Academic literature on the topic 'Nematodes'
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Journal articles on the topic "Nematodes"
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Grewal, Parwinder S., Edwin E. Lewis, and Sudha Venkatachari. "Allelopathy: a possible mechanism of suppression of plant-parasitic nematodes by entomopathogenic nematodes." Nematology 1, no. 7 (1999): 735–43. http://dx.doi.org/10.1163/156854199508766.
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Abstract A possible mechanism of suppression of a plant-parasitic nematode Meloidogyne incognita by entomopathogenic nematodes is described. Heat-killed entomopathogenic nematodes Steinernema feltiae and S. riobrave temporarily suppressed penetration of the root-knot nematode M. incognita into tomato roots, but live nematodes had no effect. Infective juvenile M. incognita were repelled from all entomopathogenic nematode treatments that included their symbiotic bacteria. They were repelled by Galleria mellonella cadavers infected with S. carpocapsae, S. feltiae, and S. riobrave and from cell-free culture filtrates of the symbiotic bacteria Xenorhabdus nematophilus, X. bovienii, and Xenorhabdus sp. "R" from the three nematode species, respectively. Cell-free filtrates from all three Xenorhabdus spp. were toxic to M. incognita infective juveniles causing 98-100% mortality at 15% concentration. Cell-free filtrate of Xenorhabdus sp. "R" also reduced the hatch of M. incognita eggs. Application of formulated bacterial cell-free filtrates temporarily suppressed M. incognita penetration into tomato roots in a greenhouse trial. The short-term effects of cell-free bacterial filtrates, namely toxicity and repellency, were almost entirely due to ammonium. These results demonstrate allelopathic interactions between plant-parasitic nematodes, entomopathogenic nematodes and their symbiotic bacteria. The likely role of allelopathy in the suppression of plant-parasitic nematodes by innundative applications of entomopathogenic nematodes is discussed. Allelopathie: Ein moglicher Mechanismus zur Unterdruckung pflanzenparasitarer Nematoden durch insektenpathogene Nematoden - Es wird ein moglicher Mechanismus zur Unterdruckung des pflanzenparasitaren Nematoden Meloidogyne incognita durch insektenpathogene Nematoden beschrieben. Durch Hitze abgetotete insektenpathogene Nematoden Steinernema feltiae und S. riobrave underdruckten das Eindringen des Wurzelgallenalchens M. incognita in Tomatenwurzeln, lebende Nematoden hatten keine Wirkung. Infektionsjuvenile von M. incognita wurden von allen Behandlungen mit insektenpathogenen Nematoden abgestossen, die auch die symbiontischen Bakterien einschlossen. Sie wurden durch die Kadaver von Galleria mellonella abgestossen, die mit S. carpocapsae, S. feltiae und S. riobrave infiziert waren sowie durch zellfreie Kultursubstrate der symbiontischen Bakterien Xenorhabdus nematophilus, X. bovienii und Xenorhabdus sp. "R" aus den drei genannten Nematodenarten. Zellfreie Kultursubstrate von allen drei Xenorhabdus spp. waren giftig fur die Infektionsjuvenilen von M. incognita und verursachten in einer Konzentration von 15% Abtotungsraten von 98-100%. Zellfreie Kultursubstrate von Xenorhabdus sp. "R" vermiderten ausserdem das Schlupfen von M. incognita-Eiern. In einem Gewachshausversuch unterdruckten formulierte zellfreie Bakterienfiltrate vorubergehend das Eindringen von M. incognita in Tomatenwurzeln. Die Kurzzeitwirkungen von zellfreien Bakterien filtraten, namentlich Giftigkeit und Abstossung, waren nahezu ganz bedingt durch Ammoniak. Diese Ergebnisse zeigen das Vorhandensein von allelopathischen Wechselwirkungen zwischen pflanzenparasitaren Nematoden, insektenpathogenen Nematoden und deren symbiontischen Bakterien. Die wahrscheinliche Rolle von Allelopathie bei der Unterdruckung pflanzenparasitarer Nematoden durch eine Massenanwendung insektenpathogener Nematoden wird diskutiert.
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Ono, Masaya, Yoichi Hayakawa, and Toyoshi Yoshiga. "Bacterial feeding nematodes ingest haemocytes in the haemocoel of the insect Galleria mellonella." Parasitology 147, no. 3 (November 18, 2019): 279–86. http://dx.doi.org/10.1017/s0031182019001550.
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AbstractInsect parasitic nematodes have acquired mechanisms to evade their host immune response for successful parasitism. Despite the importance of understanding of the evolution of evasion mechanisms from host immunity, insect immune response against non-parasitic nematodes has not been well studied. In our previous study, we demonstrated that a non-insect parasitic nematode Caenorhabditis elegans was not encapsulated by haemocytes in the larvae of the greater wax moth Galleria mellonella. To understand how nematodes influence insect haemocytes to escape encapsulation, we examined the effect of C. elegans on haemocytes in the haemocoel of G. mellonella larvae. Injection of nematodes resulted in the decrease of haemocyte density while mortality and spreading ability of haemocytes, the haematopoietic organs were not affected. In vitro co-incubation of haemocytes with nematodes resulted in a decrease of haemocyte density and we observed feeding on haemocytes by nematodes. Injection of C. elegans feeding-delay mutants into insects did not cause the decrease of haemocyte density. The decrease of haemocyte density was due to the nematode's ingestion of haemocytes. Furthermore, an entomopathogenic nematode and other bacterial feeding nematodes also showed similar feeding behaviour. The nematode's ability to feed on haemocytes may have played an important role in the evolution of nematode parasitism in bacterial-feeding nematodes.
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Xu, Zhen, Yong-Qiang Zhao, Dong-Jing Yang, Hou-Jun Sun, Cheng-Ling Zhang, and Yi-Ping Xie. "Attractant and repellent effects of sweet potato root exudates on the potato rot nematode, Ditylenchus destructor." Nematology 17, no. 1 (2015): 117–24. http://dx.doi.org/10.1163/15685411-00002856.
Full textAbstract:
Potato rot nematode (Ditylenchus destructor) is one of the most damaging pests of sweet potato in the northern region of China. Glasshouse and field experiments were conducted to explore the main invasion route used by potato rot nematodes during infection of sweet potato plants. The nematode’s host location behaviour was also investigated. Results suggested that substantial yield losses of sweet potato caused by D. destructor parasitism depend upon the existence of wounds on seedling roots. Therefore, reducing the number of nematodes that invade through such wounds would be an effective control method. We found that root exudates and extracts from underground stems of both resistant (cv. Zhenghong 22) and susceptible (cv. Lizixiang) sweet potato cultivars attracted potato rot nematodes. In addition, a strong repellent effect of latex against these nematodes was observed in both cultivars. Interestingly, octadecyl-(Z)-p-coumarate, a component of sweet potato latex, acted as a repellent for potato rot nematodes, while hexadecyl- and eicosyl-(Z)-p-coumarates did not. These findings provide a basis for understanding the mechanism underlying the host location behaviour of potato rot nematodes and can help in designing new nematode control methods.
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Yeates, G. W. "Abundance, diversity, and resilience of nematode assemblages in forest soilsThis article is one of a selection of papers published in the Special Forum on Towards Sustainable Forestry — The Living Soil: Soil Biodiversity and Ecosystem Function." Canadian Journal of Forest Research 37, no. 2 (February 2007): 216–25. http://dx.doi.org/10.1139/x06-172.
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Forest litter and soil may contain >10 × 106 individual nematodes·m–2 and, regionally, >400 species. Root-feeding nematodes may be pathogenic to young plants; microbial-feeding nematodes may increase turnover of the microbial pool; predacious and omnivorous nematodes represent higher trophic levels. The spatial distribution and abundance of nematode species in forests reflect soil type, soil fertility, climate, canopy and understorey plant species, litter depth, forest age, and management. Nematodes may be important in forest nurseries; they occur throughout the rooting depth of forest trees; hyphal-feeding species may influence mycorrhizae; and insect-vectored Bursaphelenchus species are a quarantine risk. Nematode populations interact with those of other soil animals (e.g., mites, tardigrades, enchytraeids, and protozoa). The diversity and abundance of the nematode assemblage make nematodes a useful indicator of soil condition and soil processes. Information available from forest systems suggests that, as long as physical disturbance is minimized and remaining trees or herb layer moderate the microclimate, logging and other forestry operations have only transitory effects on nematode populations. Extreme disturbance, such as bulldozing and slash-and-burn management, can significantly reduce nematode abundance and diversity. In contrast, management that enhances growth of understorey or herb layer can stimulate nematode populations. Each of these changes can be related to changes in food resource availability and environmental conditions, such as soil temperature and moisture. Although details of soil nematode contributions to nutrient processes in forest soils are sparse, that their populations are maintained through cycles of moderate management practices suggest that their beneficial contributions will also be maintained.
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Bird, A. F. "The influence of the actionmycete,Pasteuria penetrans, on the host–parasite relationship of the plant-parasitic nematode,Meloidogyne javanica." Parasitology 93, no. 3 (December 1986): 571–80. http://dx.doi.org/10.1017/s0031182000081270.
