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Yadav, Priyanka. "Factors affecting mosquito populations in created wetlands." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1253029098.
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Hoa, Vu Minh, and n/a. "Mosquito habitats and predation efficiency on mosquito populations in Ginninderra Wetland, Canberra, Australia." University of Canberra. Resource & Environmental Science, 1993. http://erl.canberra.edu.au./public/adt-AUC20060725.115344.
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The ecology of mosquito populations in relation to weather conditions,
emergent plants and predation in an urban wetland of Canberra was
studied. Anopheles annulipes, Aedes notoscriptus, Aedes australicus,
Aedes alboannulata, Culex annulirostris and Culex quinquefasciatus
were found. Temperature was a major climatic factor in determining
the abundance of mosquito populations in the wetland. First
collections and subsequent development of mosquitoes in Ginninderra wetland are likely to depend on local weather conditions each year.
The wetland proper was not a suitable habitat for mosquito breeding.
Tall emergent vegetation may have obstructed oviposition and
predation was also important in limiting colonization by mosquitoes.
Instead, isolated temporary waterbodies which were free of predators,
such as ground depressions, tyre tracks, domestic waste containers,
were the most important habitats for mosquitoes adjacent to the
Ginninderra wetland.
Field experiments found that predation of mosquito larvae by
mosquitofish Gambusia qffinis and notonectids Anisops was more
efficient in sunlight than shade and this was affected by the height of
emergent plants.
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Qualls, Whitney Allyn. "Field studies and monitoring of mosquito populations (Diptera:Culicidae) in urban environments." Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Fall/Thesis/QUALLS_WHITNEY_47.pdf.
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Anderson, Robert Derek. "Reducing orthophosphates in retention ponds and its impact on larval mosquito abundance." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 98 p, 2007. http://proquest.umi.com/pqdweb?did=1397903371&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Dalton, Sara. "Strategies for Reducing Mosquito-Borne Disease Vulnerability in Equine Populations: A Kentucky Case Study." TopSCHOLAR®, 2006. http://digitalcommons.wku.edu/theses/451.
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This research examined equine management practices that limit or contribute to the spread of West Nile virus and other mosquito-bome disease. I hypothesize that there is a relationship between equine management practices and outbreaks of mosquito-borne disease in horse populations. Improved and appropriate mosquito habitat management may limit the risk of mosquito-borne disease in humans and horses by helping to lower the mosquito populations. The study goals were to recognize equine management practices and mosquito prevention practices that foster outbreaks of mosquito-borne disease. This study used a questionnaire for county level analysis of equine management practices and the relationship to mosquito-borne disease. This study is important because horses live in a natural setting among unmanaged elements, such as pastures with ponds, wooded areas, and riparian areas. However, horses themselves are highly managed. Equine management practices include pasture horses, who live exclusively outdoors, stabled horses who receive some turn-out time, and ultra-managed horses, such as race horses. Kentucky's economy is partially dependant on the horse industry, which is responsible for over 51,000 jobs and is a major part of the culture of Kentucky. Equine diseases can significantly affect this section of the state's economy. The study area consisted of three categories of noncontiguous counties, with each group containing three to four Kentucky counties. The three selected categories of study highlighted areas of West Nile virus incidence in equine populations. Surveys were distributed to horse owners and barn managers to collect data on differences in equine management practices and outbreaks of mosquito-borne disease. Two categories represented counties with large equine populations, and one category represented counties with low equine populations. Category I consists of the three counties that were selected based on high horse populations and high incidence of West Nile virus in 2002—Barren, Fleming, and Nelson counties. Category II consists of four counties with high equine populations and low incidence of West Nile virus in 2002 - Allen, Grant, Jessamine, and Meade counties. The third category looks at low equine populations and high incidence of West Nile virus in 2002 - Carlisle, Marion, Russell, and Todd counties. Areas with low equine populations and low incidence of West Nile virus were not considered for the study because those areas do not have either high horse populations or high incidence of West Nile virus and hence were not relevant for this particular research question about equine management practices. A minimum of thirty surveys was collected for each category. Statistical analysis was used to determine relationships between incidences of disease, management practices, and knowledge of mosquito prevention. Each survey question was analyzed using the two-tailed version of the two-sample difference of proportion test. West Nile virus is an important disease to study due to the potential economic loss to the horse industry but also because the disease has been responsible for sickness and death in human and animal populations. I studied horses because of the their mix of unmanaged and managed habitat. This study did find a difference in equine management practices when it came to vaccination to prevent West Nile virus occurrences in horse populations. Horse people in categories with high horse populations had a higher use of a West Nile virus vaccine to prevent disease than people use in the low horse population category. While statistics from this study show that there is little or no difference in other equine management practices between the three categories, this research demonstrates that few horse owners and barn mangers limit mosquito habitat around their animals or are aware of IPM techniques. Vaccination lowers the chance that a horse will develop West Nile virus, but it is important that active equine management programs include limiting mosquito habitat to assist in prevention of mosquito-borne disease. Limiting mosquito-borne disease is an important preventive strategy that could protect the health of both horses and humans.
