Receptors (GPCRs in nematodes and arthropods

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Joao Carlos dos Reis Cardoso

2012-12-01

Full Text Available In vertebrates, receptors of the rhodopsin G-protein coupled superfamily (GPCRs play an important role in the regulation of feeding and energy homeostasis and are activated by peptide hormones produced in the brain-gut axis. These peptides regulate appetite and energy expenditure by promoting or inhibiting food intake. Sequence and function homologues of human GPCRs involved in feeding exist in the nematode roundworm, Caenorhabditis elegans (C. elegans and the arthropod fruit fly, Drosophila melanogaster (D. melanogaster, suggesting that the mechanisms that regulate food intake emerged early and have been conserved during metazoan radiation. Nematodes and arthropods are the most diverse and successful animal phyla on Earth. They can survive in a vast diversity of environments and have acquired distinct life styles and feeding strategies. The aim of the present review is to investigate if this diversity has affected the evolution of invertebrate GPCRs. Homologues of the C. elegans and D. melanogaster rhodopsin receptors were characterized in the genome of other nematodes and arthropods and receptor evolution compared. With the exception of bombesin receptors (BBR that are absent from nematodes, a similar gene complement was found. In arthropods, rhodopsin GPCR evolution is characterized by species-specific gene duplications and deletions and in nematodes by gene expansions in species with a free-living stage and gene deletions in representatives of obligate parasitic taxa. Based upon variation in GPCR gene number and potentially divergent functions within phyla we hypothesize that life style and feeding diversity practiced by nematodes and arthropods was one factor that contributed to rhodopsin GPCR gene evolution. Understanding how the regulation of food intake has evolved in invertebrates will contribute to the development of novel drugs to control nematodes and arthropods and the pests and diseases that use them as vectors.

Genomic characterisation of the effector complement of the potato cyst nematode Globodera pallida

NARCIS (Netherlands)

Thorpe, P.; Mantelin, S.; Cock, P.J.A.; Blok, V.C.; Coke, M.C.; Evers-van den Akker, S.; Guzeeva, E.; Lilley, C.J.; Smant, G.; Reid, A.J.; Wright, K.M.; Urwin, P.E.; Jones, J.T.

2014-01-01

Background The potato cyst nematode Globodera pallida has biotrophic interactions with its host. The nematode induces a feeding structure – the syncytium – which it keeps alive for the duration of the life cycle and on which it depends for all nutrients required to develop to the adult stage.

IMMUNE REGULATING ES-PRODUCTS IN PARASITIC NEMATODES

DEFF Research Database (Denmark)

Bahlool, Qusay Zuhair Mohammad; Buchmann, Kurt; Kania, Per Walter

work elucidates the effect of ES substances on the fish immune system by measuring immune gene expression in spleen and liver of rainbow trout (Oncorhynchus mykiss) injected intraperitoneally with ES products isolated from A. simplex third stage larvae. The overall gene expression profile of exposed...... fish showed a generalized down-regulation of the immune genes tested, suggesting a role of ES proteins in minimizing the immune reaction of rainbow trout against invading nematodes. We also tested the enzymatic activity of the ES proteins and found that lipase, esterase lipase, valine and cysteine...... arylamidases, naphthol-AS-BI-phosphohydrolase and a-galactosidase activities were present in the ES solution. This type of hydrolytic enzyme activity may play a role in nematode penetration of host tissue. Based on the notion that A. simplex ES-proteins may have an immune-depressive effect, it could also...

Ecological characterisation of the Colombian entomopathogenic nematode Heterorhabditis sp. SL0708.

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Mejia-Torres, M C; Sáenz, A

2013-05-01

The entomopathogenic nematode Heterorhabditis sp. SL0708 (Rhabditida: Heterorhabditidae) isolated from soil in Alcalá, Valle del Cauca (Colombia) was characterised ecologically using Galleria mellonella larvae (L) (Pyralidae: Galleriinae) as hosts. The effect of temperature on the viability, infectivity and reproduction, and of moisture on infectivity and storage in liquid were evaluated in infective juveniles (IJs). Significant differences were found in the viability, infectivity and reproduction of the IJs at different temperatures. No nematodes were recovered at 5 °C and 10 °C, and at 35 °C no infectivity was observed. Average daily nematode recovery was best at 25 °C, and survival of the IJs was low in substrates presenting 13% moisture. The optimal storage temperature for Heterorhabditis sp. SL0708 was between 20 °C and 30 °C, keeping its infectivity for up to 8 weeks.

Does scavenging extend the host range of entomopathogenic nematodes (Nematoda: Steinernematidae)?

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Půza, Vladimír; Mrácek, Zdenĕk

2010-05-01

Living and freeze-killed natural and laboratory hosts, with different susceptibility to entomopathogenic nematodes, were exposed to the larvae of Steinernema affine and Steinernema kraussei in two different experimental arenas (Eppendorf tubes, Petri dishes), and the success of the colonisation and eventual progeny production were observed. Both nematodes were able to colonise both living and dead larvae of Galleria mellonella (Lepidoptera) and adult Blatella germanica (Blattodea) even though the progeny production in dead hosts was lower on average. Living carabid beetles, Poecilus cupreus, and elaterid larvae (Coleoptera) were resistant to the infection, however, both nematodes were able to colonise and multiply in several dead P. cupreus and in a majority of dead elaterid larvae. By scavenging, EPNs can utilise cadavers of insects that are naturally resistant to EPN infection, and so broaden their host range. (c) 2010 Elsevier Inc. All rights reserved.