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SUMMARYThe actinomycete,Pasteuria penetrans, is a specific endoparasite of various plant-parasitic nematodes. When parasitizing the root-knot nematode (Meloidogyne javanical) the nematode's capacity to reproduce is destroyed and feeding on and stimulation of the plant host are unaffected even though the bulbous body of the female nematode becomes filled with spores. Parasitism by the actinomycete does not alter the rate of growth in the early stages of nematode development although the non-parasitized female grows more rapidly than the parasitized one for a short time immediately after the final moult.Pasteuriadid not invade or inactivate the anterior oesophageal region of the femaleMeloidogyneor influence the morphology of the giant cells induced by these nematodes in their hosts' roots. The influence of this parasite on the developmental physiology of its nematode host is discussed.
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Townsend, Monica L., Don C. Steinkraus, and Donn T. Johnson. "Mortality Response of Green June Beetle (Coleoptera: Scarabaeidae) to Four Species of Entomopathogenic Nematodes." Journal of Entomological Science 29, no. 2 (April 1, 1994): 268–75. http://dx.doi.org/10.18474/0749-8004-29.2.268.
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Four species of entomopathogenic nematodes, Steinernema carpocapsae (Weiser) (All strain), S. feltiae (Filipjev) (NC strain), S. glaseri (Steiner), and Heterorhabditis bacteriophora Poinar, were tested in the laboratory for their effect on larvae of the green June beetle, Cotinus nitida L. When nematodes were injected into the foregut of larvae (ca. 1,000 nematodes per larva), S. carpocapsae, S. feltiae, S. glaseri, and H. bacteriophora caused similar mortality (65, 45, 65, and 63%, respectively). At a concentration of 10 nematodes per larva, S. carpocapsae produced significantly higher mortality (51%) than the other three nematode species. Increasing nematode concentrations resulted in only a slight increase in mortality of larvae injected perorally with any of the four nematode species. Water filtrates from whole nematodes or ground nematode tissue supernatants from S. carpocapsae and H. bacteriophora injected perorally into the alimentary tract did not kill green June beetle larvae. Thus, live nematodes appeared to be necessary to cause mortality. Subcuticular or peroral injections of S. carpocapsae or H. bacteriophora (1,000 nematodes per larva) produced similar mortality of green June beetle larvae ranging from 60 to 70%. Nematode-killed larvae were dissected (n=277) but only two cadavers contained live nematodes and nematodes did not successfully reproduce in any nematode-killed green June beetle larvae. Possible explanations for the failure of cadavers to produce nematode progeny are discussed.
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Hai, Tang, and Ji Ya Qi Du. "The Response of the Free-Living Nematodes Species and Quantity to Grazing Intensity of Meadow Grassland." Advanced Materials Research 518-523 (May 2012): 5185–88. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.5185.
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Abstract. To study of meadow grassland soil free lifing nematodes types and quantities under the grazing intensity, the results show that we captured 13 species free lifing nematodes in different grazing area.With the increase of the grazing intensity the total number of Free life nematodes gradually reduce, among them Bacterial feeding nematode and Omnivorous predator nematode gradually reduced with the increase of nematode grazing intensity and the Fungal-feeding nematodes quantities gradually increased . the number of the Bacterial feeding nematode and Fungal-feeding nematodes gradually decrease with the deepening of the soil layer under the different grazing intensity and Omnivorous predator nematodegradually increased
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ÇAKMAK, Taylan. "The nematode assemblages of a lake ecosystem (Lake Korugöl Natural Park, Düzce, West Black Sea Cost of Türkiye): ecology and biodiversity patterns with first reports of 10 genera to the Türkiye nematofauna." Turkish Journal of Entomology 47, no. 3 (September 25, 2023): 283–94. http://dx.doi.org/10.16970/entoted.1273242.
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This research was conducted to reveal the soil nematode fauna of Korugöl, Düzce and to contribute to the nematode diversity of the Western Black Sea Region of Türkiye. Field studies within the scope of the study were implemented in 2021. As a result of the study, 29 families, 45 genera and 46 nematode taxa were identified. 10 nematode taxon, namely Aporcelinus, Baladorylaimus, Dorylaimoides, Euteratocephalus, Labronemella, Laimydorus, Lindseyus, Metateratocephalus, Paractinolaimus and Tripylella are the first report for Türkiye's nematofauna. Classification of nematodes according to their feeding types were: 27.27% bacterivorous nematodes, 2.10% fungivoresnematodes, 1.51% herbivorous nematodes, 16.35% predator nematodes and 52.77% omnivorous nematodes.
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Bekal, Sadia, Terry L. Niblack, and Kris N. Lambert. "A Chorismate Mutase from the Soybean Cyst Nematode Heterodera glycines Shows Polymorphisms that Correlate with Virulence." Molecular Plant-Microbe Interactions® 16, no. 5 (May 2003): 439–46. http://dx.doi.org/10.1094/mpmi.2003.16.5.439.
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Parasitism genes from phytoparasitic nematodes are thought to be essential for nematode invasion of the host plant, to help the nematode establish feeding sites, and to aid nematodes in the suppression of host plant defenses. One gene that may play several roles in nematode parasitism is chorismate mutase (CM). This secreted enzyme is produced in the nematode's esophageal glands and appears to function within the plant cell to manipulate the plant's shikimate pathway, which controls plant cell growth, development, structure, and pathogen defense. Using degenerate polymerase chain reaction primers, we amplified and cloned a chorismate mutase (Hg-cm-1) from Heterodera glycines, the soybean cyst nematode (SCN), and showed it had CM activity. RNA in situ hybridization of Hg-cm-1 cDNA to SCN sections confirms that it is specifically expressed in the nematodes' esophageal glands. DNA gel blots of genomic DNA isolated from SCN inbred lines that have differing virulence on SCN resistant soybean show Hg-cm-1 is a member of a polymorphic gene family. Some Hg-cm family members predominate in SCN inbred lines that are virulent on certain SCN resistant soybean cultivars. The same polymorphisms and correlation with virulence are seen in the Hg-cm-1 expressed in the SCN second-stage juveniles. Based on the enzymatic activity of Hg-cm-1 and the observation that different forms of the mutase are expressed in virulent nematodes, we hypothesize that the Hg-cm-1 is a virulence gene, some forms of which allow SCN to parasitize certain resistant soybean plants.
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Yeates, Gregor W., Surinder Saggar, Carolyn B. Hedley, and Chris F. Mercer. "Increase in 14C-carbon translocation to the soil microbial biomass when five species of plant-parasitic nematodes infect roots of white clover." Nematology 1, no. 3 (1999): 295–300. http://dx.doi.org/10.1163/156854199508298.
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Abstract Clonal white clover growing in pots was inoculated with Heterodera trifolii, Meloidogyne hapla, Meloidogyne trifoliophila, Pratylenchus sp., or Xiphinema diversicaudatum, pulse-labelled with 14C and after 15 days the distribution of 14C in compartments of the soil: plant: nematode system determined. Nematode inoculation had no effect on shoot, root and soil microbial biomasses, but the nematode treatments significantly affected the distribution of 14C in these compartments. The greatest translocation of 14C to the soil was in pots with X. diversicaudatum, M. hapla or M. trifoliophila. The percentage of 14C in the microbial biomass varied significantly, being highest with X. diversicaudatum and Pratylenchus sp., and lowest in control pots. Nematodes of all species from the soil consistently had lower specific activity than those from roots. It has now been demonstrated for a range of nematodes and soils that nematode infection increases translocation of photosynthate to soil microbial biomass. As the soil microbial biomass plays a critical role in the availability of plant nutrients it appears that low infections of plant-parasitic nematodes may lead to greater availability of plant nutrients. Anstieg der Verlagerung von 14C-Kohlenstoff in die mikrobielle Biomasse, wenn funf Arten pflanzenschadigender Nematoden Wurzeln von Weissklee befallen - In Topfen gehaltene Weisskleeklone wurden mit Heterodera trifolii, Meloidogyne hapla, Meloidogyne trifoliophila, Pratylenchus sp. oder Xiphinema diversicaudatum infiziert. Die Nematoden waren mit 14C markiert, und nach 15 Tagen wurde die Verteilung des 14C in Abschnitten des Systems Boden: Pflanze: Nematode bestimmt. Nematodenbefall hatte zwar keine Wirkung auf die Biomassen von Spross, Wurzel und Mikroben, doch beeinflusste die Behandlung mit Nematoden signifikant die Verteilung von 14C in diesen Abschnitten. Die grosste Verlagerung von 14C in den Boden fand in den Topfen mit X. diversicaudatum, M. hapla oder M. trifoliophila statt. Der Anteil von 14C in der mikrobiellen Biomasse variierte stark. Er war am hochsten in Topfen mit X. diversicaudatum und Pratylenchus sp. und am gerigsten in den Kontrolltopfen. Bei allen Arten hatten die Nematoden aus dem Boden durchweg eine geringere spezifische Aktivitat als die aus den Wurzeln. Es wurde jetzt fur eine Reihe von Nematoden und Boden gezeigt, dass Nematodenbefall die Verlagerung von Photosyntheseprodukten in die mikrobielle Biomasse des Bodens steigert. Da die mikrobielle Biomasse im Boden eine kritische Rolle bei der Verfugbarkeit von Pflanzennahrstoffen spielt, scheint es, dass geringer Befall durch pflanzenschadigende Nematoden zu einer grosseren Verfugbarkeit von Pflanzennahrstoffen fuhren kann.
