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Bohan, David Andrew. "Modelling Steinernema feltiae population biology." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261776.
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Lucero, Valerie Vanessa. "Symbiont Specificity of Steinernema Puntauvense (Nematoda: Steinernematidae)." Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/144561.
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Porter, Camille Eileen Finlinson. "A Tree Theory Case Study in Steinernema." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3504.
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It is widely assumed that current phylogenetic methods are fairly accurate at recovering the evolutionary relationships among different species, but evaluating the relative success of this enterprise is a difficult task. This study addresses some fundamental questions associated with generating phylogenetic trees. The complete genomes of five species of Steinernema were sequenced and assembled. Genes were predicted in AUGUSTUS and orthologous genes were found from those data using OrthoMCL. I aligned 3890 genes in MAFFT and eliminated poorly aligned positions with GBlocks. I created individual trees for each gene as well as a supermatrix tree in PAUP*, using a closely related taxon from another genus, Panagrellus redivivus. In the resulting gene trees, I found only a small subset of all the possible topologies. I discovered that the supermatrix tree has the same topology as the topology with the most gene trees in the gene-topology distribution. There are only a small number of histories for all of the genes and many of the genes have the same lineage. I bootstrapped the gene-topology distribution and found that the best-supported topology was sampled 22.1% of the time. I show that many genes must be sampled in order to converge on the topology with the most support from the gene trees in this dataset.
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Roder, Alexandra Catherine, and Alexandra Catherine Roder. "Influence of Xenorhabdus Symbionts on Gonad Development and Pheromone Production of First-Generation Adult Steinernema Nematodes (Nematoda: Steinernematidae)." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/626344.
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Entomopathogenic Steinernema nematodes (Nematoda: Steinernematidae) have a mutualistic relationship with Xenorhabdus bacteria (Gamma-Proteobacteria Enterobacteriaceae). The two partners form an insecticidal alliance that is successful in killing a wide range of insects. A few studies have shown that Steinernema IJs have an enhanced virulence and reproductive fitness when they associate with their cognate symbionts. However, there are unanswered questions regarding the physiological interactions that govern and perpetuate the interactions between different nematode developmental stages and their bacterial partners. In this study, we evaluated gonad development and maturation time of first-generation adults of S. carpocapsae and S. feltiae adults when reared under four bacterial scenarios: a) cognate symbiotic, b) non-cognate symbiotic bacterial strain, c) non-cognate symbiotic bacterial species and d) non-symbiotic bacteria (Serratia proteamaculans). For comparative purposes, we also considered adult nematodes reared in vivo in Galleria mellonella larvae to assess nematode development under natural conditions. Furthermore, in this study we also measured production of nematode pheromones (ascarosides), which play a key role in mating and reproduction. For this purpose, we considered in vitro rearing methods (with cognate and non-cognate Xenorhabdus symbionts) to qualitatively and quantitatively characterize ascarosides produced by first-generation adults. Our data showed that for both Steinernema spp. tested, time to adult maturation and gonad development was tightly dependent on the bacterial conditions under which juveniles were reared. However, contrasting results were observed when assessing total body length and gonad size. S. feltiae males and females size (body length and width) and respective gonad length were smaller when reared with a non-cognate symbiotic species. Additionally, non-symbiotic bacteria did not sustain S. feltiae maturation to adult stages. Contrarily, S. carpocapsae juveniles developed to adults when reared with any of the bacterial conditions tested, including with non-symbiotic Serratia proteamaculans. Additionally, S. carpocapsae adults, unlike S. feltiae, did not exhibit enhanced body and gonad size when reared with their cognate symbiont. In fact, S. carpocapsae males and females had larger gonad lengths when reared with a non-cognate symbiotic strain, XnAna (X. nematophila associated with S. anatoliense). S. carpocapsae males and females had significantly underdeveloped gonads when reared with non-symbiotic bacteria. In both Steinernema spp., sex ratio was not impacted by the bacterial condition. However, sex ratio (female:male) S. carpocapsae, decreased from 2:1 to 1:1 when reared with non-symbiotic bacteria. The body and gonad sizes of Steinernema spp. reared in vitro with their cognate symbiont were significantly smaller than those grown in vivo. Ascaroside production in either Steinernema spp. was not significantly impacted by the rearing conditions. In S. carpocapsae, a significant increase in glucoside-1 was observed when the nematodes were reared with cognate or non-cognate bacteria. No detectable quantities of asc-C11 were produced by S. feltiae nematodes when reared with a non-cognate symbiotic bacterial species. We conclude that bacterial symbionts influenced maturation and development of first-generation adults’ in both Steinernema spp. tested in this study. However, response to the bacterial symbionts was species specific. Additionally, this study showed that Xenorhabdus as a food source plays an important role in the type and amount of ascarosides produced by Steinernema spp.
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He, Hongjun. "Thermal adaptation in Xenorhabdus spp., bacterial symbionts of entomopathogenic nematodes, Steinernema spp." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0014/MQ42392.pdf.
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Barbara, Kathryn Ann. "Management of pest mole crickets using the insect parasitic nematode Steinernema scapterisci." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0009590.
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Bortoluzzi, Lilian. "Avaliação do potencial de nematóides entomopatogênicos para o controle da broca-da-bananeira Cosmopolites sordidus (Germar, 1824)." Universidade Estadual do Oeste do Paraná, 2009. http://tede.unioeste.br:8080/tede/handle/tede/1393.
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The black weevil (Cosmopolites sordidus) is the main pest of banana crops in several regions of the world, causing significant losses in productivity of the culture. The larvae build galleries in the rhizome or pseudostem base, affecting the development of the plant and the fruits, beside favoring the installation of pathogenic microrganisms. The use of nematodes to control of the pest can be an alternative, mainly because the insect's habits make them a potential target of entomopathogenic nematodes. So, this study had the objectives to evaluate isolates of entomopathogenic nematodes in laboratory conditions to their use in controlling the borer. Sixteen isolates Sterinernematidae and Heterorhabditidae were tested, applied on pseudostem (100JIs/cm2). The evaluation was performed 7 days after application. After, the most virulent isolates were compared with each other for production of nematodes in cadavers of wax moth (Galleria mellonella) and also about his compatibility with the insecticide carbofuran. All isolates were pathogenic to the adults of C. sordidus, except the isolate SC (Steinernema carpocapsae). The most virulent isolates were CB24 and CB40 (both of the Heterorhabditidae), which caused respectively 33,3% and 36,7% of mortality. The two isolates showed high production of JIs. The insecticide was compatible with isolated CB40 and incompatible with CB24, nevertheless, CB24 showed better performance in combination with carbofuran
A broca-da-bananeira (Cosmopolites sordidus) é a principal praga dos cultivos de banana em várias regiões do mundo, acarretando perdas significativas na produtividade da cultura. As larvas constroem galerias no rizoma ou base do pseudocaule, afetando o desenvolvimento da planta e dos frutos, além de favorecer a instalação de microrganismos patogênicos. O uso de nematóides para o controle da praga pode ser uma alternativa, principalmente devido aos hábitos do inseto que os tornam um potencial alvo dos nematóides entomopatogênicos. Assim, este trabalho teve como objetivos avaliar isolados de nematóides entomopatogênicos em condições de laboratório visando sua utilização no controle da broca. Foram testados 16 isolados pertencentes às famílias Sterinernematidae e Heterorhabditidae, aplicados sobre pseudocaule (100JIs/cm2). A avaliação foi realizada 7 dias após a aplicação. Os isolados mais eficientes foram comparados entre si quanto à produção de nematóides em cadáveres da traça dos favos (Galleria mellonella) e também quanto a sua compatibilidade com o inseticida carbofurano. Todos os experimentos foram realizados em delineamento inteiramente casualizado. Verificou-se que exceto o isolado SC (Steinernema carpocapsae), todos os demais foram patogênicos aos adultos de C. sordidus. Os isolados mais virulentos foram o CB24 e CB40, os quais provocaram respectivamente 33,3% e 36,7% de mortalidade, ambos da família Heterorhabditidae. Os dois isolados apresentaram alta produção de JIs, não diferindo estatisticamente entre si. O inseticida foi compatível com o isolado CB40 e incompatível com CB24, mesmo assim, CB24 apresentou melhor desempenho em associação com carbofurano
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Lee, Ming-Min. "A Phylogenetic Hypothesis on the Evolution and Interactions of Xenorhabdus Spp. (Gamma-Proteobacteria) and Their Steinernema Hosts (Nematoda: Steinernematidae)." Thesis, The University of Arizona, 2009. http://hdl.handle.net/10150/193414.
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Nematodes in the genus Steinernema (Nematoda: Steinernematidae) and their associated bacteria Xenorhabdus spp. (Gamma-Proteobacteria) are an emergent model of terrestrial animal-microbe symbiosis. Although interest in this association initially arose out of their potential as biocontrol agents against insect pests (Tanada and Kaya, 1993), this mutualistic partnership is currently viewed more broadly under the umbrella of basic sciences to inform ecology, evolution, biochemistry, molecular, among other disciplines (Burnell and Stock, 2000; Forst and Clarke, 2002).Despite advances in the discovery and field application of this nematode-bacterium partnership, and the growing popularity of this model system, relatively little has been published to uncover the evolutionary facets of their association. This study adds to the body of knowledge regarding nematode-bacteria symbiosis by 1) producing novel, multi-gene phylogenies for Steinernema and Xenorhabdus; 2) proposing a possible scenario for historical association in the form of a cophylogenetic hypothesis; 3) describing a newly discovered Steinernema species from France.
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Yu, Hao. "Parasitism of Subterranean Termites (Isoptera: Rhinotermitidae: Termitidae) by Entomopathogenic Nematodes (Nematoda: Steinernematidae: Heterorhabditidae)." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195263.
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The biological control of subterranean termites (Isoptera: Rhinotermitidae; Termitidae) using entomopathogenic nematodes (Nematoda: Steinernematidae; Heterorhabditidae) (EPN) was investigated. The desert subterranean termite Heterotermes aureus Snyder was found to be very susceptible to Steinernema riobrave Cabanillas, Poinar and Raulston. In laboratory bioassays S. riobrave (355, TP, 3-8b and 7-12 strains), S. carpocapsae Weiser (Mexican 33 strain), S. feltiae Filipjev (UK76 strain), and Heterorhabditis bacteriophora Poinar (HP88 strain) were all capable of infecting and killing H. aureus, Reticulitermes flavipes Kollar, R. virginicus Banks, Coptotermes formosanus Shiraki and Gnathamitermes perplexus Banks. In sand assays, S. riobrave caused > 90% H. aureus mortality in 3 days and 100% mortality by day 5 at 22 °C. TP strain of S. riobrave caused 75% R. flavipes mortality and 90.91% C. formosanus mortality in 7 days. EPNs utilizing termites as hosts produced smaller sized offspring, with the exception of S. feltiae. Stunted females of S. feltiae were frequently found in termite cadavers, but no progeny. Small IJs of S. carpocapsae, S. riobrave and H. bacteriophora infect, reproduce and form normal size IJs after subsequent infection in Galleria mellonella L. The progeny of small IJs were as effective as the normal size IJs, with regard to subsequent induced mortality, under the conditions tested. In laboratory two-container choice experiments, H. aureus were repelled by EPN treated areas for up to 10 days at 10,000 IJs per device. The repellency threshold was found to vary among nematodes species. We hypothesis that it is the physical movement of the nematodes that repels the termites. Temperature is a key factor affecting nematode pathogenicity. Temperature tolerance of the nematodes varied between species. After a gradual heat adaptation process, S. riobrave and H. bacteriophora caused significantly higher H. aureus mortality at 32 °C compared with original laboratory cultured strains. Further work may result in the contribution of commercially available strains with enhanced heat tolerance. Preliminary field studies confirmed EPN protection of a structure, however, termites began to reinfest 4 weeks after the application. Additional tests are necessary to provide more evidence before we can conclude nematodes as useful in the field.
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Bisch, Gaëlle. "Les bactéries entomopathogènes du genre Xenorhabdus : description pathologique et génomique de souches à la virulence atténuée." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20050/document.
