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Regio- and stereospecific biohydroxylation of small-ring moleculesBroad, Susan Ann January 1997 (has links)
No description available.
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Evaluation of exotic and South African isolates of Beauveria bassiana as potential mycoacaricides of Tetranychus urticae KochBhana, Nainisha Morar 30 June 2008 (has links)
Economic losses caused by the two spotted spider mite (Tetranychus urticae
Koch) in the agricultural industry prompted the initiation of this project to
evaluate the potential of native and exotic Beauveria bassiana isolates as
biocontrol agents against this pest. Before the selection of a potential
mycopesticide for use at a commercial scale, several crucial criteria must be taken
into consideration. The application of some of these criteria have been the focus
of this study and include: production of virulent B. bassiana inoculum, an
evaluation of the virulence of the fungus against T. urticae, monitoring of the
fungal infection cycle in T. urticae and establishing a phylogenetic evaluation of
B. bassiana isolates using rDNA sequence analysis.
A two-stage in vitro diphasic fermentation process produced B. bassiana
inoculum. In the first submerged phase the impact of nutrient treatments (carbon
and nitrogen) at different concentrations (3% and 4%) in a 1:1 ratio was
investigated for mycelium dry mass production and spore yield. The 4% nutrient
concentration yielded a higher mycelium dry mass yield compared to the 3% and
was therefore used in the second semi-solid phase to stimulate aerial conidia
formation in response to low nutrient stress. The fungal structures produced
during the first phase of the diphasic fermentation process were submerged
conidia recognized as small, spherical structures with a smooth form. In
comparison, inoculum of the second semi-solid phase produced aerial conidia
with small, spherical, rough surfaces and a brittle appearance assumed to be
related to nutrient deprivation. Nutritional parameters exploited in this study
favoured conidia production for use as a potential mycopesticide.
An in vitro bioassay compared the infectivity of exotic and native isolates of B.
bassiana against T. urticae adults. All the isolates were pathogenic with mite
mortality increasing over time. Differences in the virulence of the B. bassiana
isolates were demonstrated suggesting host-specificity. With respect to the native
isolates B. bassiana (PPRI 04305) was more virulent than the B. bassiana sensu
latu isolates (PPRI 04304 and PPRI 04306). The differences in the virulence of
the native isolates are reflections of genetic differences demonstrated in the
phylogenetic analyses in this study. The results of the preliminary bioassay study
suggest that B. bassiana has the potential as a biocontrol agent of T. urticae.
Microscopy was used to morphologically visualise the post infection cycle of a
native B. bassiana isolate (PPRI 04305) in the two-spotted spider mite. The
infection cycle observed in the current study is in agreement with those described
in a number of agricultural pests. However, aspects not observed before with T.
urticae infection included limited hyphal growth on the cuticle surface before
penetration, per os mode of entry, cuticular melanization, lateral hyphal
development under the cuticle and aerial hyphal emergence through the setal
annulum on the dorsal surface of the cadaver. These observations will stimulate
further research in the development of B. bassiana as a mycoacaricide.
rDNA analysis of the ITS1-5.8S-ITS2 regions of different Beauveria species was
assessed for strain genotyping and population studies. Fitch parsimony and
neighbour joining analyses displayed species differentiation and confirmed that B.
bassiana was not a monophyletic group but a species complex. Distinct clades in
the phylogenetic analyses in the current study were matched to four species of
Beauveria: B. bassiana, B. cf. bassiana, Beauveria brongniartii and Beauveria
caledonica species. Two South African isolates PPRI 04304 and PPRI 04306
morphologically assigned to B. bassiana, are assumed to be either B. caledonica
or a close relative of B. caledonica based on the rDNA analysis. However, due to
the lack of confirmation of the change of species identification of these native
isolates, they are regarded as B. bassiana sensu latu. Results from this study
demonstrated the importance of rDNA analysis in biocontrol studies for
population studies and species differentiation.
The material in this dissertation highlighted some important characteristics
relevant for the biocontrol of T. urticae by B. bassiana. Aerial conidia produced
by the cost-effective diphasic fermentation process were virulent against T.
urticae and demonstrated high percentage mortalities. B. bassiana was shown to
be a generalist pathogen with strain-dependent differences in nutrient preferences
and virulence against the mite. Differences in the infectivity of the native isolates
B. bassiana (PPRI 04305) and B. bassiana sensu latu (PPRI 04304 and PPRI
04306) were reflections of the genotypic separation of the isolates demonstrated
by rDNA analysis. The results obtained from this research project are promising
for the ongoing research and development of Beauveria isolates as efficient
mycoacaricides against T. urticae for the South African agricultural market.