Dissertations / Theses on the topic "Nematodes"
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Kruitbos, Laura Marina. "Influence of habitat on the behaviour of entomopathogenic nematodes." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=25963.
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Valadas, Vera Mónica Piegas. "Genetic diversity of entomopathogenic nematodes (Nematoda: Steinernematidae and Heterorhabditidae) and the nematode Bursaphelenchus xylophilus (Nematoda: Aphelenchoididae) from continental Portugal." Doctoral thesis, Universidade de Évora, 2012. http://hdl.handle.net/10174/15718.
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“Diversidade genética dos nemátodes entomopatogénicos
(Nematoda: Steinernematidae e Heterorhabditidae) e do
nemátode Bursaphelenchus xylophilus (Nematoda:
Aphelenchoididade) em Portugal continental”
Os nematodes entomopatogénicos são utilizados como agentes de controlo
biológico. Para compreender a sua diversidade, foi realizada uma prospecção
em Portugal. Cinco espécies, nomeadamente Steinernema feltiae, S.
intermedium, S. kraussei, Steinernema sp. e Heterorhabditis bacteriophora
foram identificadas. As sequências de ITS, região D2D3 do 28S rRNA, COXI e
cytb foram utilizadas para estudar a diversidade genética das duas espécies
mais abundantes, S. feltiae and H. bacteriophora, não tendo sido encontradas
diferenças significativas entre isolados.
O nemátode da madeira do pinheiro, Bursaphelenchus xylophilus, provoca
doença nos pinheiros tendo sido detectada pela primeira vez na Europa e em
Portugal em 1999. Para avaliar a diversidade genética dos isolados
Portugueses e identificar o padrão de propagação da doença, foram utilizadas
a sequência da região IGS do 5.8S rRNA, e os genes cytb e cellulase,
combinados com os padrões ISSR. Os padrões de ISSR mostraram elevada
diversidade genética entre os recentes isolados Portugueses, sugerindo a
possibilidade de uma nova introdução. As árvores filogenéticas dos genes da
celulase e cytb sugeriram uma origem Asiática para os isolados Portugueses; ABSTRACT: Entomopathogenic nematodes are used as biocontrol agents. To understand
their diversity, a survey was undertaken in Portugal. Five species, namely
Steinernema feltiae, S. intermedium, S. kraussei, Steinernema sp. and
Heterorhabditis bacteriophora were identified. The ITS, 28S rRNA D2D3 region,
COXI and cytb sequences, used to study the genetic diversity of the two most
abundant species, S. feltiae and H. bacteriophora, showed no significant
differences among the isolates.
Bursaphelenchus xylophilus causes severe disease in pine trees and was
detected for the first time in Europe and in Portugal in 1999. To evaluate the
genetic diversity of Portuguese isolates and identify disease spread pathways,
the sequence of 5.8S rRNA IGS region, cytb and cellulase genes, combined
with ISSR fingerprints were used. ISSR fingerprints show a high genetic
variability among recent Portuguese isolates, suggesting the possibility of a new
introduction. Phylogenetic trees based on cellulase and cytb genes suggests an
Asian origin for Portuguese isolates.
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Briar, Shabeg Singh. "Nematodes as bioindicators of soil food web health in agroecosystems a critical analysis /." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1173284523.
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Zervos, S. "Population regulation of thelastomatid nematodes (Nematoda: Thelastomatidae) of cockroaches." Thesis, University of Canterbury. Zoology, 1986. http://hdl.handle.net/10092/4791.
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Populations of thelastomatid nematodes in cockroach hosts were
investigated.
The population biology, life history, habits. distribution, and
gross morphology of cockroaches involved are discussed.
New species of thelastomatid nematodes from cockroaches are
described and keys to species of Protrellus and Blatticola are given.
Evidence for population regulation in six species of
thelastomatids in eight species of cockroaches collected from the field
is presented. No host contained two adult males, infrapopulations with
two juvenile males were very rare, the number of adult females per host
was small. and monogamy was common. Juvenile males were rare while
juvenile females were relatively common, indicating that, compared to
females, males develop and are eliminated rapidly from hosts (leaving
one), or that males are less common to start with. Infection prevalence
varied markedly between the cockroach species.
Reproductive competition due to crowding, and cyclical egg
production were found in two species.
these phenomena are discussed.
Mechanisms which may control
The effects of density-independent climatic factors on seasonal
variation in incidence and infrapopulation structure of one thelastomatid
population were transient.
Evidence for population self-regulation in Protrellus dixoni
was obtained from laboratory studies. Infrapopulations were regulated
by a density-dependent and sex-dependent reduction in infection intensity
with infrapopulation age. This reduction was not equal in initial speed
or intensity between the sexes (reduction in number of males was faster)
and led to infrapopulations with never more than a single adult male. and
few adult females. In structure. these laboratory-produced infrapopulations
resembled those in field collected hosts.
Unmated females produced male progeny only (probably by
arrhenotokous parthenogenesis). Female offspring probably result
from amphimixis.
Possible methods of thelastomatid infrapopulation regulation are
discussed. It is concluded that regulation is parasite-mediated and due
to chemical interference competition. Regulation benefits the surviving
nematodes because per capita fecundity is greater in uncrowded infrapopulations.
Self-regulation may be common among thelastomatids and
other parasites.
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Cho, Hyun-Bae. "Molecular characterization and phylogenetics of entomopathogenic nematodes (nematoda: stienernematidae) from Asia." Thesis, The University of Arizona, 2009. http://hdl.handle.net/10150/192304.
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Paiva, Sílvia Rodrigues de. "O efeito da remoção da palha de cana-de-açúcar na população de nematoides do solo e raiz em duas situações edafoclimáticas distintas." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/64/64133/tde-09032017-094823/.
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Os nematoides causadores de doenças em cana-de-açúcar ocasionam graves problemas no rendimento desta cultura. Os gêneros mais agressivos são Meloidogyne e Pratylenchus que formam galhas e necroses nas raízes, respectivamente. A retirada da palha de cana-de-açúcar do campo para produção de etanol de segunda geração pode resultar em mudanças no comportamento das comunidades de nematoides. Assim o objetivo deste trabalho foi quantificar a abundância de nematoides em diferentes quantidades de palha presentes na superfície do solo. O experimento foi conduzido em Capivari - SP na unidade Bom Retiro (BR) e em Valparaíso - SP na unidade Univalem (UV). O tipo de solo de cada área experimental era, respectivamente, Latossolo Vermelho distrófico típico (textura média na camada superficial) e Argissolo Vermelho-Amarelo distrófico típico (textura arenosa na camada superficial). O delineamento foi o de blocos ao acaso com seis tratamentos e quatro repetições, compostos por quantidades de palha em Mg ha-1 de massa de matéria seca, sendo em BR (0; 4,2; 8,7; 15,1; 18,9; 23,3), e em UV (0; 3,9; 10,2; 12,5; 16,4; 13,2). As amostragens de solo e raiz coletadas na profundidade de 0-20 cm na linha e entrelinha da cultura foram realizadas em BR em maio e em UV em junho, ambas em 2015. Pratylenchus zeae teve maior dominância nas áreas, seguido de nematoides de vida livre, e Helicotylenchus sp. e Meloidogyne javanica apenas foi observada na área de solo arenoso e em médias densidades. O manejo de remoção da palha de cana-de-açúcar não promoveu mudanças significativas nas abundâncias das comunidades contidas no solo, tanto de textura média quanto arenosa. Por outro lado, houve interferência das quantidades de palha na infecção pelos nematoides nas raízes, no solo de textura média 4,2 Mg ha-1 de palha diminuiu a comunidade de nematoides e no solo de textura arenosa a maior comunidade de nematoides foi em 13,2 Mg ha-1 de palha. Todavia, múltiplos fatores podem ter afetado esses resultados, não apenas o manejo de remoção da palha. São necessários mais estudos em longo prazo para se afirmar o real efeito da retirada de palha do campoThe nematodes that cause diseases in sugarcane represent serious yield problems. The most aggressive genera are Meloidogyne and Pratylenchus that form gall and necrosis in the roots, respectively. Sugarcane straw removal from the field for second generation ethanol production may change the behavior of nematode communities. Thus the objective of this study was to quantify nematode abundance in different quantities of sugarcane straw left on soil surface. The experiment was conducted in Capivari - SP at Bom Retiro (BR) mill and Valparaíso - SP at Univalem (UV) mill. The soil type of each experimental area was, respectively, Oxisol (medium texture in the surface layer) and Alfisol (sandy texture in the surface layer). The experimental design was a randomized block with six treatments and four replicates, composed of quantities of straw in Mg ha-1 of dry matter mass, where in BR (0; 4,2; 8,7; 15,1; 18,9; 23,3), and in UV (0; 3,9; 10,2; 12,5; 16,4; 13,2). Soil and root samples were collected at 0-20 cm depths in the row and inter-row position of the sugarcane crop in BR in May and UV in June, both in 2015. Pratylenchus zeae had greater dominance in both evaluated areas, followed by free-living nematodes, and Helicotylenchus sp., Meloidogyne javanica was only observed in the sandy soil area and in medium densities. Due to the high densities it would be necessary to control nematodes in the areas. In terms of communities abundance in the soil there was no difference in relation to the treatments in the two areas. However, there was interference of the straw in the nematodes infection in the roots, and this result cannot be inferred by the straw deposition. Additional long-term studies are needed to understanding the effect of straw removal from the field on nematode community
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Shrestha, Roshi. "A physiological and genetic mapping study of tolerance to root-knot nematode in rice." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2008. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=24807.