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Les entérobactéries du genre Xenorhabdus sont pathogènes de larves d'insectes et symbiotiques de nématodes du genre Steinernema. En lutte biologique, les couples Steinernema-Xenorhabdus sont utilisés contre un large spectre d'insectes ravageurs de culture. Les deux partenaires du couple modèle Steinernema carpocapsae-Xenorhabdus nematophila peuvent être expérimentalement dissociés tout en restant pathogènes pour les insectes. En revanche, certaines souches de Xenorhabdus sont non-virulentes lorsqu'elles sont injectées directement dans une larve d'insecte. L'objectif de cette thèse est de caractériser deux souches non-virulentes de Xenorhabdus, X. poinarii G6 (Xp G6) et X. bovienii CS03 (Xb CS03). Les souches appartenant à l'espèce non-virulente X. poinarii possèdent des génomes de petite taille. Nous avons mis en évidence un phénomène de réduction génomique due à la délétion de larges régions génomiques chez la souche Xp G6. Cette évolution pourrait avoir eu lieu suite à un transfert des fonctions bactériennes de virulence à son nématode hôte et/ou à sa spécialisation envers certains coléoptères. Au sein de l'espèce X. bovienii, Xb CS03 est non-virulente par injection dans les lépidoptères Spodoptera littoralis et Galleria mellonella. Par rapport à d'autres couples némato-bactériens Steinernema sp.-X. bovienii, le couple formé par Xb CS03 et son nématode symbiotique S. weiseri 583 présente également une virulence atténuée sur ces lépidoptères. Le génome de Xb CS03 est de très grande taille et contient un grand nombre de gènes dégradés (pseudogènes). Une comparaison génomique entre Xb CS03 et une souche virulente appartenant à la même espèce, X. bovienii SS-2004 (Xb SS-2004), montre que Xb CS03 est plus riche que Xb SS-2004 en gènes codant des chaînes d'assemblage enzymatiques NRPS/PKS (non-ribosomal peptide synthase/polyketide synthethase) produisant des métabolites antimicrobiens potentiels. A l'inverse, Xb SS-2004 contient davantage de gènes codant des facteurs de virulence de type hémolysine, adhésine ou systèmes de sécrétion. Ceci suggère deux scénarios évolutifs différents, privilégiant une forte virulence pour Xb SS-2004 et l'élimination des compétiteurs au sein du cadavre de l'insecte pour Xb CS03. Enfin, une recherche de facteurs de virulence potentiels a été effectuée par une approche de génomique comparative entre les souches non-virulentes Xp G6 et Xb CS03, d'une part et trois souches de Xenorhabdus virulentes, d'autre part. L'analyse fonctionnelle de gènes candidats a été entamée. En conclusion, la caractérisation de nouveaux modèles bactériens dans le genre Xenorhabdus ouvre le champ à l'identification de nouvelles stratégies de virulence et de nouveaux facteurs de virulence chez les bactéries entomopathogènesXenorhabdus are enterobacteria pathogenic of insect larvae and symbiotic of nematodes from the Steinernema genus. The Steinernema-Xenorhabdus associations are used against a wide range of insect pests. The two partners of the model Steinernema carpocapsae-Xenorhabdus nematophila association can be experimentally dissociated. Each partner is pathogenic for insect larvae. Contrarily, some other Xenorhabdus strains are non-virulent when injected directly into insect larvae. In this thesis, we characterized two non-virulent Xenorhabdus strains, X. poinarii G6 (Xp G6) and X. bovienii CS03 (Xb CS03). Strains from the X. poinarii species had small-sized genomes. We showed that the Xp G6 strain had undergone a genome reduction due to the deletion of large genomic regions. Transfer of virulence functions from the bacteria to the nematode and/or the specialization of the association towards coleopteran insects are likely the cause of this evolution. Within the X. bovienii species, Xb CS03 was non-virulent strain when injected into the Spodoptera littoralis and Galleria mellonella lepidopteran insects. When compared to other Steinernema-X. bovienii pairs, the association between Xb CS03 and its symbiotic nematode S. weiseri 583 had also a lower virulence on those insects. Xb CS03 had a large-sized genome and harbored numerous degraded genes (pseudogenes). Genome comparison between Xb CS03 and a virulent strain from the same species, X. bovienii SS-2004 (Xb SS-2004), showed that Xb CS03 contained more loci encoding NRPS/PKS enzymes (non-ribosomal peptide synthase/polyketide synthethase), producing potential antimicrobial metabolites, than Xb SS-2004. On the other hand, Xb SS-2004 contained more genes encoding virulence factors such as hemolysins, adhesins or secretion systems. This suggests that the two strains followed different evolutionary scenarios, favoring strong virulence in Xb SS-2204 and elimination of competitors for Xb CS03.Finally, we searched for potential virulence factors by comparing the genomes of the non-virulent strains Xp G6 and Xb CS03 with three virulent strains. Functional analyses of the candidates are in progress. In conclusion, characterizing new bacterial models in the Xenorhabdus genus paves the way for the identification of new virulence strategies and new virulence genes in entomopathogenic bacteria
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Batista, Elder Simões de Paula. "Nematóides entomopatogênicos como controladores biológicos de cigarrinhas do gênero Mahanarva (Hemiptera: Cercopidae)." Universidade Federal de Juiz de Fora (UFJF), 2010. https://repositorio.ufjf.br/jspui/handle/ufjf/4008.
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As cigarrinhas do gênero Mahanarva causam danos às culturas da família Poaceae, como braquiária, capim-elefante e cana-de-açúcar, em função da sucção de seiva das raízes (fase imatura) e folhas (fase adulta). Com a crescente demanda de redução do uso de inseticidas químicos para o controle de insetos praga, surge a necessidade do desenvolvimento de novos métodos de controle. Nesse cenário, o controle biológico recebe destaque e no caso das cigarrinhas, os nematóides entomopatogênicos (NEPs) são potenciais agentes de controle, pois exploram a superfície do solo, mesmo ambiente da praga enquanto esta se alimenta nas raízes. Portanto, com o objetivo de conhecer a ação de NEPs e selecionar isolados desses patógenos contra a cigarrinha-das-pastagens, Mahanarva spectabilis, e a cigarrinha-dasraízes, Mahanarva fimbriolata, experimentos foram desenvolvidos com diversos isolados de NEPs sobre diferentes fases de desenvolvimento do inseto. Em dois experimentos ninfas de M. spectabilis e M. fimbriolata foram expostos aos patógenos, em condições de laboratório e casa-de-vegetação e a partir daí foram selecionados os isolados mais patogênicos para cada espécie de praga. Em seguida, avaliou-se a eficiência de quatro métodos de aplicação de NEPs (pipetador, pulverização sobre ninfas com e sem espuma e inseto-cadáver) sobre a cigarrinha-das-pastagens, em casa-de-vegetação. Por último, avaliou-se a eficiência de uma espécie de NEP sobre ovos e adultos da cigarrinha-das-pastagens. Todos os isolados testados são patogênicos às ninfas das cigarrinhas causando mortalidade de 40 a 92% e 38 a 90% em condições de laboratório e 14 a 71% e 48 a 72% em casa-de-vegetação, para M. spectabilis e M. fimbriolata, respectivamente. Os métodos de aplicação mais eficientes foram o de pulverização sobre ninfas com espuma e inseto-cadáver, não havendo diferença na eficiência provocada pelas concentrações e isolados utilizados. Observou-se que não ocorre infecção de NEPs sobre ovos de cigarrinha-das-pastagens. Os adultos da cigarrinha não foram infectados pelos NEPs, e não houve redução no número de ovos em função da presença do patógeno. Dos isolados testados, os mais eficientes foram Steinernema riobravis, S.feltiae e Heterorhabditis amazonensis RSC1 para M. spectabilis e S. feltiae, S. riobravis, H. baujardi LPP7 e S. carpocapsae para M. fimbriolata. Conclui-se portanto que nematóides entomopatogênicos podem ser utilizados no controle de cigarrinhas do gênero Mahanarva, sendo incluídos em programas de manejo integrado, devendo ser empregados contra as ninfas, pulverizados sobre a espuma ou através de inseto-cadáver.
The spittlebugs belonging to the genus Mahanarva cause damage to the Poaceae family cultures, like signal grass, elephant grass and sugar cane, by the sap feeding on roots (immature phase) and leaves (adult phase). With the increase demand to reduce use of chemical insecticides for the insect pests’ control, comes the need to develop new control methods. In this scenario, the biological control gains highlight and in the spittlebugs case, the entomopathogenic nematodes (EPNs) are potential control agents, exploring the soil surface, the same pest environment while it feeds on roots. Thus, with the aim to know the EPNs’ action and to screening strains of these pathogens against the leaf spittlebug, Mahanarva spectabilis, and the root spittlebug, Mahanarva fimbriolata, experiments were conducted with various EPNs strains over different insect development phases. In two experiments M. spectabilis and M. fimbriolata nymphs were exposed to the pathogens, in laboratory and greenhouse conditions, and then were screened the more pathogenic strains to each pest species. Following, were evaluated the efficiency of four application methods of EPNs (pippeting, spray over nymphs with and without froth and infected host cadaver) over the leaf spittlebug, at greenhouse. At last, were evaluated the efficiency of an EPN species over eggs and adults of the leaf spittlebug. All tested strains are pathogenic to the spittlebugs nymphs causing 40-92% and 38-90% mortality at laboratory and 14-71% and 48-72% at greenhouse, to M. spectabilis and M. fimbriolata, respectively. The more efficient application methods were spray over nymphs with froth and infected host cadaver, with no difference because the concentrations and strains. Observations showed that don’t occurs eggs infection by EPNs in leaf spittlebugs. The leaf spittlebug adults not were infected by the EPNs, and no egg reduction were observed. The most pathogenic EPNs strains were Steinernema riobravis, S.feltiae and Heterorhabditis amazonensis RSC1 to M. spectabilis and S. feltiae, S. riobravis, H. baujardi LPP7 and S. carpocapsae to M. fimbriolata. Thus I conclude that entomopathogenic nematodes can be utilized to control Mahanarva genus spittlebugs, and can be inserted in integrated pest management programs, should to be applied over nymphs exclusively, sprayed over the froth or through infected host cadevers.
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Hirao, Ayako [Verfasser]. "Life cycle and development of entomopathogenic nematodes Steinernema carpocapsae and S. feltiae in monoxenic liquid culture = Lebenszyklus und Entwicklung der entomopathogenen Nematoden Steinernema carpocapsae und S. feltiae in monoxenischer Flüssigkultur / Ayako Hirao." Kiel : Universitätsbibliothek Kiel, 2009. http://d-nb.info/1019998830/34.
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Walsh, Keith Thomas. "Relationship between symbiotic and non-symbiotic bacteria during Steinernema (Nematoda) infection of Galleria larvae." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0012/MQ61510.pdf.
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Al-Own, Fada'a. "Population structure of insect pathogenic bacteria in UK soil and their associated nematodes." Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.606941.
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Surveys for entomopathogenic bacteria and their associated nematode hosts were conducted locally (University of Bath campus) and across southern England. Sampling involved trialing a novel Android app. (Epicollect) to manage sample collection data. Galleria larvae were used to bait UK soil samples. Insects which became infected were placed on White traps to collect any emerging nematodes, from which bacteria were isolated. Bacteria were also isolated from the haemolymph of any infected larvae. Bacterial isolates were classified on the basis of 16s rDNA and recA gene sequences. Serratia proteamaculans-like strains dominated the samples, and Multilocus sequence analysis (MLSA) was developed for the characterization of these Serratia isolates. We determined the sequences of (350-450-bp) fragments from five housekeeping genes of 84 isolates of Serratia proteamaculans. MLSA was shown to be effective for distinguishing closely related strains found in the insects’ haemolymph and from different nematodes. goeBURST was used to visualize the relationships between the STs, and the data showed a high level of discrimination, resolving 69 STs from the 84 isolates. In addition, the data derived from this study were represented in a phylogenetic network using the Splits Tree-network methods, to show the rate of recombination within and between the genes. From a total of 256 infected Galleria 23.04% were nematode positive. The nematodes were identified based on 18S rDNA 19 isolates were close relatives of the species Pristionchus entomophaga and Diplogasteriodes magnus (Diplogastridae). A further 16 isolates were more closely related to Steinernema glaseri (Steinernematidae). All three nematode types were isolated from diverse habitats and soil types, but were isolated more frequently in cold seasonal conditions. The bacterial sequence data suggest that the nematode- associated strains of bacteria belong to specific clades, distinct from the free living infective strains, which hints at ecological diversity within the S. proteamaculans population. Two of the Serratia proteamaculans-like strains had been chromosomally labeled with GFP to confirm the specifics of their association with the nematode hosts. The associated S. proteamaculans-like isolates isolated from Bath and Chepstow soils were examined further for their pathogenicity to Galleria mellonella and Manduca sexta larvae. Serratia Bath isolates, isolated from Pristionchus were more virulent toward both insect hosts than the Serratia from the Chepstow isolates associated with Steinernema nematodes. This suggests that host specificity may play important role in the virulence of the strain.
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Desta, Temesgen Addis [Verfasser]. "Life history traits of entomopathogenic nematodes of Steinernema spp. and Heterorhabditis bacteriophora / Temesgen Addis Desta." Kiel : Universitätsbibliothek Kiel, 2016. http://d-nb.info/1104733722/34.
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Morris, John R. (John Robert) 1949. "Biological Control of the Red Imported Fire Ant by the Entomopathogenic Nematode, Steinernema Carpocapsae (Weiser)." Thesis, University of North Texas, 1989. https://digital.library.unt.edu/ark:/67531/metadc500266/.
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Field trials were conducted in 1988 to evaluate the effectiveness of Steinernema (=Neoaplectana) carpocapsae (Weiser) in controlling the fire ant. Infective juveniles (IJ) of the nematode were applied as drench on 235 and 422 mounds, respectively for 2-month summer and 6-week fall evaluation periods. In comparative trials, amidinohydrazone (Amdro) was applied to 249 (summer) and 65 (fall) active mounds, with 245 (summer) and 78 (fall) untreated active as controls. Nematode treatments resulted in an average of 47% control (Abbott's formula) in summer trials and 19-88% control in the fall trials, compared with 39% and 47% control, respectively with amidinohydrazone. Active mounds treated with nematodes or amidinohydrazone had significantly fewer individuals than control mounds in summer trials.