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Autran, Lyris. "Feeding preferences of Chaoborus americanus larvae (Diptera:Chaoboridae) and their potential effect on mosquito populations." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33376.
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Chaoborus americanus larvae were used in laboratory experiments to assess their efficiency at decreasing mosquito larval populations. Third and fourth instar Chaoborus americanus larvae were independently fed assemblages of single prey species to test hunger and several prey species to test preference. Prey species included Daphnia and the four Aedes aegypti larval instars. The results show that Chaoborus americanus larvae will choose early instar mosquito larvae over Daphnia, however, this preference decreases as the mosquito larvae become older. Third instar Chaoborus americanus larvae will choose first instar mosquito larvae over Daphnia 76% of the time, whereas they will select third instar mosquito larvae only 30% of the time. Fourth instar Chaoborus americanus larvae will choose first instar mosquito larvae 94% of the time, and select fourth instar mosquito larvae only 3% of the time. Crowding also has an effect on feeding times; individual Chaoborus larvae take more time to ingest their prey items than do individuals within a group. Chaoborus americanus larvae are good biological control agents within a laboratory setting.
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Modelski, Kimberly A. "Comparison of climatic conditions and mosquito abundances in New Castle County, Delaware." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 3.25 Mb., 229 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1435830.
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Grisales, Alzate N. "Effectiveness of pyriproxyfen and olyset duo in controlling insecticide resistant mosquito populations in Burkina Faso." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3004604/.
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The escalation of Long-Lasting Insecticidal Nets (LLINs) mass distribution marked the beginning of a period of malaria decline in sub-Saharan Africa. However, the emergence and spread of insecticide resistance in malaria mosquitoes is a threat to the effectiveness and sustainability of this vector control method. In this context, it is necessary to design and evaluate new compounds and methods that attenuate or even reverse the insecticide resistance trend. Olyset Duo is a novel LLIN that combines the insecticide properties of permethrin and the chemosterilising effect of pyriproxyfen (PPF). The rationale is that resistant mosquitoes that survive the contact with the net would not be able to transfer the resistance genes to the offspring, eventually influencing the resistant phenotype of the mosquito population. In the first part of this study the sterilising and sub-lethal effect of PPF and Olyset Duo was evaluated by a range of bioassays with laboratory and wild mosquito populations. PPF significantly affected the longevity, oogenesis, oviposition and hatching rate of susceptible and resistant mosquitoes, although the effect was partially diminished on the resistant colonies. The possible reasons and implications of PPF performance under controlled conditions are discussed. The second part of this thesis was done within the context of an Olyset Duo Randomised Controlled Trial (RCT) set in Banfora District, Burkina Faso. The RCT had a stepped-wedge design which ensured that Olyset Duo nets gradually replaced Olyset nets in randomly allocated cluster of villages until the Olyset Duo coverage was total. Wild mosquitoes collected in sentinel sites with Olyset Duo showed evident signs of reproductive impairment even after 1 year of deployment. Insecticide resistance strength was monitored during the RCT in several sentinel sites, and time-response data showed an overall reduction of permethrin resistance strength after the distribution of Olyset Duo. This is the most detailed study on the effect of Olyset Duo on key entomological factors of wild mosquito populations. The standardised protocols as well as the dataset obtained are valuable information for ongoing evaluation of Olyset Duo and PPF as a tool for controlling malaria mosquitoes and as a potential alternative for insecticide resistance management.
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Letaw, Alathea Diana 1984. "The Effects of Rapid Climate Change on Small Populations of the Pitcher-Plant Mosquito, Wyeomyia smithii." Thesis, University of Oregon, 2009. http://hdl.handle.net/1794/10154.
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viii, 21 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.To determine the relative effects of rapid climate change on selection and drift in small populations, nine northern populations of the pitcher-plant mosquito, Wyeomyia smithii, were exposed to directional selection equivalent to 180 years of climate change, while control populations were maintained in their native climate. After three years, fitness had declined in the selected but not the control populations, indicating an adverse effect of climate change. When both selected and control populations were then reared in the selected climate, they showed no difference in fitness, indicating no genetic response to selection. Importantly, however, fitness was negatively correlated with accumulated inbreeding in both control and selected populations, pointing out that the effects of inbreeding and drift exceeded those of selection imposed by rapid climate change. Therefore, small northern populations at expanding edges of species' distributions should be most vulnerable to continued climate change.
Committee in Charge: Dr. William Bradshaw, Chair; Dr. Christina Holzapfel; Dr. Nathan Tublitz
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Yamana, Teresa K. (Teresa Keiko). "Simulations and predictions of mosquito populations in rural Africa using rainfall inputs from satellites and forecasts." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62048.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2010.Page 102 blank. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 94-101).