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McVeigh, P. "Neuropeptide signalling in nematodes." Thesis, Queen's University Belfast, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411747.
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Storey, N. "Immunity to filarial nematodes." Thesis, University of Nottingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356035.
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Sutherland, Ian Alexander. "Anthelmintic resistance in nematodes." Thesis, University of Leeds, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329191.
Full textBooks on the topic "Nematodes"
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K, Evans, Trudgill D. L, and Webster J. M. 1936-, eds. Plant parasitic nematodes in temperate agriculture. Wallingford: CAB International, 1993.
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NATO Advanced Study Institute on Cyst Nematodes (1985 Martina Franca, Italy). Cyst nematodes. New YorK: Plenum Press, 1986.
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NATO Advanced Study Institute on Cyst Nematodes (1985 Martina Franca, Italy). Cyst nematodes. New YorK: Plenum Press, 1986.
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Wharton, David A. A functional biology of nematodes. London: Croom Helm, 1986.
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Wharton, David A. A functional biology of nematodes. Baltimore, Md: Johns Hopkins University Press, 1986.
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Smith, Kirk A. Entomopathogenic nematode bibliography: Heterorhabditid and Steinernematid nematodes. Fayetteville, Ark: Arkansas Agricultural Experiment Station, 1992.
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Sumenkova, N. I. Nematodes of plants and soils. Leiden: E.J. Brill, 1989.
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Sumenkova, N. I. Nematodes of plants and soils: Neotylenchoidea. New Delhi: Oxonian Press, 1988.
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F, Southey J., ed. Laboratory methods for work with plant and soil nematodes. 6th ed. London: HMSO, 1986.
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F, Southey J., and Great Britain. Ministry of Agriculture, Fisheries and Food., eds. Laboratory methods for work with plantand soil nematodes. 6th ed. London: H.M.S.O., 1986.
Find full textBook chapters on the topic "Nematodes"
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Haque, Ziaul, and Mujeebur Rahman Khan. "Introduction." In Handbook of invasive plant-parasitic nematodes, 1–17. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789247367.0001.
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Abstract This chapter introduces some plant-parasitic nematodes and discusses their agricultural importance. It describes nematode diversity and the effects of global agricultural trade on nematode spread. It defines invasive plant-parasitic nematodes and presents the assessment criteria for a nematode as an invasive species. Invasiveness ratings (scores) are proposed for categorizing low, medium and highly invasive nematodes. Tabulated data are also given on crop losses caused by plant-parasitic nematodes to different agricultural crops.
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Specht, Sabine, and Achim Hoerauf. "Nematoda: Filarial Nematodes." In Immunity to Parasitic Infection, 217–30. Chichester, UK: John Wiley & Sons, Ltd, 2012. http://dx.doi.org/10.1002/9781118393321.ch11.
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Majdi, Nabil, and Walter Traunspurger. "Introduction to freshwater nematodes in ecology: current knowledge and research." In Ecology of freshwater nematodes, 1–30. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789243635.0001.
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Abstract This chapter provides information on nematode morphology and reproduction; role of nematodes in freshwater ecosystems; and distribution and dispersal of free-living nematodes and their role in food webs.
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Höss, Sebastian. "Single- and multi-species toxicity testing with nematodes." In Ecology of freshwater nematodes, 298–322. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789243635.0010.
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Abstract This chapter discusses the utility of nematodes in experimental ecotoxicology, and specifically in the study of freshwaters. Drawing on reports in which nematodes were used as test organisms in single-species tests as well as studies investigating nematode communities in model ecosystems (i.e. microcosms), the suitability of nematode-based experimental approaches in prospective and retrospective risk assessments of chemicals in freshwater sediments is examined. Several examples are presented of the use of Caenorhabditis elegans as a test organism in single-species bioassays, in order to demonstrate the versatility of this nematode for ecotoxicological investigations.
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Sikora, Richard A., Jon Padgham, and Johan Desaeger. "The unpredictability of adapting integrated nematode management to climate variability." In Integrated nematode management: state-of-the-art and visions for the future, 463–71. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789247541.0064.
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Abstract The areas of concern regarding the future importance of climate change and variability on nematode damage and integrated management include: shifts in the distribution of nematodes, stimulation of additional generations, increased reproductive potential, development of more severe nematode-pathogen complexes, inability to monitor with remote sensing populations over multiple seasons, negative yield due to nematodes and reduced soil moisture levels, adapting integrated nematode management (INM) to highly volatile interannual fluctuations, loss of organic matter and soil antagonistic potential, lack of an effective in-season plant curative pesticide, enhancement of cumulative multi-species impact, and inactivation or loss of plant resistance to nematodes. This chapter reflects on some of the above points and how long-term climate change and increasing climate variability may impact nematodes, crop losses and potential modification of INM under climate change induced risk. It discusses climate change and climate variability in the context of INM, climate impacts on agricultural crops, critical climate change hotspots, climate influence on nematode biological processes, and the use of degree-days to monitor temperature effects on nematode development. The use of plant parasitic nematodes as research models and immediate priorities for improved near-term climate risk management within INM are also described.
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Cole, Theodor C. H. "VI. Nematoda – Fadenwürmer – Nematodes." In Wörterbuch der Wirbellosen / Dictionary of Invertebrates, 39–44. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-662-52869-3_6.
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Fueser, Hendrik, Birgit Gansfort, Nabil Majdi, Janina Schenk, and Walter Traunspurger. "Case studies with nematodes from the individual to ecosystem level." In Ecology of freshwater nematodes, 341–71. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789243635.0012.
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Abstract Organisms smaller than 2 mm in size are ideal candidates for laboratory and field experiments with a theoretical focus. This chapter illustrates this point by drawing on recently published works in which studies of nematodes have informed theories within population and community ecology. Case studies examining the following are presented: (1) Life cycle experiments (individual level), (2) The interactions of two nematode species - competition experiments (population level), (3) Nematode community-based assessments of sediment quality (community level), (4) Nematodes in a detritus-based food web model (food web level).
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Höss, Sebastian, and Walter Traunspurger. "Freshwater nematodes as bioindicators in field studies - the NemaSPEAR[%]-index." In Ecology of freshwater nematodes, 323–40. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789243635.0011.
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Abstract This chapter, after a general introduction to quality assessments of freshwater habitats, reviews the use of freshwater nematodes as in situ bioindicators, including in monitoring the ecological quality of freshwater habitats. By drawing on studies of nematode communities in unpolluted and polluted habitats as examples, it highlights both the different methods used to assess the quality of freshwater ecosystems and their applications. A focus of the chapter is the development of a new index that uses freshwater nematodes to assess chemically induced changes in the ecological status of freshwater habitats, the NemaSPEAR[%]-index (Nematode SPEcies At Risk).
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Majdi, Nabil, Tom Moens, and Walter Traunspurger. "Feeding ecology of free-living nematodes." In Ecology of freshwater nematodes, 185–215. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789243635.0006.
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Abstract This chapter provides overview of the feeding habits and food sources of aquatic nematodes. The environmental constraints on feeding, food recognition, and feeding selectivity are also addressed, together with the complex, indirect trophic interactions between nematodes and their microbial prey. To raise awareness of the inherent methodological and/or interpretational problems in studies of nematode feeding ecology, the chapter ends with a brief look at the methods that have been adapted to quantify feeding rates in nematodes.
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Majdi, Nabil, and Walter Traunspurger. "Production of freshwater nematodes." In Ecology of freshwater nematodes, 247–69. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789243635.0008.
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Abstract This chapter focuses on the methods used to determine freshwater nematode production. It begins by briefly describing the methods used in sampling and measuring nematodes, followed by a summary of the common allometric models developed to estimate secondary production. It then presents a case study in which the results of those models are compared. Finally, it evaluates the drivers of nematode production in different lakes and streams and compares nematode secondary production with that achieved by macrobenthos, other meiobenthic taxa and microbes.
Conference papers on the topic "Nematodes"
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Niu, Haoyu, Andreas Westphal, and YangQuan Chen. "A Contactless Classification Method for Early Detection of Nematodes Using Deep Neural Networks (DNNs) and TensorFlow." In ASME 2021 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/detc2021-68557.