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Isaacson, Peter J. "Antimicrobial activity of Xenorhabdus sp. (Enterobacteriaceae), symbiont of the entomopathogenic nematode, Steinernema riobrave (Rhabditida: Steinernematidae)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0027/MQ51364.pdf.
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Addis, Desta Temesgen [Verfasser]. "Life history traits of entomopathogenic nematodes of Steinernema spp. and Heterorhabditis bacteriophora / Temesgen Addis Desta." Kiel : Universitätsbibliothek Kiel, 2016. http://d-nb.info/1104733722/34.
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Sicard, Mathieu. "Modalités écologiques et évolutives des interactions entre les nématodes entomopathogènes Steinernema et leurs symbiotes bactériens Xenorhabdus." Montpellier 2, 2003. http://www.theses.fr/2003MON20193.
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Noujeim, Abi Nader Elise. "Biodiversité et biogéographie des nématodes entomopathogènes au Liban : étude phylogénique et valorisation des potentiels en lutte biologique." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20013/document.
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Les Nématodes Entomopathogènes (NEP) de la famille des Steinernematidae et Heterorhabditidae sont des parasites pour les insectes. Ils hébergent dans leur intestin un symbiote bactérien (genres Xenorhabdus et Photorhabdus) essentiel au succès parasitaire. Les NEP sont présents dans les sols des cinq continents de la planète. Leur diversité génétique et leurs propriétés biologiques constituent une intéressante ressource biologique. Grâce à leur entomotoxicité, les NEP sont de bons outils de lutte biologique en agriculture et en culture ornementale un peu partout dans le monde. La diversité et la biogéographie des NEP dans les cinq continents de la Terre (à l'exception de l'Antarctique) ont été étudiées partout dans le monde mais le Liban est parmi les rares pays du moyen orient où aucune prospection de ces nématodes n'a été réalisée alors que des NEP en Turquie, Syrie, Jordanie, Palestine et Egypte ont déjà été trouvés et caractérisés. L'objet de la thèse est de procéder à une étude biogéographique dans le but de connaître la diversité des NEP au Liban. L'enjeu scientifique est donc de combler un « vide » dans la connaissance de la répartition et de la biodiversité mondiale des NEP. Pour cela, un échantillonnage à l'échelle des étages de végétation est mené au Liban. Des échantillons de sol sont ainsi prélevés, mis en contact avec des larves de Galleria mellonella pour isoler les nématodes entomopathogènes et leurs symbiotes. Les nématodes et leurs symbiotes sont par la suite identifiés morphologiquement et moléculairement. Par la suite, une approche à l'échelle de l'habitat fait l'objet de cette thèse également pour étudier les interactions biotiques et abiotiques influençant la présence des nématodes entomopathogènes dans le sol. Les enjeux technologiques, exposés au second volet de la thèse, sont liés aux propriétés biologiques des nématodes et de leurs symbiotes afin de valoriser leur entomotoxicité en lutte biologique. Dans ce cadre, la sensibilité des Cephalcia tannourinensis, ravageur des cédraies au Liban, par rapport aux nématodes entomopathogènes est exploitée in vitro ; différentes espèces de nématodes entomopathogènes sont testées pour suivre leur cycle à l'intérieur des CephalciaEntomopathogenic nematodes (EPNs) are parasites of soil-dwelling insects that occur in natural and agricultural soils around the world. Thanks to their entomotoxicity, EPNs are good tools for biological control in agriculture almost everywhere in the world. They are ubiquitous, having been isolated from every inhabited continent (except Antartica) from a wide range of ecologically diverse soil habitats including cultivated fields, forests, grasslands, deserts, and even ocean beaches. Biogeographic assessments of EPNs in the Eastern Mediterranean basin have been conducted in several countries such as Turkey, Syria, Jordan, Israel, Palestine and Egypt. Lebanon is among the few countries of the Middle East for which no survey of EPNs has been done. The scientific stake is thus to fill a gap in our knowledge of EPNs distribution in the Mediterranean basin. Survey of EPNs was conducted in this framework to cover the different vegetation levels defined in Lebanon. Soil samples were removed placed in contact with Galleria mellonella to isolate entomopathogenic nematode and their symbiotic bacteria. EPNs and their bacteria were then identified morphologically and molecularly. On the other hand, despite the different national surveys conducted on EPNs distribution around the world, habitat preferences remain inadequately known for entomopathogenic nematodes. Therefore, a comprehensive understanding of their distribution and the various biotic and abiotic factors influencing their presence is also a second object of our work. Beside a technological approach related to the biological properties of the nematodes and their symbiotics: valorisation of the entomotoxicity in biological control will be part of the third shutter of the thesis. In this framework, the sensibility of cedar pests, Cephalcia tannourinensis against entomopathogenic nematodes is exploited in vitro; different EPNs species were tested to study their life cycle inside Cephalcia larvae
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Ferreira, Tiarin. "Characterisation of nematode symbiotic bacteria and the in vitro liquid culture of Heterorhabditis zealandica and Steinernema yirgalemense." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80294.
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Thesis (PhD)--Stellenbosch University, 2013.ENGLISH ABSTRACT: Entomopathogenic nematodes have the potential to be outstanding biocontrol agents against agricultural pest insects. Combined with their bacterial symbionts, these biocontrol agents have proven to be very effective against numerous pests. The nematodes belong to the families Steinernematidae and Heterorhabditidae, and are ideal to be used in, and integrated with, pest management systems. There is a dire need for new and innovative methods to control agricultural pests, as numerous pest insects have developed resistance against broad-spectrum insecticides. Together with the environmental impact of these insecticides and the safety aspect regarding humans and animals, the need to develop new technologies, including entomopathogenic nematodes for pest management, is high. In this study, the associated symbiotic bacteria of three entomopathogenic nematodes species were isolated, and the potential of two nematode species to be successfully mass cultured in liquid medium was evaluated. Regarding the symbiotic bacteria, results from the study showed that bacteria species from all three nematode species, Heterorhabditis noenieputensis, Steinernema khoisanae and Heterorhabditis zealandica, were novel. Heterorhabditis noenieputensis was isolated in the Mpumalanga province during a previous survey conducted in citrus orchards. The bacterium isolated from this nematode belongs to the genus Photorhabdus, and bear closest similarity (98.6%) to the type strain of P. luminescens subsp laumondii (TT01T). Photorhabdus luminescens subsp. noenieputensis subsp. nov., derives its name from the area where the nematode was sourced, namely the farm Springbokvlei, near the settlement Noenieput close to the Namibian border. Thus far, 85 Steinernema spp. have been described worldwide, including S. khoisanae which was isolated in the Western Cape province of South Africa. Four S. khoisanae strains, namely SF87, SF80, SF362 and 106-C, were used for characterisating the new bacteria from different localities in South Africa. Using the neighbor-joining method, all the strains were aligned with 97% homology to the 16S rRNA sequences of several Xenorhabdus- type strains, indicating that they belonged to the same genus. The multigene approach was used to distinguish between the Xenorhabdus spp. and partial recA, dnaN, gltX, gyrB and infB gene sequences of the various strains were analysed. The bacterium species was named Xenorhabdus khoisanae sp. nov. after the nematode from which it was isolated. The results showed that the third bacterium species, which was isolated from H. zealandica, was new. The sequence of the bacteria strain clustered with the type strains of P. temperata and P. asymbiotica, indicate that it belonged to the genus Photorhabdus. This is the first study to show that H. zealandica associates with a luminescent Photorhabdus species, rather than with the known non-luminescent P. temperata. The potential of H. zealandica and Steinernema yirgalemense mass culture in liquid was investigated. Results illustrated that H. zealandica and its P. luminescens symbiont can be successfully cultured in liquid. However, two generations occurred during the process time, instead of the desirable one-generation. The growth curve of the symbiotic bacteria during the process time was measured, in order to determine when the stationary phase was reached, with the results showing this to occur after 36 h. Therefore, the optimum amount of time required for inoculating the IJs and for aiding in maximum infective juvenile (IJ) recovery is 36 h for adding the nematodes post pre-culturing of the bacteria. Future research goals should be to increase the percentage recovery in liquid culture, which would increase the number of nematodes produced per ml, which would, therefore, reduce the processing time significantly. The results from mass culturing the second nematode species, S. yirgalemense, indicated an asynchronous nematode development in the first generation. Growth curves were performed with the symbiotic bacteria that showed the exponential phase of Xenorhabdus started after 15 h, and that, after 42 h, the stationary phase was reached, with an average of 51 × 107 cfu·ml-1. Bioassays were performed to compare the virulence between in vitro- and in vivo-produced nematodes, with the results showing that the in vitro-produced nematodes were significantly less virulent than were the nematodes produced in vivo. The success obtained with the production of S. yirgalemense in liquid culture can serve as the first step in the optimising and upscaling of the commercial production of nematodes in industrial fermenters. The last aim of the current study was to determine when Xenorhabdus reached the stationary phase, when it is grown in a 20-L fermenter, as this would be the optimum time at which to add the IJs of S. yirgalemense. Such characteristics as the effect of stationary phase conditions on the bacterial cell density and on the DO2 rate in the fermenter were investigated. The results showed that the stationary phase of Xenorhabdus was reached after 36 h at 30˚C, which took 6 h less than did the same procedures followed with the Xenorhabdus sp. cultured in Erlenmeyer flasks on orbital shakers. This is the first step toward the liquid mass culturing of S. yirgalemense in industrial-size fermenters. Data from this study indicated the optimum amount of time that is required for adding nematodes to the bacterial culture in the fermenter, and for ensuring the optimum recovery of IJs, as well as a subsequent high yield of nematodes within a minimum processing time. This is the first report of its kind to investigate comprehensively the successful liquid culture of two South African entomopathogenic nematode species for the sole purpose of evaluating potential commercialisation. Results emanating from this study could be used as groundwork in future, in combination with similar research such as culturing nematodes intensively in large fermenters.
AFRIKAANSE OPSOMMING: Entomopatogeniese nematodes het die potensiaal om as doeltreffende biologiese beheeragente teen sleutelplaaginsekte gebruik te word. Elke nematood werk interaktief met ‘n spesifieke bakterium. Entomopatogeniese nematodes, behorende tot die families Steinernematidae en Heterorhabditidae, is ideale kandidate vir gebruik in ‘n geïntegreerde plaagbestuurprogram. Tans is daar ʼn behoefte vir nuwe metodes vir die beheer van plaaginsekte, omdat meeste insekte reeds weerstand opgebou het teen bestaande plaagdoders. As gevolg van die negatiewe impak van plaagdoders op die omgewing, asook kommer oor veiligheid vir die mens en diere, is die ontwikkeling en gebruik van alternatiewe plaagbeheermiddels noodsaaklik. In die eerste deel van die studie word drie nuwe bakterie spesies geïsoleer en beskryf. Resultate van hierdie studie het aangetoon dat die bakterië spesies vanuit die nematode spesies, Heterorhabditis noenieputensis, Steinernema khoisanae, en Heterorhabditis zealandica, tot dusver onbeskryf was. Eersgenoemde, H. noenieputensis, is afkomstig van ʼn sitrusboord in die Mpumalanga Provinsie. Die bakterie hieruit geïsoleer behoort tot die genus Photorhabdus en is biologies verwant (98.6%) aan P. luminescens subsp laumondii (TT01T). Die bakterie is benaam as Photorhabdus luminescens subsp. noenieputensis nov. en is na die nematood waaruit dit geïsoleer is vernoem. Tot dusver is wêreldwyd 82 spesies van Steinernema spp. beskryf, insluitende S. khoisanae van die Weskaap provinsie. Vier bakterie isolate is van S. khoisanae, SF87, SF80, SF362 en 106-C geïsoleer. Die buur-koppeling metode was gebruik om te bepaal dat hierdie bakterie isolate tot 97% ooreenstem met verskeie isolate van Xenorhabdus se 16S rRNA DNS volgordebepalings. Om tussen Xenorhabdus spp. te onderskei is ʼn multi-geen benadering gebruik deur gedeeltelike recA, dnaN, gltX, gyrB en infB DNS basispaar volgordebepalings van die verskeie isolate te bepaal. Hierdie bakterie isolaat is soortgelyk ook vernoem as, Xenorhabdus khoisanae sp. nov., na die nematood waaruit dit geïsoleer is. Die derde onbekende bakteriële spesie is uit H. zealandica geïsoleer. Die DNS basispaar volgordebepaling van die 16S geen van SF41 toon aan dat dit in dieselfde groep as P. temperata en P. asymbiotica val en sodoende aan die genus Photorhabdus behoort. Hierdie is die eerste studie met die bevinding dat H. zealandica ook met ʼn ander bakterie spesie geassosieer kan word buiten die normale P. temperata spesie. Die tweede deel van die studie gaan oor die teling van twee nematood spesies, H. zealandica en Steinernema yirgalemense, en hulle is geëvalueer vir hulle potensiaal om geteel te word in ʼn vloeibare medium. Die resultate het gewys dat H. zealandica met sy P. luminescens simbiont suksesvol in vloeistof aangeteel kan word, ten spyte van die feit dat daar twee generasies ontwikkel het, in plaas van die meer ideale enkel generasie. Die groeikurwe van die simbiotiese bakterie was gemonitor om te bepaal wanneer die stasionêre fase bereik word. Die resultate toon dat hierdie fase na 36 uur bereik was. Dus was die infektiewe nematode larwes eers na 36 uur tot die vloeibare medium waarin die bakterie geteel was bygevoeg. Navorsing in die toekoms moet dus gefokus wees om die persentasie herwinning van die infektiewe larwes te verhoog. Dit sal daartoe lei dat meer nematodes per ml geproduseer kan word en ook die prosesseringstyd van die nematodes verminder. ʼn Tweede nematode spesie, S. yirgalemense, was ook in vloeistof geteel. Hier het ʼn asinkroniese ontwikkeling in die eerste generasie plaasgevind wat problematies is. Groeikurwes is bepaal van die bakteriële simbiont en die resultate het gewys dat die groeifase van Xenorhabdus na 15 uur in aanvang geneem het en dat die stasionêre fase bereik was na 42 uur met ʼn gemiddelde van 51 × 107 selle·ml-1. Die virulensie van nematodes wat in vitro geteel is, is vergelyk met die virulensie van nematodes wat in vivo geteel is en die resultate het getoon dat die in vitro geteelde nematodes minder virulent was. Die teling van S. yirgalemense in vloeistof was oor die algemeen meer suksesvol as die teling van H. zealandica in dieselfde medium. Die doelwit van die laaste gedeelte van hierdie studie was om te bepaal wanneer Xenorhabdus die stasionêre fase bereik wanneer dit in ʼn 20-L fermenter gekweek word. Dit bepaal sodoende die optimale tyd wanneer die infektiewe larwes van S. yirgalemense bygevoeg behoort te word. Die uitwerking van die stasionêre fase op die bakteriële selle, asook die DO2-konsentrasie in die fermenter, was geëvalueer. Resultate het gewys dat die stasionêre fase van Xenorhabdus na 36 uur bereik was, wat 6 uur korter is as toe dit gekweek is in Erlenmeyer flesse. Hierdie studie is die eerste stap om die massa teling van S. yirgalemense in industriële fermenters suksesvol te bemeester. Die data wat verkry was, het aangedui wat die ideale tydsduur sal wees om die bakteriegetalle te vermeerder voordat die nematode bygevoeg word. Hierdie is die eerste studie wat die teling van twee Suid-Afrikaanse nematode spesies omvattend in vloeistof evalueer het. Die hoof doelwit is om die potensiaal van hierdie nematode spesies, met die oog op kommersiële gebruik, te meet. Die resultate van hierdie studie kan gekombineer word met toekomstige studies in hierdie spesifieke navorsingsveld.
