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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Aspects of the ecology and physiology of the Eurasian badger (Meles meles L.), cattle management and the epidemiology of bovine tuberculosis (Mycobacterium bovis)

McCann, P. J. J. January 2002 (has links)
No description available.
2

Epizootiology and Phylogenetics of Entomopathogenic Fungi Associated with Fiorinia externa ferris(Hemiptera: Diaspididae) in the Northeastern USA

Marcelino, Jose A. P. 10 December 2007 (has links)
The eastern hemlock [Tsuga canadensis (L.) Carrière] is one of the native dominant forest components of northeastern US. At present, these valuable stands face an alarming decline, in part due to the Fiorinia externa, elongate hemlock scale (EHS), (Hemiptera: Coccoidea: Diaspididae). The armored shield of F. externa provides an excellent defense against insecticides, natural enemies and adverse conditions. Chemical and classical biocontrol methods have been unable to stop the spread of this pest. Recently, the occurrence of an epizootic within the F. externa population in the Mianus River Gorge Preserve in Bedford, NY revealed a promising opportunity for control of this scale. Entomopathogenic fungi represent a valuable, although under-utilized, group of organisms with unique capabilities for self-sustaining pest management. Given the significant impact of this epizootic on F. externa, we have conducted extensive research on the biology, genetics and biological control potential of this epizootic. We molecularly identified a complex of entomopathogenic, phytopathogenic, and endophytic fungi associated with the epizootic in 36 localities within the states of New York, Pennsylvania, Connecticut and New Jersey. One fungus, Colletotrichum sp., was the most commonly isolated organism in populations of F. externa within areas of the epizootic. The host range of this Colletotrichum species comprised both insects and plants, although diverse life cycles occured in the different hosts. Endophytic growth was observed in 28 species of plants comprising 18 families (52% of the sampling), whereas in F. externa biotrophic and necotrophic growth was detected. Colletotrichum is a widely known phytopathogenic genus and reports of entomopathogenic activity are extremely rare. In order to understand the biological processes involved in the host-pathogen interactions we quantified the pathogenicity and virulence of this Colletotrichum sp. to four insect families and six plants families as well as the occurrence of sexual recombination in this Colletotrichum sp., both in vitro and in planta. We observed that this Colletotrichum sp. displays a propensy to induce rapid disease and mortality in F. externa hosts. Phylogenetic analysis comprising six of the most commonly studied nuclear genes in molecular phylogenetics (D1/D2 domain of the 28 rDNA gene, ITS region, β-Tubulin 2, GPDH gene, GS gene and HMG box at the MAT1-2 mating-type gene) and RAPDs showed this fungus is closely related to phytopathogenic strains of Colletotrichum acutatum and that it may represent a single population lineage of this species (i.e., Colletotrichum acutatum forma specialis fiorinia). Though a large body of information exists regarding the phytopathogenic genus Colletotrichum, ours is only the second reported entomopathogenic strain. It is not clear whether the colonization of an insect by this fungus is truly rare or a common but undetected event. Sexual recombination, observed in planta and in vitro, could be the means by which new genetic variants are generated leading to new biotypes with a selective advantage to colonize new hosts, which in this case is a novel host in a different kingdom.
3

Avalia??o experimental e estudos a campo relacionados a Theileria equi (Laveran, 1901) Mehlhorn & Schein, 1998 em Canis familiaris no Munic?pio de Serop?dica Estado do Rio de Janeiro, Brasil / Experimental Assessment and Field studies about Theileria equi (Laveran, 1901) Mehlhorn & Schein, 1998 in Canis familiaris in municipality of Serop?dica State of Rio de Janeiro Brazil

