Submitted by Ingrid Amaral null (ingridamaral88@hotmail.com) on 2016-04-12T11:56:46Z No. of bitstreams: 1 Dissertação_Mestrado_Ingrid_Amaral.pdf: 455312 bytes, checksum: 62dbe25fd5fc9414cda40cf6b569d002 (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-04-13T14:55:59Z (GMT) No. of bitstreams: 1 mariano_jlm_dr_prud.pdf: 21534624 bytes, checksum: 2f32b2e3ce64ced881d3b801c0ff70c5 (MD5) / Made available in DSpace on 2016-04-13T14:55:59Z (GMT). No. of bitstreams: 1 mariano_jlm_dr_prud.pdf: 21534624 bytes, checksum: 2f32b2e3ce64ced881d3b801c0ff70c5 (MD5) Previous issue date: 2016-02-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O ácaro Brevipalpus yothersi Baker é vetor da leprose dos citros, principal doença viral da citricultura mundial. Informações sobre a biologia de B. yothersi são essenciais para compreender a dinâmica populacional do ácaro no campo e inferir se mudanças no manejo do pomar em função da região pode alterar a biologia do ácaro. O objetivo do trabalho foi determinar a biologia e elaborar a tabela de vida de fertilidade de B. yothersi coletados em diferentes regiões citrícolas do estado de São Paulo. Os experimentos foram realizados no Laboratório de Acarologia, pertencente à Faculdade de Ciências Agrárias e Veterinárias - FCAV/UNESP, Jaboticabal - SP. Os ácaros foram coletados em pomares cítricos das regiões de Barretos, Jales e Santa Cruz do Rio Pardo, posteriormente, em laboratório, foram multiplicados em frutos de laranja. Os parâmetros biológicos avaliados foram duração das fases de desenvolvimento, oviposição, período de incubação, viabilidade dos ovos, longevidade, taxa líquida de reprodução (Ro), tempo médio de geração (T), taxa intrínseca de crescimento populacional (rm) e taxa finita de crescimento populacional (λ). Estes parâmetros foram avaliados em dois experimentos, o primeiro consistiu na biologia de B. yothersi em frutos isentos de resíduos de produtos fitossanitários à 23±1ºC e o segundo sob frutos com resíduo de espirodiclofeno à 25±1ºC. As observações foram realizadas diariamente, pela manhã e ao fim da tarde. A duração do desenvolvimento, longevidade, período de pré-oviposição, taxa de oviposição e número de ovos de B. yothersi apresentaram diferenças entre as populações. O ciclo biológico de B. yothersi criados sobre frutos de laranja varia de 18 a 24 dias, considerando os intervalos de 22º a 26 ºC, 50 a 70% de umidade relativa e fotofase de 14 horas. As diferenças biológicas entre populações de B. yothersi indicam que há diferenças na dinâmica populacional do ácaro no campo, necessitando de manejos adequados para cada região para melhor controle da leprose. / The mite Brevipalpus yothersi Baker is the vector of the citrus leprosis, major viral disease of citrus worldwide. Information about B. yothersi's biology are essential to understanding the population dynamics of the mite in the field and infer whether changes in orchard management by region can change the mite biology. The objective was to determine the biology and prepare the fertility life table of B. yothersi collected in different citrus regions of São Paulo state. The experiments were performed in Acarology Laboratory, belonging to the Faculty of Agricultural and Veterinary Sciences - FCAV/UNESP, Jaboticabal - SP. The mites were collected in citrus orchards in the regions of Barretos, Jales and Santa Cruz do Rio Pardo, later in the laboratory were multiplied in orange fruits. The biological parameters assessed were duration of the stages of development, oviposition, incubation period, egg viability, longevity, net reproductive rate (Ro), mean generation time (T), intrinsic rate of increase (rm) and finite rate increase (λ). These parameters were evaluated in two experiments, the first consisted the biology of B. yothersi in fruits free of residues of pesticides at 23 ± 1°C and the second consisting of the biology of B. yothersi under fruit with spirodiclofen residue at 25 ± 1°C . The observations were performed daily, in the morning and in the afternoon. The duration of the development, longevity, pre-oviposition period, oviposition rate and number of B. yothersi eggs showed differences between populations. The life cycle of B. yothersi created on orange fruit ranges from 18 to 24 days, considering the ranges of 22 to 26°C, 50-70% relative humidity and 14 hours. The biological differences between populations of B. yothersi indicate that there are differences in the population dynamics of the mite in the field, requiring adequate management practices for each region for better control of leprosis.