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Huot, Louise. "Analyse moléculaire de la réponse immunitaire du lépidoptère Spodoptera frugiperda au complexe nématobactérien entomopathogène Steinernema carpocapsae-Xenorhabdus nematophila." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTG084.
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Les complexes nématobactériens (CNBs) entomopathogènes sont des associations naturelles symbiotiques et mutualistes entre des nématodes et des bactéries parasites d’insectes. Dans le cadre de ces associations, le nématode sert tout d’abord de vecteur à la bactérie, qu’il transporte dans le sol et libère à l’intérieur du corps des insectes. La bactérie augmente quant à elle la virulence du CNB, puis sert de ressource nutritive au nématode dans le cadavre de l’insecte. En raison de l’originalité de ces pathogènes et de leur potentiel en lutte biologique contre les insectes ravageurs de cultures, les modalités de leurs interactions avec les insectes ont fait l’objet de nombreuses études. Ces travaux ont permis d’établir que la capacité d’un CNB à infecter et à tuer un hôte dépend d’une combinaison de facteurs écologiques et comportementaux, ainsi que du dialogue s’établissant entre chaque membre du CNB et le système immunitaire de l’insecte. Les insectes possèdent un système immunitaire élaboré et capable de répondre de façon adaptée à une grande diversité d’agents infectieux. Ce système est basé sur trois composantes principales : des barrières épithéliales, des réponses cellulaires et humorales locales et des réponses humorales systémiques. Bien qu’un grand nombre de stratégies et de facteurs permettant aux nématodes et aux bactéries de contrer ces trois composantes ait été identifié au sein de différents modèles d’interaction CNB-insecte, l’étude du dialogue s’établissant entre chaque partenaire et le système immunitaire des hôtes souffre d’un déficit de connaissance des aspects signalétiques et moléculaires des réponses immunitaires que les insectes opposent à ces infections duales.L’objectif premier de cette thèse était de contribuer au développement de ces connaissances au travers d’une analyse transcriptionnelle détaillée et structurée des réponses immunitaires d’un modèle d’insecte lépidoptère, Spodoptera frugiperda, à l’un des CNBs les plus étudiés, l’association S. carpocapsae-X. nematophila. Dans le contexte scientifique actuel, ce travail était tout d’abord caractérisé par deux nouveautés méthodologiques : l’utilisation d’une approche transcriptomique sur tissus immuno-compétents pour identifier les gènes de l’immunité affectés par l’infection par le CNB, et l’utilisation d’une méthode d’infection par injection de la bactérie et du nématode pour discriminer les réponses immunitaires induites par chaque partenaire. Ce travail a permis d’obtenir une image très résolutive et structurée des réponses immunitaires de l’insecte qui servira de base de travail pour (i) la caractérisation fonctionnelle des interactions des gènes de l’immunité identifiés avec chaque partenaire du CNB et (ii) l’étude détaillée du dialogue moléculaire entre le système immunitaire de S. frugiperda et le CNB. Ce travail a également été marqué par la découverte de deux potentiels nouveaux clusters de gènes immunitaires, les GBHs et les UNKs, qui sont parmi les gènes les plus fortement induits lors de l’interaction tripartite. Nos analyses bioinformatiques et tests d’activité préliminaires suggèrent que les GBHs pourraient avoir été acquis par tranfert horizontal de gènes bactériens et que les UNKs pourraient résulter d’une co-évolution d’insectes de la famille des noctuelles avec des CNBs Steinernema-Xenorhabdus. Cette hypothèse ouvre de nouvelles pistes de recherches pour la compréhension des variations de sensibilité aux CNBs entomopathogènes au sein de la diversité des insectesEntomopathogenic nematobacterial complexes (NBCs) are natural symbiotic associations between nematodes and bacteria that are pathogenic for insects. In these associations, the bacterial partner uses the nematode as a vector, which transports it in the soil and releases it inside the insect’s body. The bacterium then increases the NBC’s virulence and is used as a food supply by the nematode partner in the insect’s dead body. Due to the originality of these dual pathogens and to their potential for biological control of insect crop pests, studies have been conducted on diverse aspects of their interactions with insects. These works have shown the ability of an NBC to infect and kill an insect depends on a combination of ecological and behavioral factors, as well as on the dialogue between the two partners of the NBC and the insect’s immune system. Insects possess an elaborate immune system which is able the respond by adapted ways to a huge diversity of infectious agents. This system relies on three main components: epithelial barriers, local cellular and humoral responses and systemic humoral responses. A large number of strategies and factors used by NBCs to counteract these three components have already been identified in several NBC-insect interaction models. However, the study of the dialogue between each NBC partner and the hosts’ immune systems is currently suffering from a lack of knowledge of the signaling and molecular aspects of the insects’ immune responses to these dual infections.The first goal of this thesis was to increase this knowledge through a detailed and structured transcriptional analysis of the immune responses of a lepidopteran model, Spodoptera frugiperda, to one of the most studied NBCs, the S. carpocapsae-X. nematophila association. In the current scientific context, this work was mainly characterized by two methodologic novelties: the use of a topologic approach for the transcriptomic analysis of the induced immune responses to the infection by the NBC, and the use of an infection by injection method for the discrimination between the nematode- and the bacterium-induced immune responses. This work allowed the observation of a structured and highly resolutive picture of the induced immune responses, which will be used as a working base for (i) the functional characterization of the interactions of identified immune genes with each partner of the NBC, and (ii) for the detailed analysis of the molecular dialogue between the immune system of S. frugiperda and the NBC. Finally, this work also allowed the identification of two potential new clusters of immune genes, the GBHs and the UNKs, which are among the most overexpressed genes during the tripartite interaction. Our preliminary bioinformatics analyses and activity tests suggest the GBHs could have been acquired by horizontal gene transfer from bacteria and the UNKs could result from a coevolution between noctuids and some Steinernema-Xenorhabdus NBCs. This hypothesis opens new research trails for the understanding of the NBC-sensitivity variations within insect diversity
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McMullen, John George II. "Comparative Phenotypic and Genomics Approaches Provide Insight into the Tripartite Symbiosis of Xenorhabdus bovienii with Steinernema Nematode and Lepidopteran Insect Hosts." Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/596124.
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Nematodes are highly diverse animals capable of interacting with almost every other form of life on Earth from general trophic interactions to intimate and persistent symbiotic associations. Much of their recognition originates from their various parasitic lifestyles. From an agricultural standpoint, plant parasitic nematodes are widely known for the destruction they can cause to crop plants, such as the case of the root-knot nematode Meloidogyne incognita, or livestock animals, like the Trichinella spiralis, which infects pigs and other animals. From a human health perspective, nematodes can cause many debilitating diseases, for example Wuchereria bancrofti, which is a causative agent of lymphatic filariasis or elephantiasis. However, not all parasitic nematodes have bad implications for human health. For instance, the diverse interactions of insect parasitic nematodes can be used to our benefit. Many of these species have been considered as biological control alternatives to different insect pests that wreak havoc on human, animal, and plant health. There still remain many questions surrounding their evolution, ecology, and physiological capabilities. Many of these taxa are hard to cultivate in the lab due to their complex and intimate lifestyles. Entomopathogenic nematodes (EPNs) are of great interest in agriculture because they vector insect pathogenic bacteria, which are capable of causing death to an insect host within 48 hours post-infection. Much of the molecular underpinnings in this system still remain to be discovered, from understanding the basic ability of these two organisms to associate with one another to genetically engineering more robust and host specific pathogens for application in the field. The focus of the research presented herein is on Steinernematidae nematodes and their bacterial symbionts. Specifically, it focused on the relationship between Xenorhabdus bovienii and its Steinernema hosts. Bioassays were designed to investigate insect virulence of X. bovienii alone in two Lepidoptera insect species with known differential susceptibility to Steinernema-Xenorhabdus pairs. A comparative genomic analysis was performed to compare different Xenorhabdus bovienii strains with observed variation in insect virulence. Results from this analysis demonstrated that virulent strains possess a type VI secretion system (T6SS) locus that is completely absent in strains with attenuated virulence. Bacterial competition assays between T6SS+ and T6SS- strains suggest this locus is involved in bacterial competition. Additionally, symbiont preference assays were carried out to investigate whether Steinernema hosts are able to discern between virulent and attenuated X. bovienii strains. Results from these assays revealed that Steinernema nematodes are able to distinguish between cognate and non-cognate X. bovienii symbionts, giving preference to virulent strains over those with attenuated virulence. Altogether these results provide further evidence that supports the notion that symbiont-switching events have occurred over the Steinernema-Xenorhabdus co-evolutionary history. Specifically, the competitive virulence of certain X. bovienii strains may have conferred them the ability to be selected by different Steinernema hosts, therefore contributing to the success of the nematode-bacterium partnership in being pathogenic to diverse insect hosts.
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MacKay, Sharon Elizabeth. "The infection dynamics and phase change of the entomopathogenic bacterium 'Xenohabdus bovienii' and the associated nematode hose 'Steinernema feltiae'." Thesis, University of Stirling, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403582.
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Alvarado, Orellana Andrea Inés. "Hábitos parasitarios y comportamiento de un aislamiento nativo del nematodo entomopatógeno Steinernema sp. en larvas de Galleria mellonella L." Tesis, Universidad de Chile, 2012. http://repositorio.uchile.cl/handle/2250/147794.
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Memoria para optar al título profesional de Ingeniero Agrónomo Mención: Sanidad VegetalEl estado infectivo (J3) de los nemátodos entomopatógenos (NE) del género Steinernema (Steinernematidae) es la única etapa de vida libre, responsable de localizar a un insecto huésped susceptible y penetrar en su interior a través de las aberturas naturales, dirigirse al hemocele y liberar su bacteria simbionte del género Xenorhabdus (Enterobacteriaceae), la que se multiplica y causa la muerte del insecto huésped en 48 h por septicemia. Para evaluar aspectos del comportamiento de un nemátodo nativo, se hicieron 3 ensayos de laboratorio. En el primero se evaluó el efecto de varias temperaturas (5, 10, 15, 20, 25 y 30ºC), en el segundo se evaluaron suspensiones ajustadas de 10, 20, 40, 80, 120 y 240 J3 y en el tercero se evaluó un sustrato con diferentes contenidos de agua para determinar la susceptibilidad de las larvas del último instar del insecto huésped polilla de la cera, Galleria mellonella L. Además se determinó su progenie (J3 emergidos por larva) y su eficacia de penetración (J3 que penetraron al insecto huésped). La larva fue altamente susceptible a la infección por estos nemátodos, con una mortalidad cercana al 100% a las 48 h en la mayoría de los tratamientos. A 20ºC se obtuvo la máxima emergencia, por lo que esta temperatura resultó ser óptima para la reproducción y desarrollo del aislamiento evaluado. La mortalidad fue afectada por efecto de la concentración. El número de nemátodos que entraron en el hospedero aumentó con la concentración de J3 inoculados. La infectividad del nemátodo fue mayor en un contenido de agua moderado del suelo, cercana a la capacidad de campo. Se concluye que el parasitismo, progenie y eficacia de penetración del aislamiento evaluado de Steinernema sp. son afectados por factores abióticos como la temperatura y el contenido de agua del suelo.