Investigation of Nematode Diversity using Scanning Electron Microscopy and Fluorescent Microscopy

Science.gov (United States)

Seacor, Taylor; Howell, Carina

2013-03-01

Nematode worms account for the vast majority of the animals in the biosphere. They are colossally important to global public health as parasites, and to agriculture both as pests and as beneficial inhabitants of healthy soil. Amphid neurons are the anterior chemosensory neurons in nematodes, mediating critical behaviors including chemotaxis and mating. We are examining the cellular morphology and external anatomy of amphid neurons, using fluorescence microscopy and scanning electron microscopy, respectively, of a wide range of soil nematodes isolated in the wild. We use both classical systematics (e.g. diagnostic keys) and molecular markers (e.g. ribosomal RNA) to classify these wild isolates. Our ultimate aim is to build a detailed anatomical database in order to dissect genetic pathways of neuronal development and function across phylogeny and ecology. Research supported by NSF grants 092304, 0806660, 1058829 and Lock Haven University FPDC grants

NGT-3D: a simple nematode cultivation system to study Caenorhabditis elegans biology in 3D

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Tong Young Lee

2016-04-01

Full Text Available The nematode Caenorhabditis elegans is one of the premier experimental model organisms today. In the laboratory, they display characteristic development, fertility, and behaviors in a two dimensional habitat. In nature, however, C. elegans is found in three dimensional environments such as rotting fruit. To investigate the biology of C. elegans in a 3D controlled environment we designed a nematode cultivation habitat which we term the nematode growth tube or NGT-3D. NGT-3D allows for the growth of both nematodes and the bacteria they consume. Worms show comparable rates of growth, reproduction and lifespan when bacterial colonies in the 3D matrix are abundant. However, when bacteria are sparse, growth and brood size fail to reach levels observed in standard 2D plates. Using NGT-3D we observe drastic deficits in fertility in a sensory mutant in 3D compared to 2D, and this defect was likely due to an inability to locate bacteria. Overall, NGT-3D will sharpen our understanding of nematode biology and allow scientists to investigate questions of nematode ecology and evolutionary fitness in the laboratory.

Yield and fruit quality of four sweet corn hybrids (Zea mays) under conventional and integrated fertilization with vermicompost.

Science.gov (United States)

Lazcano, Cristina; Revilla, Pedro; Malvar, Rosa Ana; Domínguez, Jorge

2011-05-01

Vermicompost has been proposed as a valuable fertilizer for sustainable agriculture. The effects of vermicompost on yield and quality of sweet corn were evaluated in this study. In two field trials, sweet corn plants were grown under (i) a conventional fertilization regime with inorganic fertilizer, and integrated fertilization regimes in which 75% of the nutrients were supplied by the inorganic fertilizer and 25% of the nutrients were supplied by either (ii) rabbit manure, or (iii) vermicompost. All three types of fertilization regime were supplied at two doses. Two pairs of nearly isogenic sweet corn hybrids homozygous for sugary1 and shrunken2 mutants were included in the trials to explore fertilizer × genotype interactions. Growth, yield and ear quality of the plants were evaluated in relation to the three fertilization regimes. In general, the integrated regimes yielded the same productivity levels as the conventional treatment. Moreover, both vermicompost and manure produced significant increases in plant growth and marketable yield, and also affected the chemical composition and quality of the marketable ear. Nevertheless, most of the observed effects of the organic fertilizers were genotype-dependent. The results confirm that the use of organic fertilizers such as vermicompost has a positive effect on crop yield and quality. Nevertheless, these effects were not general, indicating the complexity of the organic amendment-plant interactions and the importance of controlling genetic variation when studying the effects of vermicompost on plant growth. Copyright © 2011 Society of Chemical Industry.

Gastric nematodes of Nile crocodiles, Crocodylus niloticus Laurenti, 1768, in the Okavango River, Botswana

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K. Junker

2006-09-01

Full Text Available The ascaridoid nematodes Dujardinascaris madagascariensis Chabaud & Caballero, 1966, Dujardinascaris dujardini (Travassos, 1920, Gedoelstascaris vandenbrandeni (Baylis, 1929 Sprent, 1978 and Multicaecum agile (Wedl, 1861 Baylis, 1923 were recovered from the stomach contents of Crocodylus niloticus Laurenti, 1768 from the Okavango River, Botswana, together with Eustrongylides sp., a dioctophymatoid nematode usually parasitizing piscivorous birds. Dujardinascaris madagascariensis was present in most of the infected hosts, while the remaining species were mostly represented in single collections in one to three hosts. All four ascaridoid nematodes represent new geographic records.

Parasitic Nematode Interactions with Mammals and Plants

NARCIS (Netherlands)

Jasmer, D.P.; Goverse, A.; Smant, G.

2003-01-01

Parasitic nematodes that infect humans, animals, and plants cause serious diseases that are deleterious to human health and agricultural productivity. Chemical and biological control methods have reduced the impact of these parasites. However, surviving environmental stages lead to persistent

Population dynamics of a host-specific root-feeding cyst nematode and resource quantity in the root zone of a clonal grass

NARCIS (Netherlands)

Van der Stoel, C.D.; Duyts, H.; Van der Putten, W.H.

2006-01-01

Recent studies have suggested that root-feeding nematodes influence plant community dynamics, but few studies have investigated the population dynamics of the nematodes. In coastal foredunes, feeding-specialist cyst nematodes (Heterodera spp.) are dominant in the soil nematode community and

Nematode diversity, abundance and community structure 50 years after the formation of the volcanic island of Surtsey

Science.gov (United States)

Ilieva-Makulec, K.; Bjarnadottir, B.; Sigurdsson, B. D.

2014-10-01

The soil nematode fauna can give important insights into soil development and other habitat changes that occur during primary succession. We investigated the generic composition, density, distribution and community structure of nematodes 50 years after the formation of a pristine volcanic island, Surtsey, Iceland. Part of the island has received additional nutrient inputs from seagulls breeding there since 1985, while the reminder has been much less affected and is at present found at a different successional sere. In total, 25 genera of nematodes were identified, of which 14 were reported on Surtsey for the first time. Nematode communities were more diverse in the more infertile area outside the gull colony, where 24 genera were found, compared to 18 inside. The trophic structure of the nematode communities showed relatively higher abundance of fungal feeders in the infertile areas, but relatively more bacterial- and plant-feeders inside the colony. Nematode abundance in surface soil was, however, significantly higher within the gull colony, with 16.7 ind. cm-2 compared to 3.6 ind. cm-2 outside. A multivariate analysis indicated that the nematode abundance and distribution on Surtsey were most strongly related to the soil C : N ratio, soil acidity, plant cover and biomass, soil temperature and soil depth.