This thesis describes studies on the use of the Hydrology, Entomology and Malaria Transmission Simulator (HYDREMATS) developed and tested against field data by Bomblies et al. (2008) in simulating and predicting the potential for malaria transmission in rural Africa. The first study examined the temporal resolution of rainfall input required by HYDREMATS. Simulations conducted over Banizoumbou village in Niger showed that for reasonably accurate simulation of mosquito populations, the model requires rainfall data with at least 1 hour resolution. The second study investigated whether HYDREMATS could be effectively forced by satellite based estimates of rainfall instead of ground based observations. The CPC Morphing technique (CMORPH) (Joyce et al., 2004) precipitation estimates distributed by NOAA are available at a 30-minute temporal resolution and 8 km spatial resolution. We compared mosquito populations simulated by HYDREMATS when the model is forced by adjusted CMORPH estimates and by ground observations. The results indicate that adjusted CMORPH rainfall estimates can be used with HYDREMATS to simulate the dynamics of mosquito populations and malaria transmission with accuracy similar to that obtained when using ground observations of rainfall. The third study tested the ability of HYDREMATS to make short term predictions about mosquito populations. A method was developed by which the rainfall forcing for HYDREMATS is constructed to suit a prediction mode. Observed rainfall is used up until the date of the prediction. The rainfall for the following two weeks (or four weeks) is assumed to be the seasonal mean for that period. HYDREMATS predictions using this method were not significantly different from simulations using observed data.This thesis describes studies on the use of the Hydrology, Entomology and Malaria Transmission Simulator (HYDREMATS) developed and tested against field data by Bomblies et al. (2008) in simulating and predicting the potential for malaria transmission in rural Africa. The first study examined the temporal resolution of rainfall input required by HYDREMATS. Simulations conducted over Banizoumbou village in Niger showed that for reasonably accurate simulation of mosquito populations, the model requires rainfall data with at least 1 hour resolution. The second study investigated whether HYDREMATS could be effectively forced by satellite based estimates of rainfall instead of ground based observations. The CPC Morphing technique (CMORPH) (Joyce et al., 2004) precipitation estimates distributed by NOAA are available at a 30-minute temporal resolution and 8 km spatial resolution. We compared mosquito populations simulated by HYDREMATS when the model is forced by adjusted CMORPH estimates and by ground observations. The results indicate that adjusted CMORPH rainfall estimates can be used with HYDREMATS to simulate the dynamics of mosquito populations and malaria transmission with accuracy similar to that obtained when using ground observations of rainfall. The third study tested the ability of HYDREMATS to make short term predictions about mosquito populations. A method was developed by which the rainfall forcing for HYDREMATS is constructed to suit a prediction mode. Observed rainfall is used up until the date of the prediction. The rainfall for the following two weeks (or four weeks) is assumed to be the seasonal mean for that period. HYDREMATS predictions using this method were not significantly different from simulations using observed data.
by Teresa K. Yamana.
S.M.
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Chepkorir, Edith. "Assessing the risk of Transmission of Yellow Fever and Dengue viruses by Aedes (Stegomyia) mosquito populations in Northern Kenya." Thesis, University of Pretoria, 2019. http://hdl.handle.net/2263/75861.
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East Africa has been experiencing an increase in the occurrence of emerging infectious diseases such as yellow fever (YF) and dengue (DEN). Increasing frequency of YF activity in East Africa constitutes a re-emergence that was not detected for over 40 years. Additionally, DEN outbreaks have also increased in frequency and continue to be detected in Kenya and in neighboring countries like Tanzania, Somalia, Djibouti, Eritrea and South Sudan. The renewed vigor of YF and dengue fever (DF) re-emergence in East Africa presents a new challenge to public health in spite of the availability of a safe and effective vaccine for YF. However, there is need to understand the potential for YF and DEN transmission along the border areas of Kenya, because Kenya is classified among countries with medium to high risk for YF transmission. This classification was mainly based on historical data, proximity to countries reporting recent YF outbreaks, the presence of non-human primates known reservoirs for these viruses, unrestricted human movement and presence of potential vector mosquito species. Both YF and DEN share a similar niche in the ecosystem and are associated with Aedes mosquito species of the subgenus Stegomyia. While the factors leading to the re-emergence of these diseases are poorly understood, a better epidemiologic understanding relating to disease ecology including presence of potential vectors, their host blood feeding preferences, the vector competence in transmission of these viruses and evidence of virus circulation in human population, will guide assessment of disease risk in the target areas and help to prevent or mitigate severe outbreaks in this region.Thesis (PhD)--University of Pretoria,2020
National Institute of Health Sciences L'oreal- UNESCO for women in science
Medical Virology
PhD in Medical Virology
Restricted
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Doherty, Melissa Kuckler. "Mosquito Populations in the Powder River Basin, Wyoming: A Comparison of Natural, Agricultural and Effluent Coal Bed Natural Gas Aquatic Habitats." Thesis, Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/doherty/DohertyM1207.pdf.