The infection status (J3) of the entomopathogenic nematodes (EPN) of the genus Steinernema (Steinernematidae) is the only free living stage, they are responsible for locating a susceptible insect host and penetrate inside through natural openings, moving toward the hemocoel and release their symbiotic bacteria of the genus Xenorhabdus (Enterobacteriaceae), which multiply and kill the insect host after about 48 hours by septicemia. In order to assess aspects of behavioral of a native nematode, three series of laboratory trials were conducted. In the first, several temperatures were evaluated (5, 10, 15, 20, 25, and 30°C). In the second, adjusted suspensions of 10, 20, 40, 80, 120 and 240 J3 were evaluated. In the third, a substrate was evaluated with various water contents to determine the susceptibility of last instar larvae of the insect host, the wax moth Galleria mellonella L. The nematode progeny (J3 emerged from each larva) and their penetration efficacy (J3 that penetrate into the insect host). The larva was highly susceptible to infection with these nematodes, with a mortality rate approaching 100% within 48 h in most treatments. Maximum emergency occurred at 20°C, so this temperature was optimal for the reproduction and development of the EPN isolate evaluated. Insect mortality was affected by EPN concentration. The number of nematodes that penetrated the host increased with the concentration of J3 inoculated. The infectivity of the nematode was greater in soil with moderate water content, near to the field capacity. In is concluted that parasitism, progeny and penetration efficiency of isolate evaluated of Steinernema sp. were affected by abiotic factors such as the temperature and the amount of water of soil.
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Gouge, D. H., K. A. Smith, C. Payne, L. L. Lee, Berkum J. R. Van, and T. J. Henneberry. "Suppression of Plant Parasitic Nematodes in Cotton Using the Antomopathogenic Nematode Steinernema Riobravis (Cabanillas, Poinar, and Raulston) (Rhabditida: Steinernematidae)." College of Agriculture, University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/211150.
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Cotton fields were treated with the entomopathogenic nematode, Steinernema riobravis, and Vydate® L for the control of plant parasitic nematodes. Short staple cotton grown near Coolidge, Arizona, was treated at a rate of 1 billion and 2 billion S. riobravis nematodes per acre, and 0.5 lb a.i. Vydate® L per acre. Untreated cotton received an application of water only. Treatments were applied through a subterranean drip system with 12 inch spaced outlets. Applications were made in the daily irrigation cycle of 0.33 inches of water, normal irrigation cycles followed Products were uniformly distributed over the treated fields. Entomopathogenic nematodes persisted throughout the 6 week experimental period at the 1 billion per acre rate. However, nematodes applied at 2 billion per acre rate disappeared rapidly. Populations of various plant parasitic nematode species were monitored subsequent to treatment application. Nematodes were extracted using a standard sugar flotation technique and counted in I ml slide samples. Both Meloidogyne incognita and Tylenchorhynchus spp. populations were reduced by S. riobravis applied at 1 billion per acre rate. Phytoparasitic nematodes were reduced following application of Vydate® L, but control was not sustained beyond one week.
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Alvarado, Orellana Andrea Inés. "Hábitos parasitarios y comportamiento de un aislamiento nativo del nemátodo entomopatógeno Steinernema sp. en larvas de Galleria mellonella L." Tesis, Universidad de Chile, 2012. http://repositorio.uchile.cl/handle/2250/116147.
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Memoria para optar al título profesional de
Ingeniero Agrónomo
Mención: Sanidad VegetalEl estado infectivo (J3) de los nemátodos entomopatógenos (NE) del género Steinernema (Steinernematidae) es la única etapa de vida libre, responsable de localizar a un insecto huésped susceptible y penetrar en su interior a través de las aberturas naturales, dirigirse al hemocele y liberar su bacteria simbionte del género Xenorhabdus (Enterobacteriaceae), la que se multiplica y causa la muerte del insecto huésped en 48 h por septicemia. Para evaluar aspectos del comportamiento de un nemátodo nativo, se hicieron 3 ensayos de laboratorio. En el primero se evaluó el efecto de varias temperaturas (5, 10, 15, 20, 25 y 30ºC), en el segundo se evaluaron suspensiones ajustadas de 10, 20, 40, 80, 120 y 240 J3 y en el tercero se evaluó un sustrato con diferentes contenidos de agua para determinar la susceptibilidad de las larvas del último instar del insecto huésped polilla de la cera, Galleria mellonella L. Además se determinó su progenie (J3 emergidos por larva) y su eficacia de penetración (J3 que penetraron al insecto huésped). La larva fue altamente susceptible a la infección por estos nemátodos, con una mortalidad cercana al 100% a las 48 h en la mayoría de los tratamientos. A 20ºC se obtuvo la máxima emergencia, por lo que esta temperatura resultó ser óptima para la reproducción y desarrollo del aislamiento evaluado. La mortalidad fue afectada por efecto de la concentración. El número de nemátodos que entraron en el hospedero aumentó con la concentración de J3 inoculados. La infectividad del nemátodo fue mayor en un contenido de agua moderado del suelo, cercana a la capacidad de campo. Se concluye que el parasitismo, progenie y eficacia de penetración del aislamiento evaluado de Steinernema sp. son afectados por factores abióticos como la temperatura y el contenido de agua del suelo.
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Hui, Elizabeth L. W. "The influence of insect larvae and seedling roots on the foraging behaviour of infective juveniles of Steinernema spp., Nematoda, rhabditida." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq37552.pdf.
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Costa, Júlio César Rocha. "Estudo da ecologia de infecção dos nematóides entomopatogênicos Heterorhabditis riobravus e Steinernema carpocapse (Rhabditida: Heterorhabditidae) em Alphitobius diaperinus (Coleoptera: Tenebrionidae)." Universidade Federal de Juiz de Fora (UFJF), 2006. https://repositorio.ufjf.br/jspui/handle/ufjf/2906.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Aphitobius diaperinus (Panzer), conhecido como o cascudinho ou "lesser mealworm" coloniza o substrato encontrado em granjas, criando-se em altas populações, causando problemas sanitários e econômicos. Eles afetam a saúde e a desempenho das aves, sendo também transmissores de agentes de doenças. Seu controle baseia-se em aplicações de inseticidas, que aumentam os custos de produção e são prejudiciais aos animais. Assim sendo, as infectividades de Heterohabditis riobravus e de Steinernema carpocapsae diante dos estádios de larva, pupa e 20 adulto deste inseto para a primeira espécie de nematóide citada, e de larva e adulto para a segunda espécie, foram avaliadas em laboratório, utilizando os seguintes tipos de substratos: cepilho + ração, papel de filtro e terra. O objetivo foi determinar o grau de virulência dos juvenis infectivos (J Is) destes nematóides em cada tratamento. Os resultados indicaram que tanto H. riobravus, quanto S. carpocapsae apresentam potencial para infectar todos os estádios de desenvolvimento da espécie A. diaperinus analisados; e que os J Is de S. carpocapsae mostraramse mais eficientes contra larvas e adultos de A. diaperinus, do que os J Is de H. riobravus, em todos os tipos de substratos testados. Como já observado em outro estudo, os estágios imaturos se mostraram mais susceptíveis aos nematóides do que os adultos. Quando comparou - se os tratamentos com as duas espécies de nematóides sobre indivíduos adultos no substrato cepilho + ração, ambiente natural da espécie a ser controlada, verificou - se que as DL50 e DL90 de J Is de S. carpocapsae, corresponderam respectivamente a apenas 54,18% da DL50 e a 40,34% da DL90, encontradas para o tratamento envolvendo o nematóide da espécie H. riobravus.
Aphitobius diaperinus (Panzer), known as cascudinho or "lesser mealworm" colonizes the substrate found at farms, developing itselves in high populations, causing sanitary and economical problems. They affect the health and performance of the birds, being also transmitters of diseases. Their control is based on the application of insecticides, which increase the production costs and are harmful to the animals. Therefore, the infectivity of Heterohabditis riobravus and of Steinernema carpocapsae in front the life stages of larvae, pupae and adult of 21 this insect - for the first mentioned species of nematode - and of larva and adult for the second species, were evaluated in laboratory, using the following types of substrate: small plane + ration, filter paper and earth. The objective was to determine the degree of virulence of the J Is of these nematodes in each treatment. The results indicated that so much H. riobravus, as well as S. carpocapsae presented potential to infect all of the life stages of development of the species A. diaperinus analyzed; and that the infective juvenile of S. carpocapsae were shown more efficient against larvae and adults of A. diaperinus, that the infective juvenile of H. riobravus, in all of the types of tested substrate. As already observed in another study, the immature life stages were shown to be more susceptible to the nematodes than the adult life stage. When we compared the treatments with the two species of adult individuals constituted by the nematodes in the substrate of small plane + ration, natural environment for the species to be controlled, we verified that DL50 and DL90 of J Is of S. carpocapsae, corresponded respectively only 54.18% of DL50 and to 40.34% of DL90, found for the treatment involving the nematode of the species H. riobravus.
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Garcia, Luiz Cláudio [UNESP]. "Avaliação de tecnologias de aplicação de nematóides entomopatogênicos visando o controle de Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) na cultura do milho." Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/105413.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
A tecnologia de aplicação desenvolvida para produtos químicos tem sido utilizada para organismos entomopatogênicos sem o estudo prévio das necessidades de adaptações que visem à manutenção da viabilidade desses agentes de controle biológico. Assim, o objetivo dessa pesquisa foi avaliar o efeito de diferentes tecnologias de aplicação sobre a concentração, viabilidade e eficácia dos juvenis infectantes dos nematóides Heterorhabditis indica e Steinernema sp. no controle da lagartas-do-cartucho (Spodoptera frugiperda), em terceiro instar, na cultura do milho. Testaram-se as dosagens de zero a 400 juvenis infectantes em placa de Petri para controle da lagarta-do-cartucho. As tecnologias de aplicação dos entomopatógenos, em ambiente controlado, abrangeram as pulverizações com pontas hidráulicas e centrífuga, com e sem fornecimento de carga elétrica à calda. Na pulverização do Steinernema sp. em plantas de milho sob condição ambiental controlada, com e sem emprego de tensoativo e lâmina de água, as dosagens variaram entre zero e 288 milhões.ha-1. Conclui-se que para matar as lagartas em terceiro ínstar de S. frugiperda em laboratório foram necessários 280 juvenis infectantes de Steinernema sp. Pode-se pulverizar os entomopatógenos, sem que haja perda significativa na concentração e viabilidade desses organismos, com equipamentos que forneçam carga elétrica à calda, ponta centrífuga e pontas hidráulicas, exceto àquelas que requerem elementos filtrantes com malha igual a 100. Os tensoativos Break-Thru®, Extravon® e Iharaguen- S® não afetaram a viabilidade dos entomopatógenos. A pulverização em plantas de milho (V6) com até 288 milhões de juvenis infectantes de Steinernema sp. por hectare, diluídos em volume de calda de até 800 L.ha-1 com 0,01 % de tensoativo ou nesse volume seguido de exposição à chuva artificial (lâmina de água de 6 mm) não proporcionaram adequado controle da praga.
Spraying technologies has been developed to work with agrochemicals, but it has been utilized with entomopatogenic organisms without a prior study of adaptation that will help maintain the viability of the biological control agents. In this way, the objective of this research was to evaluate the effect of different spraying technologies on the concentration, viability and efficiency of the infective juveniles of Heterorhabditis indica and Steinernema sp. nematodes to control fall armyworm (Spodotera frugiperda) at the third instar on corn plants. Rates between zero and 400 infective juveniles were tested in a Petri dish against fall armyworm. The study to evaluation spraying technologies stable environment, involved hydraulic nozzles and rotary spray nozzles with and without electrical charge added to the spraying mix. The dosages of Steinernema sp. sprayed on corn plants in controlled environment with or without adjuvant agent and water blade, varied of zero at 288 millions ha-1. For killing 100% the fall armyworm in laboratory, it was necessary 280 juvenile infectants of Steinernema sp. It is possible to spray entomopatogenic organisms without an significative loss in the concentration and viability of these organisms, with equipment that produces electrical charges to the spraying mix, and with those using hydraulic and rotary nozzles tips, but without mash 100 filtrating elements. Tensoactive agents Break-Thru®, Extravon® and Iharaguen-S® did not affect the viability of the entomopatogens. Spraying corn plants with up to 288 millions of juvenile infectants of Steinernema sp. per hectare, diluted in the spraying mix up to 800 L.ha-1, with 0,01% of tensoactive agent or in this volume followed by artificial rain (water blade of 6 mm), was not enough to control the infestation.