Made available in DSpace on 2015-04-11T13:55:38Z (GMT). No. of bitstreams: 1 Marcia Reis Pena.pdf: 12445938 bytes, checksum: b868fb90c9a26e2e3e48ab91d6b70a66 (MD5) Previous issue date: 2007-05-02 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The citrus blackfly (Aleurocanthus woglumi) an important pest of the citrus of Asian origin, was detected in Brazil in 2001. The aim of this research was to evaluate the biology and infestation levels of A. woglumi in three host plants (orange Pêra, C. sinensis, acid lime Tahiti, Citrus latifolia and mango, M. indica) and biometry evaluations. For this, experiments were assembled in the period of January to June of 2006 at laboratory conditions. It was verified that acid lime Tahiti had been shown as the most suitable host for A. woglumi. Orange Pêra and mango are similar, being the citrus genus the most favorable to the complete development of A. woglumi. Mango is an appropriate host for A. woglumi. The duration of embrionary development was 15 days on average for the three hosts. The fourth nymph stadium was the longest when compared to the other stages of evolutive cycle. The higher viabilities were on third nymph stages, eggs and second nymph stages. The duration of egg-adult cycle was 70 days on average (2 months and 10 days) for the three hosts evaluated. / A mosca-negra-dos-citros (Aleurocanthus woglumi Ashby) uma importante praga dos citros de origem asiática, foi detectada no Brasil em 2001. O objetivo deste estudo foi avaliar a biologia e os níveis de infestação de A. woglumi em três plantas hospedeiras (laranja Pêra, C. sinensis; lima ácida Tahiti, Citrus latifolia e manga, M. indica) e avaliações de biometria. Para isto, foram montados experimentos no período de janeiro a junho de 2006 em condições de laboratório. Foi verificado que lima ácida Tahiti se mostrou o hospedeiro mais favorável para A. woglumi. Laranja Pêra e manga assemelham-se; sendo que o gênero Citrus se mostrou mais favorável ao desenvolvimento completo de A. woglumi. Manga é um hospedeiro adequado para A. woglumi. A duração do desenvolvimento embrionário foi de 15 dias em média para os três hospedeiros. O estádio de ninfa 4 (pupário) foi o mais longo quando comparado com as outras fases do período desenvolvimento. As maiores viabilidades foram nas fases de ninfa 3, ovos e ninfa 2. A duração do ciclo ovo-adulto foi de 70 dias em média (2 meses e 10 dias) para os três hospedeiros avaliados.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / During the agroindustrial processing steps of guava, are wasted materials such as peel and seed that are considered waste. However, waste represent considerable volumes of alternative sources of nutrients for human nutrition and that are discarded. In this context, this study aimed to determine the composition, physico-chemical and technological properties of the residue of guava, peel and seed, as well as evaluate the effect of diets prepared with this residue as a source of fiber parameters on biological response in Wistar rats. Additionally, cereal bars were developed, using seed meal and peel meal of guava as source of dietary fiber. The residues were analyzed for dry-matter content, ash, protein, lipids, dietary fiber, pectin, phenolic compounds, the copper binding capacity, hidration capacity, syneresis and fat binding capacity. The biological assay was conducted using 40 male Wistar rats, divided into four treatments of 10 animals, with different dietary fiber source: CONT, feed with AIN93G, TC, feed with guava peel, TS, feed with guava seed, TCS, feed with peel and seeds of guava. Later, cereal bars with high fiber content were developed, which were evaluated sensorially and nutritionally by chemical composition. The results showed the peel is a material rich in dietary fiber, highlighting the high content of soluble fiber and pectin. The guava peel is natural source of energy and minerals, with high hydration capacity and low syneresis. The seed showed good yield as a source of fiber, especially insoluble, protein and oil. Peel and seed showed significant value of copper binding capacity and phenolic compounds. Peel and seeds of guava as fiber source in diets of rats did not affect weight gain, average feed intake, feed conversion, epididymal fat, weight of liver and pancreas, total cholesterol, glucose and total protein. The animals submitted to treatment only with peel fibers had higher digestibility, higher content of nitrogen in the faeces, greater weight of the intestine and HDL increased. Treatment only with seed as fiber source allowed shortest time of transit. Regardless of the