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Coal bed natural gas development in northeastern Wyoming has increased surface water in ranching and agricultural areas over undeveloped land. This increase of water increases larval habitat for mosquitoes, potentially increasing adult populations of West Nile virus vector mosquitoes. I compared adult and larval mosquito populations in four different habitat types in the Powder River basin including agricultural, natural, CBNG and upland sagebrush steppe. Adult mosquitoes were sampled weekly (2004) or bi-weekly (2005) using CDC miniature black-light traps baited with dry ice. A fixed-effect mixed model indicated that in a normal rainfall year (2005) mature CBNG ponds had the highest adult mosquito populations of all sites sampled, and the highest population of the WNV vector Culex tarsalis. In a drought year (2004) where total rainfall from May - August was 59% of the seasonal average, agricultural areas had the highest mosquito abundance, likely due to increased irrigation. Adult Culex tarsalis tested positive for WNV across the PRB in 2004 and 2005, with highest minimum infection rates in those areas with large Culex tarsalis populations. Larval mosquitoes were sampled bi-weekly from 13 May - 24 August 2005, using a 350 ml dipper in a 20 point vegetated transect along the pond perimeter. Pond vegetation characteristics were recorded between 3 and 17 August including vegetation density, type and class. Larval Culex tarsalis were the most abundant mosquito in the region, representing 47.7% of the total sampled population. A fixed-effects mixed model found Culex tarsalis produced at similar rates in natural, new, old and outlet CBNG sources; irrigated agriculture produced significantly less (P
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Rogasch, Eva [Verfasser], Helge [Akademischer Betreuer] Kampen, Helge [Gutachter] Kampen, and Günter [Gutachter] Schaub. "Diversity, ecology and vector potential of mosquito populations (Diptera: Culicidae) in two differentially structured zoological gardens in Germany / Eva Rogasch ; Gutachter: Helge Kampen, Günter Schaub ; Betreuer: Helge Kampen." Greifswald : Universität Greifswald, 2019. http://d-nb.info/1197232621/34.
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Rogasch, Eva Verfasser], Helge [Akademischer Betreuer] Kampen, Helge [Gutachter] Kampen, and Günter A. [Gutachter] [Schaub. "Diversity, ecology and vector potential of mosquito populations (Diptera: Culicidae) in two differentially structured zoological gardens in Germany / Eva Rogasch ; Gutachter: Helge Kampen, Günter Schaub ; Betreuer: Helge Kampen." Greifswald : Universität Greifswald, 2019. http://d-nb.info/1197232621/34.
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Rogasch, Eva Verfasser], Helge [Akademischer Betreuer] [Kampen, Helge Gutachter] Kampen, and Günter A. [Gutachter] [Schaub. "Diversity, ecology and vector potential of mosquito populations (Diptera: Culicidae) in two differentially structured zoological gardens in Germany / Eva Rogasch ; Gutachter: Helge Kampen, Günter Schaub ; Betreuer: Helge Kampen." Greifswald : Universität Greifswald, 2019. http://nbn-resolving.de/urn:nbn:de:gbv:9-opus-32630.
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Alves, R. O. N. "Avian malaria associations with British mosquitoes." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:dea2e4b0-f4d8-4fae-9209-fa02d083192c.
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Avian malaria (Plasmodium spp.) is a popular model system to study the ecology and evolution of parasite-host-vector interactions in the wild. These studies have historically focused mostly on the avian hosts and the malaria parasites. Knowledge regarding the role of vectors is essential to our understanding of these wild systems, but has only very recently started to accumulate. This thesis aimed to contribute to this field by assessing mosquito-malaria-host associations for British mosquitoes and the role of mosquito ecology in shaping these parasite systems in a British woodland study site, using molecular, field ecology and statistical modelling methodologies. From the 12 mosquito species or species groups found, I showed that the Cx.pipiens/torrentium mosquito group is likely to have a major role in avian malaria transmission in Great Britain, while Cs. annulata may be transmitting P. circumflexum. I also demonstrated a positive spatial association between mosquito density per host and avian malaria prevalence, in accordance with theoretical expectations for malaria transmission. Findings here provide evidence that avian malaria transmission in British woodlands is limited mainly to June-August, being preceded by relapse of previous infections or, alternatively, by maintenance of chronic blood parasitaemia through the colder months; this agrees with theoretical expectations and findings elsewhere for temperate climates. This thesis also described local-scale spatial heterogeneity and seasonal variation in adult mosquito abundance within a British woodland where avian malaria is endemic, with differing patterns found between species or species groups. Spatially, variation in adult mosquito abundance was associated with microclimatic and landscape variables such as distances to mosquito breeding sites, microclimate and canopy height; seasonally, variation in mosquito abundance was associated with temperature and rainfall, alongside calendar date. The heterogeneity in mosquito parameters and associations with environmental variables found at a site where avian malaria is endemic highlights the need to anticipate such complexity when trying to understand Plasmodium transmission. By doing so, we further extend the potential of these parasite systems to improve our knowledge regarding the ecology and evolution of parasite-host-vector associations.
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Sherpa, Stéphanie. "Histoire de la colonisation et déterminants du succès invasif des populations du moustique tigre Aedes albopictus en Europe." Electronic Thesis or Diss., Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAV049.