Sequence mining and transcript profiling to explore cyst nematode parasitism

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Recknor Justin

2009-01-01

Full Text Available Abstract Background Cyst nematodes are devastating plant parasites that become sedentary within plant roots and induce the transformation of normal plant cells into elaborate feeding cells with the help of secreted effectors, the parasitism proteins. These proteins are the translation products of parasitism genes and are secreted molecular tools that allow cyst nematodes to infect plants. Results We present here the expression patterns of all previously described parasitism genes of the soybean cyst nematode, Heterodera glycines, in all major life stages except the adult male. These insights were gained by analyzing our gene expression dataset from experiments using the Affymetrix Soybean Genome Array GeneChip, which contains probeset sequences for 6,860 genes derived from preparasitic and parasitic H. glycines life stages. Targeting the identification of additional H. glycines parasitism-associated genes, we isolated 633 genes encoding secretory proteins using algorithms to predict secretory signal peptides. Furthermore, because some of the known H. glycines parasitism proteins have strongest similarity to proteins of plants and microbes, we searched for predicted protein sequences that showed their highest similarities to plant or microbial proteins and identified 156 H. glycines genes, some of which also contained a signal peptide. Analyses of the expression profiles of these genes allowed the formulation of hypotheses about potential roles in parasitism. This is the first study combining sequence analyses of a substantial EST dataset with microarray expression data of all major life stages (except adult males for the identification and characterization of putative parasitism-associated proteins in any parasitic nematode. Conclusion We have established an expression atlas for all known H. glycines parasitism genes. Furthermore, in an effort to identify additional H. glycines genes with putative functions in parasitism, we have reduced the

Potato cyst nematodes Globodera rostochiensis and Globodera pallida, and their chemoecological interactions with the host plant

OpenAIRE

Čepulytė-Rakauskienė, Rasa

2012-01-01

Potato cyst nematodes Globodera rostochiensis and Globodera pallida are one of the most important solanaceous plant pests. Identification of potato cyst nematodes species is exposed to morphological similarities and overlapping morphometric measurements between species. Only modern molecular techniques allow more accurate identification of potato cyst nematode species. Hence, it is important to apply these techniques in order to reliably identify these species in Lithuania. Potato roo...

Chitosan-based nanoparticles of avermectin to control pine wood nematodes.

Science.gov (United States)

Liang, Wenlong; Yu, Aixin; Wang, Guodong; Zheng, Feng; Jia, Jinliang; Xu, Hanhong

2018-06-01

Pine wood nematode disease is a most devastating disease of pine trees. Avermectin (AVM) is a widely used bio-nematocide which can effectively to kill the pine wood nematode (PWN). However, its poor solubility in water and rapid photolysis are responsible for its poor bioavailability, which causes environmental pollution because of excessive applied rates. Here, a simple electrostatic interaction method was used to encapsulate AVM within nanoparticles composed of poly-γ-glutamic acid (γ-PGA) and chitosan (CS). The loading capacity of the resulting AVM-CS/γ-PGA nanoparticles was as much as 30.5%. The encapsulation of AVM within these nanoparticles reduced its losses by more than 20.0% through photolysis. An in vitro test showed that the rate of release of AVM from the nanoparticles was dependent on the ambient pH, with rapid release occurring in an alkaline environment. The mortality rate of nematodes which were treated with 1ppm of AVM content of AVM-CS/γ-PGA was 98.6% after 24h, while one of free AVM was only 69.9%. In addition, FITC-labeled CS/γ-PGA nanoparticles (FITC-CS/γ-PGA) showed that the nanoparticles could enrich in intestines and head of nematodes. All of these results showed that those nanoparticles of AVM are a potential multifunctional formulation to control the pest and reduce environment pollution. Copyright © 2018 Elsevier B.V. All rights reserved.

Heterodera schachtii Tyrosinase-like protein a novel nematode effector modulating plant hormone homeostasis

Czech Academy of Sciences Publication Activity Database

Habash, S.; Radakovic, Z.S.; Vaňková, Radomíra; Siddique, S.; Dobrev, Petre; Gleason, C.; Grundler, F.M.W.; Elashry, A.

2017-01-01

Roč. 7, JUL 31 (2017), č. článku 6874. ISSN 2045-2322 Institutional support: RVO:61389030 Keywords : arabidopsis-thaliana * cyst-nematode * parasitic nematode * transient expression * host plants * sequence * identification * infection * model * transformation Subject RIV: ED - Physiology OBOR OECD: Plant sciences, botany Impact factor: 4.259, year: 2016

Isolation of entomopathogenic nematodes in an apple orchard in Southern Brazil and its virulence to Anastrepha fraterculus (Diptera: Tephritidae) larvae, under laboratory conditions.

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Foelkel, E; Voss, M; Monteiro, L B; Nishimura, G

2017-03-01

Entomopathogenic nematodes (EPNs) are a promising alternative to integrated control in many fruit pests. Few studies were made on the relationship of Anastrepha fraterculus natural population with native EPNs population and other biotic and abiotic factors. The aim of this work was to verify the occurrence of endemic nematodes in an apple orchard, concerning environmental conditions and technical procedure, and access isolates virulence to A. fraterculus larvae. The experiment was conducted during a year taking monthly soil samples from an apple orchard, with and without fallen fruits just above the soil. Samples were baited with Tenebrium molitor and A. fraterculus larvae in laboratory. Canopy and fallen fruits were sampled to access the pest infestation. Seventy three EPN isolates were captured, in 23.2% soil samples, more with T. molitor than with A. fraterculus baits. From the 20 isolates tested against A. fraterculus, only five were pathogenic, and they were identified as Oscheius sp. The nematodes were captured during all seasons in a similar frequency. Soil and weather conditions, presence of fruit over the orchard soil, and A. fraterculus pupae in the fruits had no significant influence on the capture. As a conclusion, nematodes of the genera Oscheius are found in an apple orchard of Porto Amazonas constantly along the year, independently of fluctuations in A. fraterculus population, climate conditions and presence of fruit over the soil. Some of the isolates are pathogenic to A. fraterculus.