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Aalten, Patricia Mischa. "Antagonistic effects of entomopathogenic nematodes (Steinernema spp.) and fluorescent Pseudomonas rhizobacteria on the plant-parasitic nematodes Radopholus similis and Meloidogyne spp." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245334.
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Vidal, Retes Giselle Carolina. "Efecto de la textura del suelo sobre la capacidad de desplazamiento e infectividad en laboratorio de Steinernema sp. aislameinto Licán Ray." Tesis, Universidad de Chile, 2014. http://repositorio.uchile.cl/handle/2250/148656.
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Tesis para optar al Título Profesional de Ingeniero Agrónomo y Grado de Magíster en Ciencias Agropecuarias, Mención Sanidad VegetalLos nemátodos entomopatógenos (NEP) son considerados como una solución efectiva en el control de plagas del suelo, ya que son capaces de desplazarse en este hábitat para encontrar y parasitar al insecto hospedero. En este estudio se determinó la capacidad infectiva de Steinernema sp. aislamiento Licán Ray, en suelos de textura arenosa, franca y arcillosa, bajo condiciones de laboratorio. Primero se determinó la concentración adecuada en la arena experimental, por lo que se aplicaron concentraciones de 10, 50 y 100 JI cm-2. Posteriormente se midió el desplazamiento de los NEP, tanto vertical como horizontal, en arenas experimentales de 30/50/70 y 10/20/30/40 cm, respectivamente, utilizando como hospedero larvas de Galleria mellonella (L.). En los tres ensayos se midió la mortalidad al día 3, 6 y 9 después de la aplicación de los NEP. Todas las concentraciones de NEP provocaron 100% de mortalidad en todos los suelos, excepto en suelo arcilloso, donde se observó menor eficacia al utilizar la menor concentración. La velocidad de infección fue mayor cuando se aplicaron 50 y 100 JI cm-2 en las tres texturas. La capacidad de los NEP de desplazarse verticalmente e infectar al hospedero a 30 cm fue de 100% en todos los suelos, tardando más horas en infectar larvas en suelo arenoso. A 50 y 70 cm la mortalidad disminuyó, manteniendo el suelo franco la mayor eficacia. Al desplazarse horizontalmente, se observó diferencias a partir de los 30 cm en todos los suelos, siendo el NEP más eficiente en suelo franco y menos eficiente en suelo arenoso. Los resultados del presente estudio sugieren que Steinernema sp. tiene la capacidad de desplazarse tanto vertical como horizontalmente, pero su eficiencia en atacar al hospedero depende de la textura del suelo en que se encuentren.
Entomopathogenic nematodes (EPN) are considered an effective solution for the control of soil pests due to their capacity of moving in this habitat to find and parasitize the insect host. This study evaluated the infectivity of Steinernema sp. strain Licán Ray in sandy, loam and clay textured soils, under laboratory conditions. Firstly, concentrations of 10, 50 and 100 JI cm-2 were evaluated to establish the appropriate concentration of EPN in the experimental sand. Second, the displacement capacity of the EPN both vertically and horizontally was evaluated in experimental arenas at 30/50/70 and 10/20/30/40 cm, respectively, using Galleria mellonella (L.) larvae as host. In all three trials host mortality was evaluated at day 3, 6 and 9 after application of EPN. The results show that all EPN concentrations used caused 100% mortality in all soils, except for clay soil, where the efficacy decreased with the lowest concentration. The velocity of infection was highest with 50 to 100 cm-2 JI in all soil textures. The EPN capacity of vertically displacement and infection of the host at 30 cm was 100% in all textured soils, taking longer to infect larvae in sandy soil. At 50 and 70 cm mortality decreased, showing the loam soil the highest efficacy. When moving horizontally, differences were observed from 30 cm up in all textured soils, being EPN most efficient in loam and least efficient in sandy soil. These results suggest that Steinernema sp. has the capacity to displace in the soil, both horizontally and vertically, but their efficiency in attacking the host depends on the texture of the soil.
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Núñez, Salinas Tamara Marión. "Eficacia de aislamientos nativos de nemátodos entomopatógenos del género steinernema y el piretroide Lambda-Cihalotrina en el control de Plutella xylostella (L.)." Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/153139.
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Memoria para optar al título Profesional de Ingeniero AgrónomoLa polilla dorso de diamante o polilla del repollo, Plutella xylostella (L.) (Lepidoptera: Plutellidae), es una de las plagas más importante de los cultivos de brásicas a nivel mundial. La estrategia de control más utilizada ha sido el uso de insecticidas de síntesis química como piretroides, carbamatos, organofosforados y reguladores de crecimiento, sin embargo, se ha comprobado su resistencia a numerosos insecticidas, por lo cual éstos ya no son una opción viable en muchas partes del mundo. Como una alternativa para su de control, se evalúo la susceptibilidad del segundo (L2) y cuarto (L4) estado larval de P. xylostella a los nemátodos entomopatógenos (NEP) nativos Steinernema sp., aislamientos Licán Ray, Chillán 3 y Chillán 4, y se compararon con la mortalidad causada por el insecticida piretroide Lambda-cihalotrina, en condiciones de laboratorio. Para cada aislamiento se evaluaron cuatro concentraciones de juveniles infectivos (J3) (0, 100, 300, 600 J3/mL) y una dosis de insecticida a una concentración de 0,1 mL/500 cm3, incluyéndose también un tratamiento control con 1 mL de agua. Después de la aplicación se evaluó la mortalidad de las larvas cada 24 horas. En general, en los tres asilamientos y el insecticida se observó muerte de larvas de P. xylostella en ambos estadíos larvarios, aunque los únicos tratamientos que presentaron diferencias estadísticamente significativas fueron el aislamiento Chillán 4, en la concentración de 600 J3/mL aplicadas a larvas L4, y el insecticida aplicado a larvas L2.
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Miranda, Victoria Alicia. "An Assessment of the Effects of Insect Host Condition on Entomopathogenic Nematodes and Their Symbiotic Bacteria." Thesis, The University of Arizona, 2010. http://hdl.handle.net/10150/146124.
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This study investigated a system comprised of entomopathogenic nematodes (EPN) (Steinernematidae and Heterorhabditidae), their symbiotic bacteria (Xenorhabdus, Photorhabdus) and an insect host, M. sexta. The focus of this investigation was to examine the effects insect host condition on the nematode-bacterium mutualistic partnership as a whole. The EPN used in the study had varying host-searching strategies: an ambusher, Steinernema carpocapsae, and a cruiser, Heterorhabditis sonorensis. Insect host age and diet were evaluated as factors that affect insect host condition. Wandering 5th instar M. sexta were much less susceptible to EPN infection compared to non-wandering 5th instar larvae, regardless of EPN species. Insect host diet had a significant impact on H. sonorensis susceptibility to EPN infection, and a non-significant trend was observed for S. carpocapsae. EPN and bacterial symbiont fitness were unaffected by insect host condition. This is the first record of the effect of insect host condition on both EPN and their symbiotic bacteria.
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Edgington, Steven. "The diversity and distribution of entomopathogenic nematodes in Chile with descriptions of two new species of Steinernema and biological profiling of S. australe." Thesis, University of Reading, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.553089.
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This is a study on the diversity of entomopathogenic nematodes (EPN) in Chile and the bionomics of a new EPN species, Steinernema australe. Surveys for EPN were carried out in six regions of Chile, representing some of the principal habitats of the country and including desert, sub-polar, montane and rainforest habitats, by collecting approximately 1400 soil samples. Live-baiting of the samples revealed 101 isolates, 94 of which were Steinernema and seven were Heterorhabditis. Morphological and molecular characterisation revealed one species of Heterorhabditis, designated as Heterorhabditis sp. 1 and three species of Steinernema, viz., S. feltiae and two previously undescribed species, S. australe and S. unicornum. Heterorhabditis sp. 1 was only found in the northern half of the country, the majority of Steinernema were found in the southern half. The most southerly survey, Patagonia and Tierra del Fuego, had the highest proportion of positive soil samples at 18.3%, made up of S. feltiae and S. unicornum; surveys in the Atacama Desert had the lowest return (1-2%), consisting only of Heterorhabditis sp. 1. There were indications of molecular and geographical intraspecific variation in S. feltiae and S. unicornum. The incidence of the four species and a summary of habitat characteristics are provided, as well as taxonomic descriptions of S. australe, S. unicornum and Heterorhabditis sp. 1. Profiling of S. australe revealed a fast life- cycle, with new infective juveniles (IJ) observed after 6 days at 20°C and significant infection at cool, humid conditions. Five days at ea -1°C had no effect on IJ survival, but subsequent infectivity was reduced, a possible chilling-injury. Steinernema australe infected a wide range of insect pests, appearing most effective against Lepidoptera. No nictating or jumping behaviour was observed. Xenorhabdus sp. and Paenibacillus sp. of bacteria were recovered from S. australe.
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Elawad, Sami A. "Studies on the taxonomy and the biology of a newly isolated species of Steinernema (Nematoda: Steinernematidae) from the tropics and its associated bacteria." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394486.
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Walter, Ndonkeu Tita. "Effect of the axenic nematode «Steinernema carpocapsae» on the immune responses of two lepidopteran larvae, «Galleria mellonella» (F. Pyralidae) and «Malacosoma disstria» (F. Lasiocampidae)." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32289.
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Live adult and juvenile entomopathogenic as opposed to freeze-killed Steinernema carpocapsae DD136 (P. Nematoda) did not have adhering haemocytes of lepidopteran insect larvae of Galleria mellonella or Malacosoma disstria in vitro or in vivo. Haemocyte accumulation on dead nematodes was associated with cuticular activation of host phenoloxidase. Live nematodes and their exudates did not activate the enzyme. Live-nematode exudate but not dead-nematode exudate inhibited granular cell and some plasmatocyte adhesion to slides, increased granular cell but not plasmatocyte dissociation from preformed haemocyte monolayers and in vivo elevated total haemocyte counts while impairing bacterial removal from the haemolymph. Immunosuppressant activity by third stage juvenile nematodes may represent the release of non-cuticular inhibitors. Initial characterization of the immunosuppressant properties revealed the suppressant(s) were weakly hydrophobic, were not affected by repeated freeze-thawing but most were destroyed at 65oC. A residual heat-stable suppressant remained in the exudate, attributed to lipopolysaccharides. Exudate with a cocktail of protease inhibitors partially increased haemocyte adhesion with a small decline in total protein occurring indicating that non-enzymic proteins are also involved. A decrease in exudate total protein but not immunosuppression in exudate with trypsin and chymotrypsin-conjugated agarose beads indicated the presence of non-suppressant trypsin and chymotrypsin sensitive proteins. Correlation analysis between enzyme activities and level of adhering haemocytes implied several enzyme types including trypsin and chymotrypsin may participate in immunosuppLes entomopathogénes vivants juvéniles et adultes comparément aux Steinernema carpocapsae DD136 (P. Nématodes) tués par congélation, ne contenaient pas d'hemocytes adhérent provenant de larves d'insectes lépidoptères de Galleria mellonella ou de Malacosoma disstria in vitro ou in vivo. L'accumulation des hemocytes sur les nématodes morts était associée à la stimulation de la cuticule de la phenoloxidase. Les nématodes vivants et leurs exsudats n'avaient point stimulé l'enzyme. L'exsudat de nématodes vivants avait inhibé des cellules granuleuses et quelques plasmocytes adhérents aux larme, cependant l'exsudat de nématodes morts n'avait pas inhibé ces substances. L'exsudat de nématodes vivants avait aussi provoqué une quantité élevée de cellules granuleuses mais pas de division des plasmocytes provenant de couches mono moléculaires des hemocytes préformés, aussi in vivo il amplifiait le nombre total des hemocytes tout en ralentissant le retrait des bactéries de l'hémolymphe. L'activation des immunosuppresseurs par les nématodes juvéniles de la 3eme phase pourrait représenter le dégagement d'inhibiteurs non cuticulaire. La première caractéristique des immunosuppresseurs indiquait que les suppressants avait une faible hydrophobicité et ils n'étaient pas touchés par l'alternance répétée de la température, mais plusieurs d'entres eux étaient détruit sous une température de 65˚ C. Un supprésant résiduel thermostable est resté dans l'exsudat ceci étant le résultat des lipopolysaccharides. Un exsudat accompagné d'un mélange d'inhibiteurs de protéase avait augmenté l'adhérence des hemocytes avec une chute négligeable du totale de protéines$
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Burgos, Medina Eliana Aurora. "Efecto del ataque de nemátodos entomopatógenos nativos del género Steinernema sobre el gusado cortador de la papa (Agrotis bilitura Guenée) en condiciones de laboratorio." Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/152704.