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Le moustique tigre, Aedes albopictus, originaire d’Asie du Sud-Est, a colonisé l’ensemble des continents excepté l’Antarctique depuis les dernières décennies. En revanche, les raisons du succès invasif des populations à l’échelle mondiale sont encore peu connues. Nous nous sommes concentrés sur l’invasion de l’Europe, et avons combiné différentes méthodes d’analyse et des données multi-sources afin de distinguer le rôle des processus historiques et contemporains, neutres et adaptatifs, dans la structuration de la variabilité génétique des populations invasives. L’analyse de la variabilité génétique de 1000 individus appartenant à 150 populations invasives et natives a révélé trois introductions indépendantes en Europe (en Albanie, au Nord de l’Italie, et au Centre de l’Italie), à partir des Etats-Unis (aire envahie) et de la Chine (aire native). Les populations initialement introduites ont constitué des centres de dispersion en Europe et les voies de migration corrèlent avec la géographie des transports humains. Différents évènements d’admixture au moment de l’introduction ou durant l’expansion subséquente, ainsi qu’une forte connectivité des populations, ont favorisé le maintien d’une forte diversité génétique. Des adaptations au froid préexistantes dans l’aire native de l’espèce et un fort conservatisme de niche entre les populations introduites et leurs sources suggèrent que les populations introduites étaient déjà pré-adaptées pour coloniser les environnements tempérés de l’Europe. Néanmoins, des changements de fréquences alléliques le long des gradients environnementaux en Europe suggèrent également une réponse adaptative après l’introduction. Le potentiel adaptatif des populations, ainsi que la dispersion longue distance assistée par l’homme, ont favorisé l’expansion rapide en Europe. Bien que souvent négligée dans le contexte des invasions biologiques, la dispersion naturelle semble également jouer un rôle dans l’expansion des populations à l’échelle du paysage. L’étude des caractéristiques démo-génétiques des populations invasives et des caractéristiques environnementales de l’aire envahie en Europe a permis d’identifier les processus favorisant deux étapes clés du processus d’invasion: l’établissement et l’expansionThe Asian tiger mosquito, Aedes albopictus, is native to Southeast Asia and has colonized all continents but Antarctica in the last decades. However, the factors determining the invasive success of populations at the global scale remain to be elucidated. Focusing on the European invasion, we used a comprehensive framework and multi-source data for distinguishing the role of historical and contemporary processes, both neutral and adaptive, in structuring the genetic variability of invasive populations. Examining the genetic variability of 1,000 individuals from 150 invasive and native populations revealed three independent introduction events in Europe (in Albania, North Italy, and Central Italy), from the United States (previously invaded area) and from China (native range). Primary introduced populations constituted dispersal centers for the colonization of Europe, and migration routes correlate with the geography of human transportation networks. Several admixture events either during introduction or subsequent expansion, as well as high connectivity between invasive populations, promoted the maintenance of high levels of genetic diversity. Pre-existing cold adaptation within the native range of the species and niche conservatism between introduced populations and their sources suggest that these populations were already prepared for establishing under temperate European climate. Nonetheless, shifts in allele frequencies along environmental gradients within Europe suggest post-introduction adaptive changes. The adaptive potential of populations and long-distance human-aided dispersal facilitated the rapid expansion of populations. Although often neglected in the context of biological invasions, natural dispersal at the landscape scale further contributed to range filling in range edge populations. The study of the demo-genetic and environmental characteristics of the European invasion allows a better understanding of processes at play during two key stages of the invasion process: establishment and expansion
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Conway, Michael. "Improving transgenic approaches to mosquito population control." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:44ba0b39-cded-4e96-a796-570affd53de0.
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The disease vectors Aedes aegypti and Aedes albopictus are serious and growing threats to global health. As vectors of the arboviruses dengue fever and chikungunya, these mosquitoes are responsible for hundreds of millions of cases and thousands of deaths each year. Absent specific treatments or vaccines, effective control of mosquito populations remains the only option for tackling a growing public health challenge. More effective control tools are urgently needed. Recently, a novel approach to pest population control has been developed based on the release of insects carrying a repressible, dominant lethal allele. This approach has achieved dramatic reductions in Ae. aegypti populations in regulated open field experiments. Despite this success, there remains scope to improve upon the current technology. It is proposed that an 'ideal' strain would combine the following features: (i) repressible lethality in late juvenile phases; (ii) a mechanism for removing females at an early developmental stage in the release generation; and (iii) orthogonal expression control mechanisms allowing both these systems to be combined in a single strain. This thesis describes research undertaken in pursuit of a 'next generation' strain. Two novel promoters from putative Osiris genes have been identified which confer a 102-103 – fold up-regulation in transgene expression specific to late pupal stages. One of these 'Osiris' promoters has been used to develop transgenic Aedes aegypti strains. 5 lines showed pupal-specific lethality of 98-100% penetrance, which was repressed in the presence of tetracycline. An Ae. albopictus orthologue of the sex-determining gene doublesex (dsx) has been isolated and characterised and a female-specific expression system developed. Transgenic lines show female-specific expression of a transgene; however, there remains some 'leaky' expression in male insects. Finally, a potential expression control tool based on an auxin-inducible expression system has been investigated. 11 different transgenic lines were developed based on three different construct designs. None showed auxin-inducible expression of a transgene.
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Dawes, Emma J. "The population dynamics of Plasmodium within the mosquito." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/6869.