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Abstract Soil-borne plant-parasitic nematodes are microscopic, eellike roundworms. The root-knot nematodes (Meloidogyne spp.) and root-lesion nematodes (Pratylenchus vulnus) are among the most damaging in California, which are difficult to control and can spread easily in soil on tools, boots, and infested plants. Root-knot nematodes can attack many different crops, including nut and fruit trees, usually cause unusual swellings, called galls, on affected plants’ roots. It is not easy to recognize the infestations of these nematodes. For instance, researchers need to dig up walnut trees with symptoms, wash or gently tap the soil from the roots, and examine the roots for galls. The nematode extraction procedures, identification, and enumeration under a microscope are tedious and time-consuming. Therefore, in this article, the authors proposed to use a low-cost contactless radio frequency tridimensional sensor “Walabot,” and Deep Neural Networks (DNNs), to perform the early detection of nematodes in a walnut site. Radiofrequency reflectance of walnut leaves from different nematode infestation levels was measured. The hypothesis was that waveforms generated from walnut leaves can estimate the damage caused by nematodes. DNNs with Tensor-Flow were used to train and test the proposed method. Results showed that the Walabot predicted nematode infestation levels with an accuracy of 82%, which showed great potentials for early detection of nematodes.
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Malyutina, T. A. "NEUROPEPTIDES INVOLVING IN THE REGULATION OF LOCOMOTOR BEHAVIOR OF ROOT-KNOT PLANT-PARASITIC NEMATODES (REVIEW)." In THEORY AND PRACTICE OF PARASITIC DISEASE CONTROL. All-Russian Scientific Research Institute for Fundamental and Applied Parasitology of Animals and Plant – a branch of the Federal State Budget Scientific Institution “Federal Scientific Centre VIEV”, 2023. http://dx.doi.org/10.31016/978-5-6048555-6-0.2023.24.281-284.
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In the last few decades, the attention of researchers has been attracted by endogenous
FMRFamide-like neuropeptides found in a number of invertebrates, including
species of the Nematoda phylum. A foreign literature review was presented for
the functional significance of endogenous FMRFamide-like neuropeptides in
locomotor behaviour of root-knot phytonematodes, representatives of the genus
Meloidogyne Goldi, 1982, namely, Meloidogyne incognita, M. minor, M. hapla and
M. graminicola. In Russia, such studies are not carried out. The main characteristics
of phytoparasitic neuropeptides were obtained from the study of genes (flp-genes)
that encode these neuropeptides. M. incognita was found to have FMRFamidelike positive immunoreactivity in the central nervous system and 19 flp genes. The
Mi-flp-12 and Mi-flp-14 genes encode neuropeptides that stimulate locomotor
behaviour, while Mi-flp-32 encodes a neuropeptide that inhibits parasite locomotor
behaviour. Nematodes M. incognita and M. hapla were found to have G-proteincoupled receptors (GPCRs) encoded by the flp-32 gene, and their similarity
to receptor 1 (C26F1) of the free-living nematode Caenorhabditis elegans was
detected. Similar data were presented in the literature for M. graminicola. The
peptidergic signaling nervous system of root-knot phytonematodes is similar to the
system of nematodes in vertebrates and free-living nematodes, which indicates the
conservatism of the system in species of the entire Nematoda phylum.
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Sasanelli, Nicola, Ion Toderas, Elena Iurcu-Straistaru, Stefan Rusu, Alexei Bivol, Olesea Gliga, and Trifone D'Addabbo. "Sustainable agriculture in the light of climate change: effect of temperatures and exposure times on the mortality of the dagger nematode Xiphinema index." In Scientific International Symposium "Plant Protection – Achievements and Perspectives". Institute of Genetics, Physiology and Plant Protection, Republic of Moldova, 2023. http://dx.doi.org/10.53040/ppap2023.73.
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The gradual rising of average temperatures due to climate change are increasing the problem caused by phytoparasitic nematodes. To predict the effect of soil solarization on Xiphinema index, an experiment was undertaken to investigate the effect of different temperatures (from 25 to 42.5 °C) and exposure times (from 2 up to 2,048 hrs) on the mortality of the nematode. Surviving nematodes were expressed as percentages of those surviving at 25 °C. The differences to 100 were considered as mortality percentages. To kill 50% of nematode population were necessary 180, 34, 4.7 and 2.5 hours at 35, 37.5, 40 and 42.5 °C, respectively. Data fitted the model Pt=Po10-Δt/(q+mT) reported in literature.
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Sasanelli, Nicola, Ion Toderas, Elena Iurcu-Straistaru, Stefan Rusu, Varvara Migunova, and Alena Konrat. "Yield losses caused by plant parasitic nematodes graphical estimation." In International symposium ”Functional ecology of animals” dedicated to the 70th anniversary from the birth of academician Ion Toderas. Institute of Zoology, Republic of Moldova, 2019. http://dx.doi.org/10.53937/9789975315975.60.
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Curves for graphical estimation of yield losses caused by plant parasitic nematodes were calculated on the basis of the relationship between soil nematode population density and damage to plants as described by the Seinhort’s equation y = m + (1 – m) z(P-T). By a logarithmic transformation this equation was transformed as y = m + (1 – m) 1.05[(P/-T) + 1] and solved considering values of tolerance limit (T) and the minimum relative yield (m) from the literature. The obtained curves that can be defined “Curves of nematode-pathogenicity” allow a quick and easy evaluation of yield losses for each known crop-nematode relationship.
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Konrat, A. N. "NEMATICIDAL AND NEMATOSTATIC EFFICACY OF VEGETABLE JUICES OF SOME REPRESENTATIVES OF THE FAMILY SOLANACEAE." In THEORY AND PRACTICE OF PARASITIC DISEASE CONTROL. All-Russian Scientific Research Institute for Fundamental and Applied Parasitology of Animals and Plant – a branch of the Federal State Budget Scientific Institution “Federal Scientific Centre VIEV”, 2023. http://dx.doi.org/10.31016/978-5-6048555-6-0.2023.24.220-224.
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The effect of the tested substances on in vitro nematicidity and nematostaticity was
verified on saprobiotic (Caenorhabditis elegans, Turbatrix aceti) and phytoparasitic
nematodes (Ditylenchus destructor). Working solutions were prepared in the
following dilutions: 1) 1/1000, 2) 1/100, 3) 1/10, 4) 1/1, 5) undiluted, 6) control,
water, and 7) standard (horseradish root juice). The solution of above concentrations
was introduced into the plate wells of 0.5 mL in 4 repetitions, then a well-mixed
nematode suspension of 0.5 mL was added with 50±10 nematodes in average. After
24 hours of hold-times, mobile and immobile nematodes were counted, then after
48 hours nematodes were counted again. At the end of the experiment, nematodes
were washed from the drug in order to determine the nematostatic effect. In vitro
screening showed that the horseradish root juice, black nightshade berry juice, and
red nightshade leaf and berry juice had nematicidal properties. The nematostatic
effect was recorded in shoots of the green tuber, tissues of the green surface of the
tuber and tuber juices, juice of red nightshade leaves, and juice of black nightshade
leaves and berries.
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Pimenov, I. A. "GASTROINTESTINAL NEMATODE FAUNA IN SMALL CATTLE IN THE EUROPEAN RUSSIA." In THEORY AND PRACTICE OF PARASITIC DISEASE CONTROL. VNIIP – FSC VIEV, 2024. http://dx.doi.org/10.31016/978-5-6050437-8-2.2024.25.322-327.
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Gastrointestinal nematodes of small cattle are common in all Russian regions and cause diseases that can have a pronounced negative effect on the animal body. In this regard, obtaining data on the species composition of nematodes dwelling in the digestive tract of small cattle in different regions of the European part of the Russian Federation is of great scientific and practical interest since it will allow for the right strategy to control them. The study material was collected in slaughterhouses in the Moscow Region where animals were delivered from the Oryol, Astrakhan and Moscow Regions, the Republic of Dagestan and the Stavropol Territory from January to October 2023. For helminthological dissections, we used kits of gastrointestinal tracts of the sheep and goats collected immediately after slaughter. Nematodes of the species Trichostrongylus colubriformis and Teladorsagia circumcincta were found in all of the above Regions; nematodes of the species Haemonchus contortus were found in the Moscow and Astrakhan Regions as well as the Republic of Dagestan; and nematodes of the species Marshallagia marshalli were only found in the Astrakhan Region and the Republic of Dagestan. In addition to data on the species composition of gastrointestinal parasitic nematode fauna in small cattle, prevalence and infection intensity rates were determined in the above Regions of the European Russia.
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Lychagina, S. V., and V. V. Zakharova. "THE EFFECT OF MICRONUTRIENTS ON POTATO TUBERS COLONIZED BY NEMATODES DITYLENCHUS DESTRUCTOR IN ARTIFICIAL INFECTION." In THEORY AND PRACTICE OF PARASITIC DISEASE CONTROL. VNIIP – FSC VIEV, 2024. http://dx.doi.org/10.31016/978-5-6050437-8-2.2024.25.246-250.