Silva, Gil Vicente Oliveira da 19 April 2006 (has links)
Made available in DSpace on 2016-04-28T20:16:21Z (GMT). No. of bitstreams: 1 2006-Gil Vicente Oliveira da Silva.pdf: 2177431 bytes, checksum: 46c0c2291cd76db4f34ccb7eeaa34c10 (MD5) Previous issue date: 2006-04-19 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The equines piroplasmosis are diseases that may cause debilitating progress or fatal episodies, its etiologic agents are the species Theileria equi and Babesia caballi. The maintenance of these species in nature, as well as the widespread ability, are limitants factor to genetic improvement of equines herds in view of the internationals restrictions referring the accomited animals transit with these patogens. In Brazil, in economic terms these patogens have a great importance because the national erd is stimated in 5,800,000 of animals, that dropped with the asinines, arrive in 8,300,000 of animals. The eluciding of links to the natural disease history, overall the ones that propitiate the perpetuation of it in our herds, becomes urgent and necessary. Note that some species have a sight convivence with equines, among it is the Canis familiaris. With purpose to evaluate the possibility of C. familiaris to be involved on epizootiologic natural chain of T. equi, we used two boarding: experimental and epizootiologic. For the first, using material from seventeen dogs and puppies that were divided in three groups: G1 Puppies; G2 Dogs; G3 immunossuprimitted dogs and puppies, both ixodids-free since birth until end of experimental evaluations referring the possibility to C. Familiaris to be a able host to T. equi. to evaluate the occurrence of T. equi in these animals, were used some diagnostic tools, as follow: parasitologic aspect blood smears in immersion optical microscopy (IOM); sorology: using research of antibodies against T. equi, with immunofluorescence indirect test (IFT); and molecular using four differents protocols of polimerase chain reaction (PCR), in follow material: blood with EDTA; fragment of tissues; Boophilus microplus nymphs and Rhipicephalus sanguineus in adult stage. In the second moment, evaluated, for three times, twelve dogs from enzootic stability area to T. equi with a sight convivence with horses since birth occasions, using for it IMO and IFT, forming G4 group. The results were negatives in all observations. Concluding that the T. equi specie did not show the ability to establishment and development in C. Familiaris; and that specie do not involved in epizootiologic natural chain of T. equi, in municipality of Seropedica, State of Rio de Janeiro, Brazil. / As piroplasmoses eq?inas s?o doen?as que variam de progress?o debilitante a fatal, tendo como agentes causais ?s esp?cies Theileria equi e Babesia caballi. A manuten??o dessas esp?cies na natureza, bem como a habilidade de dispers?o das mesmas, s?o fatores limitantes quanto ao melhoramento gen?tico dos plant?is eq?inos tendo em vista as restri??es internacionais referentes ao tr?nsito de animais acometidos com estes pat?genos. No Brasil, em termos econ?micos estas parasitoses assumem grande vulto tendo em vista que o plantel nacional de eq?inos ? estimado em 5.800.000 de cabe?as que somado aos asininos chega-se ao total de 8.300.000. A elucida??o dos elos referentes ? hist?ria natural da doen?a, sobretudo os que propiciam a perpetua??o da mesma em nossos plant?is, torna-se urgente e necess?rio. Nota-se que algumas esp?cies mant?m um conv?vio estreito com eq??deos dentre as quais a Canis familiaris. Com o prop?sito de avaliar a possibilidade da esp?cie C. familiaris estar envolvida na cadeia epizootiol?gica da esp?cie T. equi, utilizamos duas abordagens: experimental e epizootiol?gica. Para a primeira, utilizando materiais procedentes de dezessete c?es adultos e filhotes os quais foram divididos em tr?s grupos: G1 C?es filhotes; G2 C?es adultos; G3 C?es adultos e filhotes imunossuprimidos, mantidos livres de ixod?deos, desde a ocasi?o do nascimento at? o t?rmino das avalia??es experimentais referentes ? possibilidade da esp?cie C. familiaris ser hospedeira vi?vel de T. equi. Para avaliar o estabelecimento da T. equi nestes animais, foram utilizadas para isto as seguintes ferramentas diagn?sticas: aspecto parasitol?gico - esfrega?os sangu?neos ? microscopia ?ptica de imers?o; sorol?gico - por meio de pesquisa de anticorpos anti-T. equi, utilizando a rea??o de imunofluoresc?ncia indireta (RIFI); e molecular, utilizando quatro diferentes protocolos de rea??o de polimeriza??o em cadeia (PCR), nos seguintes materiais: sangue total com EDTA; fragmentos de diversos ?rg?os; ninfas de Boophilus microplus e adultos de Rhipicephalus sanguineus. No segundo momento, Avaliou-se, por tr?s vezes, doze c?es provenientes de ?rea de estabilidade enzo?tica para T. equi com estreita conviv?ncia com cavalos desde a ocasi?o de seus nascimentos, utilizou-se para isto a MOI e RIFI, formando o grupo G4. Os resultados foram negativos em todas as observa??es. Conclui-se que a esp?cie T. equin?o se mostrou h?bil quanto ao estabelecimento e desenvolvimento em C. familiaris, e que esta esp?cie n?o est? envolvida na cadeia epizootiol?gica natural da T. equi, no Munic?pio de Serop?dica, Estado do Rio de Janeiro, Brasil.
4