proportion of peel in the diet, the faces pH waslower. The decrease of triglycerides was greater when seed was introduced into the diet. The formulations of cereal bars tested had an average of 10,93% moisture, 60,55% of total carbohydrates, 9,62% lipids, 8,41% protein, 1,38% ash and 20,02% dietary fiber, increasing the fiber content in relation to the standard formulation. The test formulations showed satisfactory acceptability in all sensory attributes. Was not observed preference by formulation or significant influence of the proportion of waste, except for the texture, for the which the formulation with the highest percentage of waste had the smaller values. The study showed that peel and seeds of guava, usually wasted, have wide applicability in the food industry, being materials nutritious and source of fiber, which can assist be alternatives in order to control of biochemical parameters relevant. The formulations of cereal bar containing peel and seed of guava are source of fiber, consistent with the requirements of today's consumers who want products with nutritional and sensory quality. / Durante as etapas de processamento da goiaba nas agroindústrias, são desperdiçados materiais como a casca e a semente, os chamados resíduos. No entanto, eles possuem volumes consideráveis de fontes alternativas de nutrientes para a nutrição humana e são descartados. Nesse contexto, o presente trabalho teve como objetivo não só determinar a composição e as propriedades físico-químicas e tecnológicas do resíduo de goiaba, casca e semente, como também avaliar o efeito de dietas elaboradas com esse resíduo, como fonte de fibras, sobre parâmetros de resposta biológica em ratos Wistar. Adicionalmente, objetivou-se desenvolver barras de cereais, utilizando a farinha de semente e casca de goiaba como fonte de fibra alimentar. Os resíduos foram analisados quanto aos teores de matéria-seca, cinzas, proteína bruta, lipídeos, fibra alimentar, pectina, compostos fenólicos, capacidade de ligação ao cobre, capacidade de ligação à água, sinérese e capacidade de ligação à gordura. O ensaio biológico foi conduzido utilizando 40 ratos Wistar machos, distribuídos em 4 tratamentos de 10 animais, variando a fonte de fibra alimentar: CONT, ração AIN93G; TC, ração com casca de goiaba; TS, ração com semente de goiaba; TCS, ração com casca e semente de goiaba. Posteriormente, desenvolveram-se barras de cereais ricas em fibras, que foram avaliadas sensorialmente e nutricionalmente através de sua composição química. Os resultados mostraram a casca como material rico em fibras alimentares, destacando o alto teor em fibra solúvel e pectina. Ela é fonte natural de energia, bem como de minerais; tem alta capacidade de hidratação e baixa sinérese. A semente mostrou bom rendimento como fonte de fibras, principalmente insolúveis, proteínas e óleo. Casca e semente apresentaram valor expressivo de CLC e de compostos fenólicos. Como fonte de fibras em dietas para ratos, casca e semente de goiaba não afetaram ganho de peso, consumo alimentar médio, conversão alimentar, gordura epididimal, peso do pâncreas e fígado, colesterol total, glicose e proteínas totais. Os animais submetidos ao tratamento apenas com casca apresentaram maior digestibilidade das fibras, maior teor de nitrogênio nas fezes, maior HDL e maior peso de intestino. O tratamento apenas com semente como fonte de fibra possibilitou menor tempo de trânsito. Independentemente da proporção de casca na dieta, observou-se menor pH das fezes, já a diminuição de triglicerídeos foi maior à medida que a semente foi introduzida na dieta. As formulações de barras de cereais testadas apresentaram em média 10,93% de umidade, 60,55% de carboidratos totais, 9,62% de lipídeos, 8,41% de proteínas, 1,38% de cinzas e 20,02% de fibra alimentar, aumentando o teor de fibras em relação à formulação padrão. As formulações teste apresentaram aceitabilidade satisfatória em todos os atributos sensoriais, sem preferência por formulação e sem influência significativa da proporção de resíduos, exceto na textura, na qual a formulação com maior percentual de resíduos proporcionou menores médias. O trabalho demonstrou que casca e semente de goiaba, usualmente desperdiçados, têm ampla aplicabilidade na indústria alimentícia, sendo materiais nutritivos, fonte de fibras, que podem auxiliar na escolha de alternativas com vista no controle de parâmetros bioquímicos relevantes e que as formulações de barra de cereal contendo casca e semente de goiaba, são fonte de fibras e condizentes com as exigências dos consumidores atuais que desejam produtos com qualidade sensorial e nutricional.