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Potatoes in our country are a vegetable crop of strategic importance. The merit of this vegetable is in its multifaceted use. But there are no potato varieties resistant to the potato tuber nematode yet. The potential is in biological and biochemical characteristics of varieties in addition to various mineral nutrition. The experiment studied the effect of various micronutrients on increasing the resistance of Gala potato plants to phytoparasitic nematodes Ditylenchus destructor during artificial infection of the apical tuber segments. Standard micronutrient chelated solutions (B10,1%K2 O44%; Ca10%; Cu15%; Fe11%; Mn13%; Zn15%) for experiments were prepared in concentrations as recommended by the manufacturer. Shallow scalpel incisions were made on the surface of each segment and a Ditylenchus destructor suspension was instilled into the incision. The segments wetted with the standard solutions were put in plastic lidded containers to preserve humidity. The variants were labeled and left for 20 days. The control variant was sprayed with clean water. At 20 days that were enough for nematode colonization in potato slices, the tuber segments and nematode populations therein were examined. The result of the Ditylenchus destructor development in the potato segments with the use of micronutrients showed that the least nematodes were observed in the variants treated with copper chelate (EDTA-Cu15%) and iron chelate (Fe11%). Slightly more of them were in the variant with potassium metaborate (B10,1%K2 O44%). The remaining experiment variants and the control variant had the largest number of nematodes and their larvae.
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Kuchboev, A. E., O. O. Amirov, R. R. Karimova, K. F. Sobirov, and A. N. Ibragimov. "GASTROINTESTINAL NEMATODES IN MOUFFLONS AND DOMESTIC SHEEP IN PROTECTED AREAS OF UZBEKISTAN." In THEORY AND PRACTICE OF PARASITIC DISEASE CONTROL. VNIIP – FSC VIEV, 2024. http://dx.doi.org/10.31016/978-5-6050437-8-2.2024.25.231-235.
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The article studied gastrointestinal nematodes in moufflons and domestic sheep in protected areas of Uzbekistan. Twenty-two nematode species were identified in the digestive tract of moufflons and domestic sheep including 21 species in domestic sheep, 7 in Severtsev’s sheep, 5 in Ustyurt mountain sheep, and 2 in Bokharan mountain sheep. Moreover, the family Trichostrongylidae includes 11 nematode species; Molineidae, 3 species; Trichinellidae, Strongylidae and Ancylostomatidae, 2 species each; and Onchocercidae, Gongylonematidae and Habronematidae, one species each. Nematodes of the species Setaria labiatopapillosa, Gongylonema pulchrum, Parabronema skrjabini are considered biohelminths, they develop with participation of beetles (Scarabiidae and Tenebrionidae fam.) and blood-sucking insects (Haematobia gen.); the rest species are geohelminths. It should be noted that the species Marshallagia marshalli and Teladosagia circumcincta were recorded in all animals studied; G. pulchrum and P. skrjabini in domestic sheep, Ustyurt mountain sheep and Severtsev’s sheep; Nematodirus abnormalis and N. helvetianis in domestic sheep and Severtsev’s sheep; and N. oiratianus in domestic sheep and Ustyurt mountain sheep.
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Khusainov, R. V. "CEPHALOBID NEMATODES (NEMATODA: CEPHALOBIDAE) IN AGROCENOSIS OF THE CENTRAL-EUROPEAN PART OF RUSSIA." In V International Scientific Conference CONCEPTUAL AND APPLIED ASPECTS OF INVERTEBRATE SCIENTIFIC RESEARCH AND BIOLOGICAL EDUCATION. Tomsk State University Press, 2020. http://dx.doi.org/10.17223/978-5-94621-931-0-2020-43.
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Investigations of fauna of cephalobid nematodes from field agrocenosis were carried from the territory of the Central-European part of Russia in 2016–2018. In total ten genera of the family Cephalobidae were found. Nematodes of genus Acrolobus (A. emarginatus) has been reported in Russia for the first time. Chiloplacus and Eucephalobus nematodes were presented by the most species diversity. Nematodes of genera Cephalobus and Eucephalobus founded in the samples constantly (93 & 90% samples respectively). The second by frequency of occurence was taken species from genera Acrobeloides and Chiloplacus (86 & 75% samples). Acrobeles spp. and Cervidellus spp. detected in almost half of the soil samplies (57 & 48%). Acrolobus and Heterocephalobus nematodes were most rarely discovered genus (24 & 16%). Acroucrainicus and Stegelletina nematodes founded in agrocenosis singly and only in the territory of the Chernozem Region. Species of genera Acrolobus and Heterocephalobus were registered into the roots generally, while of the rest cephalobid genera were founded both in soil and into damaged or necrotic roots.
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Cerevkova, Andrea, Marek Renco, and Lenka Bobulska. "DIVERSITY OF SOIL NEMATODES IN THE TREATENED ECOSYSTEMS OF PONICKA CAVE." In 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023v/6.2/s29.91.
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Ponicka Cave, situated in central Slovakia, is a natural wonder, known for its stunning stalagmites, stalactites, and underground lakes. This unique cave system has a hydrological connection to the Earth's surface, representing a very vulnerable habitat. Long-lasting intensive livestock grazing in the aquifer area of Ponicka cave and insufficiently insulated manure dump were the main reasons for the contamination of this cave. Soil nematodes are the most abundant multicellular organisms on Earth with respect to both species� richness and abundance. They are ubiquitous invertebrates in the soil that include a variety of feeding types, and they perform key functions in soil food webs. They are considered as one of the best soils bioindicators. Although the mesofauna of caves in Slovakia is relatively well described, information about soil nematodes are missing. In this study, we present the first data on the fauna of free-living and plant-parasitic nematode species from soil taken in the Karst region (karst spring, ponor, sink hole) and manure. Totally we identified 54 nematode species across 43 genera, 28 families, and 9 orders. The highest number of identified nematode species (44) was observed in Ponor, while 33 species were observed in both the karst springs and in a sinkhole and only 8 species were found in manure. Bacterivores were the dominant trophic group in all sites. Differences in nematode species composition in sites around Ponicka Cave, showing the differences in the environmental conditions nearby and site characteristic. This study emphasizes how important it is to know, understand and protect the soil biota that plays an important role in keeping the cave and the surrounding environment healthy.
Reports on the topic "Nematodes"
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Samish, Michael, K. M. Kocan, and Itamar Glazer. Entomopathogenic Nematodes as Biological Control Agents of Ticks. United States Department of Agriculture, September 1992. http://dx.doi.org/10.32747/1992.7568104.bard.
Full textAbstract:
This research project was aimed to create a basis for the use of entomopathogenic nematodes (Steinernematidae an Heterorhabditidae) for biological control of ticks. The specific objectives were to determinate: 1) Nematode virulence to various. 2) Host-parasite interactions of nametodes and ticks. 3) Effect of environmental factors of tick habitats on nematode activity. 4) To test nematodes (anti tick activity) in defined field trials. Throughout the project 12 nematode strains from five species were tested in laboratory assays against all developmental stages of eight tick species. All tick species were found susceptible to nematode infection. The nematode strains the IS-5 and IS-12 of Heterorhabditis bacteriophora were found to be the most virulent. Engorged adults, particularly females, were the most susceptible stages. Despite the high susceptibility, ticks are not suitable hosts for nematode development and propagation. Entomopathogenic namatodes enter ticks and kill them by releasing the symbiotic bacteria from their foregut. Under favorable conditions, i.e. moist soil, moderate temperature (22-27oC) and sandy soil, nematode efficacy against B. annulatus engorged females was very high (>5% w/w) and high animal manure concentration in soil adversely effect nematode efficacy. In field trails, nematodes were effective when soil moisture was maintained at high levels. The results indicate that under favorable conditions the nematodes show promise as a biological control method for ticks. However, we still face several potential obstacles to the use of nematodes under less favorable conditions.
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McClure, Michael A., Yitzhak Spiegel, David M. Bird, R. Salomon, and R. H. C. Curtis. Functional Analysis of Root-Knot Nematode Surface Coat Proteins to Develop Rational Targets for Plantibodies. United States Department of Agriculture, October 2001. http://dx.doi.org/10.32747/2001.7575284.bard.