Inquérito sorológico das infecções por Babesia bovis (Babes, 1888), Babesia bigemina (Smith e Kilborne, 1893) e Anaplasma marginale (Theiler, 1910) em bovinos no Estado de Alagoas, Brasil

PORTO, Wagnner José Nascimento 09 February 2007 (has links)
Submitted by (edna.saturno@ufrpe.br) on 2016-11-09T11:59:40Z No. of bitstreams: 1 Wagnner Jose Nascimento Porto.pdf: 485977 bytes, checksum: 38cc1a2dbc36f847dab429353687fd56 (MD5) / Made available in DSpace on 2016-11-09T11:59:40Z (GMT). No. of bitstreams: 1 Wagnner Jose Nascimento Porto.pdf: 485977 bytes, checksum: 38cc1a2dbc36f847dab429353687fd56 (MD5) Previous issue date: 2007-02-09 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The prevalence of serum antibodies to Babesia bovis, Babesia bigemina and Anaplasma marginale infections were investigated in cattle farming herds from three regions called Sertão, Agreste and Leste of Alagoas State, Brazil. Sera samples from 1,155 cattle raised in 26 farms were evaluated by enzyme immunoassay (indirect ELISA). At the same time a questionnaire survey was conducted in the data were also analyzed. According to the results, 70.22% (811/1155) of the animals were positive for B. Bovis and 77.40% (894/1155) for B. bigemina and 27.45% (317/1155) of the animals were positive for antibodies against A. marginale The seroprevalence showed that the State of Alagoas is considered enzootically unstable for B. bovis and A. marginale enzootically stable for B. bigemina. The prevalence of Babesia sp infection was higher (p<0.05) in beef cattle than for dairy cattle and mixed herds. Regarding the infection by A. marginale, antibodies levels were more elevated in dairy cattle than others kind of rearing, but this difference was not significant. It is concluded that preventive measures should be adopted especially unstable areas. / A prevalência de anticorpos séricos para infecções por Babesia bovis, Babesia bigemina e Anaplasma marginale foram investigados em bovinos das Mesorregiões do Agreste, Leste e Sertão do Estado de Alagoas, Brasil. Amostras de soro de 1155 bovinos provenientes de 26 propriedades foram analisadas pelo ensaio imunoenzimático (ELISA). Os resultados mostraram que 70,22% (811/1155) dos animais foram sororreagentes para B. bovis, 77,40% (894/1155) para B. bigemina e 27,45% (317/1155) foram positivos à infecção por A. marginale, o que evidencia que o Estado de Alagoas pode ser classificado como área de instabilidade enzoótica para B. bovis e A. marginale, e estabilidade enzoótica para B. bigemina. A prevalência da infecção por Babesia sp foi mais alta (p<0,05) em rebanhos de corte do que nos rebanhos leiteiros ou de aptidão mista. Com relação à infecção por Anaplasma marginale houve diferença não significativa. Conclui-se que medidas preventivas devem ser adotadas especialmente nas áreas de instabilidade enzoótica.
5

Coral Disease Epizootiology in the Florida Keys (U.S.A.) and Cayman Islands (British West Indies), and the Development of the Simulation of Infected Corals Model

Brandt, Marilyn Elizabeth 11 December 2007 (has links)
Understanding coral disease dynamics within the heterogeneous populations in which they act is critical for predicting how the structure of reefs may change as a result of enzootic or epizootic levels of these important sources of mortality. This work focused on combining field studies and the development and testing of a spatially-explicit, individual-based epizootiological computer model with the aim of gaining a greater understanding of the dynamics and impact of white plague, a significant source of mortality on reef-building corals in the Caribbean region. Field studies focused on the incidence and distribution of all sources of coral mortality, including suspect white plague in situ, at two locations; the Florida Keys (United States of America) and Little Cayman Island (Cayman Islands, British West Indies). Results indicated that in both regions disease was the most significant source of mortality during the monitoring time periods, and that suspect white plague type II in Cayman is likely contributing to major structural changes. In Florida, observations made during a mass bleaching event indicated that a significant relationship exists between bleaching severity and disease incidence, and that mortality during the event was largely the result of disease and not bleaching. The simulation model was developed using a long-term data set from Little Cayman, and results of calibration indicated that suspect white plague type II on these reefs is transmissible between colonies within a limited field and require a yearly input from an outside source, and that host susceptibility to infection is low and likely not variable among species. Parameters describing the distribution and composition of the coral population were varied, and results indicated a significant effect of colony density, aggregation, and mean size on the impact of disease. Scenario testing of various disease management strategies indicated that should local prevention measures be developed in the future, it is they, and not treatment, that will likely be the most effective in limiting the impact of disease.
6

