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Dissertations / Theses on the topic 'Tea Pests'
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Pathak, Sunil Kumar. "Population dynamics and feeding impact of some sucking pests on Darjeeling Tea." Thesis, University of North Bengal, 2004. http://hdl.handle.net/123456789/1046.
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Saha, Dhiraj. "Assessment of Population Variability at Subcellular Level of Some Common Sucking Tea Pests from Darjeeling Hill and its Adjoining Plain." Thesis, University of North Bengal, 2013. http://hdl.handle.net/123456789/951.
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Sarker, Mayukh. "A Study on certain hydrolases and oxidoreductases of major arthropod pests of tea from Darjeeling foothill and its adjoining plain." Thesis, University of North Bengal, 2007. http://hdl.handle.net/123456789/1080.
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De, Damayanti. "Study on the entomapathogenic bacteria of major lepidopteran tea pests and evaluation of their prospect as biopesticide." Thesis, University of North Bengal, 2010. http://hdl.handle.net/123456789/1422.
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Pradhan, Bina. "Rearing and evaluation of performance of some common Lepidopteran tea pests on natural and artificial diets from Darjeeling region." Thesis, University of North Bengal, 2004. http://hdl.handle.net/123456789/995.
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Biswa, Ritesh. "Study on termites of tea plantations in terai region of Darjeeling foothills with insecticide tolerance status of two commonly occurring termite pests." Thesis, University of North Bengal, 2018. http://hdl.handle.net/123456789/2723.
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Khewa, Subba Sangita. "Survey, isolation and characterization of entomopathogenic bacteria of some sporadic lepidopteran pests of tea foliage from Darjeeling foothills and plains." Thesis, University of North Bengal, 2017. http://hdl.handle.net/123456789/2701.
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Sannigrahi, Subhasish. "Studies on population dynamics of some anthropods infesting young tea cultivars in Darjeeling plain and predation potentiality of Geocoris ochropterus (Fiber) (Hemiptera: Lygaeidae) on these pests." Thesis, University of North Bengal, 1993. http://hdl.handle.net/123456789/1064.
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Kirana, Chandra. "Bio-active compounds isolated from mistletoe (Scurulla oortiana (Korth.) Danser) parasitizing tea plant (Camellia sinensis L.)." Title page, contents and summary only, 1996. http://web4.library.adelaide.edu.au/theses/09A/09ak58.pdf.
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Bibliography: leaves 87-96. This thesis investigates non-proteinaceous low molecular weight flavonoid and alkaloid compounds in Scurulla oortiana (Korth.) Danser grown on Camellia sinens. Three flavonols are identified in S. oortiana (Korth.) Danser growing on different hosts. The identification and characterisation of these flavonoids are carried out using various chromatographic and spectrometric procedures. Two purine alkaloids are isolated from and identified in S. oortiana (Korth.) Danser parasitizing tea plant, C. Sinensis. The antifungal activity of the phenolic compounds isolated from mistletoe parasitizing tea plant is examined.
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Spies, Christoffel F. J. (Christoffel Frederik Jakobus). "The inoculum ecology of Botrytis cinerea in Rooibos nurseries." Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/20943.
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Thesis (MScAgric)--University of Stellenbosch, 2005.ENGLISH ABSTRACT: Grey mould, caused by Botrytis cinerea, is the most important foliar disease of rooibos seedlings. Although the disease is primarily controlled with applications of fungicides, the improvement of cultural methods of disease management should lessen this dependence on chemical control. Such improvements would, however, not be possible without knowledge of the inoculum sources and dispersal of the pathogen. The aim of this study was to investigate the inoculum ecology of B. cinerea in rooibos nurseries in order to identify primary sources of inoculum and to improve the environmentally friendly management of the disease. The study was conducted in four nurseries over two production seasons (March to July 2003 and 2004). Levels of airborne inoculum of B. cinerea were monitored on a monthly basis inside and around the nurseries with spore traps. Samples of plant material and organic debris were taken in the corresponding areas to determine the incidence of plant material infected by the pathogen and the incidences of grey mould in the nurseries were recorded. Low numbers of B. cinerea colonies were observed on the spore traps. Similar levels of airborne inoculum were observed inside and around the nurseries. The incidence of plant material yielding B. cinerea was higher outside the nurseries than inside, indicating the importance of such materials as potential sources of inoculum. Since patterns of airborne inoculum observed in this study confirmed reports of the local dispersal of B. cinerea, the removal of possible hosts outside the nurseries could aid in the management of grey mould in rooibos nurseries. Resistance to dicarboximide fungicides is a genetically stable trait in B. cinerea, and therefore has the potential to be used as a phenotypic marker. This marker can be used to gain knowledge on the dispersal of B. cinerea inoculum inside and outside rooibos nurseries. Isolates of B. cinerea collected from the air and from plant material in and around four rooibos nurseries were assessed for resistance to iprodione at 1 and 3 μg/ml a.i. Some of the isolates showed resistance to iprodione at 1 μg/ml a.i. However, none of the isolates showed resistance at 3 μg/ml a.i. iprodione. The initial incidence of dicarboximide-resistance at the nurseries was slightly higher than expected. As the season progressed, the incidence of iprodione-resistant isolates decreased towards May, after which an increase was observed towards July. A relatively high percentage of isolates collected outside the nurseries was found to be dicarboximide-resistant. Two of the nurseries had a significant higher incidence of resistant isolates on plant material collected inside, than on plant material collected outside the nursery. However, when looking at resistance levels of airborne isolates, no significant differences were found in the incidence of resistant isolates sampled inside and outside the four nurseries. The data indicated the importance of organic debris and seed-borne infections in the survival and dispersal of dicarboximide-resistant isolates of the pathogen. With the current emphasis on organic agriculture the knowledge gained in this study presents valuable possibilities of improving the cultural management of grey mould in rooibos nurseries.
AFRIKAANSE OPSOMMING: Vaalvrot, veroorsaak deur Botrytis cinerea, is die belangrikste bo-grondse siekte van rooibossaailinge. Alhoewel die beheer van die siekte hoofsaaklik op die gebruik van fungisiede berus, behoort die verbetering van verbouingspraktyke hierdie afhanklikheid van chemiese beheer te verminder. Sulke verbeteringe sal egter slegs moontlik wees indien voldoende kennis van die inokulumbronne en verspreiding van die patogeen beskikbaar is. Die doel van hierdie ondersoek was om die inokulum ekologie van B. cinerea in rooibos kwekerye te ondersoek sodat primêre inokulumbronne opgespoor en omgewingsvriendelike siektebestuurspraktyke verbeter kan word. Die ondersoek is in vier kwekerye oor twee produksie seisoene (Maart tot Julie 2003 en 2004) uitgevoer. Vlakke van luggedraagde inokulum van B. cinerea is op ’n maandelikse basis met behulp van spoorvangers binne en buite die kwekerye gemonitor. Monsters van plantmateriaal en organiese materiaal is in ooreenstemmende areas geneem om die voorkoms van B. cinerea geïnfekteerde plantmateriaal vas te stel en die voorkoms van vaalvrot in die kwekerye is aangeteken. Min B. cinerea kolonies is op die spoorvangers waargeneem. Soortgelyke vlakke van luggedraagde inokulum is binne en buite die kwekerye waargeneem. Die hoër voorkoms van B. cinerea geïnfekteerde plantmateriaal buite die kwekerye as binne, dui op die belang van sulke materiaal as potensiële inokulumbronne. Aangesien die patrone van luggedraagde inokulum, soos waargeneem in hierdie ondersoek, ander berigte van B. cinerea se beperkte verspreidingsvermoë bevestig, kan die verwydering van moontlike alternatiewe gashere buite die kwekerye die bestuur van die siekte binne die kwekerye verbeter. Weerstand teen dikarboksimied fungisiede is ’n geneties-stabiele kenmerk in B. cinerea en het daarom potensiaal om as ’n fenotipiese merker gebruik te word. Hierdie merker kan gebruik word om kennis aangaande die verspreiding van B. cinerea in en om rooibos kwekerye in te samel. Botrytis cinerea isolate in lug en op plantmateriaal in en om vier rooibos kwekerye is gedurende 2003 en 2004 versamel. Die isolate is vir weerstandbiedendheid teen iprodioon by konsentrasies van 1 en 3 μg/ml aktiewe bestandeel (a.b.) getoets. Isolate met weerstand teen 1 μg/ml a.b. iprodioon is waargeneem, maar nie teen 3 μg/ml nie. Die aanvanklike voorkoms van dikarboksimiedweerstand by die kwekerye was hoër as verwag. Hierdie vlak het egter gedaal met die verloop van die seisoen tot in Mei, waarna ’n toename tot in Julie waargeneem is. Die persentasie dikarboksimied-weerstandbiedende isolate buite die kwekerye was relatief hoog. In twee van die kwekerye was die voorkoms van weerstandbiedende isolate op plantmateriaal in die kwekerye betekenisvol hoër as op plantmateriaal buite die kwekerye. Daar was egter geen betekenisvolle verskille in die voorkoms van luggedraagde weerstandbiedende isolate nie, ongeag van die kwekery of posisie. Die data dui op die belang van organiese materiaal en saadgedraagde infeksies in die oorlewing en verspreiding van dikarboksimied-weerstandbiedende isolate van die patogeen. Met die huidige klem op organiese landbou bied die inligting wat in hierdie ondersoek versamel is moontlike praktyke wat geïmplementeer kan word om die beheer van vaalvrot in kwekerye met behulp van verbouingspraktyke te verbeter.
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Encalada, Salazar Ashley, Agüero Gabriela Giraldo, Meza Juan Andres Olivos, García Adrián Joel Ruiz, and Lopez Cesar Ullilen. "Proyecto Meaw Tea." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2007. http://hdl.handle.net/10757/652793.
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Este proyecto surgió en base a que pudimos identificar que a pesar de que las personas que tienen un gato como mascota están aumentando, siguen siendo escasos los productos para la salud de estos. Además, de que encontramos en base a ciertos experimentos que estas mascotas suelen enfermarse con frecuencia desarrollando comportamientos (agresividad, ansiedad, excitación, no hacer uso de su arenero o nerviosismo) que suelen preocupar a su dueño.
Descubriendo que el principal motivo de estos males para los gatos es el estrés. Es que hemos planteado en nuestra idea de producto una bebida hecha principalmente en base de Nepeta Cataria o mejor conocida como menta para gatos. Esta planta es atractiva para el gato y de igual forma lo relaja, produciendo una mejora en su comportamiento. Otros efectos positivos encontrados es que incita a los gatos al juego, lo que los hace que se vuelvan más activos físicamente evitando la obesidad. Asimismo, hace que el gato no presente caída de pelaje o se autolesione. Igualmente, incluimos la valeriana para que esta planta pueda reforzar el sistema nervioso, añadiendo más efectividad al momento de relajar al gato. Además, la valeriana añade un efecto antiinflamatorio intestinal que ayuda a la digestión del gato.
Meaw Tea se va a enfocar en un segmento específico, el cual es Lima Metropolitana, abarcando así 5 distritos: Miraflores, San Isidro, Jesús María, Surco y La molina. Siendo estos lugares los primeros que obtendrán nuestro producto para el cuidado de la salud de su gato.This project came up from the fact that we were able to identify that even though people who have a cat as a pet are increasing, their health products are still scarce. Based on certain experiments we found that these pets often get sick frequently developing behaviors (aggressiveness, anxiety, excitement, not using their litter box or nervousness) that usually worry their owner. Discovering that the main reason for these ills for cats is stress. It is that we have proposed in our product idea a drink that is mainly based on Nepeta Cataria or better known as mint for cats. This plant is attractive to the cat and relaxes it, producing an improvement in its behavior. Other positive effects we found are that it encourages cats to play, which makes them become more physically active while avoiding obesity. It also prevents the cat from hair loss or self-harm. Additionally, we include valerian so this plant can support the nervous system, adding more effectiveness to relax the cat. Also, valerian adds an anti-inflammatory intestinal effect that helps the cat to digest. Meaw Tea is going to focus on a specific segment, which is Metropolitan Lima, covering 5 districts: Miraflores, San Isidro, Jesús María, Surco and La Molina. These places are going to be the first to obtain our product for the health care of their cat.
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Encalada, Salazar Ashley, Agüero Gabriela Giraldo, Meza Juan Andres Olivos, García Adrián Joel Ruiz, and Lopez Cesar Eduardo Ullilen. "Proyecto Meaw Tea." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/652793.
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Este proyecto surgió en base a que pudimos identificar que a pesar de que las personas que tienen un gato como mascota están aumentando, siguen siendo escasos los productos para la salud de estos. Además, de que encontramos en base a ciertos experimentos que estas mascotas suelen enfermarse con frecuencia desarrollando comportamientos (agresividad, ansiedad, excitación, no hacer uso de su arenero o nerviosismo) que suelen preocupar a su dueño.
Descubriendo que el principal motivo de estos males para los gatos es el estrés. Es que hemos planteado en nuestra idea de producto una bebida hecha principalmente en base de Nepeta Cataria o mejor conocida como menta para gatos. Esta planta es atractiva para el gato y de igual forma lo relaja, produciendo una mejora en su comportamiento. Otros efectos positivos encontrados es que incita a los gatos al juego, lo que los hace que se vuelvan más activos físicamente evitando la obesidad. Asimismo, hace que el gato no presente caída de pelaje o se autolesione. Igualmente, incluimos la valeriana para que esta planta pueda reforzar el sistema nervioso, añadiendo más efectividad al momento de relajar al gato. Además, la valeriana añade un efecto antiinflamatorio intestinal que ayuda a la digestión del gato.
Meaw Tea se va a enfocar en un segmento específico, el cual es Lima Metropolitana, abarcando así 5 distritos: Miraflores, San Isidro, Jesús María, Surco y La molina. Siendo estos lugares los primeros que obtendrán nuestro producto para el cuidado de la salud de su gato.This project came up from the fact that we were able to identify that even though people who have a cat as a pet are increasing, their health products are still scarce. Based on certain experiments we found that these pets often get sick frequently developing behaviors (aggressiveness, anxiety, excitement, not using their litter box or nervousness) that usually worry their owner. Discovering that the main reason for these ills for cats is stress. It is that we have proposed in our product idea a drink that is mainly based on Nepeta Cataria or better known as mint for cats. This plant is attractive to the cat and relaxes it, producing an improvement in its behavior. Other positive effects we found are that it encourages cats to play, which makes them become more physically active while avoiding obesity. It also prevents the cat from hair loss or self-harm. Additionally, we include valerian so this plant can support the nervous system, adding more effectiveness to relax the cat. Also, valerian adds an anti-inflammatory intestinal effect that helps the cat to digest. Meaw Tea is going to focus on a specific segment, which is Metropolitan Lima, covering 5 districts: Miraflores, San Isidro, Jesús María, Surco and La Molina. These places are going to be the first to obtain our product for the health care of their cat.
Trabajo de investigación
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Nham, Toan. "Suivi in vivo et en temps réel du processus infectieux induit par Yersinia pestis." Phd thesis, Université Paris-Diderot - Paris VII, 2012. http://tel.archives-ouvertes.fr/tel-00731170.