Full textAbstract:
The goal of this research was to provide a better understanding of the interface between root-knot nematodes, Meloidogyne spp., and their host in order to develop rational targets for plantibodies and other novel methods of nematode control directed against the nematode surface coat (SC). Specific objectives were: 1. To produce additional monoclonal SC antibodies for use in Objectives 2, 3, and 4 and as candidates for development of plantibodies. 2. To determine the production and distribution of SC proteins during the infection process. 3. To use biochemical and immunological methods to perturbate the root-knot nematode SC in order to identify SC components that will serve as targets for rationally designed plantibodies. 4. To develop SC-mutant nematodes as additional tools for defining the role of the SC during infection. The external cuticular layer of nematodes is the epicuticle. In many nematodes, it is covered by a fuzzy material termed "surface coat" (SC). Since the SC is the outermost layer, it may playa role in the interaction between the nematode and its surroundings during all life stages in soil and during pathogenesis. The SC is composed mainly of proteins, carbohydrates (which can be part of glycoproteins), and lipids. SC proteins and glycoproteins have been labeled and extracted from preparasitic second-stage juveniles and adult females of Meloidogyne and specific antibodies have been raised against surface antigens. Antibodies can be used to gain more information about surface function and to isolate genes encoding for surface antigens. Characterization of surface antigens and their roles in different life-stages may be an important step towards the development of alternative control. Nevertheless, the role of the plant- parasitic nematode's surface in plant-nematode interaction is still not understood. Carbohydrates or carbohydrate-recognition domains (CROs) on the nematode surface may interact with CROs or carbohydrate molecules, on root surfaces or exudates, or be active after the nematode has penetrated into the root. Surface antigens undoubtedly play an important role in interactions with microorganisms that adhere to the nematodes. Polyclonal (PC) and monoclonal (MC) antibodies raised against Meloidogyne javanica, M. incognita and other plant-parasitic nematodes, were used to characterize the surface coat and secreted-excreted products of M. javanica and M. incognita. Some of the MC and PC antibodies raised against M. incognita showed cross-reactivity with the surface coat of M. javanica. Further characterization, in planta, of the epitopes recognized by the antibodies, showed that they were present in the parasitic juvenile stages and that the surface coat is shed during root penetration by the nematode and its migration between root cells. At the molecular level, we have followed two lines of experimentation. The first has been to identify genes encoding surface coat (SC) molecules, and we have isolated and characterized a small family of mucin genes from M. incognita. Our second approach has been to study host genes that respond to the nematode, and in particular, to the SC. Our previous work has identified a large suite of genes expressed in Lycopersicon esculentum giant cells, including the partial cDNA clone DB#131, which encodes a serine/threonine protein kinase. Isolation and predicted translation of the mature cDNA revealed a frame shift mutation in the translated region of nematode sensitive plants. By using primers homologous to conserved region of DB#131 we have identified the orthologues from three (nematode-resistant) Lycopersicon peruvianum strains and found that these plants lacked the mutation.
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Gaugler, Randy, Itamar Glazer, Daniel Segal, and Sarwar Hashmi. Molecular Approach for Improving the Stability of Insecticidal Nematodes. United States Department of Agriculture, November 2002. http://dx.doi.org/10.32747/2002.7580680.bard.
Full textAbstract:
Our overall goal is to improve insecticidal nematodes by genetically engineering strains capable of entering an enhanced state of dormancy that provides improved stability. Objectives: 1. Clone and sequence tps-l homologue from Steinernema carpocapsae. (Revised: A failure to isolate the tps gene group from Steinernema precipitated a redirection to identifying other genes involved in insecticidal nematode desiccation process.) 2. Incorporate cloned tps-l gene into S. carpocapsae to obtain overexpression, thereby, enhancing desiccation tolerance. (Revised: Other stress genes in addition to tps-l genes were cloned and efforts at expression in S. carpocapsae were conducted) 3. Characterize the transgenic strains. No other biological control agent offers more impressive attributes than insecticidal nematodes. However, their potential is limited by the bane of nearly all biological control agents: poor stability. This leads to inadequate shelf-life and ultimately reduced field efficacy. Nematode storage is based on desiccation, yet insecticidal species are only capable of partial desiccation termed quiescent anhydrobiosis. Overwhelming evidence has shown that when the disaccharide compound trehalose is elevated in anhydrobiotic organisms such as yeast, plants, and nematodes it enables these organisms the ability to survive environmental stresses i.e., desiccation. Armed with this information our goal was to improve insecticidal nematodes stability by engineering trehalose overexpression.
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Phillips, Donald A., Yitzhak Spiegel, and Howard Ferris. Optimizing nematode management by defining natural chemical bases of behavior. United States Department of Agriculture, November 2006. http://dx.doi.org/10.32747/2006.7587234.bard.
Full textAbstract:
This project was based on the hypothesis that nematodes interacting with plants as either parasites or beneficial saprophytes are attracted to their host by natural products. This concept was supported by numerous observations that parasitic nematodes are attracted to root exudates. Our overall goal was to identify nematode sensory compounds from root exudates and to use that information for reducing nematicide applications. We applied skills of the investigators to achieve three specific objectives: 1) Identify nematode behavioral cues (e.g., attractants or repellents) in root exudates; 2) Identify new natural nematicidal compounds; and 3) Combine a natural attractant and a nematicide into a nematode trap. Because saprophytic nematodes benefit plants by mineralizing organic matter, we sought compounds attractive primarily to parasitic nematodes. The project was constructed on several complementary foundations. First, data from Dr. Spiegel’s lab showed that under aseptic conditions Ditylenchus dipsaci, a parasite on onion, is attracted to certain fractions of onion root exudates. Second, PI Phillips had a sizeable collection of natural plant products he had identified from previous work on Rhizobium-legume interactions, which could be tested “off the shelf”. Third, Dr. Ferris had access to aseptic and natural populations of various saprophytic and parasitic nematodes. The project focused on five nematode species: D.dipsaci, Heterodera avenae, and Tylenchulussemipenetransat ARO, and Meloidogyne javanicand Caenorhabditis elegans at UCD. Ten pure plant compounds, mostly flavonoids, were tested on the various nematode species using six different assay systems. Results obtained with assorted test systems and by various scientists in the same test systems were essentially irreproducible. Many convincing, Many convincing, i.e. statistically significant, results in one system or with one investigator could not be repeated with other assays or different people. A recent report from others found that these compounds, plus another 30, were inactive as attractants in three additional parasitic nematode species (Wuyts et al. Nematology 8:89- 101, 2006). Assays designed to test the hypothesis that several compounds together are required to attract nematodes have thus far failed to find a reproducibly active combination. In contrast to results using pure plant compounds, complex unfractionated exudates from aseptic onion root reproducibly attracted D. dipsaci in both the ARO and UCD labs. Onion root exudate collection, separation into HPLC fractions, assays using D. dipsaci and MS-MS experiments proceeded collaboratively between ARO and UCD without any definitive identification of an active compound. The final active fraction contained two major molecules and traces of several other compounds. In the end, analytical studies were limited by the amount of onion root exudate and the complexity of the purification process. These tests showed that aseptic plant roots release attractant molecules, but whether nematodes influence that release, as insects trigger release of attractants from plants, is unknown. Related experiments showed that the saprophyte C. elegans stimulates its prey, Pseudomonas bacteria, to increase production of 2, 4-diacetylphloroglucinol (DAPG) a compound that promotes amino acid exudation by plant roots. It is thus possible that saprophytic nematodes are attracted primarily to their bacterial or fungal prey and secondarily to effects of those microorganisms on root exudation. These observations offer promising avenues for understanding root-zone interactions, but no direct routes to controlling nematodes in agriculture were evident. Extracts from two plant sources, Chrysanthemum coronarium and Sequoia sempervirens, showed nematicidal activity at ARO and UCD, respectively. Attempts to purify an active compound from S. sempervirens failed, but preliminary results from C. coronarium are judged to form a potential basis for further work at ARO. These results highlight the problems of studying complex movement patterns in sentient organisms like nematodes and the issues associated with natural product isolation from complex mixtures. Those two difficulties combined with complications now associated with obtaining US visas, slowed and ultimately limited progress on this project. As a result, US investigators expended only 65% of the $207,400 originally planned for this project. The Israeli side of the project advanced more directly toward its scientific goals and lists its expenditures in the customary financial report.
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Glazer, Itamar, Randy Gaugler, Yitzhak Spiegel, and Edwin Lewis. Host Adaptation in Entomopathogenic Nematodes: An Approach to Enhancing Biological Control Potential. United States Department of Agriculture, April 1996. http://dx.doi.org/10.32747/1996.7613023.bard.
Full textAbstract:
The overall objective of our research was to develop methods to match species of entomopathogenic nematodes against the insect pests which they would be best adapted to control. The underlying hypothesis for this work was that entomopathogenic nematodes should be most effective when used against insect species to which they are naturally adapted to parasitize. Toward this end, we undertook a number of related studies focusing primarily on nematode foraging strategies. We found that foraging strategies affected host associations directly and indirectly. Nematodes' responses to host cues, and the role of their sensory organs based on lectin binding, led to new approaches to determining host range for these parasites. Based on this work, we developed a laboratory bioassay of host recognition behavior designed to predict field results. We also determined that nematodes that forage in a stationary manner (ambushers) have a slower metabolic rate than do active forgers (cruisers), thus their infective stage juveniles are longer lived. This study helps predict the duration of field activity after application and may partially explain field distributions of natural populations of entomopathogenic nematodes. The common thread linking all of these studies was that they led to a deeper understanding of the associations between entomopathogenic nematodes and insects as hosts.
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Spiegel, Yitzhak, Michael McClure, Itzhak Kahane, and B. M. Zuckerman. Characterization of the Phytophagous Nematode Surface Coat to Provide New Strategies for Biocontrol. United States Department of Agriculture, November 1995. http://dx.doi.org/10.32747/1995.7613015.bard.