Commercialisées depuis 1996, les plantes génétiquement modifiées produisant une toxine insecticide (toxine Cry) dérivée de Bacillus thuringiensis et appelées plantes Bt ciblent certains Lépidoptères ou Coléoptères ravageurs. Au fil des ans, les surfaces cultivées en plantes Bt sont de plus en plus importantes et contrôlent de larges populations d'insectes. Pour limiter le risque de développement de populations résistantes, une stratégie agricole appelée 'Haute Dose / Zone Refuge' est actuellement recommandée aux Etats-Unis par l'Environmental Protection Agency. Cette stratégie préventive nécessite la plantation d'une 'zone refuge' composée de plantes non-Bt utilisables par le ravageur ciblé et plantée à proximité de la 'zone Bt' qui synthétise une haute dose de toxine Cry. Mon projet de recherche s’inscrit dans le cadre de l’évaluation de l'efficacité de cette stratégie et s’articule en deux phases : une phase expérimentale et une phase théorique. La première se concentre sur la caractérisation en laboratoire de l'impact des toxines Cry sur la biologie d'un ravageur. Cette phase constitue un support au volet théorique : la mise au point d’un modèle mathématique évaluant l'efficacité de la stratégie HD/R. L'originalité de ce projet repose entre autre sur l'interactivité entre ces deux volets. Volet expérimental. Impact des toxines Cry sur la biologie de Plodia interpunctella. Nous évaluons séparément l'impact d'une gamme de concentrations de deux toxines Cry (CryXX et CryYY) sur une série de paramètres comportementaux et biologiques d'un insecte commun des denrées stockées: Plodia interpunctella (Hübner) (Lepidoptera : Pyralidae). Ces paramètres sont sélectionnés car leur variation pourrait avoir un impact sur l'efficacité de la stratégie HD/R dans le contrôle de la résistance. Il est donc pertinent de les quantifier pour intégrer dans le modèle des ordres de grandeur réalistes et générer des résultats qui ne sont pas uniquement basés sur des spéculations théoriques. Volet théorique A. Efficacité de la stratégie HD/R pour des plantes Bt synthétisant une ou deux toxines simultanément. La stratégie 'HD/R' a été développée pour prévenir la résistance envers les plantes Bt synthétisant une seule toxine. Or, depuis 2003, de nouvelles variétés de coton Bt synthétisant simultanément deux toxines Cry sont commercialisées (BollgardII® et WidestrikeTM). Nous évaluons, grâce au modèle que nous avons développé, l'efficacité de cette stratégie lors d'une utilisation exclusive de plantes Bt synthétisant une ou deux toxines. Volet théorique B. Impact du ralentissement du développement des insectes sur les plantes Bt sur l'efficacité de la stratégie HD/R. Le volet expérimental met en évidence un allongement de la durée du développement des larves se nourrissant sur une diète contaminée en toxine Cry. Ce ralentissement induit une séparation temporelle entre l'émergence des adultes de la zone Bt et de la zone refuge et perturbe une hypothèse principale de la stratégie HD/R: le croisement aléatoire entre adultes, indépendamment du génotype et de la zone d'origine. Dans ce troisième chapitre, nous étudions l'impact de la perturbation du croisement aléatoire sur l'efficacité de la stratégie HD/R. Nous testons également deux options pour optimiser la stratégie en cas d'asynchronie: l'utilisation de plantes Bt synthétisant une faible concentration en toxine (atténuant le décalage entre l'émergence des adultes) ou l'augmentation de la taille de la zone refuge (favorisant la survie des individus porteurs d'allèle de sensibilité et donc optimisant la dilution de la résistance à la génération suivante). Ce travail s'intègre dans une problématique actuelle et utilise des outils de biologie théorique (théories de la dynamique et de la génétique des