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Performance Analysis Of A Compression Ignition Internal Combustion Engine Using Superheated Ethanol VaporAksu, Cagdas 01 December 2011 (has links) (PDF)
The aim of this study is to experimentally measure performance characteristics of a compression ignition (CI) internal combustion engine using superheated ethanol vapor. The engine is a 1.3L inline 4 cylinder direct injection (DI) turbocharged compression ignition (CI) engine. While the engine will be fed with superheated ethanol as homogeneous fuel-air mixture through intake manifold, the amount of diesel fuel that the engine requires to run at idle will also be supplied in order to initiate combustion. Ethanol will be superheated using a new patented double heat exchanger has been manufactured by Prof. Dr. Demir Bayka, Dr. Anil Karel and Deniz Ç / akar. The results will indicate if the suggested concept can be applicable.
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An investigation of coastal fumigation effects on nuclear accident consequences in Hong KongHuang, Aiping, 黃愛平 January 1996 (has links)
published_or_final_version / Mechanical Engineering / Master / Master of Philosophy
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Untersuchungen zur Embryotoxizität von Ozon nach einer in ovo-Begasung beim HuhnThiele, Margrit 21 November 2011 (has links) (PDF)
Die derzeit angewendete Formalinbegasung von Bruteiern zur Keimreduktion stellt ein wichtiges Mittel zum Schutz des Verbrauchers vor dem Eintrag der Salmonellose aus der Geflügelindustrie in die Lebensmittelkette dar. Jedoch verlangt sein kanzerogenes Potenzial die Suche nach einer ebenso effektiven und einfach zu praktizierenden, aber weniger gesundheitlich bedenklichen alternativen Methode. In dieser Arbeit wurde die Eignung einer in ovo-Ozonbegasung zur Bruteidesinfektion hinsichtlich ihrer Auswirkung auf die Embryonalentwicklung untersucht.
Dafür wurden befruchtete Eier vor ihrem Einsatz in den Brüter mit unterschiedlichen Ozonkonzentrationen zwischen 0,5% bis >5,0% (wt/ wt O3 in O2) bei einer relativen Luftfeuchte von 70% in einer Laborkammer begast. Die verwendeten Ozonkonzentrationen wurden dabei in drei Konzentrationsgruppen eingeteilt: hoch (2,8% bis 5,0%), mittel (1,1% bis 2,5%) und niedrig (0,5% bis 1,0%). Nach Erreichen der Zielkonzentration blieben die Eier für eine definierte Einwirkzeit (EWZ) zwischen 0 bis 24 h in der Kammer. Am Bruttag (BT) 18, 19 oder 20 wurden die Überlebensrate (ÜLR), Gewicht und Länge erhoben sowie histologische Untersuchungen der Organe Herz, Leber, Milz und Niere vorgenommen. Bei vier Versuchen erfolgte zusätzlich die Untersuchung am BT 6 und BT 12. Insgesamt wurden 13 Versuchsreihen mit Begasungen in der Laborkammer in den drei genannten Konzentrationsgruppen durchgeführt.
Des Weiteren sollte die Übertragbarkeit der ermittelten Ergebnisse auf eine großtechnische Lösung, durch die Anwendung in einer projektintern entwickelten Prototyp-Kammer überprüft werden. Die Konzipierung dieses Prototyps folgte den technischen Gegebenheiten unter Einbeziehung der ermittelten Ergebnisse zur Embryotoxizität, zur Effektivität der Keimreduktion sowie der Veränderung der Eiinhaltsstoffe. Im Prototyp wurde daher die Begasungskonzentration von 0,7% Ozon bei einer EWZ von 2 h angewendet und in 2 Versuchsreihen hinsichtlich ihrer Auswirkungen auf die Lebensfähigkeit und die morphologische Entwicklung getestet.
Um zusätzlich eine Aussage treffen zu können, welche Wirkung eine hohe Ozonkonzentration bei der Applikation während der Bebrütung zur Folge hat, wurde in zwei weiteren Versuchsreihen jeweils am BT 3, 4 und 5 eine Ozondosis von 5,0% in Kombination mit 1 h EWZ appliziert. Nach der Entnahme der Embryonen am BT 6 bzw. BT 8 erfolgte die morphologische Untersuchung.