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Memoria para optar al título profesional de Ingeniera AgrónomaAl desarrollarse en el suelo, las larvas de Agrotis bilitura (Lepidoptera: Noctuidae) se alimentan tanto de plántulas como de las partes subterráneas de plantas en cultivos hortícolas. Los estadíos L3-L6 son los más dañinos, provocando pérdidas de hasta el 100% en ataques severos. El control de esta plaga con insecticidas es ineficiente, debido a los refugios que ofrece el suelo. En este contexto, los nematodos entomopatógenos (NEP) pueden ser una alternativa de gran valor en el control de ésta y otros insectos plaga que utilizan este hábitat, por su habilidad de moverse activamente en el perfil del suelo en busca de hospederos. Los NEP del género Steinernema (Steinernematidae) cuentan con un estado infectivo (IJ), el que ingresa al cuerpo del hospedero por heridas o aberturas naturales, liberando en su interior una bacteria simbionte del género Xenorhabdus (Enterobacteriaceae), la cual provoca la muerte del insecto por septicemia en un período de 24 a 48 horas.
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Garcia, Luiz Cláudio 1971. "Avaliação de tecnologias de aplicação de nematóides entomopatogênicos visando o controle de Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) na cultura do milho /." Botucatu, [s.n.], 2006. http://hdl.handle.net/11449/105413.
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Orientador: Carlos Gilberto RaetanoBanca: Wilson Badiali Crocomo
Banca: Antonio Batista Filho
Banca: Luis Garrigós Leite
Banca: Hamilton Humberto Ramos
Resumo: A tecnologia de aplicação desenvolvida para produtos químicos tem sido utilizada para organismos entomopatogênicos sem o estudo prévio das necessidades de adaptações que visem à manutenção da viabilidade desses agentes de controle biológico. Assim, o objetivo dessa pesquisa foi avaliar o efeito de diferentes tecnologias de aplicação sobre a concentração, viabilidade e eficácia dos juvenis infectantes dos nematóides Heterorhabditis indica e Steinernema sp. no controle da lagartas-do-cartucho (Spodoptera frugiperda), em terceiro instar, na cultura do milho. Testaram-se as dosagens de zero a 400 juvenis infectantes em placa de Petri para controle da lagarta-do-cartucho. As tecnologias de aplicação dos entomopatógenos, em ambiente controlado, abrangeram as pulverizações com pontas hidráulicas e centrífuga, com e sem fornecimento de carga elétrica à calda. Na pulverização do Steinernema sp. em plantas de milho sob condição ambiental controlada, com e sem emprego de tensoativo e lâmina de água, as dosagens variaram entre zero e 288 milhões.ha-1. Conclui-se que para matar as lagartas em terceiro ínstar de S. frugiperda em laboratório foram necessários 280 juvenis infectantes de Steinernema sp. Pode-se pulverizar os entomopatógenos, sem que haja perda significativa na concentração e viabilidade desses organismos, com equipamentos que forneçam carga elétrica à calda, ponta centrífuga e pontas hidráulicas, exceto àquelas que requerem elementos filtrantes com malha igual a 100. Os tensoativos Break-Thru®, Extravon® e Iharaguen- S® não afetaram a viabilidade dos entomopatógenos. A pulverização em plantas de milho (V6) com até 288 milhões de juvenis infectantes de Steinernema sp. por hectare, diluídos em volume de calda de até 800 L.ha-1 com 0,01 % de tensoativo ou nesse volume seguido de exposição à chuva artificial (lâmina de água de 6 mm) não proporcionaram adequado controle da praga.
Abstract: Spraying technologies has been developed to work with agrochemicals, but it has been utilized with entomopatogenic organisms without a prior study of adaptation that will help maintain the viability of the biological control agents. In this way, the objective of this research was to evaluate the effect of different spraying technologies on the concentration, viability and efficiency of the infective juveniles of Heterorhabditis indica and Steinernema sp. nematodes to control fall armyworm (Spodotera frugiperda) at the third instar on corn plants. Rates between zero and 400 infective juveniles were tested in a Petri dish against fall armyworm. The study to evaluation spraying technologies stable environment, involved hydraulic nozzles and rotary spray nozzles with and without electrical charge added to the spraying mix. The dosages of Steinernema sp. sprayed on corn plants in controlled environment with or without adjuvant agent and water blade, varied of zero at 288 millions ha-1. For killing 100% the fall armyworm in laboratory, it was necessary 280 juvenile infectants of Steinernema sp. It is possible to spray entomopatogenic organisms without an significative loss in the concentration and viability of these organisms, with equipment that produces electrical charges to the spraying mix, and with those using hydraulic and rotary nozzles tips, but without mash 100 filtrating elements. Tensoactive agents Break-Thru®, Extravon® and Iharaguen-S® did not affect the viability of the entomopatogens. Spraying corn plants with up to 288 millions of juvenile infectants of Steinernema sp. per hectare, diluted in the spraying mix up to 800 L.ha-1, with 0,01% of tensoactive agent or in this volume followed by artificial rain (water blade of 6 mm), was not enough to control the infestation.
Doutor
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Quezada, Cepeda María de los Ángeles. "Capacidad de diferentes especies hortícolas de atraer nemátodos entomopatógenos del género Steinernema al ser atacadas por el gusano cortador de la papa (Agrotis bilitura Guenée)." Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/153140.
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Memoria para optar al título profesional de Ingeniero AgrónomoVarios estudios señalan que las plantas han desarrollado un mecanismo de defensa llamado “respuesta guardaespaldas”, la cual se activa cuando son atacadas por algún insecto herbívoro, liberando compuestos volátiles y atrayendo a enemigos naturales, entre los que destacan los nematodos entomopatógenos (NEP), como defensa indirecta al ataque. Se ha demostrado que la respuesta guardaespaldas actúa de forma específica en el sistema planta-plaga-enemigo natural. Este estudio comparó el nivel de atracción de 6 especies vegetales, cuando son atacadas por el gusano cortador de la papa Agrotis bilitura Guenée (Lepidoptera: Noctuidae), hacia el NEP Steinernema sp. aislamiento Licán Ray en condiciones de laboratorio. Para ello, las 6 especies vegetales fueron comparadas en grupos de a 3: Betarraga, repollo y trébol rosado en el grupo 1 y lechuga, acelga y tomate en el grupo 2. Para esto, se utilizó un olfactómetro de PVC de seis brazos para cada grupo, estructura compuesta por una maceta central a la cual están conectados de manera equidistante, 6 brazos de igual longitud. Además, cada brazo está conectado a una maceta más pequeña en su extremo distal por medio de un tubo conector que posee una malla de 75 μm para colectar los nemátodos. Esta estructura se encontraba llena de suelo franco a capacidad de campo, tratado con calor húmedo para eliminar la presencia de otros organismos. Se trasplantaron 4 plantas con 4-6 hojas de cada especie a comparar, en las macetas distales de forma alternada en el olfactómetro, dejando una maceta sin plantas entre cada tratamiento como control. Se colocaron dos larvas de A. bilitura en estadío L6 en cada maceta, para que se alimentara libremente de las plantas. Al cabo de tres días, se aplicó 3mL con 2000 J3 del NEP aprox. en la maceta central. 48 horas después, el suelo contenido en el tubo conector con la malla de 75 μm se procesó con el método de tamizado, contabilizando los nematodos colectados en una lupa a 50X. Los resultados arrojaron que, en términos relativos, el repollo fue el más atractivo para los NEP y la lechuga, la menos atractiva. En un segundo experimento, se colectó el agua de riego que se utilizó para plantas de repollo atacadas por A. bilitura, y al igual que en la descripción anterior, se utilizó un olfactómetro para comparar la atracción de repollos atacados por A. bilitura, lechugas atacadas por A. bilitura y lechuga regada con el agua colectada desde macetas con repollo. En este caso, no hubo diferencias significativas entre el repollo y la lechuga atacadas por el herbívoro. La lechuga regada con exudados de repollo mostró un menor nivel de atracción hacia el NEP. Del experimento 1, se infiere que el repollo, cuando es atacado por A. bilitura, libera compuestos volátiles que son más atractivos para el NEP frente a las otras especies vegetales estudiadas. Con respecto al experimento 2, se deduce que podría utilizarse un método más preciso para colectar exudados y que disminuya la probabilidad de difusión de activos para evaluar este efecto.
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田邊, 博司. "Steinernema属昆虫病原性線虫のカシノナガキクイムシに対する殺虫活性と宿主探索行動." 京都大学, 2012. http://hdl.handle.net/2433/157689.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第16898号
農博第1914号
新制||農||997(附属図書館)
学位論文||H24||N4659(農学部図書室)
29573
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 二井 一禎, 教授 舟川 晋也, 教授 佐久間 正幸
学位規則第4条第1項該当
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Cardoso, Ricardo Nunes. "Efeito do nematóide entomopatogênico Steinernema glaseri (Steiner, 1929) (Rhabditida: Steinernematidae) isolado santa rosa sobre os parâmetros biológicos de ninfas ingurgitadas de Amblyomma cajennense (Fabrícius, 1787) (Acari: Ixodidae)." Universidade Federal de Juiz de Fora (UFJF), 2007. https://repositorio.ufjf.br/jspui/handle/ufjf/2998.
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Amblyomma cajennense (Fabrícius, 1787) (Acari: Ixodidade) é um ectoparasito típico de eqüídeos, amplamente distribuído nas Américas do Sul e Central. O uso indiscriminado dos carrapaticidas tem levado as populações destes artrópodes a um grave quadro de resistência aos produtos fitossanitários. Além disso, o uso exclusivo de carrapaticida é pouco viável a longo prazo e em termos econômicos tornando-se necessário o emprego de métodos alternativos de controle. Os nematóides entomopatogênicos tem sido apontados como agentes promissores no controle de carrapatos, entretanto como é pequeno o número de estudos a esse respeito objetivou-se avaliar o potencial de Steinernema glaseri (Steiner, 1929) isolado Santa Rosa como agente de controle biológico do carrapato Amblyomma cajennense. O experimento foi realizado no Laboratório de Parasitologia, Embrapa Gado de Leite, Juiz de Fora – MG, no período de outubro de 2005 e janeiro de 2006. Avaliou-se o potencial de S. glaseri nas concentrações de 0, 156, 325, 675, 1250, 2500, 5000 e 10000 juvenis infectantes (JI) por unidade experimental (UE). Cada um desses tratamentos foi composto por 10 unidades experimentais que foram montadas com placas de Petri contendo areia autoclavada, 4ml de água destilada e 10 ninfas, num total de 100 espécimes por tratamento. As placas de Petri foram fechadas com parafilme e mantidas em estufa climatizada do tipo B.O.D (27±1ºC e U.R>80%) por 72 horas. Após este período as ninfas ingurgitadas de A. cajennense foram lavadas com água destilada e transferidas para placas de Petri limpas observadas a cada 24±1 hora durante 20 dias, a fim de se observar as alterações nos parâmetros biológicos, tais como: Período de ecdise (PE), Período de pré-ecdise (PPE), Percentual de ecdise (%Ec) e Período de muda (PM). Cada parâmetro foi analisado em relação aos adultos, englobando machos e fêmeas e também para cada um dos sexos isoladamente por unidade experimental. Para x iii análise dos dados foi utilizado o Software Graphpad Instat Versão 2.05 com Análise de Variância, Teste de Tukey-Kramer, Kruskal-Wallis e Dunn’s (p 0.05). No tratamento com 5000 JI/UE ocorreu redução significativa no PPE total, assim como PM, em relação ao controle e considerando-se apenas os machos, o PM também sofreu redução significativa. No tratamento com 10000 JI/UE houve um aumento significativo do PPE total e o PE total foi reduzido significativamente neste tratamento, em relação ao controle. O período de ecdise dos machos apresentou um aumento significativo em quatro dos oito tratamentos (tratamentos com 156, 612, 2500 e 5000 JI). A mortalidade, assim como a redução do percentual de ecdise só foi significativa no tratamento com 10000 JI /UE. Mesmo sem abertura genital nas ninfas de A. cajennense, S. glaseri foi capaz de exercer ação deletéria em concentrações superiores a 5000 JI /UE. As doses de 5000 e 10000 JI /UE foram deletérias a determinados processos da fase não parasitária de A. cajennense. Entretanto novos estudos são necessários, ainda in vitro, com doses superiores a 10000 JI /EU, a fim de se confirmar o potencial entomopatogênico de A. cajennense sobre populações de S. glaseri.