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Malaria remains one of the world’s most devastating vector-borne parasitic diseases and existing control tools may not be enough to meet the challenge of eliminating malaria in areas of high transmission. Understanding the population dynamics of Plasmodium within the mosquito vector is essential for developing, optimising, and evaluating novel control measures aimed at reducing transmission by targeting this important interface. Malaria research and mathematical models of transmission classically assume that the processes involved in the progression and development of the Plasmodium parasite within Anopheles mosquitoes are independent of parasite density. The research presented in this thesis challenges this assumption, investigating the impact of parasite density on population processes and regulation. A multidisciplinary approach has been taken, including statistical analyses, practical experimentation, and mathematical modelling. The results show that the progression of the rodent malaria Plasmodium berghei through Anopheles stephensi mosquitoes depends nonlinearly on parasite density, with the presence of both negative and positive density-dependent processes in operation. Analyses of other Plasmodium– Anopheles species combinations also indicate that the traditional assumption of density independence may be an oversimplification. Experimental investigation of mosquito mortality illustrates that the survival of a mosquito depends both on mosquito age and parasite density, again in contrast to the assumptions of malaria transmission modelling. A framework for a mathematical model tracking Plasmodium density within the mosquito has been developed as part of this thesis. Further investigation of sporogonic processes will allow this model to be further refined and extended for use in the future design and evaluation of interventions which target the mosquito or the parasite whilst within the vector.
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Hambrick, Bethany Lynn. "Population Dynamics and Community Structure of Mosquitoes (Diptera: Culicidae) Recorded in Denton, Texas from 2005 to 2015." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1157552/.
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A population survey was conducted on the mosquito species recorded in Denton, Texas for the years of 2005 to 2015. Data used in this project were obtained from an ongoing, long-term surveillance program led by the City of Denton and conducted through the University of North Texas. Research focused on the population dynamics and community structure of mosquitoes collected within urban areas of Denton, Texas in relation to certain environmental variables. A total of 80,837 female mosquitoes were captured and represented 38 species found under the following genera: Aedes, Anopheles, Coquillettidia, Culex, Culiseta, Mansonia, Orthopodomyia, Psorophora, Toxorhynchites, and Uranotaenia. Culex quinquefasciatus was the most abundant species followed by Aedes vexans. Seasonal patterns of the most abundant species revealed high variability throughout the study. Container breeders were most abundant in August and those that breed in floodwaters were most abundant in the months of May and September. Samples were tested for arbovirus presence through the Texas Department of State Health Services in Austin, Texas and multiple pools tested positive for West Nile virus throughout the study. Stepwise multiple regression and Spearman's rank correlation analyses were performed to examine the relationship between the mosquito community and environmental variables. Data revealed that temperature, precipitation, and dew point were the most important variables influencing the mosquito population in the City of Denton.
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Renshaw, Melaine. "Population dynamics and ecology of Aedes cantans (Dipitera: Culicidae) in England." Thesis, University of Liverpool, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317233.
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Bataille, Arnaud. "Population Genetics and Disease Ecology of Mosquito species in Galapagos." Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.509032.
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O'Donnell, Deborah Ladner. "Ecology and population differentiation of the Asian tiger mosquito, Aedes albopictus." Connect to Electronic Thesis (CONTENTdm) Connect to Electronic Thesis (ProQuest), 2009. http://worldcat.org/oclc/525201539/viewonline.
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Walker, Melody. "Modelling Allee effects in a transgenic mosquito population during range expansion." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83598.
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Mosquitoes are vectors for many diseases that cause significant mortality and morbidity across the globe such as malaria, dengue fever and Zika. As mosquito populations expand their range into new areas, they may undergo mate-finding Allee effects such that their ability to successfully reproduce becomes difficult at low population densities. With new technology, creating target specific gene modification may now be a viable method for mosquito population control. We develop a mathematical model to investigate the effects of releasing transgenic mosquitoes into newly established low-density mosquito populations. Our model consists of two life stages (aquatic and adult), which are further divided into three genetically distinct groups: heterogeneous and homogeneous transgenic alleles that cause female infertility and a homogeneous wild type. We perform analytical and numerical analyses on the equilibria to determine the level of saturation needed to eliminate mosquitoes in a given area. This model demonstrates the potential for a gene drive system to reduce the spread of invading mosquito populations.Master of Science
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Mina, Petrić. "Modelling the influence of meteorological conditions on mosquito vector population dynamics (Diptera, Culicidae)." Phd thesis, Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, 2020. https://www.cris.uns.ac.rs/record.jsf?recordId=114757&source=NDLTD&language=en.