populations) ainsi que le développement d'un modèle mathématique. Il apporte des éléments de réponse et de réflexion sur l'optimisation de la gestion de la résistance des insectes mais c'est aussi une illustration de la complémentarité entre la biologie expérimentale et théorique. / On the market since 1996, genetically modified plants synthesizing an insecticidal toxin (Cry toxin) stemmed from Bacillus thuringiensis, called Bt plants, target several insect pests (Lepidoptera or Coleoptera). Bt crops cover increasingly larger areas and control important pest populations The Insect Resistance Management Strategy (IRM) strategy currently recommended in the U.S.A. to limit the development of resistant populations is the High Dose / Refuge zone (HD/R) strategy. This pre-emptive strategy requires a refuge zone composed by non-Bt plants, usable by the target insect and in close proximity of the Bt zone synthesizing a high toxin concentration. My research project contributes to the effectiveness assessment of this HD/R strategy. It is structured on two main parts: an experimental, and a theoretical section. The first part characterizes the impact of Cry toxins on the biology of an insect pest. It is the basis of the theoretical part: the implementation of a mathematical model, which evaluates the effectiveness of the HD/R strategy. The originality of this project is based on the interactivity of these two components. Experimental section. Impact of the Cry toxins on the biology of Plodia interpunctella. We assess the impact of a range of concentrations of two Cry toxins (CryXX et CryYY) on several behavioural and biological parameters of a common pest of stored products: Plodia interpunctella (Hübner) (Lepidoptera : Pyralidae). These parameters are selected because their variation could influence the effectiveness of a HD/R strategy. So, it is important to quantify these parameters so that realistic values can be integrated in our model. The results of the model are thus not based on theoretical assumptions alone. Theoretical section A. Effectiveness of a HD/R strategy with Bt plants synthesizing one or two toxins. Initially, the HD/R strategy has been developed to limit the resistance towards Bt plants synthesizing one toxin. However, since 2003, new Bt cotton varieties synthesize two toxins simultaneously (BollgardII® et WidestrikeTM). We assess, with our model, the effectiveness of this strategy for Bt plants synthesizing one or two toxins. Theoretical section B. Impact of the slowing down of the insect development reared on Bt plants on the effectiveness of the HD/R strategy. The experimental part demonstrates that larvae reared on a Bt diet have a protracted development duration. The consequence of this is a temporal separation between adult emergence in the two zones (Bt zone and refuge zone). This could affect the main assumption of the HD/R strategy, i. e. random mating independently of the genotype and of the native zone. In this third chapter, we study the impact of random mating disruption on the effectiveness of a HD/R strategy. We test two options to optimise the strategy in case of asynchrony: the use of Bt plants synthesizing a lower toxin concentration (limiting emergence asynchrony) or increasing the refuge zone size (favouring the survival of insect carrying one or two susceptible allele and thus optimising the dilution of resistance at the next generation). This work is applied to a current issue. It uses some of the tools of theoretical biology (theories of population dynamics and population genetics) and develops a mathematical model. It provides some responses and some elements of thought about insect resistance management. It is also an illustration of the complementarity between experimental and theoretical biology.