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Necrophoresis and the behavioral responses of the European red ant, Myrmica rubra L. (Hymenoptera: formicidae) to the fungel entomopathogen Beauveria bassiana (Bals.) Vuill /Graham, Carrie E., January 2007 (has links) (PDF)
Thesis (M.S.) in Entomology--University of Maine, 2007. / Includes vita. Includes bibliographical references (leaves 46-52).
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Necrophoresis and the Behavioral Responses of the European Red Ant, Myrmica rubra L. (Hymenoptera: Formicidae) to the Fungel Entomopathogen Beauveria bassiana (Bals.) Vuill.Graham, Carrie E. January 2007 (has links) (PDF)
No description available.
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Toll signaling immune function and evolution in Anopheline mosquitoesRhodes, Victoria L. M. January 1900 (has links)
Doctor of Philosophy / Department of Biology / Kristin Michel / Malaria remains a major human vector-borne disease, greatly contributing to global human morbidity and mortality. Control of mosquito vectors that transmit malaria continues to be dependent on the widespread application of chemical insecticides through indoor residual spraying and insecticide treated bed nets. However, resistance to these insecticides is spreading within many mosquito populations, adding an ever-increasing urgency to the development of alternative vector control measures. The mosquito immune system is a potential novel target for such alternative measures, as the immune response initiated in these insects during infection with vector-borne disease agents is a key determinant of vector competence and, thus, contributes to a species’ vectorial capacity. These immune responses, additionally, interact with and respond to parasitic or symbiotic biocontrol agents employed to kill or manipulate infection outcome with vector-borne disease agents. Entomopathogenic fungi, including Beauveria bassiana, have been considered as an alternative vector control measure, functioning as biopesticides. The Toll pathway is a key antifungal immune pathway in insects that impacts an insect’s ability to survive fungal infections. A better understanding of Toll signaling immune function and evolution in anophelines, both vector and nonvector, can thus help to improve future biocontrol methods of important vector mosquitoes like Anopheles gambiae. In this dissertation, I report the use of B. bassiana strain I93-825 in An. gambiae to analyze the impact of Toll pathway modulation on mosquito survival. Mosquito survivorship was strongly affected by B. bassiana exposure dose by several measured parameters including median survival, longevity, and hazard. Modulation of Toll signaling, by way of knockdown by RNA interference, revealed a dose-dependent trade-off between immune activation state and survivorship in An. gambiae. To better determine the full Toll immune signaling repertoire in mosquitoes, I annotated and describe the evolutionary history of intracellular Toll pathway members and Toll-like receptors (TLRs) within 21 mosquito genomes. The intracellular signaling pathway is conserved with 1:1 orthology, and evolutionary rates across different intracellular pathway members vary widely as compared to the conserved protein core of these mosquito species. In contrast, TLRs evolved largely by duplication events within certain anopheline lineages, most dramatically in the An. gambiae complex, where six TOLL1/5 paralogs likely possess different ligand binding specificities. Thus, these TLRs should be prioritized for experimental analyses of TLR immune function in An. gambiae.
Taken together, the work in this dissertation identifies Toll pathway modulation as a potential resistance mechanism that could impact malaria biocontrol strategies and provides a foundation for future detailed studies of Toll pathway function in important mosquito vector species.