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Meteorological conditions have a significant influence on the time of occurrence, abundance and activity of the mosquito vector. In the current context of climate change, it is of great importance to assess the impact of shifts in climatic conditions on the suitability for the establishment and annual activity of the vector species. Moreover, changes in the variability of meteorological elements and their extremes can generate unexpected changes in the mosquito vector population which in turn have an important effect on human health. One of the ways to put these causes and effects into perspective is to simulate the activity of the vector within a processbased framework which allows for the analysis of the contribution of individual factors on the different life stages of the vector. Such analysis is presented by use of sophisticated dynamical models simulating the characteristics of the biological population, forced by observed meteorological data, capturing the localmicro-environment of the vector habitat, and validated by the observed entomology.Numerical models are being developed to model vector population dynamics and the expected circulation of the virus within a closed system. Two modelling approaches are standardly applied to modelling vector population dynamics: Mechanistic and Stochastic. The advantage of mechanistic overstatistical models is that they can provide a deterministic framework allowing for the isolated evaluation of each input parameter and their effect on the modelled system. Mechanistic dynamical models are used to describe the biophysical processes or partof the process as a response to changes in the meteorological conditions.The work carried out in this thesis can be summarized as follows: (i) Analysis of the association between the most important abiotic drivers influencing the population dynamics, annual activity and time of occurrence of Culex pipiens and Aedes aegypti; (ii) Identifying the most important climatic factors and model settings as a function of climatic characteristics of the study region; (iii) Modelling the vector population dynamics and stability analysis of the dynamical system (iv) Analysis of different verification techniques and implications in terms of model application; (v) Feasibility analysis ofimproving the model with a Land-Surface Parametrization scheme and short-range forecasting of pest population dynamics.Meteorološki uslovi bitno utiču na vreme pojave, brojnost vektora i njihovu aktivnost. U uslovima evidentnih promene klime, od ogromne je važnosti sagledati uticaj očekivanih promena klime na pogodnost uslova na pojavu izabranih vektora.Takodje, značajne promene kolebanja meteoroloških elemenata u odnosu na višegodišnji prosek i sve češće pojave nepovoljnih vremenskih prilika dovode do neočekivanog ponašanja populacije komarca što značajno utiče na kvalitet života i zdravlje ljudi. Jedini način da se sagledaju uzroci i posledice navedenih pojava zasniva se na simulaciji aktivnosti i brojnosti vektora uz mogućnost testiranja uticaja svakog pojedinačnog faktora. Ovu mogućnost pružaju samo visoko sofistikovani dinamički modeli koju su prošli proces kalibracije i validacije zasnovanna izmerenim vrednostima meteoroloških elemenata i karakteristika biološke populacije.Sofistikovani modeli za simulaciju dinamike populacije vektora i očekivane cirkulacije vektorskih transmisivnih bolesti se koriste sa ciljem modeliranja potencijalnog rizika od zaraze i epidemije. Modeli zasimulaciju dinamike vektora mogu da se podele na dve glavne grupe: Mehanističke i Statističke. Prednost mehanističkih modela nad statističkim je što mogu da se koriste za evaluaciju uticaja izolovanog faktora na dinamički sistem i odgovarajuće promene brojnosti unutar svake faze u razvoju vektora. Mehanistički dinamički sistemi se koriste kako bi se opisao mehanizam biofizičkog procesa ili dela procesa u zavisnosti od forsirajuće veličine.Predmet istraživanja u ovom radu jeste identifikovanje najznačajnijih bioloških i fizičkih procesa kao i odgovarajućih faktora koji utiču na brojnost i aktivnost vektora roda Aedes i Culex. Ciljevi istraživanja mogu da se sumiraju na sledeći način: (i)analiza najznačajnijih meteoroloških parametara koji utiču na vreme pojave, brojnost i aktivnost vektora Aedes i Culex roda; (ii) definisanje najznačajnijih klimatskih faktora i stepena osetljivosti procesa na njih; (iii) modeliranje dinamike populacije vektora i analiza stabilnosti dinamičkog sistema; (iv) verifikacija i analiza metoda verifikacije i validacije dinamičkog modela; (v) kratkoročna prognoza dinamike populacije komarca i formulacija hidrološkog modula upotrebom SURFEX površinskešeme sa ECOCLIMAP fiziogeografskim podacima.
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Bolling, Bethany G. "Use of Geographic Information System and Remote Sensing Technologies to Describe Mosquito Population Dynamics in the Ray Roberts Greenbelt, Denton County, Texas." Thesis, University of North Texas, 2003. https://digital.library.unt.edu/ark:/67531/metadc4160/.
Full textAbstract:
A population survey was conducted from April through September 2002 on mosquito species occurring on the Ray Roberts Greenbelt, a riparian corridor used for public recreation on the Elm Fork of the Trinity River, in Denton County, Texas. ArcGIS software was used to set up a stratified random sampling design based on habitat parameters. Multivariate analyses of sampling data and climatic variables were used to describe spatial and temporal patterns of mosquito species. A total of 33 species were collected during this study belonging to the following genera: Aedes, Anopheles, Coquillettidia, Culex, Mansonia, Ochlerotatus, Orthopodomyia, Psorophora, Toxorhynchites, and Uranotaenia. Seasonal distributions of the dominant species revealed population fluctuations. Aedes vexans was the primary species collected in April and May, occurring in low numbers throughout the rest of the sampling period. Psorophora columbiae reached its highest population density in June, with a smaller peak occurring in late July. Present from May through the end of September, Culex erraticus was the most abundant species collected with major peaks in mid-June and the end of July. Abundance of Culex salinarius followed the same general trend as that for Cx. erraticus, but with smaller numbers. The specimens were tested for a variety of arboviruses by the Texas Department of Health. One pool of Cx. erraticus and Cx. salinarius, collected in August 2002, tested positive for West Nile virus. Variables that were important factors for determining dominant species abundance were temperature, wind speed, rain accumulation occurring one-week and two-weeks prior to sampling, number of day since last rain event, dew point, and average canopy coverage.