Inadequately treated wastewater effluent is harmful to the receiving aquatic environment. Water-borne chemicals and microbial pathogens pose a health risk to anyone living downstream from sewage treatment facilities. This study assessed the effluent from a package plant with a design capacity of 48kℓ/24 hours, servicing 12 household units and a restaurant in Mogale City. Over a 12 month period, fortnightly water samples were collected from ten selected sites including two boreholes, a river and two dams. Standard parameters including physical (pH, EC, temperature, DO and SS), chemical (nutrient concentration) and biological (bacterial counts) were analysed using handheld meters, standard membrane filter techniques and colorimetric methods. One borehole was affected by pathogen and nitrate runoff from an adjacent poultry farm. If regularly monitored, the package plant effectively removed microbes (most samples contained 0 cfu/100mℓ) but above limit COD, ammonia and phosphate was released in the effluent (with maximum values of 322 mg/ℓ, 42.52 mg/ℓ and 7.18 mg/ℓ, respectively). Generally, river and dam water at the site was of good quality. / Environmental Science / M. Sc. (Environmental Science)

Inadequately treated wastewater effluent is harmful to the receiving aquatic environment. Water-borne chemicals and microbial pathogens pose a health risk to anyone living downstream from sewage treatment facilities. This study assessed the effluent from a package plant with a design capacity of 48kℓ/24 hours, servicing 12 household units and a restaurant in Mogale City. Over a 12 month period, fortnightly water samples were collected from ten selected sites including two boreholes, a river and two dams. Standard parameters including physical (pH, EC, temperature, DO and SS), chemical (nutrient concentration) and biological (bacterial counts) were analysed using handheld meters, standard membrane filter techniques and colorimetric methods. One borehole was affected by pathogen and nitrate runoff from an adjacent poultry farm. If regularly monitored, the package plant effectively removed microbes (most samples contained 0 cfu/100mℓ) but above limit COD, ammonia and phosphate was released in the effluent (with maximum values of 322 mg/ℓ, 42.52 mg/ℓ and 7.18 mg/ℓ, respectively). Generally, river and dam water at the site was of good quality. / Environmental Science / M. Sc. (Environmental Science)

Commercialisées depuis 1996, les plantes génétiquement modifiées produisant une toxine insecticide (toxine Cry) dérivée de Bacillus thuringiensis et appelées plantes Bt ciblent certains Lépidoptères ou Coléoptères ravageurs. Au fil des ans, les surfaces cultivées en plantes Bt sont de plus en plus importantes et contrôlent de larges populations d'insectes. Pour limiter le risque de développement de populations résistantes, une stratégie agricole appelée 'Haute Dose / Zone Refuge' est actuellement recommandée aux Etats-Unis par l'Environmental Protection Agency. Cette stratégie préventive nécessite la plantation d'une 'zone refuge' composée de plantes non-Bt utilisables par le ravageur ciblé et plantée à proximité de la 'zone Bt' qui synthétise une haute dose de toxine Cry. <p><p>Mon projet de recherche s’inscrit dans le cadre de l’évaluation de l'efficacité de cette stratégie et s’articule en deux phases :une phase expérimentale et une phase théorique. La première se concentre sur la caractérisation en laboratoire de l'impact des toxines Cry sur la biologie d'un ravageur. Cette phase constitue un support au volet théorique :la mise au point d’un modèle mathématique évaluant l'efficacité de la stratégie HD/R. L'originalité de ce projet repose entre autre sur l'interactivité entre ces deux volets.<p><p>Volet expérimental. Impact des toxines Cry sur la biologie de Plodia interpunctella. Nous évaluons séparément l'impact d'une gamme de concentrations de deux toxines Cry (CryXX et CryYY) sur une série de paramètres comportementaux et biologiques d'un insecte commun des denrées stockées: Plodia interpunctella (Hübner) (Lepidoptera :Pyralidae). Ces paramètres sont sélectionnés car leur variation pourrait avoir un impact sur l'efficacité de la stratégie HD/R dans le contrôle de la résistance. Il est donc pertinent de les quantifier pour intégrer dans le modèle des ordres de grandeur réalistes et générer des résultats qui ne sont pas uniquement basés sur des spéculations théoriques.<p><p>Volet théorique A. Efficacité de la stratégie HD/R pour des plantes Bt synthétisant une ou deux toxines simultanément. La stratégie 'HD/R' a été développée pour prévenir la résistance envers les plantes Bt synthétisant une seule toxine. Or, depuis 2003, de nouvelles variétés de coton Bt synthétisant simultanément deux toxines Cry sont commercialisées (BollgardII® et WidestrikeTM). Nous évaluons, grâce au modèle que nous avons développé, l'efficacité de cette stratégie lors d'une utilisation exclusive de plantes Bt synthétisant une ou deux toxines.