Full textAbstract:
Chemical composition and biological role of the surface coat (SC) of the root-knot nematodes, Meloidogyne spp. are described. SC proteins of M. incognita race 3 infective juveniles (J2) were characterized by electrophoresis and western blotting of extracts from radioiodine and biotin-labelled nematodes. J2 labelled with radioiodine and biotin released 125I and biotin-labelled molecules into water after 20 hours incubation, indicating that SC proteins may be loosely attached to the nematode. Antiserum to the principal protein reacted with the surface of live J2 and with surface proteins previously separated by electrophoresis. Human red blood cells (HRBC) adhered to J2 of several tylenchid nematodes over the entire nematode body. HRBC adhered also to nylon fibers coated with SC extracted from M. javanica J2; binding was Ca++/Mg++ dependent, and decreased when the nylon fibers were coated with bovine serum albumin, or pre-incubated with fucose and mannose. These experiments support a working hypothesis that RBC adhesion involves carbohydrate moieties of HRBC and carbohydrate-recognition domain(s) (CRD) distributed on the nematode surface. To our knowledge, this is the first report of a surface CRD i the phylum Nematoda. Gold-conjugated lectins and neoglycoproteins combined with silver enhancement have been used for the detection of carbohydrates and CRD, respectively, on the SC of M. javanica J2. Biotin reagents were used to trace surface proteins, specifically, on live J2. The labile and transitory nature of the SC was demonstrated by the dynamics of HRBC adherence to detergent-treated J2, J2 at different ages or fresh-hatched J2 held at various temperatures. SC recovery was demonstrated also by a SDS-PAGE profile. Monoclonal antibodies developed to a cuticular protein of M. incognita J2 gave a slight, but significant reduction in attachment of Pasteuria penetrans spores. Spore attachment as affected by several enzymes was inconsistent: alcian blue, which specifically blocks sulfyl groups, had no afffect on spore attachment. Treatment with cationized ferritin alone or catonized ferritin following monoclonal antibody caused significant decreases in spore attachment. Those results suggest a role in attachment by negatively charged groups.
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Brown Horowitz, Sigal, Eric L. Davis, and Axel Elling. Dissecting interactions between root-knot nematode effectors and lipid signaling involved in plant defense. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7598167.bard.
Full textAbstract:
Root-knot nematodes, Meloidogynespp., are extremely destructive pathogens with a cosmopolitan distribution and a host range that affects most crops. Safety and environmental concerns related to the toxicity of nematicides along with a lack of natural resistance sources threaten most crops in Israel and the U.S. This emphasizes the need to identify genes and signal mechanisms that could provide novel nematode control tactics and resistance breeding targets. The sedentary root-knot nematode (RKN) Meloidogynespp. secrete effectors in a spatial and temporal manner to interfere with and mimic multiple physiological and morphological mechanisms, leading to modifications and reprogramming of the host cells' functions, resulted in construction and maintenance of nematodes' feeding sites. For successful parasitism, many effectors act as immunomodulators, aimed to manipulate and suppress immune defense signaling triggered upon nematode invasion. Plant development and defense rely mainly on hormone regulation. Herein, a metabolomic profiling of oxylipins and hormones composition of tomato roots were performed using LC-MS/MS, indicating a fluctuation in oxylipins profile in a compatible interaction. Moreover, further attention was given to uncover the implication of WRKYs transcription factors in regulating nematode development. In addition, in order to identify genes that might interact with the lipidomic defense pathway induced by oxylipins, a RNAseq was performed by exposing M. javanicasecond-stage juveniles to tomato protoplast, 9-HOT and 13-KOD oxylipins. This transcriptome generated a total of 4682 differentially expressed genes (DEGs). Being interested in effectors, we seek for DEGs carrying a predicted secretion signal peptide. Among the DEGs including signal peptide, several had homology with known effectors in other nematode species, other unknown potentially secreted proteins may have a role as root-knot nematodes' effectors which might interact with lipid signaling. The molecular interaction of LOX proteins with the Cyst nematode effectors illustrate the nematode strategy in manipulating plant lipid signals. The function of several other effectors in manipulating plant defense signals, as well as lipids signals, weakening cell walls, attenuating feeding site function and development are still being studied in depth for several novel effectors. As direct outcome of this project, the accumulating findings will be utilized to improve our understanding of the mechanisms governing critical life-cycle phases of the parasitic M. incognita RKN, thereby facilitating design of effective controls based on perturbation of nematode behavior—without producing harmful side effects. The knowledge from this study will promote genome editing strategies aimed at developing nematode resistance in tomato and other nematode-susceptible crop species in Israel and the United States.
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Davis, Eric L., Yuji Oka, Amit Gal-On, Todd Wehner, and Aaron Zelcer. Broad-spectrum Resistance to Root-Knot Nematodes in Transgenic Cucurbits. United States Department of Agriculture, June 2013. http://dx.doi.org/10.32747/2013.7593389.bard.
Full textAbstract:
Root-knot nematodes (RKN), Meloidogyne spp., are extremely destructive pathogens of cucurbit crops grown in the United States and Israel. The safety and environmental concerns of toxic nematicides, and limited sources of natural cucurbit resistance to the four major species of Meloidogyne that threaten these crops in Israel and the U.S., have emphasized the use of biotechnology to develop cucurbits with novel RKN resistance. The U.S. scientists have identified over 40 unique RKN parasitism genes that encode nematode secretions involved in successful plant root infection by RKN, and they have demonstrated that expression of a double-stranded RNA (dsRNA) complementary to a RKN parasitism gene (called 16DIO) in Arabidopsis thaliana induced RNA interference (RNAi)-mediated silencing of the RKN16DlO gene and produced transgenic plants with strong resistance to all four major RKN species. The expression 8D05 parasitism gene was found to coincide with the timing of upregulation of NtCel7 promoter (identified to be upregulated in giantcells by US scientists). NtCel7 promoter was used to express the genes at the right time (early stages of infection) and in the right place (giant-cells) in transgenic plants. US partners produced NtCel7 (nematode-induced promoter)-driven 16DlO-RNAi and 8DOS-RNAi constructs, pHANNIBAL 4D03-RNAi construct and modified 16DlO-RNAi construct (for increased RNAi expression and efficacy) for cucurbit transformation in Israel. In Arabidopsis, some 16DlO-RNAi plant lines show greater levels of resistance to M. incognita than others, and within these lines resistance of greater than 90% reduction in infection is observed among almost all replicates in US. The level of observed nematode resistance is likely to be directly correlated with the level of RNAi expression in individual plants. In Israel, all the RKN parasitism genes-RNAi constructs were successfully transformed into cucumber and melon. The transgenic lines were evaluated for expression of the transgene siRNA in leaves and roots. Those displaying transgene siRNA accumulation were passed on for nematode resistance analysis. Rl seedlings from different lines were subjected to evaluation for resistance to M. javanica. None of the lines was resistant to the nematode in contrast with US partner's results in Arabidopsis. This could be for the following reasons: a) The level of transgene siRNA was insufficient in cucumber and tomato to cause resislance. b) 111e nemalode species on cucwnber IIlay be different ur act in a different manner. c) The assay was performed in soil with a high level of nematode inoculation, and not in petri dish, which may not permit the observation of a low level of resistance.
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Glazer, Itamar, Randy Gaugler, Daniel Segal, Parwinder Grewal, Yitzhak Spiegel, and Senthamizh Selvan. Genetic Enhancement of Environmental Stability and Efficacy of Entomopathogenic Nematodes for Biological Control. United States Department of Agriculture, August 1995. http://dx.doi.org/10.32747/1995.7695833.bard.
Full textAbstract:
The overall obejctive of the research project was to enhance the intrinsic biological control potential of entomopathogenic nematodes through genetic manipulation. We have chosen heat and desiccation tolerance as prime traits to be enhanced in order to increase the overall efficacy of these nematodes against insect pests under harsh conditions. Initially, we used mutagenesis and selection approaches to enhance these traits. In the mutagenesis experiments several morphological mutants of Heterorhabditis bacteriophora HP88 were isolated and characterized phenotypically and genetically. Infective juveniles of H. bacteriophora HP88 were subjected to heat and desiccation selection regimes for several generations. Small increase was recorded, after 4 and 6 rearing cycles for both traits. However, in both selection regimes a significant deterioration in the reproductive capability of the nematodes was observed. In a screen of new nematode populations, from arid regions in Israel, a heat tolerant (IS5 strain) and desiccation tolerant (IS6 strain) were isolated. Both strains were taxonomically identified and their beneficial characteristics (environmental tolerance, insecticidal virulence and reproduction) were determined. We further investigated the stability of the enhanced heat tolerance trait in, and the storage capacity of, the newly discovered IS5 strain. Genetic studies demonstrated that the heat tolerance of the IS5 strain is genetically based and is dominant. The trait for heat tolerance was transferred from the IS5 strain to the HP88 strain of H. bacteriophora. The transfer was accomplished by allowing the heat tolerant strain (IS5) to mate with the commercial strain (HP88). The hybrid nature of the progeny was confirmed using a recessive marker mutant of the HP88 strain (H-dpy-2). We have used (RAPD-PCR) to compare genetic variation in the IS5 and the HP88 strains of H. baceriophora. The results indicated that genetic variation in the HP88 was significantly less than in the IS5 strain which was recently isolated from the field. The new IS5 strain may be used as an effective biological control agent in warm environments. In addition, IS5 can be used as a genetic source for cross-hybridization with other H. bacteriophora strains.
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Hicks, Kiley. Causes and Consequences of Mitochondrial Variation in Caenorhabditid Nematodes. Portland State University Library, January 2000. http://dx.doi.org/10.15760/etd.928.
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