Aus der vorliegenden Arbeit wird zusammenfassend geschlussfolgert:
Ozon besitzt einen dosisabhängigen Effekt auf die ÜLR: je höher die Dosis, desto geringer die Überlebensrate. Bei niedrigen Ozonkonzentrationen zwischen 0,5% und 1,0% kommt es zu ÜLR von 90% und 100%.
Die Einwirkzeit stellt einen wichtigen Einflussfaktor auf die Überlebensrate dar. Eine Kombination einer hohen Ozondosis mit langer EWZ hat eine höhere Embryomortalität zur Folge, als eine hohe Ozondosis ohne EWZ. Eine erhöhte Mortalitätsrate zeigt sich auch bei der Kombination einer mittleren Ozondosis mit einer langen EWZ. Keinen Einfluss zeigt sie bei der Kombination mit einer niedrigen Ozonkonzentration.
Ozonierte Embryonen zeigen dosisabhängig eine geringere Längen- oder Gewichtsentwicklung im Vergleich zur Kontrollgruppe. Signifikante Gewichts- und Längenunterschiede lagen nur vereinzelt bei der Begasung mit hoher Ozonkonzentration vor.
Pathohistologische Befunde an Organen, die mit einer Ozonbegasung in Zusammenhang gebracht werden können, konnten nicht erhoben werden.
Die Versuche zur Begasung während der Organogenese wiesen nicht auf ein teratogenes Potenzial von Ozon hin. Korrespondierend mit den Ergebnissen der Begasung am BT 0 zeigte sich ebenfalls eine deutliche Embryotoxizität.
Die Wirkung von Ozon folgt einem Alles-oder-Nichts-Prinzip: entweder die Schädigung ist so stark, dass es zu keiner Entwicklung mehr kommt, oder aber der überlebende Embryo bzw. Fetus zeigt ein phänotypisch normales Aussehen.
Mit den vorgestellten Untersuchungen konnte bewiesen werden, dass bei einer in ovo-Begasung von befruchteten Hühnereiern am Bruttag 0 mit einer niedrigen Ozonkonzentration von 0,5% bis 1,0% in Kombination mit einer mittleren und geringen EWZ keine teratogenen oder embryotoxischen Veränderungen zu erwarten sind.
Aus diesen Befunden ergibt sich ein unbedenklicher Einsatze von Ozon als alternative Methode zur Bruteidesinfektion. Die Voraussetzung dafür ist, dass die großtechnische Lösung die Anwendung von 1,0% Ozonkonzentration in Kombination mit 2 h EWZ ermöglicht, um eine sehr gute ÜLR, Entwicklung und eine 100%ige Inaktivierung des in Legehennenbeständen vorherrschenden Serovars Salmonella Enteritidis zu gewährleisten.
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Estudo para minimização do processo de fumigação empregado na limpeza e desinfecção de salas limpas em Bio-Manguinhos/ FIOCRUZ / Study for minimization of the process of fumigation used in the cleanness and disinfection of clean rooms in Bio-Manguinhos/FIOCRUZStella Martins Patitucci 16 January 2008 (has links)
As indústrias farmacêuticas que utilizam salas limpas, em seus processos produtivos, devem controlar ao máximo o nível de contaminantes microbiológicos, baseada na legislação RDC 210 que determina o cumprimento das diretrizes estabelecidas no Regulamento Técnico das Boas Práticas para a Fabricação de Medicamentos.
Diante deste cenário, a proposta deste trabalho é avaliar o processo de fumigação com o reagente formaldeído, para a limpeza e desinfecção de salas limpas do Instituto de Tecnologia de Imunobiológicos Bio-Manguinhos. Então, foram desenvolvidas as seguintes etapas: diagnóstico com as indústrias farmacêuticas para traçar um perfil quanto ao uso da fumigação; quantificação de resíduos gerados; avaliação da exposição dos operadores ao formaldeído que é cancerígeno e acompanhamento dos resultados do monitoramento ambiental do ar e de superfícies, inicialmente na sala limpa do SEFBC, cuja atividade principal é a formulação de vacinas bacterianas e biofármacos, após a implantação do espaçamento da fumigação.