Amblyomma cajennense (Fabrícius, 1787) (Acari: Ixodidade) is an ectoparasitic kind of horse, widely distributed in south and central America. The indiscriminate use of acaricidal has taken this animals population to a critical resistence situation to drugs and the exclusive use of acaricidal is just viable in pratical and economical terms became necessary the job of alternative control method. The nematodes entomopathogenic has bem indicated as sucessiful agents to control ticks, however is short the number of the studies about that, the target is analyse the potential os Steinernema glaseri strain Santa Rosa as biological agent control of A. cajennense. The experiment was made in the EMBRAPA GADO DE LEITE, Parasitology Laboratory – Juiz de Fora (MG), between october of 2005 and january of 2006. Has ben tested differents concentrations of S. glaseri (0, 156, 325, 650, 1250, 2500, 5000 e 10000 infectives juveniles (IJ) per tested unity (UT). Each one of this treatment was composed per 10 tested unitys crated with Petri dish sterilized, 4 ml of destil water and 10 nynphs in na total of 100 types for treatament. The Petri dish was closed with parafil and keeped in a humid chamber kind of BOD (27±1ºC and RH>80%) per 72 hours. After that period the engorged nynphs of A. cajennense was washed with destil water and removed to a Petri dish without sand or IJ and observed by each 24±1 hour during 20 days, with the objetive to observe wich alterations in a parametres biological such as: ecdysis period (EP), pre-ecdysis period (PEP), ecdysis percentual (%Ec), and mouthing period (MP). Each parametres was analysed about adults connections, comprising male and female ande for each one of the sex separating by tested unitys as will. The statistic data treatment was maked with Variance Analyse, Tukey- Kramer Test, Kruskal-Wallis and Dunn’s (p 0.05) On the treatment with 5000 IJ/UT happens the significant reduction of PEP totally, such as MP, in connections with control and xv considerating only the males. The MP had soffer the significant reduction too. On the treatment with 10000 IJ/UT had a significant increase of PEP totally and the EP totally was reduced highly expressive in this treatment by connection with control. The male ecdysis period had present a significant increase in four of the seven treatments (treatmments with 156, 612, 2500 and 5000 IJ). The mortality such as the percentual reduction of ecdysis just was significant on the treatment with 10000 IJ/UT. Until without genital hole of A. cajennense nynphs, S. glaseri was able to make the deleterious action in concentration up 5000 IJ/UT. The treatment of 5000 and 10000IJ/UT was deleterious by determined process of no parasitary phase of A. cajennense. However new studyies are necessary, in vitro yet, with superior doses than 10000 IJ/UT, due to confirm the entomopathogenic potential of A. cajennense under de S. glaseri population.
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Allende, Juri Geraldine Sipora. "Efecto del contenido de materia orgánica en el suelo y su grado de descomposición sobre el desplazamiento de Steinernema sp. aislamiento Licán Ray bajo condiciones de laboratorio." Tesis, Universidad de Chile, 2015. http://repositorio.uchile.cl/handle/2250/147611.
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Memoria para optar al Título Profesional de: Ingeniera AgrónomaLos nemátodos entomopatógenos (NEP) son controladores naturales de una amplia gama de insectos que habitan en el suelo, hábitat natural de los NEP. Esto ha hecho considerarlos una alternativa efectiva para controlar plagas de suelo y en los últimos años, numerosos estudios han evaluado la capacidad infectiva de los NEP bajo distintas condiciones. En este estudio se evaluó el efecto de la materia orgánica en el suelo, sobre el desplazamiento del nemátodo nativo Steinernema sp. aislamiento Licán Ray, evaluando su infectividad sobre larvas de la polilla mayor de la cera, Galleria mellonella (L.), en condiciones de laboratorio. Para ello, se mezcló suelo de textura franca y materia orgánica en dosis de 0, 2, 4 y 6%, en estados de descomposición inicial, intermedio y avanzado, definidos por tamaño de partícula y análisis químico, además de un tratamiento con suelo calcinado, eliminando toda la materia orgánica de éste. Todos los tratamientos fueron expuestos a altas temperaturas para disminuir la carga microbiológica y posteriormente congelados. Cada mezcla fue puesta en arenas experimentales, las cuales fueron inoculadas con una solución de 1x106 NEP m-2 a 20 cm de una placa Petri con 5 larvas de último estadío de G. mellonella. La mortalidad de larvas se evaluó cada 48 horas. El análisis estadístico mostró que los factores “dosis de materia orgánica” y “estado de descomposición” no interactuaron, por lo que los resultados fueron analizados por separado. A partir de las 48 horas, se observaron síntomas de infección en las larvas, ocurriendo reducción de la movilidad, cambio de color y flacidez. En todos los tratamientos, a las 96 horas se obtuvo la mayor mortalidad en promedio, superando el 80%, y siendo 100% en los tratamientos con dosis de materia orgánica de 2 y 4% en estado avanzado de descomposición. Es decir, los nemátodos se desplazaron a través del suelo hasta encontrar a su presa. Evaluando por separado los factores, se observó un 80% de mortalidad en promedio para el factor “dosis de materia orgánica” y 90% de mortalidad en promedio para el factor “estado de descomposición de la materia orgánica”. En el tratamiento con suelo calcinado no ocurrió mortalidad de larvas en ninguna de las repeticiones. De esta forma, se infiere que la materia orgánica ejerce cambios en las propiedades del suelo que resultan favorables para el movimiento y sobrevivencia de Steinernema sp. aislamiento Licán Ray bajo condiciones controladas de laboratorio.
Entomopathogenic nematodes (EPN) are natural controllers of a wide range of soil- inhabiting insects, their natural habitat. This has brought to consider them an effective biocontrol agent and during recent years, numerous studies have successfully evaluated the infective capacity of EPN under different conditions. The effect of soil organic matter on the displaceability of the native nematode Steinernema sp. strain Licán Ray, was evaluated through its infective capacity on the wax moth larvae, Galleria mellonella (L.), under laboratory conditions. For this purpose, organic matter was added to loam textured soil in doses of 0, 2, 4 and 6% in initial, intermediate and advanced state of decomposition, defined by size particle and chemical analysis. Also, a treatment of calcined soil was included, in which all existing organic matter was eliminated. All treatments were treated with heat, in order to eliminate microorganisms, and then frozen. Each treatment was put in experimental arenas, which was inoculated with a 1x106 EPN m-2 solution within a distance of 20 cm of a Petri dish containing 5 larvae of G. mellonella in their last instar. Then, larval mortality was assessed every 48 hours. The statistical analysis showed that the factors “organic matter doses” and “decomposition state” did not interact; therefore the results were analyzed separately. Symptoms of infection in the larvae, less mobility, change of color and flaccidity, were observed at 48 hours. In average, greater mortality was observed in all the treatments after 96 hours, reaching values above 80% and 100% in the treatments with advanced decomposition state and doses of organic matter of 2 and 4%, showing that nematodes moved through the soil to find its prey. When each factor was evaluated separately, an average mortality of 80 and 90% for the “organic matter dose” and “decomposition state of the organic matter”, respectively, was recorded. In the treatment of calcined soil no larvae mortality occurred in none of the repetitions. These results suggest that the presence of organic matter modify physical soil properties, and this has a favorable impact on the mobility and survival of Steinernema sp. strain Licán Ray under controlled laboratory conditions.
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Bal, Harit Kaur. "Spatial Ecology of Entomopathogenic Nematodes with Contrasting Foraging Strategies." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1357164528.
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Emelianoff, Vanya. "Les problèmes de couple dans les symbioses némato-bactériennes parasites d'insecte." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2008. http://tel.archives-ouvertes.fr/tel-00528291.
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Les nématodes entomopathogènes Steinernema sont associés symbiotiquement à des bactéries du genre Xenorhabdus. Leur cycle de vie comprend deux phases : une phase libre, dans le sol, où les nématodes portent leurs symbiotes dans le tube digestif, et une phase parasite, dans l'insecte, où les deux partenaires se multiplient côte à côte. Le bilan fin de l'interaction, globalement bénéfique pour les deux partenaires, a été peu étudié pour le moment. Dans un premier temps, nous avons abordé ces symbioses d'un point de vue coûts-bénéfices pour le nématode afin d'identifier les pressions de sélection agissant sur son investissement dans la symbiose. Nous montrons que l'association est à la fois bénéfique (reproduction en phase parasitaire) et coûteuse (mortalité en phase libre) pour le nématode, en proportion de sa charge symbiotique. Ces corrélations engendrent un compromis survie-reproduction pour le nématode, médié par ses symbiotes. Selon les conditions environnementales, elles pourraient éventuellement déstabiliser l'association, et, notamment, altérer sa spécificité. Dans un second temps, nous avons donc exploré la spécificité de ces associations dans la nature et au laboratoire. Lors d'un échantillonage de terrain, nous avons retrouvé la spécificité de ces associations largement décrite par ailleurs. Au laboratoire, la réassociation expérimentale entre nématodes et bactéries non natives montre que le spectre des bactéries retenues est plus étroit que le spectre des bactéries bénéfiques. De plus, des différences de modalités d'association apparaissent entre espèces de nématodes, qui suggèrent que la correspondance nématode - bactérie ne serait pas aussi stricte que prévu.
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Emelianoff, Vanya. "Les problèmes de couple dans les symbioses némato-bactériennes parasites d'insecte." Phd thesis, Montpellier 2, 2008. http://www.theses.fr/2008MON20054.
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Les nématodes entomopathogènes du genre Steinernema sont associés symbiotiquement à des bactéries du genre Xenorhabdus. Ces associations sont traditionnellement qualifiées de mutualistes car chacun des partenaires bénéficie de la présence de l'autre. Toutefois, l'originalité du cycle de vie de ces associations permet de s'interroger sur la réalité de cette réciprocité des bénéfices. En effet, le cycle de vie de ces associations comprend deux phases : une phase libre, dans le sol, où les nématodes portent leurs symbiotes dans le tube digestif, et une phase parasite, dans l'insecte, où les deux partenaires se multiplient côte à côte. La symbiose est clairement bénéfique pour le nématode en phase parasite, ce qui est moins net en phase libre ; c'est le contraire pour la bactérie. Dans un premier temps, nous avons abordé ces symbioses d'un point de vue coûts-bénéfices pour le nématode afin d'identifier les pressions de sélection agissant sur son investissement dans la symbiose. Nos résultats montrent que l'association est coûteuse pour le nématode en termes de survie en phase libre, et que ce coût augmente avec le nombre de bactéries portées. D'un autre côté, le nématode bénéficie de l'association en termes de reproduction en phase parasitaire, en proportion de sa charge symbiotique. Ces corrélations engendrent un compromis survie-reproduction pour le nématode, médié par ses symbiotes. Selon l'environnement, le bilan de l'association serait donc mitigé pour les nématodes. Ce découplage des coûts et bénéfices peut mener à des pressions de sélection contraires entre les deux phases du cycle de vie. De plus, les coûts à l'association manifestent un conflit d'intérêts entre partenaires, qui pourrait éventuellement déstabiliser l'association, et, notamment, altérer sa spécificité. Dans un second temps, nous avons donc exploré la spécificité de ces associations dans la nature et au laboratoire. Lors d'un échantillonage de terrain, nous avons retrouvé la correspondance entre une espèce de nématode et une espèce de bactérie largement décrite par ailleurs. Au laboratoire, la réassociation expérimentale entre nématodes et bactéries non natives montre que le spectre des bactéries retenues est plus étroit que le spectre des bactéries bénéfiques. De plus, des différences de modalités d'association apparaissent entre espèces de nématodes, qui suggèrent que la correspondance nématode - bactérie ne serait pas aussi stricte que prévuEntomopathogenic nematodes from Steinernema genus are symbiotically associated with Xenorhabdus bacteria. These associations are traditionally considered as mutualistic as both partners benefit from each other. However the original life cycle of these associations raises questions about their real reciprocally-beneficial status. Indeed, the symbiosis life cycle comprises two phases : a free stage in the soil, where bacteria are carried inside nematodes' gut and a parasitic stage in the insect, where both partners are separated and multiply in parallel. Benefits of the association for nematodes are clear in parasitic, but not in free stage, and it is the opposite for bacteria. We first tried to measure the balance between costs and benefits in these symbioses to identify selective pressures acting on nematode's symbiotic investment. We showed that nematodes endure costs to the association in free stage in terms of survival, these costs increasing with bacterial load. On the other side, nematodes benefit from the symbiosis in proportion of bacterial load in parasitic stage in terms of reproduction. These two antagonistic effects lead to a trade-off between nematodes' survival and reproduction which is mediated by their bacterial symbionts. Thus, depending on the environment, symbiosis has mitigated outcomes for nematodes. This decoupling of costs and benefits along the life cycle may lead to contradictory selective pressures between the two stages of the cycle. Moreover, costs of the association for nematodes indicate a conflict of interests between partners, which could challenge association stability, in particular its specificity. In a second part, we addressed the question of symbiosis specificity in natura as well as in laboratory. Field samples confirmed the already-known constancy of association between a nematode species and a bacteria species all over the world. Experimental re-associations between two nematode species and foreign bacteria showed differences between retention and benefit specificities as well as inter-specific variability. Thus the one-to-one association between nematode and bacteria species may not be as strict as previously thought
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Kunkel, Brian A. "Plant Fungal Endosymbionts Alter Host-Parasite Relationships Between Generalist Herbivores (Lepidoptera: Noctuidae) and An Entomopathogenic Nematode." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1047328087.
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Mohr, Lutz. "Neusalza-Sprembergs Denkmale – Steinerne Zeugen der Lokalgeschichte." Lutz Mohr, 2018. https://slub.qucosa.de/id/qucosa%3A17134.
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Schmidt, Andreas K. "Vom steinernen Berlin zum Freilichtmuseum der Stadterneuerung : die Geschichte des grössten innerstädtischen Sanierungsgebietes der Bundesrepublik: Wedding-Brunnenstrasse 1963 - 1989/95 /." Hamburg : Kovač, 2008. http://opac.nebis.ch/cgi-bin/showAbstract.pl?u20=9783830039747.
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Schmidt, Andreas K. "Vom steinernen Berlin zum Freilichtmuseum der Stadterneuerung die Geschichte des grössten innerstädtischen Sanierungsgebietes der Bundesrepublik: Wedding-Brunnenstrasse 1963 - 1989/95." Hamburg Kovač, 2007. http://d-nb.info/98969643X/04.
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