Aspectos biológicos de Neozygites floridana (Weiser & Muma) (Zygomycetes : Entomophthorales) e dinâmica populacional deTetranychus evansi Baker & Prictchard (Acari : Tetranychidae) e seus inimigos naturais em Solanum americanum Mill / Biological aspects of Neozygites floridana (Weiser & Muma) (Zygomycetes: Entomophorales) and population dynamics of Tetranychus evansi Baker & Pritchard (Acari: Tetranychidae) and their natural enemies in Solanum americanum Mill.

RIBEIRO, Ana Elizabete Lopes 20 February 2009 (has links)
Submitted by (edna.saturno@ufrpe.br) on 2016-11-22T13:47:20Z No. of bitstreams: 1 Ana Elizabete Lopes Ribeiro.pdf: 647150 bytes, checksum: d6f6ac0c70b90999363b5fddfcd687c2 (MD5) / Made available in DSpace on 2016-11-22T13:47:20Z (GMT). No. of bitstreams: 1 Ana Elizabete Lopes Ribeiro.pdf: 647150 bytes, checksum: d6f6ac0c70b90999363b5fddfcd687c2 (MD5) Previous issue date: 2009-02-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Neozygites floridana (Weiser & Muma) (Zygomycetes: Entomophthorales) infects several species of Tetranychidae in different locations around the world. In Brazil, N. floridana was reported in Tetranychus evansi Baker & Pritchard and Tetranychus urticae Koch. Disease caused by this pathogen on tetranychids indicates its potential in biological control programs. In this study was tested the specificity of N. floridana isolates to different species of Tetranychidae, the epizootiology of this fungus in a greenhouse, in semi-field and in the field on T. evansi in Solanum americanum Mill., and evaluated the combination of some biotic and abiotic factors on the formation of resting spores. For all strains studied contamination, infection and mummification was always higher to the species of mites from which the strains were obtained. The main natural enemies of T. evansi were N. floridana and Phytoseiulus longipes Evans. The population increase of tetranychids was always followed by increases in the density of natural enemies. It was found that the population density of natural enemies is strongly influenced by climatic factors and the density of T. evansi. The occurrence of N. floridana appears to be restricted to periods of highest rainfall from May to September. The predator P. longipes had itshighest population density during the dry period of the year, from October to February. The mites with resting spores were only 0.03%, from 13,516 mites evaluated. All mites found with resting spores belonged to the species T. evansi and to isolate LQ4. During the dry season we did not observe N. floridana structures in adult females of T. evansi under conditions of semi-field. S. americanum is a natural host for maintenance of populations of T. evansi and also allows the development of natural enemies such as N. floridana and P. longipes in the field. / Neozygites floridana (Weiser & Muma) (Zygomycetes: Entomophthorales) tem sido relatado infectando diversas espécies de Tetranychidae em diferentes locais do mundo. No Brasil, N. floridana foi relatado em Tetranychus evansi Baker & Pritchard e Tetranychus urticae Koch. Epizootias causadas por este patógeno a populações de tetraniquídeos indicam um potencial para uso deste agente no controle biológico. Neste trabalho testou-se a especificidade de cinco isolados de N. floridana a diferentes espécies de Tetranychidae; estudou-se a epizootiologia deste fungo e a ação de Phytoseiulus longipes Evans (Acari: Phytoseiidae) em condições de casa-de-vegetação, semi-campo e campo sobre T. evansi em Solanum americanum Mill., além do efeito de alguns fatores bióticos e abióticos na formação de esporos de resistência de N. floridana. Os estudos revelaram que os isolados estudados apresentaram maior contaminação, infecção e mumificação para as espécies de ácaros das quais foram obtidos. Os principais inimigos naturais de T. evansi em S. americanum no Recife-PE foram N. floridana e P. longipes. O aumento populacional desse tetraniquídeo foi sempre seguido por aumentos na densidade dos inimigos naturais. Verificou-se que, além de estar diretamente ligada à densidade de T. evansi, a densidade populacional dosinimigos naturais é bastante influenciada por fatores climáticos. A época de ocorrência de N. floridana esta restrita ao período de maior precipitação, entre os meses de maio-setembro. O predador P. longipes teve sua densidade populacional elevada durante o período mais seco do ano, entre outubro e fevereiro. A proporção de ácaros com esporos de resistência foi 0,03%, em um total de 13.516 ácaros avaliados. Todos os ácaros encontrados com esporos de resistência pertenciam à espécie T. evansi e ao isolado LQ4. S. americanum é um hospedeiro natural para manutenção de populações de T. evansi e também permite o desenvolvimento de inimigos naturais como N. floridana e P. longipes em condições de campo.
7