The genome and life-stage specific transcriptomes of Globodera pallida elucidate key aspects of plant parasitism by a cyst nematode

KAUST Repository

Cotton, James A

2014-03-03

Background: Globodera pallida is a devastating pathogen of potato crops, making it one of the most economically important plant parasitic nematodes. It is also an important model for the biology of cyst nematodes. Cyst nematodes and root-knot nematodes are the two most important plant parasitic nematode groups and together represent a global threat to food security. Results: We present the complete genome sequence of G. pallida, together with transcriptomic data from most of the nematode life cycle, particularly focusing on the life cycle stages involved in root invasion and establishment of the biotrophic feeding site. Despite the relatively close phylogenetic relationship with root-knot nematodes, we describe a very different gene family content between the two groups and in particular extensive differences in the repertoire of effectors, including an enormous expansion of the SPRY domain protein family in G. pallida, which includes the SPRYSEC family of effectors. This highlights the distinct biology of cyst nematodes compared to the root-knot nematodes that were, until now, the only sedentary plant parasitic nematodes for which genome information was available. We also present in-depth descriptions of the repertoires of other genes likely to be important in understanding the unique biology of cyst nematodes and of potential drug targets and other targets for their control. Conclusions: The data and analyses we present will be central in exploiting post-genomic approaches in the development of much-needed novel strategies for the control of G. pallida and related pathogens. 2014 Cotton et al.; licensee BioMed Central Ltd.

Does Integration Help Adapt to Climate Change? Case of Increased US Corn Yield Volatility

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Verma, M.; Diffenbaugh, N. S.; Hertel, T. W.

2012-12-01

In absence of of new crop varieties or significant shifts in the geography of corn production, US national corn yields variation could double by the year 2040 as a result of climate change and without adaptation this could lead the variability in US corn prices to quadruple (Diffenbaugh et al. 2012). In addition to climate induced price changes, analysis of recent commodity price spikes suggests that interventionist trade policies are partly to blame. Assuming we cannot much influence the future climate outcome, what policies can we undertake to adapt better? Can we use markets to blunt this edge? Diffenbaugh et al. find that sale of corn- ethanol for use in liquid fuel, when governed by quotas such as US Renewable Fuel Standard (RFS), could make US corn prices even more variable; in contrast the same food-fuel market link (we refer to it as intersectoral link) may well dampen price volatility when the sale of corn to ethanol industry is driven by higher future oil prices. The latter however comes at the cost of exposing corn prices to the greater volatility in oil markets. Similarly intervention in corn trade can make US corn prices less or more volatile by distorting international corn price transmission. A negative US corn yield shock shows that domestic corn supply falls and domestic prices to go up irrespective of whether or not markets are integrated. How much the prices go up depends on how much demand adjusts to accommodate the supply shock. Based on the forgoing analysis, one should expect that demand would adjust more readily when markets are integrated and therefore reduce the resulting price fluctuation. Simulation results confirm this response of corn markets. In terms of relative comparisons however a policy driven intersectoral integration is least effective and prices rise much more. Similarly, a positive world oil price shock makes the US oil imports expensive and with oil being used to produce gasoline blends, it increases the price of gasoline

Caenorhabditis elegans Predation on Bacillus anthracis: Decontamination of Spore Contaminated Soil with Germinants and Nematodes.

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Schelkle, Bettina; Choi, Young; Baillie, Leslie W; Richter, William; Buyuk, Fatih; Celik, Elif; Wendling, Morgan; Sahin, Mitat; Gallagher, Theresa

2017-01-01

Remediation of Bacillus anthracis -contaminated soil is challenging and approaches to reduce overall spore levels in environmentally contaminated soil or after intentional release of the infectious disease agent in a safe, low-cost manner are needed. B. anthracis spores are highly resistant to biocides, but once germinated they become susceptible to traditional biocides or potentially even natural predators such as nematodes in the soil environment. Here, we describe a two-step approach to reducing B. anthracis spore load in soil during laboratory trials, whereby germinants and Caenorhabditis elegans nematodes are applied concurrently. While the application of germinants reduced B. anthracis spore load by up to four logs depending on soil type, the addition of nematodes achieved a further log reduction in spore count. These laboratory based results suggest that the combined use of nematodes and germinants could represent a promising approach for the remediation of B. anthracis spore contaminated soil. Originality-Significance Statement: This study demonstrates for the first time the successful use of environmentally friendly decontamination methods to inactivate Bacillus anthracis spores in soil using natural predators of the bacterium, nematode worms.

Diversity of bacteria carried by pinewood nematode in USA and phylogenetic comparison with isolates from other countries.

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Diogo Neves Proença

Full Text Available Pine wilt disease (PWD is native to North America and has spread to Asia and Europe. Lately, mutualistic relationship has been suggested between the pinewood nematode (PWN, Bursaphelenchus xylophilus the causal nematode agent of PWD, and bacteria. In countries where PWN occurs, nematodes from diseased trees were reported to carry bacteria from several genera. However no data exists for the United States. The objective of this study was to evaluate the diversity of the bacterial community carried by B. xylophilus, isolated from different Pinus spp. with PWD in Nebraska, United States. The bacteria carried by PWN belonged to Gammaproteobacteria (79.9%, Betaproteobacteria (11.7%, Bacilli (5.0%, Alphaproteobacteria (1.7% and Flavobacteriia (1.7%. Strains from the genera Chryseobacterium and Pigmentiphaga were found associated with the nematode for the first time. These results were compared to results from similar studies conducted from other countries of three continents in order to assess the diversity of bacteria with associated with PWN. The isolates from the United States, Portugal and China belonged to 25 different genera and only strains from the genus Pseudomonas were found in nematodes from all countries. The strains from China were closely related to P. fluorescens and the strains isolated from Portugal and USA were phylogenetically related to P. mohnii and P. lutea. Nematodes from the different countries are associated with bacteria of different species, not supporting a relationship between PWN with a particular bacterial species. Moreover, the diversity of the bacteria carried by the pinewood nematode seems to be related to the geographic area and the Pinus species. The roles these bacteria play within the pine trees or when associated with the nematodes, might be independent of the presence of the nematode in the tree and only related on the bacteria's relationship with the tree.