Os resultados discutidos na presente dissertação mostraram, que a maior parte das indústrias farmacêuticas, não realiza a desinfecção por intermédio da fumigação e que o resíduo gerado neste processo é o mais crítico. E, sobretudo, o monitoramento microbiológico do ar e de superfícies da sala limpa do SEFBC, a partir da metodologia adotada de espaçamento da fumigação, comprovou que não é necessário o emprego deste processo de forma rotineira, para garantir os níveis exigidos de limpeza e desinfecção da respectiva área / Pharmaceutical industries that use clean rooms for their productive processes, must control to a maximum the level of microbiological contaminants, based on RDC 210 legislation that determines the fulfillment of lines in the directions established by the Technical Regulation Program for a Good Medicine Manufacturing.
Ahead to this scene, the purpose of this work was to evaluate the process of fumigation with reacting formaldehyde, for the cleanness and disinfection of clean rooms of the Bio-Manguinhos Institute of Technology of Imunobiológicos. Then, the following stages had been developed: diagnosis with the pharmaceutical industries in order to get a scenario on the use of fumigation; quantification of the residues generated; evaluation of the exposition of operators to formaldehyde, a cancerigenous agent, and screening of the results of the environment monitoring of the air and surfaces, initially in the clean room of the SEFBC, in the areas of biopharmaceuticals formulation, and after a proper implementation of a fumigation process, at pre-defined intervals.
The results thus obtained showed that most of the pharmaceutical industries no longer use disinfection for fumigation and that the residues generated in this process is the most critical problem. The overall microbiological monitoring of the air and surfaces of SEFBC clean room, according to the proposed methodology for fumigation, proved that the use of this process as a routine is not essential to guarantee the demanded levels of cleanness and disinfection of the respective areas
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Phosphine resistance in North American Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)Cato, Aaron January 1900 (has links)
Master of Science / Department of Entomology / Thomas W. Phillips / Resistance of stored-grain insects to the fumigant gas phosphine is becoming common, due to genetic-based resistance. Using proper resistance management, phosphine can continue to be effective with efficient monitoring methods. This thesis focuses on assessing the levels of phosphine resistance across North America in a common stored-product pest, the red flour beetle, Tribolium castaneum (Herbst), and on refining a rapid bioassay method so that resistance can be easily and accurately detected.
Previous work found that phosphine resistance was present in two regions of the USA, the Southeast and Midwest. In this study a discriminating-dose bioassay was used with adult beetles to determine the number of resistant and susceptible individuals in a test population. Adult T. castaneum from 25 locations across the United States and Canada were collected, and 25-60 adults from each population were assessed for the percentage of resistant individuals. Thirteen populations were deemed susceptible with no resistant insects in the samples, while eight populations had 52% or fewer individuals scored as resistant, and four populations had between 88 and 100% resistant individuals. Dose-mortality experiments were conducted to characterize the “strength” of resistance. One population with 41% resistant beetles in the discriminating dose assay was 4.5-fold resistant relative to the susceptible laboratory strain, compared to 127-fold resistant for a population with all 100% scored as resistant. Adult beetles from twelve populations were used to determine if a “knockdown” test of insects exposed to a high concentration of phosphine (3000 ppm) could assess resistance as well as the discriminating-dose mortality assay. The time required for five out of ten beetles to be knocked down, called the KT[subscript]50 for the time to knockdown 50% of the sample, was useful to characterize resistance. Phosphine susceptible beetles had KT[subscript]50 values less than 15 minutes, while samples from resistant populations had KT[subscript]50’s between 15 and 52 minutes. The refined quick test and knowledge of current levels of phosphine resistance in the United States and Canada reported in this thesis point to the importance of such information in developing phosphine resistance management programs for grain insects.
