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Les organismes constituant des assemblages d’ennemis naturels des herbivores peuvent interagir de façon variable, influençant ainsi l’efficacité de la lutte biologique. En serriculture, la mouche blanche, Trialeurodes vaporariorum est effectivement contrôlée par une gamme d’ennemis naturels dont le prédateur zoophytophage, Dicyphus hesperus, le champignon entomopathogène Beauveria bassiana et le parasitoïde Encarsia formosa. Cette étude explore les interactions entre ces agents afin d’identifier celles qui sont efficaces. En laboratoire, la capacité discriminatoire du prédateur D. hesperus envers des proies saines, parasitées ou infectées a été étudiée. Le prédateur attaque tant les proies saines que les proies parasitées par E. formosa, mais rejette les proies présentant des symptômes d’infection avancée par B. bassiana. En serre expérimentale, l’impacte de B. bassiana sous sa formule commercialisée de BotaniGard® sur la lutte biologique a été évaluée pendant une saison de production de huit semaines. Une réduction la de prédation des mouches blanches par D. hesperus suggère que ce pathogène interfère avec le prédateur, ce qui pourrait être evité par l’aménagement de refuges dans l’espace et dans le temps pour le prédateur, lors de l’utilisation de B. bassiana. / In Canada, an increasing diversity of natural enemies, which includes generalist predators, is available in the control of greenhouse pests such as the greenhouse whitefly on tomato crops. Successful whitefly suppression is now achieved through the concurrent use of the specialist parasitoid Encarsia formosa, the native zoophytogphagous predatory bug Dicyphus hesperus and products such as biological insecticide BotaniGard®, an entomopathogenic formulation based on the conidia of fungus Beauveria bassiana strain GHA. In this study, experiments conducted in the laboratory and greenhouse evaluated the impact of interactions among these organisms on non-target organisms. In the laboratory, we identified an important decrease in predation of infected whitefly at late infection stages, but not of parasitized whitefly suggesting that D. hesperus may interfere with parasitoid biological control. In the greenhouse, reduced predation of B. bassiana infected whitefly by D. hesperus may be avoided by applying temporal or spatial separation between these two agents.

Orientador: Rogério Lopes Vieites / Banca: Giuseppina Pace P. Lima / Banca: Maria Amalia Brunini / Banca: Moacir Pasqual / Banca: José Darlan Ramos / Resumo: Esta pesquisa teve por objetivo utilizar diferentes doses de irradiação gama sobre frutos de mamão 'Formosa' (Carica papaya L.) pré-cortados e refrigerados, visando facilitar as etapas do processamento mínimo e o consumo, além de encontrar a dose ideal de irradiação que proporcione total segurança alimentar com relação aos microrganismos, ampliando, desta forma, o período de vida útil dos frutos e mantendo as características de qualidade. Todo o processamento do mamão até a embalagem foi executado na Empresa Verde Limpo, situada em Botucatu/SP. Os frutos já embalados foram irradiados na Companhia Brasileira de Esterilização (CBE), em Jarinú/SP. As doses aplicadas foram 0,0; 0,2; 0,4; 0,6; 0,8 e 1,0kGy. Após a irradiação os frutos minimamente processados foram armazenados à temperatura de 9 l 1ºC e umidade relativa de 90 l 5% durante nove dias. As avaliações foram a cada dois dias, exceto as análises microbiológicas que foram nos 1º, 5º e 9º dias de conservação. As alterações na qualidade pós-colheita foram detectadas por meio das seguintes análises: perda de massa fresca (PMF), aparência, textura, acidez titulável (AT), pH, sólidos solúveis (SS), vitamina C, açúcares totais (A.Totais) e redutores (AR), sacarose (S), pectinas total (PT) e solúvel (PS), enzimas poligalacturonase (PG) e pectina metilesterase (PME), análise sensorial (cor, aroma, textura e sabor), índice de doenças e conservação pós-colheita. Para as análises microbiológicas foram identificadas bactérias aeróbicas (mesófilas e psicrotróficas), fungos (leveduras e bolores) e coliformes (totais e fecais). O delineamento estatístico empregado foi DIC inteiramente casualizado com quatro repetições por tratamento, utilizando o programa SISVAR® e teste de Scott-Knott ao nível de 5% de significância...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objective of this research was to evaluate the influence of gamma irradiation on 'Formosa' papaya fresh-cut fruits (Carica papaya L.), stored under refrigeration, in order to facilitate the minimal processing stage and human consumption, finding ideal dose of irradiation that provides total nutritional safety against microorganisms, enlarging fruit shelf life and sustaining quality characteristics. Processing till packing of papaya was executed in Verde Limpo Enterprise, situated on Botucatu/SP. Packing fruits were irradiated on Companhia Brasileira de Irradiação (CBE), placed at Jarinú/SP. Used dose were 0,0; 0.2; 0.4; 0.6; 0.8; and 1.0kGy. After irradiation, the fruits were stored under temperatures of 48.2ºF l 33.8ºF and relative humidity of 90 l 5%, during 9 days and appraised each 2 days. Evaluations were performed each two days, except microbiological analysis, carried up on 1st, 5th and 9th days of conservation. Changes in postharvest quality were detected in the following analysis: loss of fresh weight (LFW), appearance, firmness, titratable acidity (TA), pH, total soluble solids (TSS), vitamin C, total reducer sugars (TRS), reducer sugar (RS), sucrose (S), total pectin (TP), soluble pectin (SP), activity of polygalacturonase (aPG) and pectin methyl esterase (aPME), sensorial analysis (color, aroma, firmness and flavor), disease index and postharvest conservation. Microbiological analysis was performed to identify aerobic bacteria (mesophilic and psychrotrophic), fungi (yeasts and moulds) and coliforms (total and fecal). Data were analyzed according to a completely randomized design, with 4 repetitions per treatment, using SISVAR™ program and Scott-Knottþs test at 5% level of significance. Based on results obtained, it was observed that appearance, color, TA, TP and aPME were significantly improved by gamma irradiation at 0.6kGy...(Complete abstract, click electronic access below) / Doutor

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