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Secretoma de Beauveria bassiana relacionado à infecção no carrapato bovino Rhipicephalus microplusKlein, Lisete Aparecida Silva 24 November 2016 (has links)
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Previous issue date: 2017-06 / O controle biológico é considerado uma ferramenta natural e alternativa ecológica para superar os problemas causados pela utilização de métodos químicos no controle de pragas. Além disso, os biocontroladores apresentam inúmeras vantagens quando comparados aos seus análogos químicos, principalmente quanto ao impacto ambiental, custo, manuseio, especificidade e desenvolvimento de resistência. Entre os diversos microrganismos utilizados no controle biológico, os fungos se destacam e, entre estes, o fungo filamentoso e patógeno de artrópodes Beauveria bassiana está entre os mais estudados e aplicados. Neste estudo, utilizando proteômica e ferramentas de bioinformática, foram identificadas um total de 256 proteínas. Proteínas envolvidas em diferentes processos importantes para o biocontrole como degradação da cutícula (proteases, lipases), defesa/antioxidantes (catalases, oxidoredutases) e efetoras (glicosil hidrolases) foram observadas. A maioria destas proteínas parecem ser secretadas, seja por rotas clássicas como não clássicas. A identificação dos mecanismos moleculares de infecção do fungo em pragas específicas possibilita o entendimento mais refinado do biocontrole e, consequentemente, no desenvolvimento de estratégias para otimizar este processo. A identificação de proteínas em um sistema que mimetiza as condições de infecção possibilita a busca orientada de microrganismos mais eficientes com maior virulência e especificidade no controle biológico do artrópode R. microplus. / The biological control is considered a natural and ecological alternative tool to overcome the problems caused by the use of chemical methods in pest control. In addition, the biocontrol presents several advantages when compared to its chemical analogues, regarding to environmental impact, cost, handling, specificity and resistance development. Among microorganisms used in biological control, fungi stand out and, the filamentous fungus and arthropod pathogen Beauveria bassiana. This fungus is one of the most studied and applied worldwide. In this study, using proteomics and bioinformatics approaches, a total of 256 proteins were identified. Proteins involved in different important processes for the biocontroling, including degradation of the cuticle (proteases, lipase), defense/antioxidants (catalases, oxidoreductases) and effectors (glycoside hydrolases) were observed. The identification of the molecular mechanisms involved in the fungal infection on specific pests provides understanding of biocontrol and consequently helping to develop strategies to optimize this process. The identification of proteins in a model that mimics the infection condition enables the oriented search for more efficient micro-organisms with greater virulence and specificity in the biological control of R. microplus tick.
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Application de Beauveria bassiana contre la punaise terne Lygus lineolaris (Palisot de Beauvois) (Hémiptères: Miridés) dans les vignoblesZiani, Jamal January 2008 (has links) (PDF)
Les insecticides chimiques sont de plus en plus considérés comme des moyens de derniers recours pour lutter contre les populations de ravageurs, car ils augmentent considérablement les coûts de production et que leur usage abusif peut entraîner des effets néfastes sur la santé humaine, animale et environnementale. Dans ce contexte, la recherche de méthode alternative de lutte prend toute son importance afin de remplacer leur emploi par des outils à risque réduit. A l'instar de plusieurs autres insectes, certaines populations de la punaise terne, Lygus lineolaris (Palisot de Beauvois) (Hémiptères: Miridés), qui est un ravageur cosmopolite, phytophage et d'importance économique en Amérique du Nord, sont résistantes à plusieurs pesticides chimiques actuellement homologués. Les microorganismes entomopathogènes occupent une place importante parmi les méthodes alternatives de lutte contre les insectes ravageurs. Le champignon Beauveria bassiana (Balsamo) Veuillemin, est un agent entomopathogène naturellement présent dans les écosystèmes. II offre un potentiel très intéressant pour contrôler les populations de la punaise terne.
L'objectif général de cette étude était de mesurer l'impact de l'emploi des préparations insecticides à base de B. bassiana sur les populations de la punaise terne dans les vignobles. La première étape de notre démarche visait à déterminer, à l'aide d'épreuves biologique, la pathogénicité et la virulence (CL₅₀ et TL₅₀) des isolats INRS-CFL et INRS-1P de B. bassiana sur les populations adultes et nymphales de la punaise terne. Les résultats ont montré une susceptibilité des nymphes et des adultes de L. lineolaris soumis aux préparations à base de B. bassiana. La seconde étape de notre démarche, a consisté en l'étude comparative de l'effet de l'application de ces deux isolats de B. bassiana et de l'insecticide chimique cyhalothrin-λ (Matador®) sur les populations des adultes de la punaise terne dans les vignobles. Les résultats ont montré que les mortalités provoquées par B. bassiona étaient comparables à celles obtenues avec le cyhalothrin-λ. Ces résultats suggèrent l'utilisation d'une formulation à base de l'isolat lNRS-CFL de B. bassiana contre les populations adultes de la punaise terne avec une concentration de 5 x 10¹³ conidies/ ha. Nos résultats démontrent aussi que l'activité insecticide des conidies des isolats INRS-IP et INRS-CFL de B. bassiana est maintenue jusqu'a six jours suivant l'application. Des applications multiples sur une base hebdomadaire sont donc requises tout au long de la durée de floraison de la vigne si l'on désire maintenir une activité insecticide permettant de contrôler les populations de la punaise terne. En complément de l'objectif précédent, la troisième étape devait permettre de suivre la persistance des conidies de B. bassiana sur les feuilles de la vigne. La persistance des conidies semble être le facteur déterminant l'activité insecticide des préparations à base de B. bassiana. Ainsi, nos résultats montrent que les conidies des isolats INRS-IP et INRS-CFL de B. bassiana sont présentes durant six jours suite à leur application sur les feuilles des plants de la vigne. Ces résultats mettent en évidence la nécessité d'élaborer une formulation permettant d'accroître la persistance des conidies sur le
feuillage augmentant ainsi l'efficacité des applications. La dernière étape avait comme objectif de déterminer l'effet des applications multiples de B. bassiana sur la survie des populations nymphales de L. lineolaris. Le suivi des populations nymphales de la punaise terne par la technique de frappe montre qu'il y a une diminution significative du nombre de nymphes vivantes en fonction du temps. Nos résultats au laboratoire et en champ de la vigne démontrent le fort potentiel de l'agent entomopathogène B. bassiana contre les populations de la punaise terne. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : La punaise terne, Beauveria bassiana, Épreuves biologique, Cyhalothrin-λ, Pathogénicité, Virulence, Activité insecticide, Persistence.
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Identification of up-regulated genes of the hyphomycete, Beauveria bassiana, during infection of Leptinotarsa decemlineataDuperchy, Esther. Unknown Date (has links) (PDF)
University, Diss., 2003--Heidelberg.
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Studium diversity a rozšíření virů entomopatogenní houby \nl{}\kur{Beauveria bassiana} v České republiceVANĚČEK, Petr January 2015 (has links)
Mycoviruses are viruses that infect and replicate in fungal cells, but unlike most known viruses of plants and animals, they exceptionally produce deleterious effects on their host. Nonetheless, the last discoveries showed that some mycoviruses can decrease the virulence of their phytopathogenic fungal hosts, making them very attractive for their possible use as biological control agents. Most mycoviruses have dsRNA genomes and are widespread in all major taxa of fungi. Beauveria bassiana is one of the most studied species of entomopathogenic fungi; it has a cosmopolitan distribution and is used as biocontroller against invertebrates in agriculture. In the present work, a collection of 137 isolates of B. bassiana obtained at different locations and from different habitats in the Czech Republic was analysed. These isolates were analysed for the presence of dsRNA elements indicative of viral infections. The results revealed a high prevalence of viral infections in Czech B. bassiana isolates, with 22.6% of the isolates containing dsRNA elements with viral characteristics. Obtained dsRNA electropherotypes showed that virus diversity in infected isolates was high and that mixed virus infections occurred among them. Based on the characteristics of the electrophoretic band patterns, it could be hypothesized that B. bassiana isolates collected in the Czech Republic could harbour members of the viral families Totiviridae, Partitiviridae, Chrysoviridae and Hypoviridae.
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Técnica de criação e associação de métodos de controle da broca-do-café, Hypothenemus hampei (FERRARI)CELESTINO, F. N. 28 November 2014 (has links)
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Previous issue date: 2014-11-28 / A broca-do-café, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae:
Scolytinae), tem sido a grande responsável por perdas causadas à cafeicultura.
Desta forma, tem-se buscado alternativas para o controle dessa praga, tais como os inseticidas botânicos e o fungo entomopatogênico Beauveria bassiana (Bals.) Vuillemin (Ascomycota: Hypocreales). Assim, esse trabalho teve como objetivos: (1) avaliar técnicas de criação da broca-do-café; (2) avaliar a utilização de inseticidas botânicos, óleos minerais e o inseticida contedo azadiractina (ICA); e (3) verificar a compatibilidade in vivo entre o óleo de mamona e o fungo B. bassiana, visando ao manejo de H. hampei. A partir dos resultados, verificou-se que a melhor técnica para criação da broca-do-café é em café robusta em coco, sem a necessidade de qualquer processo de assepsia, podendo ser armazenado em freezer a -20 ºC para ser utilizado durante a entressafra. Com base nos estudos de atividade inseticida, o
ICA (3,0% v v-1) e o óleo de mamona (3,0% v v-1) causaram 40,8 e 53,7% de mortalidade da broca-do-café, respectivamente. O extrato da torta da semente de mamona não apresentou toxicidade sobre H. hampei. O óleo de mamona causou a mortalidade da broca-do-café, sendo provavelmente devido ao bloqueio dos espiráculos, impedindo a respiração desse inseto. Óleo de mamona apresentou efeito antagônico sobre B. bassiana reduzindo a mortalidade da broca-do-café. Houve redução da mortalidade de H. hampei causada pela interação entre B. bassiana e o óleo de mamona em função do aumento da concentração do óleo de mamona. Para concentrações mais elevadas de B. bassiana observou-se menor interferência do óleo de mamona. Mediante os resultados encontrados, o manejo de H. hampei pode ser realizado utilizando-se a associação entre o óleo de mamona e o fungo B. bassina, desde que se observe a viabilidade econômica e a concentração
de ambos.
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