Epizootiologie et contribution à la caractérisation de l'agent infectieux de la maladie du muscle marron, une pathologie émergente de la palourde japonaise, Venerupis philippinarum / Epizootiology and contribution to the characterization of the infectious agent of the brown muscle disease, an emergent pathology of the Manila clam, Venerupis philippinarum

Binias, Cindy 06 December 2013 (has links)
Seconde espèce de mollusque bivalve la plus exploitée au monde, la palourde japonaise Venerupis philippinarum représente un intérêt économique majeur. A l’échelle du bassin d’Arcachon, la maladie du muscle marron ou BMD (pour Brown Muscle Disease), pathologie émergente découverte en 2005 inquiète tout particulièrement le secteur de la pêche. Cette pathologie affecte le muscle adducteur postérieur de la palourde et perturbe l’ouverture-fermeture des valves. Cette perturbation entraine la remontée des individus à la surface du sédiment et la mort.Ces travaux de thèse ont porté d’une part sur l’épizootiologie de la maladie et son impact sur l'hôte et d’autre part sur l’identification de l’agent responsable de la maladie.Une étude sur la distribution des palourdes dans le bassin d’Arcachon (littoral Atlantique français) montre que la prévalence de la BMD a diminué entre 2010 et 2012. Toutefois cette baisse ne concerne pas les individus ayant atteint la taille légale de pêche (> 35mm). De plus, la maladie semble apparaitre chez des individus de plus en plus petit et risque donc d’accroitre la mortalité aux plus jeunes stades. L’analyse des facteurs environnementaux impliqués dans la distribution de la maladie souligne la corrélation entre la prévalence de la BMD et un hydrodynamisme relativement « calme ».La BMD affecte tout particulièrement le métabolisme énergétique de l’hôte, les mécanismes de réponse au stress oxydant et également le système immunitaire. De nombreuses fonctions sont surexprimées chez les hôtes malades mais d’autres voies comme celle de l’apoptose sont régulées négativement par l’agent infectieux.Si l’origine virale est maintenant une hypothèse solide (microscopie électronique, transcriptomique), la nature exacte de l’agent étiologique (famille virale) ne peut à ce jour être déterminée avec certitude. Des particules virales ont bien été observées dans les tissus malades mais pas dans les tissus sains, et ont pu être purifiées sur gradient de sucrose. Toutefois, les essais pour provoquer la maladie chez des individus sains ont échoué. / The Manila clam Venerupis philippinarum is the second most exploited mollusk bivalve in the world and represents a major economic interest. At the scale of Arcachon bay, the Brown Muscle Disease or BMD, an emergent pathology discovered in 2005, concerns fishing activity. This pathology affects the posterior adductor muscle of the clam and disrupts the valve opening and closing process. It induces the migration of clams to the surface and their death.This thesis concerns on the one hand the epizootiology of the disease and its impact on host and on the other hand the identification of the causal agent of the disease. A study of the clam distribution in Arcachon bay (French Atlantic coast) shows that prevalence of BMD decreased between 2010 and 2012. However this decrease doesn't affect clams of the legal harvesting size (> 35mm). Furthermore, the disease seems to appear in individuals with increasingly smaller size and thus risks to increase mortality in the youngest stages. The analysis of the environmental factors that are involved in the disease distribution highlights the correlation between prevalence of the BMD and relatively "quiet" hydrodynamism.BMD particularly affects the energy metabolism of the host, the oxidative stress response mechanisms and the immune system.Many functions are up-regulated in the BMD-affected hosts but other ways, as the apoptosis, are down-regulated by the infectious agent.Although viral origin of BMD is now a convincing hypothesis (electronic microscopy, transcriptomic), the nature of the etiological agent (viral family) cannot so far be determined with certainty. Viral particles were observed in tissues of BMD-diseased hosts but not in tissues of healthy host. They have been purified on sucrose gradient. However, the attempt to provoke the disease in healthy individuals failed.

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