Introdução: Armadilhas entomológicas são ferramentas importantes nas atividades de vigilância e controle. Poucos estudos foram realizados para avaliar a eficácia de armadilhas contendo Lurex3 como ferramenta na pesquisa entomológica de culicídeos no Vale do Ribeira. Objetivo: Comparar a eficácia das armadilhas, CDC luminosa, CDC com CO2 mais lurex® e Mosquito Magnet® (MM) Independence com lurex® para a captura de culicídeos. Métodos: foram definidos três pontos próximos da mata, onde foram instaladas as armadilhas, sempre às 15:00 hs e removidas às 21:00 hs com revezamento diário, por três dias consecutivos ao mês, por um ano. Resultados: A armadilha CDC-luz capturou o menor número de mosquitos (1.368), seguida da CDC+CO2+lurex (2.284) e da MM (5.477). O teste de Tukey mostrou diferença significativa, indicando a armadilha MM superior, quando comparada com a CDC-luminosa (p < 0,01) e CDC-CO2-lurex (p < 0,03). Não houve diferença significante entre o total de mosquitos coletados na CDC-luminosa e na CDC-CO2- lurex. O número de espécies capturadas na armadilha MM (63 espécies) foi maior do que na CDC-luminosa (p < 0,001) e CDC-CO2-lurex (p < 0,03). Houve uma associação positiva (OR > 1) para as espécies Ae. scapularis, An. bellator, An. cruzii e Ps. ferox quando utilizada a MM e a CDC-CO2-lurex, não houve associação (OR = 1) para a espécie Ae. serratus e Cx. nigripalpus . Conclusões: O poder de captura da MM mostrou ser significativamente maior em comparação às outras duas. A associação entre as espécies antropofílicas, com interesse epidemiológico, foi maior com a MM / Traps are important appliance in entomological surveillance and control activities. Few studies have been conducted to evaluate the efficacy of traps containing Lurex3 in entomological research of mosquitoes in the Ribeira Valley. Objective: Compare the efficacy of traps, CDC light, CO2 plus lurex with CDC and Mosquito Magnet ® (MM) Independence with lurex ® to capture mosquitoes. Methods: defined three points near the forest, where the traps were installed, always at 15:00 pm and removed at 21:00 pm to relay daily for three consecutive days a month in one year. Jaccard and Sorensen indices indicated similarity between traps. To assess diversity employed Renyi profiles. Statistical analyses applied were: ANOVA with Fishers exact test, Tukey test and p value; Chi-square association test and linear regression. Results: The CDC light traps captured the lowest number of mosquitoes (1368), followed by the CDC + CO2 + lurex (2284) and the MM (5477). The Tukey test showed significant differences, indicating the trap MM superior when compared with CDC-light (p <0.01) and CDC-lurex-CO2 (p <0.03). There was no statistically significant difference between the total number of mosquitoes collected in CDC light-and CO2-CDC-lurex. The number of species caught in the trap MM (63 species) was higher than the CDC-light (p <0.001) and CDC-lurex-CO2 (p <0.03). There was a positive association (OR> 1) for the species Ae. scapularis, Anopheles bellator, Anopheles cruzii and Ps. ferox when using the CDC and MM-CO2-lurex, no association (OR = 1) for the species Ae. serratus and Cx nigripalpus. Conclusions: The efficacy of capture of MM was significantly higher compared to the other two. The association between anthropophilic species with epidemiological interest was higher in MM

Orientador: Jose Luiz Boldrini / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-10T14:04:36Z (GMT). No. of bitstreams: 1 Araujo_AndersonLuisAlbuquerquede_M.pdf: 835300 bytes, checksum: 26817c8db069e82f056a44e0e6ebd1d5 (MD5) Previous issue date: 2008 / Resumo: Neste trabalho, consideramos um problema de controle ótimo governado por uma equação diferencial parcial parabólica, que modela o crescimento e a difusão de uma população de mosquitos em uma certa região do plano. Para este modelo relativamente simples, mostramos a existência de uma trajetória ótima a ser seguida por uma unidade volante de pulverização de inseticida, no sentido de minimizar um certo funcional que leva em conta a população total de mosquitos bem como os custos da operação. Caracterizamos também tais trajetórias (controles) ótimas pela derivação de suas respectivas condições de otimalidade de primeira ordem. Para isso, usamos o formalismo de Dubovitskii e Milyutin, o qual está baseado na separação de certos cones associados ao funcional a ser minimizado e ás restrições do problema, incluindo a equação. Também analisamos o problema do ponto de vista do método de penalização / Abstract: In this work, we consider an optimal control problem governed by a parabolic partial differential equation, which models the growth and diffusion of a mosquito population in a certain region of the Euclidean plane. For this relatively simple model, we show the existence of an optimal trajectory to be followed by a insecticide spraying device, in the sense of minimizing a certain functional that takes in consideration both the the total mosquito population and the operational costs. We also characterize such optimal trajectories (controls) by deriving their respective first order optimal conditions. For this, we use the Dubovitskii and Milyutin formalism, which is based on the separation of certain cones associated to the functional to be minimized, and to the restrictions of the problem, including the equation. We also analyze the problem from the point of view of the penalization method / Mestrado / Analise Matematica / Mestre em Matemática

There are thousands of species of mosquitoes, but only a handful of these species carry pathogens that cause human diseases. Here, we study two species, Aedes albopictus and Aedes aegypti, which transmit infections such as dengue, Zika, Mayaro virus, and La Crosse virus. Curtailing these diseases is a good reason to consider control of mosquito populations. However, mosquitoes are quite hardy and spraying of pesticides is typically a short-term solution. Thus, more long-term solutions require careful thought about mosquito populations, including early juvenile aquatic stages: egg, larva, and pupa. In this dissertation, we examine the factors that affect the dynamics of aquatic stages by creating mathematical models. The goal is to assess what key biological features most impact the total population. Both Aedes albopictus and Aedes aegypti lay eggs in small containers, producing limitations on space and food. We investigate how restricting resources changes development time, survival to adulthood, and body mass at emergence. The interactions between these changes are complicated, so to disentangle their effects we create three different mathematical models. The first model is discrete in time and focuses on the best way to incorporate the influence of larval density. We compare the impact of larval density by inputting seven different functional forms altering survival and development time. Larval density used in the model is determined from the average of the population size over the past one to thirty-six days. The second model is also discrete in time but focuses on the interaction between survival, development time, and mass. This model considers three levels of mass. Here, we use the density-dependent function determined from our first model and fit the maximum value for development time from experimental data. Survival values are fit using constants and a density-dependent function. Finally, growth is built in as a function of food. Food decreases at each time point as a function of the total larvae in the environment. We compare between model formulations with Akaike information criterion. The third model examines the ramifications of constricting resources on growth verses death. We employ a partial differential equation that has three independent variables: time, age, and mass. We find that density dependence is highly influential in the maturation of mosquitoes, and it is more essential to include its impacts on development time than on survival. These findings can be incorporated into a larger framework of disease dynamics, and give insight into better control of mosquitoes and disease spread. / Doctor of Philosophy / There are thousands of species of mosquitoes, but only a handful of these species spread human diseases. We specifically study mosquitoes that transmit diseases such as dengue and Zika, which plague large portions of the world. One way to reduce disease spread by mosquitoes is to eliminate the mosquito population, but mosquitoes are becoming resistant to commonly used insecticides. Thus, additional ways to combat mosquitoes are needed. To do so requires a better understanding of how mosquito populations change. This necessitates incorporating information from all life stages of the mosquito, including the juvenile stages that live in the water. In this dissertation, we examine various factors that affect the population size and characteristics of young mosquitoes by creating mathematical models. The goal is to assess what key biological features most impact the population. As young mosquitoes live in aquatic environments, there are limitations on space and food. We investigate how restricting resources changes the time it takes for mosquitoes to develop into adults, how many survive to adulthood, and what their body mass is as new adults. These outcomes interact in complicated way. To disentangle this, we create three different mathematical models. The first model focuses on the best way to incorporate the influence of limiting space or density on population size. The second model focuses on the interaction between mosquito body mass, survival, and time spent as a juvenile. The third model examines how resources alter growth and death and the ensuing mass of mosquitoes. Models are fit to experimental data and validated based on how accurately they describe known patterns. We find that population density is highly influential in the maturation of juvenile mosquitoes and its most important effect is on time spent as a juvenile mosquito. By correlating growth of juvenile mosquitoes to density and resources, our second model is better able to reproduce data. These findings provide important understanding on mosquito populations, which provides insight into how to better control mosquitoes and the diseases they spread.

No description available.

An examination of the Companion Animal Parasite Council's (CAPC) canine heartworm data to clarify the spatial prevalence of heartworm in the United States. Factors thought to influence the spatial risk of disease, as identified in a recent CAPC workshop, are discussed.

Aedes albopictus is an important vector of dengue and chikungunya viruses, and, over recent decades, has resisted traditional control strategies allowing it to spread from its native Southeast Asia throughout the world. In this thesis, two alternative control methods are assessed and developed: transinfection with the inherited bacteria Wolbachia, for population replacement with a refractory strain; and a genetic equivalent to the sterile insect technique, RIDL (Release of Insects carrying a Dominant Lethal), for population suppression. Wolbachia is a genus comprising maternally inherited intracellular α-proteobacteria which primarily infect arthropods. Certain strains of Wolbachia both have the ability to manipulate host reproduction through cytoplasmic incompatibility (CI) which allows Wolbachia to invade host populations by conferring a reproductive advantage on infected females, and have been shown to confer broad-spectrum pathogen resistance on their hosts. Here, a transinfection of wMel in Aedes albopictus (Uju.wMel) was generated which shows complete bidirectional CI with the natural Wolbachia infection of Ae. albopictus, in the absence of any major fitness costs and (as shown by collaborators) completely abolishes dengue and chikungunya virus transmission. It was also shown that the pathogen inhibition in Uju.wMel occurs in the absence of immune stimulation. Evidence supporting cholesterol sequestration by wMel as a mechanism for the pathogen inhibition observed in Uju.wMel was found. Previous attempts to produce a conditionally inviable genetic sexing Ae. albopictus RIDL line have resulted in a sub-optimal strain in which the construct was not sufficiently specific or repressible, resulting in a high proportion of off-target inviable mosquitoes. Here, the mating competitiveness of RIDL males was shown to be not significantly different from wild-type, confirming the potential utility of the system. Multiple truncations of the promoter were made in an attempt to reduce the off-target expression.

Female mosquitoes of the species, Aedes aegypti (yellow fever mosquito, Diptera), blood feed for oogenesis. Therefore, mosquitoes are exposed to high iron loads and possibly blood-borne pathogens. We are interested in studying iron metabolism in A. aegypti to find methods for controlling mosquito populations, and thereby reduce human exposure to these pathogens. First, we found that the expression of the Aedes ferritin light chain homologue (LCH) is up-regulated by blood feeding. Ferritin LCH and heavy chain homologue (HCH) genes are closely clustered together and both mRNA transcripts increase with iron and oxidative stress (H2O2 and hemin). Second, we show A. aegypti larval cells synthesize and secrete ferritin in response to iron. Cytoplasmic ferritin is maximal at low levels of iron, consists of a specific subunit composition and reflects cytoplasmic iron levels. Secreted ferritin increases in linear relationship to increasing iron dose and is composed of different subunits than cytoplasmic ferritin. HCH and LCH transcripts increase with increasing cytoplasmic iron suggesting transcriptional control of ferritin synthesis. We previously reported that the mosquito HCH mRNA has an iron responsive element (IRE), but LCH mRNA does not have a canonical IRE. We show that iron regulatory protein 1 (IRP1)/IRE binding activity declines in response to increasing cytoplasmic iron levels. These data would indicate that HCH synthesis is controlled at transcription and translation. Third, we report that A. aegypti larval cell cytoplasmic iron concentration does not change temporally with iron treatment. However, membrane iron levels increase with iron over time. Iron temporally up-regulates both HCH and LCH mRNA. Ferritin secretion increases with time in response to iron and reflects that most of the intracellular ferritin is found in the membrane fraction. Membrane ferritin has the same subunit composition as cytoplasmic ferritin. Finally, membrane ferritin is found in both non-iron and iron-treated cells. This suggests a mechanism to store iron from a blood meal in membrane ferritin. These results indicate Aedes ferritin could act as an antioxidant and holoferritin secretion is likely the mechanism whereby mosquito cells protect against iron overload and, thus reduce the intracellular potential for iron-mediated oxidative stress during blood feeding.

Arboviruses are transmitted between vertebrate hosts by arthropod vectors, such as mosquitoes or ticks. In vertebrates arboviruses cause cytopathic effects and disease, however, arbovirus infection of arthropods usually results in persistence. Control of arboviral infection is mediated by the arthropod’s immune system. Pathways such as RNAi, JAK/STAT, Toll and IMD have previously been implicated in controlling arbovirus infections. In contrast, the antiviral role of other pathways in mosquitoes, such as melanisation, is unknown. Using high through output 454 sequencing the transcriptome of U4.4 cells infected with the model arbovirus Semliki Forest virus (SFV)(Togaviridae, Alphavirus) was generated. This experiment revealed intriguing patterns of differential transcript abundance that suggest a broad impact of SFV infection in U4.4 cells, such as in metabolism, cell structure and nucleic acid processing. SFV infection induces differential expression of genes in pathways such as apoptosis, stress response and cell cycle. Most interestingly, this study indicated that melanisation might have an antiviral role in mosquitoes. In arthropods, melanisation is a process involved in wound healing and antimicrobial defences. Phenoloxidase (PO), a key enzyme involved in melanisation, is cytotoxic and therefore kept in its inactive form, prophenoloxidase (PPO), until activation is triggered. The PPO activation process is tightly regulated by serine protease inhibitors (serpins) which inhibit the proteolytic activation reaction. In this thesis I demonstrate that the supernatant of cultured Aedes albopictus-derived U4.4 cells contains a functional proPO-activating system, which is activated by infection with bacteria and virions of SFV. Activation of this pathway reduces the spread and infectivity of SFV in vitro and in vivo. In order to further characterise the PO cascade and its antiviral role the serpins in Ae. albopictus were also investigated. Using the transcriptome sequencing and bioinformatics we identified and classified 11 serpins. We silenced each of the serpins and monitored PPO levels and antiviral activity showing that homologues to drosophila’s serpin- 27a plays a role in melanisation against SFV in vitro. Collectively, these results characterise the mosquito PO cascade as a novel immune defence against arbovirus infection in mosquitoes.

Arboviruses are blood-borne pathogens that threaten half of the world’s population. The recent outbreak of Zika virus (ZIKV) in Brazil has highlighted the importance of developing new strategies to limit virus spread. While vaccines are in development, one way to immediately suppress viral transmission is through biocontrol of mosquito vector. Novel biocontrol strategies utilize microbe – mosquito interactions to inhibit the transmission of pathogens. A powerful tool under investigation is the intracellular bacteria, Wolbachia pipientis, which are maintained in insect populations through maternal transmission. The Wolbachia strain wMel can be trans-infected into mosquitos limiting ZIKV transmission. However, thermal stress can hinder maternal transmission of the wMel strain of Wolbachia. For Wolbachia-based technologies of vector control, it is important to have additional strains with viral suppression capabilities available. We characterized alternative Wolbachia strains in A. albopictus mosquito cell lines and the underlying mechanisms of these interactions. We identified two novel Wolbachia strains with robust arbovirus repression. wAlbB, native to mosquitos blocked 90% of ZIKV growth. More strikingly, wStri, a nonnative symbiont, ablated ZIKV growth in A. albopictus cells below the limit of detection. After showing that ZIKV growth is rescued in wStri infected A. albopictus cells by the pharmacological removal of Wolbachia, we established these cells as an in vitro model for mechanistic studies. Using novel labeling and reporter techniques, we isolate a block in virus growth by Wolbachia at two stages of viral growth, entry and translation. We further show that cholesterol, which can partially rescue viral growth in Wolbachia wStri infected cells, aids in viral entry but does not promote viral growth post entry. Beyond our Wolbachia studies, we further investigated the limited arbovirus growth observed in many A. aegypti cell lines and identified two insect–specific viruses which interfere with arbovirus growth. To address the limited biocontrol tools in C. pipiens mosquitos, we characterized commensal microbiota that may be used as a direct competitor of viruses or as a tool to genetically enhance an antiviral response in the mosquito gut. Together this work expands our understanding of Wolbachia-mediated biocontrol strategies and offers novel resources to suppress arbovirus transmission. / 2020-07-18T00:00:00Z

Estágio realizado na CITEVE-Centro Tecnológico das Indústrias Têxtil e do Vestuário de POotugal e orientado pelo Eng.ª Antónia Andarde Lopes e Eng.º José Morgado / Tese de mestrado integrado. Engenharia Química. Faculdade de Engenharia. Universidade do Porto. 2009