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Modelagem e simulação de sistemas de injeção de gás ozônio para fumigação de grãos de milho (Zea mays L.) utilizando a mecânica dos fluidos computacional / CFD modeling and simulation of ozone gas injection systems for maize grainsPereira Júnior, João Rodrigues 17 April 2009 (has links)
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Previous issue date: 2009-04-17 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The national crop production of grains from 2007 to 2008 was the largest in the history of Brazil, reaching 143.87 million of tons. Among this amount, maize grains respond for 40.7% (58.58 million of tons). The pest control in stored grains is carried out mainly by fumigation with fosfine. It is verified in literature that some insects has been developed resistance to fosfine, and there is no practical fumigant available. The ozone gas is a strong oxidant and it consists on a new technology with great potential for pest control in stored grains. Due to the size of the Brazilian structures for grain storage, experimental tests with alternative fumigants are essentially costly, so the computational fluid mechanics (CFD) arises as a powerful tool for prediction and design injection systems for ozone gas. The aim of this study was the modeling and simulation of injection systems for ozone gas for maize grains stored in a commercial bin using the CFD technique applied to porous media. Two one-dimensional cases of mass transport by convection-diffusion and diffusion-reaction, in which the exact solutions were known, were employed to validate the CFD model. The effects of Péclet number and Thiele modulus on the mass transfer along the porous media were investigated. It was verified that for smaller Péclet numbers the gradient concentration tend to be smooth and constant along the porous media, and when the Péclet number increase, a mesh refinement should be made near the outlet. When the Thiele modulus increases, the concentration gradient for the ozone gas also increases due to its fast consumption by reaction when compared to the axial diffusion transport. The Thiele modulus for the ozone is 41, which means that the decomposition rate is greater than the diffusion rate in the grains mass. Thus, different from the application of fumigants such as the fosfine, the ozone should be injected by convection into the grains mass. For the convectiondiffusion- reaction transport of ozone gas in porous media, the decomposition and saturation kinetics were modeled and used in the CFD model. The ozone gas transport in the model was used to simulate the ozone gas in a fixed bed and the concentration profile was compared to experimental data reported by Kells et al. (2001). The simulation results show good agreement to experimental results and the associated error norm was low. Therefore, the proposed CFD model can be used for simulation of gas ozone injection systems in maize grains. The performance of two injection systems of ozone gas was compared using CFD simulation in a commercial storage bin. Two injection systems were simulated: injection at the base of the silo and using probes. A minimum injection rate of 1.27 kg s-1 and 9.50 kg s-1, for injection at the base and by probes, respectively, was required to reach 50 ppm of ozone in more than 95% of the grain mass. Thus, the injection by the base of the bin is more efficient since it require a smaller mass flow. The proposed model for the ozone transport in porous media is valid and it can be used in other studies of injection systems of ozone in stored grains. / A safra nacional de grãos 2007/2008 foi uma das maiores na história do Brasil, atingindo uma marca em torno de 143,87 milhões de toneladas, com destaque para o milho que responde por, aproximadamente, 40,7% (58,58 milhões de toneladas) deste total. O controle de pragas em grãos armazenados tem sido feito por meio de fumigação e a fosfina é o principal produto usado. São muito escassas as opções para substituir a fosfina, o que representa um grande risco de desenvolvimento de resistência dos insetos a esse produto. O gás ozônio, um forte oxidante, é uma nova tecnologia com potencial para o controle de pragas. Diante deste contexto e devido aos sistemas nacionais de armazenamento que tornam os testes experimentais essencialmente dispendiosos, a mecânica dos fluidos computacional (CFD) desponta como uma importante técnica para predição, manipulação e estudo dos processos de injeção do gás ozônio em sistemas de armazenamento de grãos. Sendo assim, objetivou-se com este trabalho modelar um sistema de injeção de gás ozônio para utilização em armazéns a granel utilizando a técnica de CFD aplicada a meios porosos. Foram modelados dois casos unidimensionais de transporte de massa por convecção-difusão e difusão-reação com soluções analíticas conhecidas. As simulações foram realizadas variando-se o número de Péclet (Pe), no primeiro caso, e o módulo de Thiele (λ), no segundo. Foram sugeridos e ajustados os modelos para a cinética de decomposição e saturação do ozônio. O terceiro caso foi um estudo do transporte de O3 em um leito fixo em que as medidas experimentais de Kells et al. (2001) foram comparadas com os resultados obtidos nas simulações. O quarto caso estudado foi um problema de transporte de ozônio em um leito fixo de milho em que foram avaliadas duas formas de injeção do gás ozônio em um silo de armazenamento. Para o primeiro caso, verificou-se que quanto menor o valor de Pe maior é o gradiente de concentração entre a entrada e saída da coluna (predomínio do termo difusivo). Observou-se que para elevados valores de Pe, um refinamento de malha deve ser efetuado. No segundo caso, verificou-se que, para altos valores do λ, os gradientes de concentração de ozônio são elevados e ocorre rápido consumo devido à reação (predomínio do fenômeno reativo em relação ao difusivo). O módulo de Thiele para o ozônio é 41, o que decorre em maior taxa de decomposição em relação à taxa de difusão na massa de grãos. Desta forma, diferente da aplicação de fumigantes tais como a fosfina, o ozônio deve ser aplicado por um fluxo convectivo. Os resultados obtidos pelo modelo proposto no terceiro caso apresentam um bom ajuste em relação aos resultados experimentais. O erro associado é baixo e a diferença em relação aos dados experimentais pode ser explicada pela diferença nas propriedades físicas do milho utilizadas. O modelo proposto é válido e possibilita a simulação de sistemas de injeção de ozônio em colunas. Foram simulados dois sistemas de injeção de ozônio: pela base do silo e por sondas. Para atingir a concentração de 50 ppm de ozônio (dose letal para insetos) em mais de 95 % da massa de grãos é necessária uma injeção mínima de ozônio pela base e por sonda de 1,27 kg s-1 e 9,50 kg s-1, respectivamente. Desta forma, conclui-se que a injeção pela base do silo é mais eficiente, pois requer um menor fluxo de massa. O modelo proposto para o transporte de ozônio em meios porosos é válido e pode ser utilizado em outros estudos de sistemas de injeção de ozônio em grãos.
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Estudo para minimização do processo de fumigação empregado na limpeza e desinfecção de salas limpas em Bio-Manguinhos/ FIOCRUZ / Study for minimization of the process of fumigation used in the cleanness and disinfection of clean rooms in Bio-Manguinhos/FIOCRUZStella Martins Patitucci 16 January 2008 (has links)
As indústrias farmacêuticas que utilizam salas limpas, em seus processos produtivos, devem controlar ao máximo o nível de contaminantes microbiológicos, baseada na legislação RDC 210 que determina o cumprimento das diretrizes estabelecidas no Regulamento Técnico das Boas Práticas para a Fabricação de Medicamentos.
Diante deste cenário, a proposta deste trabalho é avaliar o processo de fumigação com o reagente formaldeído, para a limpeza e desinfecção de salas limpas do Instituto de Tecnologia de Imunobiológicos Bio-Manguinhos. Então, foram desenvolvidas as seguintes etapas: diagnóstico com as indústrias farmacêuticas para traçar um perfil quanto ao uso da fumigação; quantificação de resíduos gerados; avaliação da exposição dos operadores ao formaldeído que é cancerígeno e acompanhamento dos resultados do monitoramento ambiental do ar e de superfícies, inicialmente na sala limpa do SEFBC, cuja atividade principal é a formulação de vacinas bacterianas e biofármacos, após a implantação do espaçamento da fumigação.
Os resultados discutidos na presente dissertação mostraram, que a maior parte das indústrias farmacêuticas, não realiza a desinfecção por intermédio da fumigação e que o resíduo gerado neste processo é o mais crítico. E, sobretudo, o monitoramento microbiológico do ar e de superfícies da sala limpa do SEFBC, a partir da metodologia adotada de espaçamento da fumigação, comprovou que não é necessário o emprego deste processo de forma rotineira, para garantir os níveis exigidos de limpeza e desinfecção da respectiva área / Pharmaceutical industries that use clean rooms for their productive processes, must control to a maximum the level of microbiological contaminants, based on RDC 210 legislation that determines the fulfillment of lines in the directions established by the Technical Regulation Program for a Good Medicine Manufacturing.
Ahead to this scene, the purpose of this work was to evaluate the process of fumigation with reacting formaldehyde, for the cleanness and disinfection of clean rooms of the Bio-Manguinhos Institute of Technology of Imunobiológicos. Then, the following stages had been developed: diagnosis with the pharmaceutical industries in order to get a scenario on the use of fumigation; quantification of the residues generated; evaluation of the exposition of operators to formaldehyde, a cancerigenous agent, and screening of the results of the environment monitoring of the air and surfaces, initially in the clean room of the SEFBC, in the areas of biopharmaceuticals formulation, and after a proper implementation of a fumigation process, at pre-defined intervals.
The results thus obtained showed that most of the pharmaceutical industries no longer use disinfection for fumigation and that the residues generated in this process is the most critical problem. The overall microbiological monitoring of the air and surfaces of SEFBC clean room, according to the proposed methodology for fumigation, proved that the use of this process as a routine is not essential to guarantee the demanded levels of cleanness and disinfection of the respective areas
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Microbial Community Response to Fumigation in Potato SoilsSmart, Trevor Blake 01 April 2018 (has links)
Soil microorganisms have a variety of beneficial and deleterious effects on plants, impacting such processes as plant growth, soil nutrient cycling, crop yield, disease resistance and tolerance to an array of biotic and abiotic stressors. The disruption of soil microbial community structures, particularly when beneficial soil biota are altered, has been shown to reduce crop yield and leave plants susceptible to disease. Long-term disruption of microbial communities may occur with repeated fumigation, being the application of gaseous pesticides, in agricultural soils. For this reason, we characterized bacterial, fungal, oomycete and nematode populations in paired fumigated and nonfumigated potato fields located in Idaho, Oregon, Washington and Minnesota. Samples were taken at three distinct timepoints: one before a fall fumigation event and two others at important stages in potato production, row closure and vine death. Soil biota populations were assessed by targeting the 16S, 18S and ITS1 gene regions. FunGuild, a database capable of guild and trophic assignment of fungal lineages, was used to sort fungal OTUs in different trophic modes. Fungal analyses indicated an increase in relative abundances of saprotrophic fungal populations and a decrease in pathotrophic fungal populations, both during row closure. Principally, the fungal genera of Humicola and Mortierella were responsible for the increase of saprotrophs while Alternaria decreased the most for pathotrophs. Other fungi occupying multiple trophic modes, such as Fusarium, also decreased during row closure. We found that fumigation treatments, in combination with various pesticide and fertilizer applications, alter both alpha- and beta- bacterial soil diversity although certain treatments, i.e. chloropicrin, may alter bacterial populations more than other treatment types such as metam-sodium. Nematode populations were likewise distinct at each location with soils from Boardman, OR, Minidoka, ID and Pine Point, MN with these having higher levels of nematodes associated with better soil health, i.e. Dorylaimidae. Conversely, nematodes associated with plant pathogenesis were found in higher relative abundances at Minidoka, ID and Quincy, WA. In this study, we characterize the populations of bacteria, fungi, oomycetes and nematodes with an emphasis on fungal taxa. We found that relative abundances of fungal trophic modes vary temporally. Additionally, we catalogue several other high abundance taxa with seasonal differential abundances whose functional capacity in potatoes remain uncharacterized.
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An Integrated Approach for Controlling Verticillium Wilt of StrawberryKoster, Jack T 01 September 2022 (has links) (PDF)
Strawberry (Fragaria x ananassa, Duch.) is an important crop in California, with more than 35,000 acres planted in 2018 resulting in a farm gate value of $3.1 billion. In 2020, California strawberry production accounted for more than 85% of national strawberry production and faces serious threats to production due to various soil-borne diseases. One such disease, Verticillium wilt, is caused by the fungal pathogen Verticillium dahliae and is commonly found in temperate zones around the world where strawberries are grown. Due to the phase-out of efficacious fumigants like methyl bromide, alternative disease management methods have become necessary to alleviate threats to production. Alternative fumigation practices such as crop termination have recently been investigated, and the integration of crop termination with bed fumigation and host resistance can play an integral role in control of Verticillium wilt. A field trial was established at California Polytechnic State University, San Luis Obispo to examine the efficacy of integrative management solutions for control of Verticillium wilt of strawberry in a naturally infested field. The efficacy of sequential fumigation applications of crop termination and bed fumigation was examined. Further, the integration of a resistant cultivar was also implemented in hopes of further decreasing plant mortality and increasing yield. Different fumigant products such as metam potassium, metam sodium, and chloropicrin were used to assess their performance in different fumigation applications. Metam potassium and metam sodium were used for crop termination. When used for crop termination, both products delivered significant reduction in soil inoculum density and adequate crop injury. Metam potassium, metam sodium, and chloropicrin were used for bed fumigation. All products reduced soil inoculum density. Lower plant mortality and higher yield resulted from sequential applications of crop termination and bed fumigation, with average plant mortality for non-treated control plots and sequentially fumigated plots being 67.2% and 24.1%, respectively. There were no significant increases in yield for plots bed fumigated and sequentially crop terminated and bed fumigated, but significant increases in yield for all plots treated versus the non-treated plots were found. The integration of a moderately resistant cultivar Valiant after the fumigation series showed lower mortality and higher yield versus a susceptible cultivar Seascape. A two-year study was also conducted in order to evaluate host resistance to Verticillium wilt in 74 cultivars and elite breeding lines from five strawberry breeding programs. Genotypes were established in a field naturally infested with V. dahliae on the campus farm at California Polytechnic State University, San Luis Obispo. All five breeding programs had a wide range of susceptibility to Verticillium wilt, ranging from 1.5% to 100% mortality for both years of the trial. Twenty-three cultivars and elite breeding lines were common to both years of the trial; of these, five cultivars showed vastly different results between the two years. For example, ‘Monterey’ showed 78.8% mortality in 2021 and 11.5% mortality in 2022. This demonstrates the importance of evaluating host resistance over multiple years under different environmental conditions and field locations.
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Evaluation of Alternative Control Methods for Eliminating Insecticide-Resistant Bed Bugs (Cimex lectularius L.)Todd, Dakotah Brooks 07 February 2023 (has links)
The common bed bug, Cimex lectularius L, has been a persistent pest of humans. Conventional pyrethroid-formulation insecticides are known to be ineffective for controlling modern bed bug populations. This study evaluates alternative treatment methods such as whole-home heat, a biological control agent (Beauveria bassiana), and the fumigant sulfuryl fluoride for control of insecticide-resistant bed bugs. Three heat systems with different energy sources (propane, electric, and glycol) were evaluated to determine attributes contributing to heat treatment efficacy. The glycol system produced the most mortality of the three systems, killing all nymphs, eggs, and most adults. Heat treatment duration and achieving lethal temperatures in complex environments were found to be the most important factors for treatment efficacy. These factors were directly correlated with technician diligence, specifically regarding monitoring surface temperatures and repositioning equipment. A formulation of B. bassiana was evaluated in the laboratory to determine its ability to infect bed bugs under varying conditions of temperature (15°C, 21°C, and 32°C) and humidity (30%, 50%, and 70%). It was found that humidity conditions (30%-50%) at ≈21°C produced the greatest bed bug mortality and the shortest bed bug median survival time. The fumigant sulfuryl fluoride was evaluated for its ability to eliminate bed bugs from motor vehicles and cargo trailers filled to 85% capacity. This study was the first to document that sulfuryl fluoride fumigation at the 1.9X dosage factor can kill all pyrethroid-resistant bed bug life stages (including eggs) in motor vehicles as well as in chambers filled with personal items. / Master of Science in Life Sciences / Since the world-wide bed bug (Cimex lectularius L.) resurgence began in the late 1990s, populations of the common bed bug have been evaluated, but most have been found to be highly resistant to pyrethroid insecticides. This resistance has been particularly troublesome due to the fact that the 1996 US Food Quality Protection Act has eliminated the use of many existing chemistries from indoor use and has inadvertently limited the development of new active ingredients for indoor use due to the cost of the required animal testing to document the No Observable Effects Level (NOEL). Due to the lack of novel chemistry for addressing modern bed bug infestations, pest management professionals have had to identify new methods for applying existing products (chemical and non-chemical) for bed bug control. This study evaluated gaseous, mechanical, and biological control methods for bed bug elimination to determine which factors contribute the most to their efficacy, as well as how these methods might be applied in novel ways for control of bed bugs in homes, personal belongings, and even vehicles.
At the turn of the 20th century heat treatments were used for controlling bed bug infestations in homes and other structures. Today, mechanical heating systems are again being used to control bed bug infestations in homes and apartments. This study investigated the utility of three commercial heating systems for their ability to control existing infestations in apartment units. The three heat systems utilized different energy sources, different types of delivery equipment, and required different set up and take down procedures in apartments of different cubic footage and clutter levels. Overall, the Assault glycol heating system was found to be the most effective in its ability to get (almost) all of our hidden (in hard to heat locations) temperature sensors up to bed bug lethal temperature. Interestingly, our statistical analysis determined that getting the hard to heat locations up to lethal temperature was directly correlated with heat technician activity. The more times that the technician entered the home to monitor the treatment and adjust the equipment positions, the greater the chance of getting the hidden sensors up to bed bug lethal temperature (and killing the bed bugs). However, it was also found that none of the heat systems tested killed all of the sentinel bed bugs in every replicate. Therefore, we learned heat treatments cannot be expected to eliminate each and every bed bug in a home, and that supplemental control products such as desiccants dusts should be applied after every heat treatment. When attempting to determine which heat system was the most effective for killing bed bugs, it was determined that regardless of which heat systems was being used, the attention and activity (monitoring temperatures and adjusting equipment) of the heat treatment technician was the most important factor contributing to bed bug mortality as well as the achievement of bed bug lethal temperatures in cracks and crevices for all three systems.
Our second study examined the environmental factors that influenced fungal growth after bed bug exposure to the insecticidal product Aprehend® (active ingredient Beauveria bassiana). Over the last several decades, this fungus has been widely used to control multiple insect pests. Recently, it has been labelled for bed bug control in indoor environments. This second study was intended to determine the atmospheric conditions (temperature and humidity) under which Aprehend sporulation was most effective for killing bed bugs. It was found that humidity conditions of 30-50% combined with temperatures of ~21°C produced the highest frequency of fungal infection and the shortest median bed bug survival time. This result was surprising because it was originally hypothesized that the 70% humidity condition would be equally effective for promoting fungal growth. However, at all of the temperatures tested, bed bug fungal infection rates at 70% humidity were not as high as those observed when the humidity was within the 30-50% range. Therefore, this study was able to document that the temperatures and humidity combinations that would typically be found within human homes (21oC at 30-50% humidity) were the most effective for producing fungal infections when bed bugs were exposed to the Aprehend product.
The final study addressing novel methods for controlling insecticide resistant bed bugs investigated the efficacy of using Vikane gas fumigant (sulfuryl fluoride) at the 1.9× dosage rate for eliminating bed bugs in two challenging infestation situations: personal vehicles, and confined spaces densely packed with personal belongings. The vehicles used in this study were large minivans with seating that folded into the floor. The confined spaces were cargo trailers filled to 85% capacity with books, furniture, and other household items. Each van and trailer was equipped with ~90 sentinel bed bugs consisting of three groups of 9-11 bed bug eggs, 10 nymphs, and 10 adults. The Vikane Fumiguide calculator was used to determine the target dosage (g-h/m3) to apply in each replicate (e.g., one van or trailer). Sulfuryl fluoride concentrations were measured throughout the fumigation process using a Spectros SF-ReportIR. Concentration readings were input into the Fumiguide to determine when the accumulated dosage (g-h/m3) was achieved, and when aeration should be initiated. After aeration was complete, the sentinel bed bugs were removed from the replicates and bed bug nymph and adult mortality was recorded. Bed bug eggs were monitored for 23 d to determine latent mortality. Fumigated bed bug mortality for each replication was 100% regardless of life stage. Latent mortality was observed in a single bed bug egg, where the nymph never fully hatched. This study determined that fumigation with sulfuryl fluoride at the 1.9× dosage factor is an effective method for eliminating insecticide resistant bed bugs from vehicles and personal belongings in densely packed situations.
Overall, it was found that the Beauveria bassiana product was most effective when applied under atmospheric conditions that are typically found in indoor home environments. This discovery was very reassuring, because the Aprehend product is one of very few that actually have residual activity with regard to bed bug control. This study also found that whole home heat treatments require rigorous pest technician attention and monitoring to achieve the best results. It was also determined that heat treatments cannot be assumed to be 100% effective on their own, and that they should be supplemented with additional (residual) treatment applications. Not surprisingly, fumigation with sulfuryl fluoride was determined to be 100% effective for eliminating bed bugs in personal belongings that had been packed into treatment chambers. The fumigation process also proved to be 100% effective for eliminating bed bug infestations in transport vehicles which cannot not be adequately treated and are at risk for having electronic components damaged if treated with heat.
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