Further Screening of Entomopathogenic Fungi and Nematodes as Control Agents for Drosophila suzukii

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Andrew G. S. Cuthbertson

2016-06-01

Full Text Available Drosophila suzukii populations remain low in the UK. To date, there have been no reports of widespread damage. Previous research demonstrated that various species of entomopathogenic fungi and nematodes could potentially suppress D. suzukii population development under laboratory trials. However, none of the given species was concluded to be specifically efficient in suppressing D. suzukii. Therefore, there is a need to screen further species to determine their efficacy. The following entomopathogenic agents were evaluated for their potential to act as control agents for D. suzukii: Metarhizium anisopliae; Isaria fumosorosea; a non-commercial coded fungal product (Coded B; Steinernema feltiae, S. carpocapsae, S. kraussei and Heterorhabditis bacteriophora. The fungi were screened for efficacy against the fly on fruit while the nematodes were evaluated for the potential to be applied as soil drenches targeting larvae and pupal life-stages. All three fungi species screened reduced D. suzukii populations developing from infested berries. Isaria fumosorosea significantly (p < 0.001 reduced population development of D. suzukii from infested berries. All nematodes significantly reduced adult emergence from pupal cases compared to the water control. Larvae proved more susceptible to nematode infection. Heterorhabditis bacteriophora proved the best from the four nematodes investigated; readily emerging from punctured larvae and causing 95% mortality. The potential of the entomopathogens to suppress D. suzukii populations is discussed.

Functional diversification of Argonautes in nematodes: an expanding universe.

Science.gov (United States)

Buck, Amy H; Blaxter, Mark

2013-08-01

In the last decade, many diverse RNAi (RNA interference) pathways have been discovered that mediate gene silencing at epigenetic, transcriptional and post-transcriptional levels. The diversity of RNAi pathways is inherently linked to the evolution of Ago (Argonaute) proteins, the central protein component of RISCs (RNA-induced silencing complexes). An increasing number of diverse Agos have been identified in different species. The functions of most of these proteins are not yet known, but they are generally assumed to play roles in development, genome stability and/or protection against viruses. Recent research in the nematode Caenorhabditis elegans has expanded the breadth of RNAi functions to include transgenerational epigenetic memory and, possibly, environmental sensing. These functions are inherently linked to the production of secondary siRNAs (small interfering RNAs) that bind to members of a clade of WAGOs (worm-specific Agos). In the present article, we review briefly what is known about the evolution and function of Ago proteins in eukaryotes, including the expansion of WAGOs in nematodes. We postulate that the rapid evolution of WAGOs enables the exceptional functional plasticity of nematodes, including their capacity for parasitism.

Nematode communities in sediments of the Kermadec Trench, Southwest Pacific Ocean

Science.gov (United States)

Leduc, Daniel; Rowden, Ashley A.

2018-04-01

Hadal trenches are characterized by environmental conditions not found in any other deep-sea environment, such as steep topography and periodic disturbance by turbidity flows, which are likely responsible for the distinct nature of benthic communities of hadal trenches relative to those of the abyssal plain. Nematodes are the most abundant metazoans in the deep-sea benthos, but it is not yet clear if different trenches host distinct nematode communities, and no data are yet available on the communities of most trenches, including the Kermadec Trench in the Southwest Pacific. Quantitative core samples from the seafloor of the Kermadec Trench were recently obtained from four sites at 6000-9000 m depth which allowed for analyses of meiofauna, and nematodes in particular, for the first time. Nematode community and trophic structure was also compared with other trenches using published data. There was a bathymetric gradient in meiofauna abundance, biomass, and community structure within the Kermadec Trench, but patterns for species richness were ambiguous depending on which metric was used. There was a change in community structure from shallow to deep sites, as well as a consistent change in community structure from the upper sediment layers to the deeper sediment layers across the four sites. These patterns are most likely explained by variation in food availability within the trench, and related to trench topography. Together, deposit and microbial feeders represented 48-92% of total nematode abundance in the samples, which suggests that fine organic detritus and bacteria are major food sources. The relatively high abundance of epigrowth feeders at the 6000 and 9000 m sites (38% and 31%, respectively) indicates that relatively freshly settled microalgal cells represent another important food source at these sites. We found a significant difference in species community structure between the Kermadec and Tonga trenches, which was due to both the presence/absence of

Dynamics in the tomato root transcriptome on infection with the potato cyst nematode Globodera rostochiensis.

Science.gov (United States)

Swiecicka, Magdalena; Filipecki, Marcin; Lont, Dieuwertje; Van Vliet, Joke; Qin, Ling; Goverse, Aska; Bakker, Jaap; Helder, Johannes

2009-07-01

Plant parasitic nematodes infect roots and trigger the formation of specialized feeding sites by substantial reprogramming of the developmental process of root cells. In this article, we describe the dynamic changes in the tomato root transcriptome during early interactions with the potato cyst nematode Globodera rostochiensis. Using amplified fragment length polymorphism-based mRNA fingerprinting (cDNA-AFLP), we monitored 17 600 transcript-derived fragments (TDFs) in infected and uninfected tomato roots, 1-14 days after inoculation with nematode larvae. Six hundred and twenty-four TDFs (3.5%) showed significant differential expression on nematode infection. We employed GenEST, a computer program which links gene expression profiles generated by cDNA-AFLP and databases of cDNA sequences, to identify 135 tomato sequences. These sequences were grouped into eight functional categories based on the presence of genes involved in hormone regulation, plant pathogen defence response, cell cycle and cytoskeleton regulation, cell wall modification, cellular signalling, transcriptional regulation, primary metabolism and allocation. The presence of unclassified genes was also taken into consideration. This article describes the responsiveness of numerous tomato genes hitherto uncharacterized during infection with endoparasitic cyst nematodes. The analysis of transcriptome profiles allowed the sequential order of expression to be dissected for many groups of genes and the genes to be connected with the biological processes involved in compatible interactions between the plant and nematode.

The Role of Programmed Cell Death Regulator LSD1 in Nematode-Induced Syncytium Formation

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Mateusz Matuszkiewicz

2018-03-01

Full Text Available Cyst-forming plant-parasitic nematodes are common pests of many crops. They inject secretions into host cells to induce the developmental and metabolic reprogramming that leads to the formation of a syncytium, which is the sole food source for growing nematodes. As in other host-parasite models, avirulence leads to rapid and local programmed cell death (PCD known as the hypersensitive response (HR, whereas in the case of virulence, PCD is still observed but is limited to only some cells. Several regulators of PCD were analyzed to understand the role of PCD in compatible plant–nematode interactions. Thus, Arabidopsis plants carrying recessive mutations in LESION SIMULATING DISEASE1 (LSD1 family genes were subjected to nematode infection assays with juveniles of Heterodera schachtii. LSD1 is a negative and conditional regulator of PCD, and fewer and smaller syncytia were induced in the roots of lsd1 mutants than in wild-type Col-0 plants. Mutation in LSD ONE LIKE2 (LOL2 revealed a pattern of susceptibility to H. schachtii antagonistic to lsd1. Syncytia induced on lsd1 roots compared to Col0 showed significantly retarded growth, modified cell wall structure, increased vesiculation, and some myelin-like bodies present at 7 and 12 days post-infection. To place these data in a wider context, RNA-sequencing analysis of infected and uninfected roots was conducted. During nematode infection, the number of transcripts with changed expression in lsd1 was approximately three times smaller than in wild-type plants (1440 vs. 4206 differentially expressed genes, respectively. LSD1-dependent PCD in roots is thus a highly regulated process in compatible plant–nematode interactions. Two genes identified in this analysis, coding for AUTOPHAGY-RELATED PROTEIN 8F and 8H were down-regulated in syncytia in the presence of LSD1 and showed an increased susceptibility to nematode infection contrasting with lsd1 phenotype. Our data indicate that molecular regulators

The Role of Programmed Cell Death Regulator LSD1 in Nematode-Induced Syncytium Formation

Science.gov (United States)

Matuszkiewicz, Mateusz; Sobczak, Miroslaw; Cabrera, Javier; Escobar, Carolina; Karpiński, Stanislaw; Filipecki, Marcin

2018-01-01

Cyst-forming plant-parasitic nematodes are common pests of many crops. They inject secretions into host cells to induce the developmental and metabolic reprogramming that leads to the formation of a syncytium, which is the sole food source for growing nematodes. As in other host-parasite models, avirulence leads to rapid and local programmed cell death (PCD) known as the hypersensitive response (HR), whereas in the case of virulence, PCD is still observed but is limited to only some cells. Several regulators of PCD were analyzed to understand the role of PCD in compatible plant–nematode interactions. Thus, Arabidopsis plants carrying recessive mutations in LESION SIMULATING DISEASE1 (LSD1) family genes were subjected to nematode infection assays with juveniles of Heterodera schachtii. LSD1 is a negative and conditional regulator of PCD, and fewer and smaller syncytia were induced in the roots of lsd1 mutants than in wild-type Col-0 plants. Mutation in LSD ONE LIKE2 (LOL2) revealed a pattern of susceptibility to H. schachtii antagonistic to lsd1. Syncytia induced on lsd1 roots compared to Col0 showed significantly retarded growth, modified cell wall structure, increased vesiculation, and some myelin-like bodies present at 7 and 12 days post-infection. To place these data in a wider context, RNA-sequencing analysis of infected and uninfected roots was conducted. During nematode infection, the number of transcripts with changed expression in lsd1 was approximately three times smaller than in wild-type plants (1440 vs. 4206 differentially expressed genes, respectively). LSD1-dependent PCD in roots is thus a highly regulated process in compatible plant–nematode interactions. Two genes identified in this analysis, coding for AUTOPHAGY-RELATED PROTEIN 8F and 8H were down-regulated in syncytia in the presence of LSD1 and showed an increased susceptibility to nematode infection contrasting with lsd1 phenotype. Our data indicate that molecular regulators belonging to the

The life cycle of the free-living marine nematode Innocuonema tentabunda De Man 1890

Digital Repository Service at National Institute of Oceanography (India)

Singh, R.; Ingole, B.S.; Nanajkar, M.R.

The free-living marine nematode Innocuonema tentabunda was collected from the mangrove sediment of a mud-flat at Chorao Island, Goa, India, and reared in the laboratory to investigate its life cycle at 27 plus or minus 2 degrees C. The nematodes...

Structural insights into viral determinants of nematode mediated Grapevine fanleaf virus transmission.

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Pascale Schellenberger

2011-05-01

Full Text Available Many animal and plant viruses rely on vectors for their transmission from host to host. Grapevine fanleaf virus (GFLV, a picorna-like virus from plants, is transmitted specifically by the ectoparasitic nematode Xiphinema index. The icosahedral capsid of GFLV, which consists of 60 identical coat protein subunits (CP, carries the determinants of this specificity. Here, we provide novel insight into GFLV transmission by nematodes through a comparative structural and functional analysis of two GFLV variants. We isolated a mutant GFLV strain (GFLV-TD poorly transmissible by nematodes, and showed that the transmission defect is due to a glycine to aspartate mutation at position 297 (Gly297Asp in the CP. We next determined the crystal structures of the wild-type GFLV strain F13 at 3.0 Å and of GFLV-TD at 2.7 Å resolution. The Gly297Asp mutation mapped to an exposed loop at the outer surface of the capsid and did not affect the conformation of the assembled capsid, nor of individual CP molecules. The loop is part of a positively charged pocket that includes a previously identified determinant of transmission. We propose that this pocket is a ligand-binding site with essential function in GFLV transmission by X. index. Our data suggest that perturbation of the electrostatic landscape of this pocket affects the interaction of the virion with specific receptors of the nematode's feeding apparatus, and thereby severely diminishes its transmission efficiency. These data provide a first structural insight into the interactions between a plant virus and a nematode vector.

Enhanced resistance to soybean cyst nematode Heterodera glycines in transgenic soybean by silencing putative CLE receptors.

Science.gov (United States)

Guo, Xiaoli; Chronis, Demosthenis; De La Torre, Carola M; Smeda, John; Wang, Xiaohong; Mitchum, Melissa G

2015-08-01

CLE peptides are small extracellular proteins important in regulating plant meristematic activity through the CLE-receptor kinase-WOX signalling module. Stem cell pools in the SAM (shoot apical meristem), RAM (root apical meristem) and vascular cambium are controlled by CLE signalling pathways. Interestingly, plant-parasitic cyst nematodes secrete CLE-like effector proteins, which act as ligand mimics of plant CLE peptides and are required for successful parasitism. Recently, we demonstrated that Arabidopsis CLE receptors CLAVATA1 (CLV1), the CLAVATA2 (CLV2)/CORYNE (CRN) heterodimer receptor complex and RECEPTOR-LIKE PROTEIN KINASE 2 (RPK2), which transmit the CLV3 signal in the SAM, are required for perception of beet cyst nematode Heterodera schachtii CLEs. Reduction in nematode infection was observed in clv1, clv2, crn, rpk2 and combined double and triple mutants. In an effort to develop nematode resistance in an agriculturally important crop, orthologues of Arabidopsis receptors including CLV1, CLV2, CRN and RPK2 were identified from soybean, a host for the soybean cyst nematode Heterodera glycines. For each of the receptors, there are at least two paralogues in the soybean genome. Localization studies showed that most receptors are expressed in the root, but vary in their level of expression and spatial expression patterns. Expression in nematode-induced feeding cells was also confirmed. In vitro direct binding of the soybean receptors with the HgCLE peptide was analysed. Knock-down of the receptors in soybean hairy roots showed enhanced resistance to SCN. Our findings suggest that targeted disruption of nematode CLE signalling may be a potential means to engineer nematode resistance in crop plants. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

Nematode assemblages of some insular and continental lizard hosts of the genus Mabuya Fitzinger (Reptilia, Scincidae along the eastern Brazilian coast

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Carlos Frederico D. Rocha

2003-12-01

Full Text Available Nematode assemblages associated to three species of lizards of the genus Mabuya Fitzinger, 1826 [M. agilis (Raddi, 1823, M. caissara Rebouças-spieker, 1974 and M. macrorhyncha Hoge, 1946] from three mainland sites and three island sites along the eastern Brazilian coast were analyzed. A total of six nematode species were recorded, with total nematode richness varying from one to four and overall nematode prevalences varying from 6.7% to 90.5% among host populations. Number of nematode species per host individual (including all hosts, infected and uninfected varied among host populations from 0.07 to 1.05, but most infected lizards in all six host populations harbored a single nematode species. Both insular and continental populations of Mabuya spp. exhibited generally poor nematode assemblages, and no clear tendency for insular host populations to have more depauperate nematode faunas and/or lower infection rates compared to mainland ones (or vice versa was evident on the basis of the present data.

Testing deep-sea biodiversity paradigms on abyssal nematode genera and Acantholaimus species

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Lins, Lidia; da Silva, Maria Cristina; Neres, Patrícia; Esteves, André Morgado; Vanreusel, Ann

2018-02-01

Biodiversity patterns in the deep sea have been extensively studied in the last decades. In this study, we investigated whether reputable concepts in deep-sea ecology also explain diversity and distribution patterns of nematode genera and species in the abyss. Among them, three paradigms were tackled: (1) the deep sea is a highly diverse environment at a local scale, while on a regional and even larger geographical scale, species and genus turnover is limited; (2) the biodiversity of deep-sea nematode communities changes with the nature and amount of organic matter input from the surface; and (3) patch-mosaic dynamics of the deep-sea environment drive local diversity. To test these hypotheses, diversity and density of nematode assemblages and of species of the genus Acantholaimus were studied along two abyssal E-W transects. These two transects were situated in the Southern Ocean ( 50°S) and the North Atlantic ( 10°N). Four different hierarchical scales were used to compare biodiversity: at the scale of cores, between stations from the same region, and between regions. Results revealed that the deep sea harbours a high diversity at a local scale (alpha diversity), but that turnover can be shaped by different environmental drivers. Therefore, these results question the second part of the paradigm about limited species turnover in the deep sea. Higher surface primary productivity was correlated with greater nematode densities, whereas diversity responses to the augmentation of surface productivity showed no trend. Areas subjected to a constant and low food input revealed similar nematode communities to other oligotrophic abyssal areas, while stations under high productivity were characterized by different dominant genera and Acantholaimus species, and by a generally low local diversity. Our results corroborate the species-energy hypothesis, where productivity can set a limit to the richness of an ecosystem. Finally, we observed no correlation between sediment

Genomic characterisation of the effector complement of the potato cyst nematode Globodera pallida.

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Thorpe, Peter; Mantelin, Sophie; Cock, Peter Ja; Blok, Vivian C; Coke, Mirela C; Eves-van den Akker, Sebastian; Guzeeva, Elena; Lilley, Catherine J; Smant, Geert; Reid, Adam J; Wright, Kathryn M; Urwin, Peter E; Jones, John T

2014-10-23

The potato cyst nematode Globodera pallida has biotrophic interactions with its host. The nematode induces a feeding structure - the syncytium - which it keeps alive for the duration of the life cycle and on which it depends for all nutrients required to develop to the adult stage. Interactions of G. pallida with the host are mediated by effectors, which are produced in two sets of gland cells. These effectors suppress host defences, facilitate migration and induce the formation of the syncytium. The recent completion of the G. pallida genome sequence has allowed us to identify the effector complement from this species. We identify 128 orthologues of effectors from other nematodes as well as 117 novel effector candidates. We have used in situ hybridisation to confirm gland cell expression of a subset of these effectors, demonstrating the validity of our effector identification approach. We have examined the expression profiles of all effector candidates using RNAseq; this analysis shows that the majority of effectors fall into one of three clusters of sequences showing conserved expression characteristics (invasive stage nematode only, parasitic stage only or invasive stage and adult male only). We demonstrate that further diversity in the effector pool is generated by alternative splicing. In addition, we show that effectors target a diverse range of structures in plant cells, including the peroxisome. This is the first identification of effectors from any plant pathogen that target this structure. This is the first genome scale search for effectors, combined to a life-cycle expression analysis, for any plant-parasitic nematode. We show that, like other phylogenetically unrelated plant pathogens, plant parasitic nematodes deploy hundreds of effectors in order to parasitise plants, with different effectors required for different phases of the infection process.

Using SNP markers to dissect linkage disequilibrium at a major quantitative trait locus for resistance to the potato cyst nematode Globodera pallida on potato chromosome V.

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Achenbach, Ute; Paulo, Joao; Ilarionova, Evgenyia; Lübeck, Jens; Strahwald, Josef; Tacke, Eckhard; Hofferbert, Hans-Reinhard; Gebhardt, Christiane

2009-02-01

The damage caused by the parasitic root cyst nematode Globodera pallida is a major yield-limiting factor in potato cultivation . Breeding for resistance is facilitated by the PCR-based marker 'HC', which is diagnostic for an allele conferring high resistance against G. pallida pathotype Pa2/3 that has been introgressed from the wild potato species Solanum vernei into the Solanum tuberosum tetraploid breeding pool. The major quantitative trait locus (QTL) controlling this nematode resistance maps on potato chromosome V in a hot spot for resistance to various pathogens including nematodes and the oomycete Phytophthora infestans. An unstructured sample of 79 tetraploid, highly heterozygous varieties and breeding clones was selected based on presence (41 genotypes) or absence (38 genotypes) of the HC marker. Testing the clones for resistance to G. pallida confirmed the diagnostic power of the HC marker. The 79 individuals were genotyped for 100 single nucleotide polymorphisms (SNPs) at 10 loci distributed over 38 cM on chromosome V. Forty-five SNPs at six loci spanning 2 cM in the interval between markers GP21-GP179 were associated with resistance to G. pallida. Based on linkage disequilibrium (LD) between SNP markers, six LD groups comprising between 2 and 18 SNPs were identified. The LD groups indicated the existence of multiple alleles at a single resistance locus or at several, physically linked resistance loci. LD group C comprising 18 SNPs corresponded to the 'HC' marker. LD group E included 16 SNPs and showed an association peak, which positioned one nematode resistance locus physically close to the R1 gene family.

Ethiopian Wheat Yield and Yield Gap Estimation: A Spatial Small Area Integrated Data Approach

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Mann, M.; Warner, J.

2015-12-01

Despite the collection of routine annual agricultural surveys and significant advances in GIS and remote sensing products, little econometric research has been undertaken in predicting developing nation's agricultural yields. In this paper, we explore the determinants of wheat output per hectare in Ethiopia during the 2011-2013 Meher crop seasons aggregated to the woreda administrative area. Using a panel data approach, combining national agricultural field surveys with relevant GIS and remote sensing products, the model explains nearly 40% of the total variation in wheat output per hectare across the country. The model also identifies specific contributors to wheat yields that include farm management techniques (eg. area planted, improved seed, fertilizer, irrigation), weather (eg. rainfall), water availability (vegetation and moisture deficit indexes) and policy intervention. Our findings suggest that woredas produce between 9.8 and 86.5% of their potential wheat output per hectare given their altitude, weather conditions, terrain, and plant health. At the median, Amhara, Oromiya, SNNP, and Tigray produce 48.6, 51.5, 49.7, and 61.3% of their local attainable yields, respectively. This research has a broad range of applications, especially from a public policy perspective: identifying causes of yield fluctuations, remotely evaluating larger agricultural intervention packages, and analyzing relative yield potential. Overall, the combination of field surveys with spatial data can be used to identify management priorities for improving production at a variety of administrative levels.

Nematode consumption by mite communities varies in different forest microhabitats as indicated by molecular gut content analysis.

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Heidemann, Kerstin; Ruess, Liliane; Scheu, Stefan; Maraun, Mark

2014-01-01

Soil animals live in complex and heterogeneous habitats including litter of various types but also microhabitats such as mosses, fungal mats and grass patches. Soil food webs have been separated into a slow fungal and a fast bacterial energy channel. Bacterial-feeding nematodes are an important component of the bacterial energy channel by consuming bacteria and forming prey for higher trophic levels such as soil microarthropods. Investigating the role of nematodes as prey for higher trophic level consumers has been hampered by methodological problems related to their small body size and lack in skeletal structures which can be traced in the gut of consumers. Recent studies using molecular gut content analyses suggest that nematodes form major prey of soil microarthropods including those previously assumed to live as detritivores. Using molecular markers we traced nematode prey in fourteen abundant soil microarthropod taxa of Mesostigmata and Oribatida (both Acari) from three different microhabitats (litter, grass and moss). Consumption of nematodes varied between mite species indicating that trophic niche variation contributes to the high diversity of microarthropods in deciduous forests. Further, consumption of nematodes by Mesostigmata (but not Oribatida) differed between microhabitats indicating that trophic niches vary with habitat characteristics. Overall, the results suggest that free-living bacterial-feeding nematodes form important prey for soil microarthropods including those previously assumed to live as detritivores.