<p><p>Volet théorique B. Impact du ralentissement du développement des insectes sur les plantes Bt sur l'efficacité de la stratégie HD/R. Le volet expérimental met en évidence un allongement de la durée du développement des larves se nourrissant sur une diète contaminée en toxine Cry. Ce ralentissement induit une séparation temporelle entre l'émergence des adultes de la zone Bt et de la zone refuge et perturbe une hypothèse principale de la stratégie HD/R: le croisement aléatoire entre adultes, indépendamment du génotype et de la zone d'origine. Dans ce troisième chapitre, nous étudions l'impact de la perturbation du croisement aléatoire sur l'efficacité de la stratégie HD/R. Nous testons également deux options pour optimiser la stratégie en cas d'asynchronie: l'utilisation de plantes Bt synthétisant une faible concentration en toxine (atténuant le décalage entre l'émergence des adultes) ou l'augmentation de la taille de la zone refuge (favorisant la survie des individus porteurs d'allèle de sensibilité et donc optimisant la dilution de la résistance à la génération suivante). <p><p>Ce travail s'intègre dans une problématique actuelle et utilise des outils de biologie théorique (théories de la dynamique et de la génétique des populations) ainsi que le développement d'un modèle mathématique. Il apporte des éléments de réponse et de réflexion sur l'optimisation de la gestion de la résistance des insectes mais c'est aussi une illustration de la complémentarité entre la biologie expérimentale et théorique.<p><p><p>/<p><p>On the market since 1996, genetically modified plants synthesizing an insecticidal toxin (Cry toxin) stemmed from Bacillus thuringiensis, called Bt plants, target several insect pests (Lepidoptera or Coleoptera). Bt crops cover increasingly larger areas and control important pest populations The Insect Resistance Management Strategy (IRM) strategy currently recommended in the U.S.A. to limit the development of resistant populations is the High Dose / Refuge zone (HD/R) strategy. This pre-emptive strategy requires a refuge zone composed by non-Bt plants, usable by the target insect and in close proximity of the Bt zone synthesizing a high toxin concentration.<p><p>My research project contributes to the effectiveness assessment of this HD/R strategy. It is structured on two main parts: an experimental, and a theoretical section. The first part characterizes the impact of Cry toxins on the biology of an insect pest. It is the basis of the theoretical part: the implementation of a mathematical model, which evaluates the effectiveness of the HD/R strategy.<p>The originality of this project is based on the interactivity of these two components.<p><p>Experimental section. Impact of the Cry toxins on the biology of Plodia interpunctella. We assess the impact of a range of concentrations of two Cry toxins (CryXX et CryYY) on several behavioural and biological parameters of a common pest of stored products: Plodia interpunctella (Hübner) (Lepidoptera :Pyralidae). These parameters are selected because their variation could influence the effectiveness of a HD/R strategy. So, it is important to quantify these parameters so that realistic values can be integrated in our model. The results of the model are thus not based on theoretical assumptions alone.<p> <p>Theoretical section A. Effectiveness of a HD/R strategy with Bt plants synthesizing one or two toxins. Initially, the HD/R strategy has been developed to limit the resistance towards Bt plants synthesizing one toxin. However, since 2003, new Bt cotton varieties synthesize two toxins simultaneously (BollgardII® et WidestrikeTM). We assess, with our model, the effectiveness of this strategy for Bt plants synthesizing one or two toxins.<p><p>Theoretical section B. Impact of the slowing down of the insect development reared on Bt plants on the effectiveness of the HD/R strategy. The experimental part demonstrates that larvae reared on a Bt diet have a protracted development duration. The consequence of this is a temporal separation between adult emergence in the two zones (Bt zone and refuge zone). This could affect the main assumption of the HD/R strategy, i. e. random mating independently of the genotype and of the native zone. In this third chapter, we study the impact of random mating disruption on the effectiveness of a HD/R strategy. We test two options to optimise the strategy in case of asynchrony: the use of Bt plants synthesizing a lower toxin concentration (limiting emergence asynchrony) or increasing the refuge zone size (favouring the survival of insect carrying one or two susceptible allele and thus optimising the dilution of resistance at the next generation). <p><p>This work is applied to a current issue. It uses some of the tools of theoretical biology (theories of population dynamics and population genetics) and develops a mathematical model. It provides some responses and some elements of thought about insect resistance management. It is also an illustration of the complementarity between experimental and theoretical biology.<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished