Made available in DSpace on 2014-07-29T15:30:43Z (GMT). No. of bitstreams: 1 AntonioWilson-2006.pdf: 6802842 bytes, checksum: 8134652d892262dcb956b18b01349113 (MD5) Previous issue date: 2006-03-31 / The Chagas disease occurs from the United States to Patagonia, affecting about 16 million peopleThis disease was always associated with poverty conditions which are represented by the primitive houses made out of wood and mud The incidence of this infection in Brazil was estimated at a hundred thousand annual new cases in the end of the seventies and has a prevalence of 4,2% in the rural population The highest rates were found in Minas Gerais and Rio Grande do Sul with the seroprevalence of 8,8% following by Goiás (7,4%) and Bahia (5,4%) In Goiás within 2000 and 2003 249.868 home units were investigated and 51.570 triatomíneos were captured with 335 specimens infected by T. cruzi The peridomiciliar infestation was significantly bigger than the intradomiciliar by the species Triatoma sordida following by Panstrongylus megistus The inverse was observed with the species Rhodnius neglectus Panstrongylus geniculatus and Triatoma pseudomaculata (p <0,018) There was not significant difference in the infestations intra and peridomiciliar by the species Panstrongylus diasi Triatoma costalimai and Triatoma williami Only one specimen of Triatoma infestans was captured in the year 2000 / A infecção chagásica ocorre desde os Estados Unidos até a Patagônia acometendo cerca de 16 milhões de pessoas Essa doença sempre esteve associada às condições de pobreza representadas pelas casas primitivas construídas de artefatos de madeira e barro A incidência dessa infecção no Brasil foi estimada em 100 mil casos novos anuais no final dos anos 70 e prevalência de 4,2% na população rural Os coeficientes mais elevados dessa doença foram encontrados em Minas Gerais e Rio Grande do Sul com a soroprevalência de 8,8% seguidos por Goiás (7,4%) e Bahia (5,4%) Em Goiás no período de 2000 a 2003 foram investigadas 249.868 unidades domiciliares e capturados 51.570 triatomíneos com 335 espécimes infectados com T. cruzi A infestação peridomiciliar foi significativamente maior do que a intradomiciliar na espécie Triatoma sordida, seguida de Panstrongylus megistus O inverso ocorreu nas espécies Rhodnius neglectus Panstrongylus geniculatus e Triatoma pseudomaculata (p< 0,018) Não houve diferença significativa nas infestações intra e peridomiciliar nas espécies Panstrongylus diasi Triatoma costalimai e Triatoma williami. Apenas um exemplar da espécie Triatoma infestans foi capturado no ano de 2000

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The tomato (Lycopersicon esculentum Mill) is an important crop in the world and an important product for trade "in nature and for industry. The amount of fungicides used in tomato crop for control of diseases is high and contributes significantly to production costs of tomato, besides the high risk of intoxication of the applicator and environmental problems. So, the use of disease forecasting systems based on mathematical models to manage the applications of fungicides for foliar diseases control in tomato may to reduce production costs, by decreasing the number of fungicide applications and machinery operation during the culture cycle. The objective was to test the systems for predicting occurrence of late blight (Phytophthora infestans) and early blight (Alternaria solani) on irrigated tomato under two climatic conditions and estimate the cost of deployment. Three experiments were conducted, the first experiment in the spring of 2007, in Santa Maria - RS. The other two were accomplished in Cristalina - GO. There were two seasons of transplanting (01/04/08 and 03/05/08). Used the hybrid U2006 (UNILEVER), with growth habit determined. The spacing between the rows of plants was 1.3 m between plants in rows of 0,3 m. The randomized block design with three replications was used, each plot of 5,2 m wide, consisting of 4 rows of plants with 5 m long. The systems for predicting disease FAST, to early blight, and Blitecast to late blight were used. Irrigation was performed by spraying in Santa Maria and sprinkler, surface drip and subsurface in Cristalina-GO. The results showed that the use of disease forecasting systems is the most appropriate way to control diseases in tomato, as with the use of disease forecasting systems that can significantly reduce the number of fungicide applications in relation the calendar, based on weekly applications in areas with conditions generally unfavorable to the development of disease. Considering the scenarios of reductions of the number of fungicide applications (30, 43 and 65%), compared to the weekly application, in climatic conditions unfavorable to disease development, it is possible to recover the costs of implementing the system prediction in all scenarios. / A cultura do tomate (Lycopersicon esculentum Mill) é uma das mais expressivas culturas no cenário agrícola mundial, constituindo importante produto para o comércio in natura e indústria de extratos. O volume de fungicidas utilizado na cultura do tomateiro no controle das principais doenças é elevado e contribui significativamente nos custos de produção de tomate, além do elevado risco de intoxicação do aplicador e dos problemas ambientais. Nesse sentido, utilização de sistemas de previsão e aviso, baseados em modelos matemáticos para gerenciar o manejo das aplicações de fungicidas para o controle das principais doenças foliares no tomateiro poderá auxiliar na redução dos custos de produção, através da diminuição do número de aplicações de fungicidas e de operações de máquinas durante o ciclo de desenvolvimento da cultura. O objetivo do trabalho foi testar os sistemas de previsão de ocorrência de requeima e alternaria em tomateiro industrial irrigado sob duas condições climáticas e estimar o seu custo de implantação. Foram realizados três experimentos, o primeiro experimento no segundo semestre de 2007, em Santa Maria RS. Os outros dois foram realizados no município de Cristalina GO. Realizaram-se duas épocas de transplante (01/04/08 e 03/05/08). Utilizou-se a cultivar híbrida U2006 (UNILEVER), de hábito de crescimento determinado. O espaçamento entre as fileiras de plantas foi de 1,3 m e entre as plantas nas fileiras de 0,3 m. Utilizou-se o delineamento experimental de Blocos ao Acaso com três repetições, sendo cada parcela de 5,2 m de largura, composta de 4 fileiras de plantas com 5 m de comprimento. Utilizaram-se os sistemas de previsão de doenças FAST, para mancha de alternaria, e BLITECAST, para requeima. A irrigação foi realizada por aspersão em Santa Maria e por aspersão, por gotejamento superficial e subsuperficial em Cristalina. Os resultados mostraram que o uso de sistemas de previsão de doenças é a maneira mais adequada para o controle de doenças na cultura do tomateiro, pois com o uso de sistemas de previsão de doenças se consegue reduzir significativamente o número de aplicações de fungicidas, em relação ao calendário semanal, em regiões com condições geralmente desfavoráveis ao desenvolvimento de doenças. Considerando-se os cenários de reduções do número de aplicação de fungicidas (30, 43 e 65%), em relação ao calendário semanal de aplicação, condições climáticas desfavoráveis ao desenvolvimento de doenças, é possível recuperar os custos de implantação do sistema de previsão em todos os cenários.

Doctor of Philosophy / Department of Plant Pathology / Karen A. Garrett / Late blight of potato, caused by Phytophthora infestans, is a pernicious disease of potatoes worldwide. This disease causes yield losses as a result of foliar and tuber damage. Many models exist to predict late blight risk for control purposes with-in season but rely upon fine-scale weather data collected in hourly, or finer, increments. This is a major constraint when working with disease prediction models for areas of the world where hourly weather data is not available or is unreliable. Weather or climate summary datasets are often available as monthly summaries. These provide a partial solution to this problem with global data at large time-steps (e.g., monthly). Difficulties arise when attempting to use these forms of data in small temporal scale models. My first objective was to develop new approaches for application of disease forecast models to coarser resolution weather data sets. I created metamodels based on daily and monthly weather values which adapt an existing potato late blight model for use with these coarser forms of data using generalized additive models. The daily and monthly weather metamodels have R-squared values of 0.62 and 0.78 respectively. These new models were used to map global late blight risk under current and climate change scenarios resistant and susceptible varieties. Changes in global disease risk for locations where wild potato species are indigenous, and disease risk for countries where chronic malnutrition is a problem were evaluated. Under the climate change scenario selected for use, A1B, future global late blight severity decreases. The risk patterns do not show major changes, areas of high risk remain high relative to areas of low risk with rather slight increases or decreases relative to previous years. Areas of higher wild potato species richness experience slightly increased blight risk, while areas of lower species richness experience a slight decline in risk.

Les oomycètes représentent un groupe d’organismes très diversifiés responsables de diverses maladies d’animaux et de plantes. En agriculture le mildiou de la pomme de terre, causé par un oomycète phytopathogène, occasionne à lui seul des pertes économiques mondiales annuelles de 3 à 5 milliards de dollars américains. La lutte contre le mildiou de la pomme de terre et de la laitue, causés respectivement par, Phytophthora infestans et Bremia lactucae, repose en grande partie sur l’utilisation de fongicides. Cependant, l’apparition de nouvelles souches résistantes au métalaxyl a réduit de manière substantielle l’efficacité des fongicides de synthèse. De plus, les fongicides doivent être appliqués au moment opportun pour être efficaces contre le mildiou. L’approche par modélisation constitue donc une option intéressante pour améliorer la lutte contre les mildious en offrant la possibilité de prédire les périodes à risque et d’améliorer la régie d’application des fongicides. Toutefois, l’évaluation de ces modèles a montré qu’ils manquent de précision et que leur efficacité varie d’une année à l’autre. Ce manque de précision peut s’expliquer en partie par l’absence de considération de la présence ou de l’abondance de l’inoculum aérien. P. infestans et B. lactucae produisent un inoculum adapté à la dispersion aérienne. Cependant, il existe un manque de connaissance notable dans la littérature sur l’aérobiologie de ces deux oomycètes phytopathogènes. Un modèle de simulation dynamique qui intègrerait l’information sur l’aérobiologie de l’agent pathogène permettrait de prédire plus efficacement les périodes de risque d’infection par le mildiou. Ainsi, l’objectif général de ce projet de doctorat était d’améliorer la connaissance sur l’aérobiologie de deux oomycètes (P. infestans et B. lactucae) dans l’optique de mieux comprendre et prédire les périodes d’infection du mildiou de la pomme de terre et de la laitue. Dans un premier temps, la distribution spatiotemporelle des spores à l’échelle d’une région de production de monoculture de pommes de terre a été déterminée. Les résultats ont montré que la distribution des spores est hétérogène et l’efficacité des mesures prophylactiques peut être évaluée à l’aide de l’aire sous la courbe de progression de l’inoculum aérien. De plus, l’information dérivée de l’implantation d’un réseau de capteur permet de pondérer le risque d’infection estimé par les modèles prévisionnels. Dans un deuxième temps, la relation entre la concentration aérienne de spores et l’intensité du mildiou a été établie. Cette relation a permis de définir des seuils d’intervention basés sur la concentration aérienne de spores. Dans le pathosystème de la pomme de terre, le seuil d’intervention varie en fonction des lignées clonales de P. infestans alors que dans celui de la laitue, ce seuil ne tient pas compte des lignées clonales de B. lactucae. Un outil moléculaire pour le comptage des spores a été développé pour pallier aux inconvénients liés à la quantification des spores au microscope. Les résultats de cette étude ont montré, entre autres, que sous conditions climatiques au Canada deux heures de mouillure sont suffisantes pour l’établissement d’une infection par B. lactucae, contrairement aux trois à quatre heures de mouillure proposées dans la littérature. Dans un troisième temps, un modèle de simulation de la concentration aérienne des spores a été développé. La relation entre le nombre de spores observées à l’heure et le nombre de spores prédit à l’heure est linéaire. Dans plus de 94% des cas, les coefficients de détermination de la régression entre le nombre de spores observées et celui prédit sont supérieurs à 0,7. Même si ce modèle est une première dans la littérature publiée et représente une avancée significative dans l’aérobiologie des oomycètes, il est à améliorer notamment dans l’optique de pouvoir développer un modèle générique comme outil de recherche pour l’étude de l’aérobiologie des oomycètes phytopathogènes. En effet, l’étape à venir sera d’incorporer ce modèle comme module dans un système de support décisionnel pour prédire efficacement l’apparition des symptômes de mildiou. Les auteurs espèrent que ce modèle constituera la base pour le développement d’un modèle générique pour tous les oomycètes phytopathogènes à dispersion aérienne.

BACKGROUND:Interruption of vector-borne transmission of Trypanosoma cruzi remains an unrealized objective in many Latin American countries. The task of vector control is complicated by the emergence of vector insects in urban areas.METHODS:Utilizing data from a large-scale vector control program in Arequipa, Peru, we explored the spatial patterns of infestation by Triatoma infestans in an urban and peri-urban landscape. Multilevel logistic regression was utilized to assess the associations between household infestation and household- and locality-level socio-environmental measures.RESULTS:Of 37,229 households inspected for infestation, 6,982 (18.8% / 95% CI: 18.4 - 19.2%) were infested by T. infestans. Eighty clusters of infestation were identified, ranging in area from 0.1 to 68.7 hectares and containing as few as one and as many as 1,139 infested households. Spatial dependence between infested households was significant at distances up to 2,000 meters. Household T. infestans infestation was associated with household- and locality-level factors, including housing density, elevation, land surface temperature, and locality type.CONCLUSIONS:High levels of T. infestans infestation, characterized by spatial heterogeneity, were found across extensive urban and peri-urban areas prior to vector control. Several environmental and social factors, which may directly or indirectly influence the biology and behavior of T. infestans, were associated with infestation. Spatial clustering of infestation in the urban context may both challenge and inform surveillance and control of vector reemergence after insecticide intervention.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Memoria para optar al Titulo Profesional de Médico Veterinario / Mediante el uso de morfometría geométrica, el presente estudio generó una base de datos de las características morfométricas de cabezas de T. infestans de laboratorio, lo que permitirá realizar comparaciones con vectores capturados en el medio ambiente, estableciendo las posibles variaciones presentes entre poblaciones silvestres y de laboratorio. Se estudió un total de 200 individuos obtenidos del Laboratorio de Parasitología de la Facultad de Medicina, Campus Occidente de la Universidad de Chile, los que fueron mantenidos bajo condiciones de laboratorio (25 ºC, 45% humedad relativa y alimentados con sangre de ave). Estos correspondieron a imagos machos, imagos hembras y ninfas IV y V, utilizándose 50 individuos de cada estadio. Para los análisis se recurrió a los programas computacionales de la serie TPS (Thin-plate spline), TPSdig, TPSreg y TPSrelw; para los análisis multivariados se utilizó el programa estadístico JMP (S.A.S. Institute). No se observaron diferencias en conformación entre individuos y entre grupos mediante los análisis de componentes principales y análisis discriminante, pero si se evidenció diferencia significativa en cuanto al tamaño de los diferentes estadios (p < 0.0001). Este aumenta desde el estadio ninfal IV hacia el estadio adulto. Además, se evidenció dimorfismo sexual mediante los análisis de tamaño, siendo la hembra más grande que el macho. Las ninfas de IV estadio presentaron una baja predicción, mientras que las ninfas de V mostraron mayor valor predictivo en relación a las de IV estadio. La ausencia de similitudes en conformación posiblemente se debe a que los grupos pertenecen a una misma población con características genéticas propias y sometidas a un medio ambiente homogéneo. El aumento de tamaño desde los estadios ninfales al adulto está dado por el desarrollo hemimetabólico. Debido al bajo nivel de predicción de las ninfas de IV estadio, se recomienda utilizar las ninfas de V estadio, ya que presentaron un mayor valor predictivo, mostrando cambios más marcados que permiten diferenciarlos de los adultos. Se corroboró la utilidad del ocelo como punto utilizado en estudios de morfometría geométrica y tradicional. Se determinó la utilidad del punto de unión entre cuello y cabeza como punto homólogo, permitiendo comparar los estadios ninfales con los adultos / Proyecto Nº 1070960 del Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)

Memoria para optar al Título Profesional de Médico Veterinario / La enfermedad de Chagas, zoonosis ampliamente distribuida en América, es causada por el protozoo Trypanosoma cruzi que es transmitido principalmente a través de las deyecciones de insectos hematófagos de la subfamilia Reduviidae. En Chile existen tres vectores reconocidos: Triatoma infestans (ciclo doméstico), Mepraia spinolai (ciclo silvestre) y Mepraia gajardoi (ciclo silvestre, pero de zonas costeras) denominadas vulgarmente como vinchucas. El objetivo de esta memoria fue determinar la frecuencia de infección por T. cruzi en los perros procedentes de las viviendas con índice de infestación positivo a T. infestans en las provincias de Petorca, San Felipe y Los Andes durante el periodo 2005-2007. Durante mayo 2008 a enero 2009 se muestrearon 175 perros de viviendas cuyos vectores se encontraron positivos a la infección de T cruzi y de manera proporcional se muestrearon 81 perros de las casas cuyos vectores estaban negativos a T cruzi. Para realizar el diagnóstico se uso por primera vez en Chile una técnica serólogica por inmunocromatografía (Trypanosoma Detect Rapid Test for Canine, InBios. Inbios International, Inc.563 1st Ave. South Suite 600 Seattle, WA 98104). Se dispuso de 200 tiras reactivas. Los resultados obtenidos fueron negativos. Pudiendo concluir, que los perros al ser considerados animales centinelas para esta infección, no existe transmisión activa, a pesar de que la población esta expuesta. Lo anterior se podría deber a que los perros no son una fuente de alimentación preferencial para las vinchucas, o, que las vinchucas provienen de focos silvestres, ya alimentadas, y que solo llegan de manera circunstancial a las viviendas y no lo hacen en búsqueda de alimento

<i>Phytophthora infestans</i>, the oomycete pathogen responsible for late blight of potato and tomato, is regarded as the biggest threat to global potato production and is thought to cost the industry around £6 billion annually. Traditionally, fungicides have been used to control the disease, but this is both economically and environmentally costly, as multiple chemical applications may be required during a single growing season. <i>P. infestans</i> has rapidly overcome genetic resistances introduced into cultivated potato from wild species. This provides the rationale for developing artificial resistance genes to create durable resistance to late blight disease.<i>Phytophthora</i> species secrete essential effectors into plant cells that target critical host cellular mechanisms to promote disease. One such <i>P. infestans</i> effector is AVR3a^KI which is recognised by the potato R3a protein, a member of the CC-NB-LRR type resistance gene family. However, the closely related virulent form, AVR3a^EM, which is homozygous in more than 70% of wild <i>P. infestans</i> isolates, evades this recognition. Domain swapping experiments have revealed that the LRR domain of R3a is involved in recognition of AVR3a^KI, as the CC-NB domain of an R3a-paralog which does not mediate recognition of AVR3a^KI, is able to induce a HR when combined with the LRR of wild-type R3a. However, a chimeric protein consisting of the CC-NB domain of a more distantly-related homolog of R3a and the LRR of domain of R3a, is unable to recognise AVR3a^KI, suggesting that function is achieved only when the different domains of an R protein are attuned to recognition and signalling. Gain-of-function variants of <i>R3a</i> (<i>R3a*</i>), engineered by an iterative process of error-prone PCR, DNA fragmentation, re-assembly of the leucine rich repeat (LRR)-encoding region of <i>R3a</i>, are able to recognise both forms of AVR3a. This gain-of-recognition is accompanied by a gain-of-mechanism, as shown by a cellular re-localisation from the cytoplasm to prevacuolar compartments upon perception of recognised effector forms. However, R3a* variants do not confer resistance to AVR3a^EM-carrying isolates of <i>P. infestans</i>.Future efforts will target the NB-ARC domain of R3a, in a bid to fine-tune the intra-cellular signalling of gain-of-recognition R3a* variants. It is hoped that a shuffled <i>R3a*</i> gene, capable of conferring resistance to <i>P. infestans</i> isolates harbouring AVR3a^EM, will provide durable late blight resistance when deployed in the field in combination with other mechanistically different R proteins.

In this thesis, I set out to investigate the nature of nonhost resistance responses of Nicotianae sylvestris against Phytophthora capsici and P. infestans. Schulze-Lefert and Panstruga (2011) proposed that the inability of a pathogen to establish infection in nonhost plants could be a feature of the phylogenetic distance between host and nonhost plants. In distantly related plants PAMP triggered immunity is thought to be the major contribution to resistance as effectors are inappropriately attuned to perturb their orthologous plant targets. In contrast, effector triggered immunity (ETI) could be the major contributor to resistance in nonhost plants that are more closely related to the host plants. P. capsici and P. infestans can both infect Solanaceae plants including Solanum lycopersicum and N. benthamiana but both fail to cause disease or complete their life-cycle in N. sylvestris. Based on the hypothesis of Schulze-Lefert and Panstruga (2011), ETI should be contributing towards effective nonhost resistance responses in N. sylvestris against both pathogens. In addition, it is tempting to speculate that N. sylvestris, with a limited availability of functional resistance genes including Nucleotid binding-Leucine rich repeats (NB-LRRs), could be setup to recognise and responds to sequence-related effectors from P. infestans and P. capsici, rather than to have resistance genes that are specifically attuned to either pathogen. I conducted three research strands to test this theory. In Chapter 3 I used MCL clustering to classify 563 P. infestans and 515 P. capsici RXLR effector genes and defined families on the basis of sequence similarity. I found that the P. infestans and P. capsici RXLR complements are mostly species-specific. To investigate the role of ETI in nonhost resistance, 48 P. capsici and 82 P. infestans RXLR were screened for recognition by the nonhost plant N. sylvestris. Using this approach I identified 4 P. infestans and 8 P. capsici effectors that are consistently recognised in N. sylvestris (Chapter 4). Surprisingly, most of the recognised effectors are part of species-specific clusters. In Chapter 5 I established and implemented PathSeq, an enrichment and sequencing tool that facilitates the massively parallel study of naturally occurring diversity of pathogen effectors, including those that are recognised in N. sylvestris. In the same chapter I also used PathSeq and de novo prediction to expand the P. infestans RXLR complement from 563 to 1220 putative effectors. In this thesis I have shown that P. infestans and P. capsici effector set are diversifying at the sequence level. My data also suggests that ETI might play a part in nonhost resistance of N. sylvestris to P. capsici and P. infestans. Finally I have presented PathSeq, a tool that allows the study of the effectors set in multiple isolates at the time, and this, for a fraction of the cost of a full genome sequencing experiment.