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Après trois pandémies majeures responsables de millions de morts, la peste n'a pas encore disparu. Cette maladie est causée par la bactérie Yersinia pestis, dont les mécanismes de virulence sont encore mal compris. Le suivi d'infection de la peste bubonique chez la souris, méthode classique pour étudier le processus infectieux, requiert beaucoup d'animaux et de temps pour obtenir des résultats significatifs. L'imagerie in vivo et en temps réel par bioluminescence permet de suivre la progression du pathogène au cours du processus infectieux en observant les animaux de façon non invasive. Nous avons transformé la souche virulente CO92 avec le plasmide pEm7-luxCDABE et confirmé la production de bioluminescence in vitro et in vivo. Nous avons pu quantifier la charge bactérienne dans plusieurs organes colonisés sans sacrifier l'animal et établir le schéma de progression de la bactérie au cours de la maladie. Après formation d'un foyer infectieux au site d'injection, la colonisation du ganglion lymphatique inguinal drainant ce site a été observée. Nous avons démontré que la bactérie suit un trajet direct du ganglion lymphatique inguinal au ganglion lymphatique axillaire. L'étape suivante est la colonisation des organes filtrant le sang, puis survient la septicémie dans les phases terminales de la mort. Nous avons établi que la forte variabilité dans le processus infectieux était due au temps pendant lequel la bactérie était contenue au site d'injection. À partir du moment où les ganglions lymphatiques sont colonisés, la cinétique de progression est à la fois régulière et rapide ; la septicémie survient dans les deux jours, suivie de près par la mort.
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Roy, Somnath. "Evolution of the levels of insecticide susceptibility of helopeltis theivora waterhouse (Heteroptera : miridae) and development of an efficacious strategy for management of the pest in dooars tea plantation of North Bengal." Thesis, University of North Bengal, 2008. http://hdl.handle.net/123456789/1563.
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Basnet, Kumar. "Enzyme-based detection of pesticide tolerance in the sucking tea pest, helopeltis theivora waterhouse (insecta: heteroptera: miridae) with a study on bio-ecological aspects of its common spider predator from the terai tea plantations of Darjeeling foothills and plains." Thesis, University of North Bengal, 2017. http://hdl.handle.net/123456789/2626.
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Pereira, Mariana Pinto Leitão. "Pesos e tear e elementos de tear na pré-história recente portuguesa : contributos para repensar o processo arqueológico." Master's thesis, Porto : [Edição do Autor], 2010. http://hdl.handle.net/10216/56091.
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O trabalho realizado representa um estudo dos “elementos de tear” provenientes de Castanheiro do Vento, no período compreendido entre o final do IV e o final do III milénios a.C.. Para o enquadramento teórico, foi feito um levantamento bibliográfico relativo a materiais semelhantes mencionados por outros investigadores, bem como uma abordagem aos “elementos de tear” encontrados noutros sítios arqueológicos em Portugal. Ao longo desta investigação, argumentámos a favor de uma mudança da expressão “peso de tear” para “elemento de tear”, por considerarmos que a primeira designação nem sempre é a mais apropriada para mencionar estes materiais. Os “elementos de tear” formam um grupo heterogéneo de objectos, que têm vindo a ser interpretados como vestígios da prática de tecelagem. Porém, confirmámos, através do estudo contextual dos “elementos” provenientes da estrutura subcircular A de Castanheiro do Vento, que eles nem sempre remetem para essa prática, já que dependem do contexto em que estão incluídos e das relações que se estabelecem entre eles e outros materiais. Finalmente, considerámos importante criar um guia para o estudo dos “elementos de tear”, que tem como objectivo uniformizar os registos efectuados e as informações recolhidas sobre estes, uma vez que nos confrontámos com alguma ausência de dados para a elaboração deste estudo.
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Pereira, Mariana Pinto Leitão. "Pesos e tear e elementos de tear na pré-história recente portuguesa : contributos para repensar o processo arqueológico." Dissertação, Porto : [Edição do Autor], 2010. http://aleph.letras.up.pt/F?func=find-b&find_code=SYS&request=000207275.
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O trabalho realizado representa um estudo dos “elementos de tear” provenientes de Castanheiro do Vento, no período compreendido entre o final do IV e o final do III milénios a.C.. Para o enquadramento teórico, foi feito um levantamento bibliográfico relativo a materiais semelhantes mencionados por outros investigadores, bem como uma abordagem aos “elementos de tear” encontrados noutros sítios arqueológicos em Portugal. Ao longo desta investigação, argumentámos a favor de uma mudança da expressão “peso de tear” para “elemento de tear”, por considerarmos que a primeira designação nem sempre é a mais apropriada para mencionar estes materiais. Os “elementos de tear” formam um grupo heterogéneo de objectos, que têm vindo a ser interpretados como vestígios da prática de tecelagem. Porém, confirmámos, através do estudo contextual dos “elementos” provenientes da estrutura subcircular A de Castanheiro do Vento, que eles nem sempre remetem para essa prática, já que dependem do contexto em que estão incluídos e das relações que se estabelecem entre eles e outros materiais. Finalmente, considerámos importante criar um guia para o estudo dos “elementos de tear”, que tem como objectivo uniformizar os registos efectuados e as informações recolhidas sobre estes, uma vez que nos confrontámos com alguma ausência de dados para a elaboração deste estudo.
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Ghosh, Bappaditya. "Genetic Characterization of Nucleopolyhedrovirus Isolated from Hyposidra talaca Walker (Lepidoptera: Geometridae), a Tea Pest in Terai Region of Darjeeling Foothills, India." Thesis, University of North Bengal, 2022. http://ir.nbu.ac.in/handle/123456789/5086.
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Moura, Rogério Goularte. "Diversidade de himenópteros parasitoides (Hymenoptera: Chalcididae) e coleobrocas (Coleoptera: Cerambycidae) associados à cultura de Tectona grandis Linn. f. (Lamiaceae)." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/91/91131/tde-30102012-160901/.
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Com o objetivo de analisar a fauna de himenópteros parasitoides (Hymenoptera:Chalcididae) e de coleobrocas (Coleoptera: Cerambycidae) associados à cultura de T. grandis, foram utilizadas 5 armadilhas de Malaise instaladas no interior da floresta plantada. As coletas foram realizadas, semanalmente, de outubro de 2009 a setembro de 2010, em área de reflorestamento situado no município de Cáceres, MT. Foram analisados os índices faunísticos de frequência, constância, abundância e dominância e também diversidade de espécies. Foram coletados 414 parasitoides; pertencentes às famílias Chalcididae e distribuídos em 3 gêneros e 16 espécies e 715 espécies de coleobrocas, pertencentes à família Cerambycidae e distribuídos em 2 subfamílias, 18 tribos, 33 gêneros e 36 espécies. As espécies de parasitoides mais abundantes foram Brachymeria pandora e Ceyxia ventrispinosa. As espécies mais abundantes de coleobrocas foram Neoclytus pusillus, Achryson surinamum, Chlorida festiva, Coleoxestia atrata, Cosmoplatidius abare, Hexoplon uncinatum e Megacyllene acuta.This research deals with the association of parasitoids (Hymenoptera: Chalcididae) with wood borers (Coleoptera: Cerambycidae) in a commercial forest of Tectona grandis located in Cáceres, State of Mato Grosso, Brazil. The insects were collected by using five Malaise traps in different sites of the forest, from October 2009 to September 2010. The following indexes were analyzed: frequency, constancy, abundance, dominance and species diversity. A total of 414 Chalcididae parasitoids and 715 Cerambycidae wood borers were collected. The most abundant parasitoid species were Brachymeria pandora and Ceyxia ventrispinosa while the most wood borers ones were Neoclytus pusillus, Achryson surinamum, Chlorida festiva, Coleoxestia atrata, Cosmoplatidius abare, Hexoplon uncinatum and Megacyllene acuta.
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Simpson, David. "The impotence of participation, an examination of the integrated pest management ; farmer field school program in Svay Teap, Cambodia." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0006/MQ32379.pdf.
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Simpson, David (David James) 1969 Carleton University Dissertation International Affairs. "The Impotence of participation; an examination of the Integrated Pest Management-Farmer Field School program in Svay Teap, Cambodia." Ottawa.:, 1997.
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Chevé-Aicardi, Dominique. "Les corps de la Contagion. Etude anthropologique des représentations iconographiques de la peste (XVIème – Xxème siècles en Europe)." Phd thesis, Université de la Méditerranée - Aix-Marseille II, 2003. http://tel.archives-ouvertes.fr/tel-00011965.
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Etude anthropologique des représentations du corps (épidémie, mort, mal)Deux axes structurent ce travail : les « corps de la peste » elle-même comme identification à la mort et allégorie du mal ; les corps pestiférés figurés. L'étude s'attache à l'imaginaire du mal, de la mort et du sort, à la symbolique et à la réalité épidémiques. La peste a valeur d'un paradigme anthropologique en Occident, celui de la confrontation des populations au mal par le biais de l'épidémie, schème où se joue le vécu corporel, la confrontation à l'irréversible, la mort, l'autre / les autres, l'irrationnel et la faute : autant de figures de l'altérité. Les expressions de l'atteinte et des crises sociales liées aux épidémies, celle de la commensurabilité mal / maladie et de leurs correspondances forment un noyau invariant mais complexe de significations. Il atteste en nous alors que les pestes ont disparu en Occident une sorte de présence de l'inactuel, par la médiation du corps et la matérialité de la chair atteinte.
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Laperrière, Vincent. "Apport de la modélisation individu-centrée spatialement explicite à la compréhension de L'expression d'une maladie transmissible : la peste bubonique à Madagascar." Phd thesis, Université de Pau et des Pays de l'Adour, 2009. http://tel.archives-ouvertes.fr/tel-00445563.
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La peste est une maladie qui n'a jamais disparu et réémerge même dans certains pays, dont Madagascar. Les recherches consacrées à sa forme bubonique se sont d'abord concentrées sur l'identification des agents hôtes et vecteurs, rongeurs et puces, impliqués dans le cycle épidémiologique, de leur dépendance à l'égard des facteurs environnementaux et des processus de transmission du bacille. Ces facteurs et mécanismes opérant au niveau individuel sont désormais mieux connus, grâce aux acquis des études observationnelles et expérimentales. Un enjeu actuel des recherches concerne l'analyse des processus endémo-épidémiques d'expression de la peste, dans les populations d'hôtes et de vecteurs. Dans ce sens, les modèles mathématiques compartimentaux traditionnels échouent à prendre en compte l'effet, potentiellement décisif sur le devenir de l'infection, du caractère localisé et contingent de la transmission, lié à la distribution hétérogène et changeante des puces et rongeurs. Il est donc important de considérer l'hétérogénéité individuelle et le contexte géographique dans lequel la maladie se développe pour préciser le risque épidémiologique au niveau local et chercher à éviter les cas humains. L'objet de notre recherche est de montrer l'apport d'une démarche de modélisation individu-centrée s'inscrivant dans le paradigme de la complexité, intégrant les connaissances au niveau individuel et fondée sur un formalisme multi-agents, pour étudier localement les processus endémo-épidémiques de la peste bubonique. Le modèle, appliqué au foyer malgache, nous permet d'évaluer l'effet de l'abondance et de la distribution des rats et des puces sur le devenir de l'infection.
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Baldacchino, Frédéric. "Écologie des Tabanidae en zones pastorales méditerranéennes et perspectives de lutte." Phd thesis, Université Paul Valéry - Montpellier III, 2013. http://tel.archives-ouvertes.fr/tel-00942818.
Full textAbstract:
Les zones pastorales méditerranéennes sont favorables à la diversité et à l'abondance des Tabanidae. Or, la réémergence de certaines maladies animales en Europe (e.g. besnoitiose bovine) a mis en avant leur rôle de vecteur mécanique. Cependant, la richesse biologique et la vulnérabilité des milieux pastoraux impliquent de réduire l'usage des insecticides contre les ectoparasites. Nous avons donc cherché à mieux connaître l'activité des taons dans les estives et àréfléchir à des méthodes de contrôle pratiques, efficaces et sélectives. Les pièges attractifs ou les répulsifs utilisables dans une stratégie " push-pull " impliquant de bien connaître l'olfaction des espèces cibles, nous nous sommes intéressés à la physiologie olfactive des taons et aux composés chimiques qui modulent les interactions avec leurs hôtes.Les travaux sur l'écologie des taons dans les Pyrénées ont montré que l'exposition, l'altitude et la structure paysagère influençaient leur distribution spatio-temporelle, et que les conditions climatiques influençaient l'activité de piqûre des femelles. De plus, le caractère trophique opportuniste des femelles a été confirmé et le cerf est apparu comme un hôte de choix. Les réponses physiologiques et comportementales de Tabanus bromius et d'Atylotus quadrifarius aux odeurs d'urines et de leurs constituants ont révélé des différences de sensibilité olfactive entre ces deux espèces, la forte attractivité de l'urine de cheval s'expliquant probablement par la présence de composés volatiles qui agiraient en synergie. Pour conclure, nous proposons pour les troupeaux en estives des mesures de protection contre les taons et des perspectives de recherche pour ce groupe.
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Imbert, Charles-Edouard. "Expansion d'un ravageur forestier sous l'effet du réchauffement climatique : la processionnaire du pin affecte-t-elle la biodiversité entomologique dans les zones nouvellement colonisées ?" Phd thesis, Université d'Orléans, 2012. http://tel.archives-ouvertes.fr/tel-00717391.
Full textAbstract:
Sous les latitudes tempérées, les aires de distribution respectives des espèces d'insectes sont généralement conditionnées par les températures hivernales au travers de seuils minimaux de tolérance pour la survie et le développement. Ainsi, le déplacement des aires de répartition est un des effets les plus notables du réchauffement climatique sur les espèces sensibles au froid. Cependant, les conséquences de la colonisation de nouveaux milieux par les espèces en expansion, notamment sur les interactions interspécifiques restent largement inexplorées. La processionnaire du pin est un ravageur d'origine méditerranéenne, dont l'aire de répartition s'est considérablement étendue vers le nord et en altitude ces deux dernières décennies. Cette expansion est liée à la hausse des températures hivernales qui permet une meilleure survie des colonies se développant durant cette période. Notre étude s'est développée autour de deux axes de recherches : (1) la réponse des ennemis naturels à l'expansion de leur hôte ; (2) l'impact de la colonisation sur une espèce protégée inféodée à la même ressource alimentaire, l'Isabelle de France. Nos résultats ont montré que dans les zones nouvellement colonisées, la processionnaire du pin est libérée de la pression de ses parasitoïdes oophages. Ainsi, au niveau du front d'expansion, une femelle de processionnaire du pin produira plus de descendants que dans le coeur de son aire de répartition. De plus, la défoliation par la processionnaire du pin a un effet négatif sur le développement des chenilles d'Isabelle de France. Nos résultats contribuent à comprendre les causes de l'expansion de ce ravageur forestier et ses conséquences sur les espèces autochtones des zones nouvellement colonisées.
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Jacquot, Marion. "Usage des rodenticides anticoagulants et conséquences en termes d'exposition et d'impact pour les populations de renard roux." Phd thesis, Université de Franche-Comté, 2013. http://tel.archives-ouvertes.fr/tel-00917412.
Full textAbstract:
Les rodenticides anticoagulants (RA) constituent le principal moyen de lutte contre les rongeurs. L'exposition aux RA du renard roux et l'impact des RA sur les populations de ce prédateur sont étudiés. En France, on distingue un contexte " biocide " (BCD) où les RA sont principalement utilisés près des bâtiments et un contexte " phytopharmaceutique " (PP) où la bromadiolone (un RA) est également utilisée en plein champs contre le campagnol terrestre. La contamination des rongeurs aux RA est mesurée : 5 RA sont détectés en contexte BCD alors que la bromadiolone est la molécule majoritaire en contexte PP ; les espèces de rongeurs non ciblées par les RA étant exposées dans les 2 contextes. L'exposition est maximale chez les espèces ciblées ou celles au mode de vie similaire. L'exposition du renard est évaluée par la mesure des résidus de RA dans des fèces collectées in situ. La bromadiolone est retrouvée dans 97 % des fèces positives et les RA sont plus retrouvés dans les fèces en cas de traitements PP. En contexte PP, le ratio de fèces positives augmente non linéairement avec la surface traitée dans un rayon d'1 km autour des fèces. L'impact des traitements PP sur les populations de renards est évalué (période 2003-2009, département du Doubs). Les indices d'abondance de renard mesurés sur une commune le printemps d'une année n diminuent avec l'augmentation des quantités d'appâts utilisées les années n-1 et n-2. Pendant la période suivie, la mise en place d'une lutte intégrée contre le campagnol terrestre s'est traduite par une diminution des quantités d'AR utilisées et donc par une diminution des impacts sur les populations de renards.
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Mollot, Grégory. "Régulations biologiques de Cosmopolites sordidus dans le réseau trophique des bananeraies." Phd thesis, Université d'Avignon, 2012. http://tel.archives-ouvertes.fr/tel-00932464.
Full textAbstract:
Dans les agroécosystèmes, les réseaux trophiques sont souvent structurés à partir de la plante d'intérêt agronomique, qui permet aux herbivores qui lui sont associés de se développer, notamment les bioagresseurs. La monoculture de bananiers a permis au charançon du bananier (Cosmopolites sordidus) de prospérer. Les larves de C. sordidus se nourrissent exclusivement de bananiers et provoquent leur chute, réduisant fortement le rendement dans la plupart des régions de production. Cette thèse a cherché à élucider la structure et le fonctionnement du réseau trophique de la bananeraie et particulièrement les interactions trophiques qui lient le C. sordidus aux autres espèces. L'objectif appliqué en ligne de mire était de favoriser les prédateurs généralistes pour augmenter la régulation naturelle de C. sordidus.1. Quel est l'effet de l'ajout d'une plante de couverture sur la prédation de C. sordidus ? En utilisant une variété de méthodes - isotopes stables, piégeage, infestation artificielle de bananiers, nous avons testé avec succès l'hypothèse selon laquelle l'enherbement induit, via le développement de proies alternatives, un changement de régime alimentaire des prédateurs généralistes, une augmentation de leurs abondances et une plus forte prédation des oeufs de C. sordidus.2. Quel est la structure du réseau trophique ? Nous avons combiné le séquençage haut-débit (technologie 454) avec le concept de codes-barres à ADN pour identifier les proies présentes dans le contenu stomacal des consommateurs. Nous avons utilisé un marqueur chloroplastique (boucle P6 trnL) pour identifier le bol alimentaire des herbivores, et un marqueur mitochondrial (mini-CO1) pour les prédateurs. Cette approche a permis de détecter des espèces qui n'avaient pas été échantillonnées, d'identifier les prédateurs naturels de C. sordidus au champ, et de quantifier les interactions à l'échelle des populations.3. Comment la structure du réseau trophique peut-elle influencer la régulation de C. sordidus ? Nous avons cherché les différents éléments structuraux (motifs) présents dans le réseau trophique de deux agroécosystèmes bananiers (sur sol nu et sur sol enherbé), et analysé leurs fonctions. Nous avons notamment décelé un motif composé de 4 espèces (2 ressources et 2 consommateurs) qui est représenté en grand nombre par rapport à un modèle neutre de réseau trophique. Ce motif s'est révélé systématiquement déséquilibré en faveur d'une proie, ce qui démontre qu'une distribution asymétrique des forces d'interactions permet de structurer le réseau. L'analyse de la position de C. sordidus dans les motifs décelés a permis de révéler ses interactions préférentielles avec les autres espèces de la communauté.Cette thèse montre comment le couplage de méthodes innovantes et complémentaires permet d'avoir une approche globale du fonctionnement trophique de l'agroécosystème. Les résultats montrent l'importance des ressources primaires (autres que la plante cultivée) sur la structuration du réseau trophique des arthropodes et sur le potentiel de régulation des bioagresseurs. Ce travail illustre également le lien entre la structure globale d'une communauté et l'évaluation des fonctions qui y sont associées
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Guichard, Sylvain. "Modelling the proximal source of intercepted exotic insects." Lincoln University, 2009. http://hdl.handle.net/10182/1472.
Full textAbstract:
Biological invasions are major threats to any nation’s economy and biodiversity. To detect new biological incursions of some species biosecurity agencies deploy pheromone sentinel traps for targeted species at high risk sites such as airports, seaports and transitional facilities. A good example is the gypsy moth surveillance program in New Zealand. Following the detection of an incursion by an unwanted organism, ground-based searches to locate the source can be very expensive, but are essential to identify the introduction pathway and to increase the chances of success eradicating the unwanted organism. In such circumstances, the possibility of better targeting the search for the source of the incursion using a modelling approach is worthy of investigation A stochastic mechanistic model to hindcast moth flight from a recapture location to the release location was developed based on insect behaviour in response to wind and pheromones. The model was composed of two main processes, 1) downwind dispersal, assumed to result from an appetitive behaviour, indicated by an analysis of a previous mark-release-recapture experiment on painted apple moth (Teia anartoides, Walker) and, 2) anemotaxic dispersal inspired by pheromone anemotaxis theory but up-scaled from a fine-scaled behaviour model to a 2 m scale. A genetic algorithm was used to fit some model parameters. A specialised fitness function was developed to allow the genetic algorithm to identify parameters that resulted in models that reflected both the spread and density patterns in the trapping data. The resulting function allowed the stochastic model results to be compared with the inherently stochastic trapping data. The resulting individual based model simulates the spatio-temporal dispersal pattern of painted apple moth recorded during a previous mark-release-recapture experiment. While the proposed model is shown to have limitations with respect to accuracy and precision it is also demonstrated to greatly improve biosecurity incursion response capability, by more efficient targeting of search effort for the proximal source of an incursion.
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Meiss, Helmut. "Diversifying crop rotations with temporary grasslands : potentials for weed mangement and farmland biodiversity." Phd thesis, Université de Bourgogne, 2010. http://tel.archives-ouvertes.fr/tel-00575607.
Full textAbstract:
Crop rotation may be used to prevent the continuous selection of particular weed species adapted to one crop type. This might be useful for weed management, economy in herbicide applications and promoting biodiversity. Common simple crop sequences might be diversified by introducing perennial forage crops. Impacts of such perennial crops on weeds were studied with four approaches : 1) Large-scale weed surveys in 632 fields in western France showed that weed species composition differed most strongly between perennial alfalfa crops and annual crops. Comparisons of fields before, during and after perennial alfalfa suggested that community composition varies in a cyclic way during such crop rotations. Several weed species problematic in annual crops were suppressed during and after perennial crops, but the appearance of other species led to equal or even higher plant diversities. 2) A 3-year field experiment with contrasting crop management options allowed an investigation of the underlying mechanisms for this: The absence of soil tillage reduced weed emergence but increased the survival of established plants. The permanent vegetation cover and frequent hay cuttings reduced weed growth, plant survival and seed production. 3) Greenhouse experiments testing the regrowth ability of individual plants after cutting showed strong differences between species and functional groups. An two-factorial experiment suggested that the negative impacts of cutting and competition on weed growth were mainly additive. 4) Special measurements of weed seed predation in the field experiment showed positive correlations with vegetation cover, indicating that this ecosystem service may be particularly fostered by perennial crops. Consistent preferences of seed predators for certain weed species indicates that seed predation may be another cause of the observed weed community shifts.
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Tsai, Ru-Shiow, and 蔡如秀. "Pheromones of tea pests: Andraca bipunctata Walker and Euproctis pseudoconspersa (Strand)." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/35634935391906178874.
Full textAbstract:
博士國立臺灣師範大學
生物研究所
87
SEX PHEROMONES OF TEA PESTS: ANDRACA BIPUNCTATA WALKER AND EUPROCTIS PSEUDOCONSPERSA (STRAND) ABSTRACT Octadecanal, (E)-11-octadecenal, (E)-14-octadecenal and (E,E)-11,14-octadecadienal were isolated from the female pheromone gland of Andraca bipuncata in Taiwan. All four compounds were synthesized and bioassayed by electroantennography. Among these compounds, only (E,E)-11,14-octadecadienal could elicited big EAG response from male A. bipuncata. In the field test, only lures contained (E,E)-11,14-octadecadienal could catch male moths of A. bipuncata. 10,14-Dimethylpentadecyl isobutyrate was identified from extracts of pheromone glands of the female tea tussock moth, Euproctis pseudoconspersa (Strand) by gas chromatography in Taiwan. EAG records showed that (R)- and (S)-enantiomers and pheromone extract could cause male antennal responses. Crude pheromone extract elicited a larger EAG response than did (R)-10Me14Me-15:iBu, but the EAG response to the (S)-enantiomer was smaller than that to crude extract or the (R)- enantiomer. In field tests, the (R)-enantiomer showed better attractancy than did both the (S)-enantiomer and racemic mixtures in July 1998. However, later in the season, the (R)-enantiomer and racemic mixtures showed a similar attractancy, and both were better than the (S)-enantiomer. Traps baited with 20 μg of racemic mixtures and those with 2 virgin females showed similar attractancies, however, more males were caught with 80-μg baited traps. The antennae of A. bipunctata are sexually dimorphic; those of males are pectinate with 43 pairs of branches, and those of females are filiform without branches. The antennae of both male and femae E. pseudoconspersa are pectinate, however, the one of the male is twice larger than the female''s. In both species, most sensilla are on the frontal (windward, ventral) side, and the types of sensilla differ in the 2 sexes. The main type of male A. bipunctata is sensillum trichodeum (s. trichodeum), but in females are s. basiconicum and the short s. chaeticum. In E. pseudoconspersa the main type of the male is long s. trichodeum, however, of the female is short s. trichodeum. Each putative pheromone-sensitive s. trichodeum of A. bipunctata was innervated by 2 bipolar neurons enveloped by three sheath cells. The single sensillum recording of a s. tirchodium showed spikes of 2 different amplitudes after (E,E)-11,14-octadecadienal stimulation. This result indicated that s. trichodea were indeed the sex pheromone receptor.
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Chen, Wei-Chia, and 陳威嘉. "Annual damage fluctuations of Helopeltis fasciaticollis Poppius and identification of the insect pests and diseases in organic tea plantation." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/55421173401627299184.
Full textAbstract:
碩士國立中興大學
植物醫學暨安全農業碩士學位學程
105
Tea mosquito bug, Helopeltis fasciaticollis Poppius (Hemiptera: Miridae) is one of the major sucking insect pests of tea (Camellia sinensis (L.) O. Kuntze). Both nymphs and adults of H. fasciaticollis prefer to feed on the buds and young leaves of tea plants and cause brown feeding spots. Severely damaged shoot will become defoliation and cause loss of yield. The result in lab shows the female adult of H. fasciaticollis can cause the most number of 29.7 ± 3.2 feeding spots, and the highest mean feeding area is 93.8 ± 10.3 mm2. The field annual survey began from February 2016, at the organic tea plantation of Tung-Pang organic black tea company in Puli, Nantou County. The result showed that the mean damage rate of TTES No.18 is 26.9 ± 2.7%, the highest is 91.1% in 6/17, and the lowest is 0.3% in 7/15. The mean damage rate of TTES No.7 is 3.3 ± 0.4%, the highest is 14.6% in 6/17 and no significant difference with 11.7% in 6/4, and the lowest is 0.2% in 7/15. The mean damaged areas of per fresh shoot of TTES No.18 is 40.8 ± 4.6 mm2, the highest is 83.1 mm2 in December and the lowest is 2.9 mm2 in July. The mean damaged area of per fresh shoot of TTES No.7 is 3.7 ± 0.6 mm2, the highest is 9.7 mm2 in June and the lowest is 0 mm2 in September. H. fasciaticollis may prefer to TTES No.18 because there is significantly different between two cultivars except February and July. We used Pearson product-moment correlation to analyze the correlation between climatic parameters and annual fluctuations of the mean damaged area of per fresh shoot of TTES No.18. The result shows that relative humidity was found to be positively correlated to H. fasciaticollis infestation of TTES No.18 (with correlation coefficient r = 0.36). Wind speed, precipitation and day of precipitation was found to be negatively correlated to H. fasciaticollis infestation of TTES No.18 (with correlation coefficient r = -0.67, r = -0.34, r = -0.68, respectively). The result of identification of the tea insect pests includes 5 orders (Hemiptera, Lepidoptera, Coleoptera, Diptera, Orthoptera) 20 species, and spider mites includes 2 species of Acariformes. Identification of diseases of tea includes blister blight of Exobasidiales, Exobasidium; gray blister of Xylariales, Pestalotiopsis; sooty mold of Capnodiales, Capnodium; Algal spot of Trentepohliales, Cephaleuros 4 species.
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Kirana, Chandra. "Bio-active compounds isolated from mistletoe (Scurulla oortiana (Korth.) Danser) parasitizing tea plant (Camellia sinensis L.)." Thesis, 1996. http://hdl.handle.net/2440/109033.
Full textAbstract:
This thesis investigates non-proteinaceous low molecular weight flavonoid and alkaloid compounds in Scurulla oortiana (Korth.) Danser grown on Camellia sinens. Three flavonols are identified in S. oortiana (Korth.) Danser growing on different hosts. The identification and characterisation of these flavonoids are carried out using various chromatographic and spectrometric procedures. Two purine alkaloids are isolated from and identified in S. oortiana (Korth.) Danser parasitizing tea plant, C. Sinensis. The antifungal activity of the phenolic compounds isolated from mistletoe parasitizing tea plant is examined.Thesis (M.Ag.Sc.) -- University of Adelaide, Dept. of Horticulture, Viticulture and Oenology, 1997
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Tesfagiorgis, Habtom Butsuamlak. "Studies on the biocontrol of seedling diseases caused by Rhizoctonia solani and Pythium sp. on sorghum and tef." Thesis, 2003. http://hdl.handle.net/10413/6254.
Full textAbstract:
Rhizoctonia solani and Pythium spp. are aggressive soil-borne fungal pathogens responsible
for seed rot and seedling damping-off of many crops. With increased environmental and
public concern over the use of chemicals, biological control of these diseases has been
attracting more attention. However, success with this strategy depends on the development of
effective antagonists, which requires repeated in vitro and in vivo tests.
Bacillus spp. were isolated from a soil sample obtained from a field where sorghum and tef
had been grown for at least two years. Potential Bacillus isolates were screened for their
ability to inhibit in vitro growth of R. solani and Pythium sp. Among 80 isolates tested,
endospore forming Bacillus spp. H44 and H51 gave highest antifungal activity against the two
test-pathogens in three consecutive tests. Results demonstrated that both H44 and H51 have
potential as biocontrol agents against diseases caused by these two pathogenic fungi.
The interaction between three isolates of Trichoderma (T. harzianum Eco-T, Trichoderma spp.
SY3 and SY4) and Pythium sp. were investigated using in vitro bioassays together with
environmental scanning electron microscopy (ESEM). Visual observation on the dual culture
tests revealed that hyphal growth of Pythium was inhibited by these antagonists soon after
contact between the two organisms within 3-4 days of incubation. The ESEM investigations
showed that all three isolates of Trichoderma grew toward the pathogen, attached firmly,
coiled around and penetrated the hyphae of the pathogen, leading to the collapse and
disintegration of the host's cell wall. Degradation of the host cell wall was postulated as being
due to the production of lytic enzymes. Based on these observations, antibiosis (only by Eco-T)
and mycoparasitism (by all three isolates) were the mechanisms of action by which in vitro
growth of Pythium sp. was suppressed by these Trichoderma isolates.
The reduction of seedling diseases caused by R. solani and a pythium sp. were evaluated by
applying the antagonists as seed coating and drenching antagonistic Bacillus spp. (B81, H44
and H51) and Trichoderma (T. harzianum Eco-T and Trichoderma spp. SY3 and SY4). On
both crops, R. solani and Pythium sp. affected stand and growth of seedlings severely. With
the exceptions of H51, applications all of isoltes to seeds reduced damping-off caused by R.
solani in both crops. Application of Eco-T, H44 and SY3 to sorghum controlled R. solani and
Pythium sp. effectively by yielding similar results to that of Previcur®. On tef, biological
treatments with Eco-T and SY4 reduced seedling damping-off caused by R. solani and
Pythium sp., respectively, by providing seedling results similar to the standard fungicides,
Benlate® and Previcur®. Most other treatments gave substantial control of the two pathogens
on tef. Overall, Bacillus sp. H44 and T harzianum Eco-T were the best biocontrol agents from
their respective groups in reducing damping-off by the two pathogens. In all instances, effects
of application method on performance of biocontrol agents and adhesive on emergence and
growth of seedlings were not significant.
A field trial was conducted at Ukulinga Research Farm at the University of Natal,
Pietermaritzburg, South Africa, to determine efficacy of biological and chemical treatments on
growth promotion and reduction of damping-off incited by R. solani and Pythium sp., and to
evaluate the effects of a seed coating material, carboxymethyl cellulose (CMC), on seedling
emergence and disease incidence. Seeds of sorghum and tef were treated with suspensions of
antagonistic Bacillus H44 or T harzianum Eco-T, or sprayed with fungicides, Benlate® or
Previcur®. Application of Benlate® and Previcur® during planting significantly increased the
final stand and growth of sorghum seedlings. Seed treatments with both H44 and Eco-T
substantially controlled damping-off caused by Pythium, resulting in greater dry weights of
seedlings than the standard fungicide. However, they had negative effects when they were
tested for their growth stimulation and control of R. solani. The CMC had no significant effect
on germination and disease levels. These results showed that these antagonists can be used as
biocontrol agents against Pythium sp. However, repeated trials and better understanding of the
interactions among the antagonists, the pathogens, the crop and their environment are needed
to enhance control efficiency and growth promotion of these antagonists.
Some of these biocontrol agents used in this study have the potential to diseases caused by R.
solani and Pythium sp. However, a thorough understanding of the host, pathogen, the
antagonist and the environment and the interactions among each other is needed for successful
disease control using these antagonists.Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.
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Mamabolo, Lerato Katedi. "Selection of appropriate plants parts with suitable chemical properties for the development of Jatropha zeyheri indigenous tea beverage." Thesis, 2020. http://hdl.handle.net/10386/3443.
Full textAbstract:
Thesis (M.Sc. (Horticulture)) -- University of Limpopo, 2020Most rural communities harvest different plant parts of Jatropha zeyheri for nutritional and medicinal purposes. However, the decision of choosing to harvest the plant part with desired chemical components is essential for quality purposes. Nevertheless, there is a lack of information regarding the distribution of chemical composition in different plant parts of J. zeyheri tea. Therefore, the objectives of the study were to: (1) investigate the effect of different plant parts (stems, roots and leaves) of J. zeyheri on mineral composition and, (2) determine the effect of different plant parts (stems, roots and leaves) of J. zeyheri on phytochemicals and antioxidant activity. A study was conducted with three treatments, namely stems, roots and leaves arranged in a randomised complete block design (RCBD), with 10 replications. Plant materials were collected in the wild from mature plants between June-July 2018. Leaves and stems were manually separated, while roots were cut into smaller pieces, dried at 60°C for 48 hours in an air-forced oven and later finely ground using an electric grinder. Mineral elements were determined using Inductive Coupled Plasma Emission (ICPE-9000 Shimadzu, Japan). Phytochemical tests were performed to detect the presence of flavonoids, tannins, alkaloids and saponins, whereas 2,2-Diphenyl-1-picrylhydrazyl (DPPH) antioxidant qualitative test was performed using TLC plates. Antioxidant activity and phytochemicals constituents were quantified using UV/Visible spectrophotometer. Results of this study demonstrated that plant parts had a highly significant effect on essential mineral elements, copper (Cu), iron (Fe), potassium (K), magnesium (Mg), zinc (Zn), manganese (Mn), phosphorus (P) and nickel (Ni) contributing 82, 75, 97, 88, 86, 96, 79 and 82% to total treatment variation (TTV), respectively, whereas, calcium (Ca) had a significant effect contributing 69%, while no significant effect on sulphur (S) was observed. Among the tested essential mineral elements, Ca, Zn, Cu and Ni were consistently the highest in the leaf, followed by stem whereas, the root had the lowest contents. Manganese and Mg were consistently the highest in the stem, followed by leaf whereas, the root had the lowest content. Iron was highest in the leaf followed by root and was lowest in the stem. Also, the stem had the highest content of K whereas, the leaf and the root had moderately lower content, and P was high in the leaf, whereas, stem and root had lower content. Similarly, plant parts had a highly significant effect on non-essential mineral elements, aluminium (Al), sodium (Na), cobalt (Co) and chromium (Cr) contributing 85, 72, 84 and 81% in TTV, respectively, whereas, not significant on silicon (Si). Among the tested non-essential mineral elements, the leaf had the highest content of Al, Na, Cr, and Co followed by the stem, whereas, the root had the lowest. The screening of phytochemicals showed that flavonoids, tannins, alkaloids and saponins were present within different plant parts of J. zeyheri. The results from DPPH qualitative assay of J. zeyheri plant parts showed more yellow spots in leaf and root whereas, there was lesser amount in stem indicating that the plant exhibited antioxidant activity. Plant parts had highly significant effect on total flavonoids contributing 72% in TTV, however, had a significant effect on tannins and antioxidant activity contributing 56 and 79% in TTV, respectively. In contrast, plant parts were not significant on total phenols. The leaf had the lowest of total flavonoids content, whereas root and stem reported the higher contents and root had a lower content of tannins and antioxidant activity, whereas stem and leaf reported higher contents. In conclusion, the majority of chemical properties were recorded in leaves followed by stems and lastly in the roots. The result of this study suggested that J. zeyheri tea beverage can be brewed from leaves predominantly followed by stems or alternatively they can be combined.
National Research Foundation (NRF) and Limpopo Agro-Food Technology Station (LATS)
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Gebus, Caroline, and Ina Attree. "Interactome des antigènes protecteurs V de Pseudomonas aeruginosa et de Yersinia pestis : Mécanisme d'assemblage et interaction avec l'aiguille de sécrétion de type III." Phd thesis, 2008. http://tel.archives-ouvertes.fr/tel-00335165.
Full textAbstract:
Pseudomonas aeruginosa et Yersinia pestis sont responsables d'infections graves chez les individus immunodéprimés et de la peste, respectivement. Leur pathogénicité repose sur de nombreux facteurs de virulence dont le système de sécrétion de type III (SST3) qui a une action prépondérante lors d'infections aiguës. Le SST3 est composé d'une base ancrée dans la double membrane bactérienne, d'une aiguille creuse érigée à la surface et d'un pore de translocation inséré dans la membrane de la cellule hôte permettant à la bactérie d'y injecter des toxines. L'objet de cette thèse est l'étude de l'interactome de l'antigène protecteur V, PcrV chez P. aeruginosa et LcrV chez Y. pestis. Celui-ci est situé au sommet de l'aiguille et est nécessaire au processus de translocation des toxines. L'étude des propriétés biochimiques de la protéine in vitro nous a permis de mettre en évidence sa capacité à former des oligomères présentant une structure en forme d'anneaux. Les multimères ont été observés par chromatographie d'exclusion de taille, gel natif, spectrométrie de masse native et MET. Leur formation est dépendante de la présence de l'hélice α12 C terminale de PcrV et de l'intégrité de ses résidus hydrophobes. Le processus d'assemblage de la protéine est nécessaire à sa fonction in vivo : des mutants qui sont incapables d'oligomériser perdent leur cytotoxicité envers les cellules eucaryotes. Puis, l'interaction directe entre PcrV et la sous unité formant l'aiguille, PscF, a été mise en évidence in vitro par co-purification. De plus, deux mutants ponctuels de PscF dont le phénotype présente un défaut de translocation se sont montrés défectueux pour la liaison avec PcrV. Enfin, l'hélice C terminale de PscF est échangeable avec l'hélice α12 C terminale de PcrV comme l'atteste la capacité de polymérisation d'un hybride créé entre ces deux protéines, suggérant un rôle de celle-ci dans la formation du complexe F-V. L'ensemble de ces études montre que l'assemblage multimérique des antigènes V ainsi que leur position au sommet de l'aiguille sont des éléments essentiels à leur fonction, avec un rôle prépondérant de l'hélice α12 C terminale de PcrV. Ces conclusions pourraient permettre de mieux cibler les développements futurs de nouveaux vaccins ou agents antimicrobiens.
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Hossain, Mohammed Tufazzal. "Studies of the impact of mycoflora associated with oryza sativa (rice) in South Africa." Thesis, 2014. http://hdl.handle.net/10500/13266.
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The objective of this research was to investigate the occurrence of mycoflora in rice plants and rice seeds in South Africa and their negative impact.
A total of six species of Fusarium were isolated from diseased rice plants and rice seeds and identified as F. anthophilum, F. chlamydosporum, F. compactum, F. equiseti, F. fujikuroi and F. semitectum. In the translation elongation factor data set, Fusarium equiseti isolates grouped together within the F. incarnatum - equiseti Species Complex (FIESC). The isolates from rice clustered together in a single clade with the F. equiseti and F. incarnatum isolates forming two separate sub-clades.The isolates of F. equiseti present a new phylogenetically distinct species in FIESC.
In the pathogenicity tests, isolates of both F. anthophilum and F. fujikuroi caused bakanae disease to rice plants. Fifty four rice cultivars and lines were tested by the standardized test tube inoculation method for resistance and susceptibility against bakanae isolate of F. anthophilum and the bakanae isolate of F. fujikuroi. None of the rice cultivars and lines was found to be resistant to bakanae isolates of Fusarium spp.
The fungicide, benomyl was found to be most effective as a seed treatment for controlling bakanae disease of rice due to isolates of both F. anthophilum and F. fujikuroi. Thiram was found to be the least effective fungicide for controlling bakanae disease of rice caused by isolates of both the Fusarium spp.
Apart from Fusarium species, other fungi that were also isolated from diseased rice plants and rice seeds were identified as Alternaria alternata, Alternaria longipes, Cochliobolus miyabeanus, Nigrospora sphaerica, Phoma eupyrena, Phoma jolyana, Phoma sorghina and Pithomyces sp. In mycotoxin tests, the isolates of both F. anthophilum and F. fujikuroi produced moniliformin. None of the isolates of F. anthophilum and F. fujikuroi produced fumonisins.
This research is important as it identifies many fungal species in rice plants and seeds in South Africa for the first time. Currently, there is very little literature that makes reference to such findings under South African conditions. In addition, this investigation unravels previously unknown information on the resistance of rice to bakanese disease. Finally, information is provided on the effectiveness of commonly used fungicides (benomyl and thiram) to control rice diseases. This knowledge is crucial information that is useful to plant pathologists, the farming community and the scientists that are involved in strategies of fighting or reducing rice diseases so as to help contribute to food security.Environmental Sciences
D. Phil. (Environmental Science)
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Chissingui, António Valter. "Aplicação dos sistemas de informação geográfica ao sector mineral: caso de estudo – região da Jamba - Angola." Master's thesis, 2010. http://hdl.handle.net/10362/5436.
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Dissertação apresentada como requisito parcial para obtenção do grau de Mestre em Ciência e Sistemas de Informação Geográfica.Há ainda pouco conhecimento sobre o potencial mineral de Angola devido a exiguidade dos estudos feitos até ao presente. Nesta fase procura-se fomentar o sector mineral e uma das várias tecnologias que pode ser utilizada é a tecnologia SIG. A gestão mineral é uma área que muito tem beneficiado dos desenvolvimentos dos SIG e da detecção remota. Os SIG quando usados na gestão mineral como recurso a abordagens e modelos especializados, permitem a caracterização e até a descoberta de novos jazigos e ocorrências minerais. A metodologia aplicada na integração de dados em ambiente SIG foi o método dos pesos de evidência que para este trabalho mostrou ser muito útil. Neste trabalho em particular, o método dos pesos de evidência tornou possível a combinação de evidências como geologia, geoquímica e as zonas de alteração hidrotermal, com base em operações de análise espacial, em ambiente ArcSDM. Os resultados deste estudo foram a criação do mapa de aptidão mineral de ferro para a região da Jamba em Angola, que realça os benefícios da utilização da tecnologia SIG em estudos desta natureza. O conhecimento das várias correlações entre as variáveis usadas no estudo e o produto final que é o mapa de aptidão mineral. A apresentação das vantagens da aquisição e utilização de dados digitais, para desenvolvimento do sector mineral no país e, da Jamba em particular, para correcção de eventuais lacunas existentes.
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Nkosi, Brightness Zama. "Characterisation of Fusarium oxysporum species complex associated with Fusarium wilt of sweet potato in South Africa." Diss., 2020. http://hdl.handle.net/10500/26613.
Full textAbstract:
Sweet potato is a popular food security crop in South Africa and has a considerable commercial value. Fusarium wilt (FW), caused by the fungal pathogen Fusarium oxysporum formae speciales (f. sp.) batatas, has been reported worldwide and is widespread in sweet potato production areas in South Africa. Preliminary molecular identification of South African isolates from diseased sweet potato plants indicated that there are other formae speciales besides F. oxysporum f. sp. batatas associated with FW. The objectives of the study were to conduct a field survey and to characterise the isolates of the Fusarium oxysporum species complex (FOSC) using phylogenetic analyses, morphological characterisation and DNA barcoding. Phylogenetic analyses revealed two other formae speciales, namely F. oxysporum f. sp. tuberosi and F. oxysporum f. sp. vanillae that were associated with FW. This study has contributed in understanding and knowledge of FOSC associated with FW of sweet potato in South Africa.Life and Consumer Sciences
M. Sc. (Life Sciences)