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Sikaala, Chadwick. "Community-based monitoring of vector control interventions impact upon mosquito population dynamics in rural Zambia." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2006479/.
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Over the last decade, the malaria burden has reduced drastically across many parts of sub-Saharan Africa. This is mainly due to effective implementation of integrated malaria control programmes that include large scale application of vector control in the form of long-lasting insecticidal nest (LLINs) and indoor residual spraying (IRS), both of which target the most efficient human-seeking malaria vector species. However, in spite of these efforts, malaria has yet to be eliminated from most of Africa. However, recent increases in the physiological resistance of vector populations, especially to the pyrethroids that remain the only active ingredients currently used on nets threaten these achievements. Furthermore, various forms of behavioural resilience and resistance exhibited by some vector species to LLIN and IRS delivery formats for insecticides respectively limit and undermine these valuable impacts upon malaria transmission. To monitor the impact that LLINs and IRS have on vector population dynamics and malaria transmission, more effective, practical and affordable entomological surveillance systems are required. Currently, surveillance of mosquito populations are conducted by the centralized specialist teams with limited personnel, resources and geographic outreach. None of these existing systems can adequately monitor vector population dynamics longitudinally across the vastness of entire countries. The overall goal of the study was to demonstrate how a community-based surveillance system can be applied to longitudinally monitor vector population dynamics and assess the impact that LLINs and IRS have on malaria transmission in rural Zambia. To achieve this overall goal, the following specific objectives were addressed: (1) To evaluate the efficacy of exposure-free mosquito trapping methods for measuring malaria vector density, as alternatives to human landing catch; (2) To assess the cost-effectiveness using a community-based (CB) mosquito trapping scheme for monitoring vector population dynamics; (3) To determine the extent to which a community-based mosquito trapping scheme captures trends in epidemiological indicators of malaria infection risk; (4) To determine the impact of indoor residual spraying with different classes of insecticides on malaria infection burden and vector abundances in an area of high coverage with insecticide treated nets using a community-based platform. To address objective 1, a 3 x 3 Latin square method was used to evaluate the sensitivity of the Center for Disease and Control and Prevention miniature light traps (LT), the Ifakara tent trap (ITT), window exit traps (WET) and the resting boxes (RB) using the golden standard human land catch (HLC) as the reference method. The mean catches of HLC indoor, HLC outdoor, CDC-LT, ITT, WET, RB indoor and RB outdoor, were 1.687, 1.004, 3.267, 0.088, 0.004, 0.000 and 0.008 for Anopheles quadriannulatus Theobald respectively, and 7.287, 6.784, 10.958, 5.875, 0.296, 0.158 and 0.458, for An. funestus Giles, respectively. The LT (Relative rate (RR) [95% Confidence Interval] = 1.532 [1.441, 1.628] P < 0.001) and ITT (RR = 0.821 [0.765, 0.881], P < 0.001), were the only exposure-free alternatives which had comparable sensitivities relative to HLC indoor for sampling An. funestus. To address objectives 2 and 3, the two most sensitive of these exposure-free trapping methods, the LT and ITT, were applied through a CB longitudinal entomological surveillance system implemented by local community health workers (CHW) trained in basic entomology. This surveillance platform was conducted using a monthly sampling cycle for over 2 years in 14 population clusters distributed across two rural districts covering over 4,000km2 of south-east Zambia. Parallel active surveillance of malaria parasite infection rates amongst humans was also conducted by CHWs in the same population clusters to determine the epidemiological relevance of these CB entomological surveys. Prior to the end of the study, a controlled quality assurance (QA) survey was conducted by a centrally supervised expert team using HLC, LT and ITT to evaluate accuracy of the CB trapping data. While the relative sampling efficiencies of both CB surveys were less than their QA counterparts, the costs of implementing per sampling night were far less expensive than any QA survey. The cost per specimen of Anopheles funestus captured was lowest for CB-LT ($5.3), followed by potentially hazardous QA-HLC ($10.5) and then CB-ITT ($28.0). Time-trends of malaria diagnostic positivity (DP) followed those of An. funestus density with a one-month lag and the wide range of mean DP across clusters was closely associated with mean densities of An. funestus caught by CB-LT (P<0.001). To address objective 4, the same 14 cluster populations, with pre-existing high coverage of pyrethroid-impregnated long-lasting insecticidal nets (LLINs), were quasi-randomly assigned to receive IRS with either of two pyrethroid formulations, namely Deltamethrin (Wettable granules (WG)) (DM-WG) and Lambdacyhalothrin (Capsule suspension (CS)) (LC-CS), or with an emulsifiable concentrate (EC) or CS formulation of the organophosphate pirimiphosmethyl (PM), or with no supplementary vector control measure. DP conducted is described in objective 2. Over the first 3 months, the PM-CS IRS supplement offered the greatest level of protection against malaria followed by LC-SC and then by DM-WG. Neither pyrethroid formulation provided protection beyond 3 months after spraying, but both PM CS and EC formulations persisted for 6 months and 12 months respectively. The CS formulation of PM provided greater protection than the combined pyrethroid IRS formulations throughout its effective life (Incremental protective efficacy (IPE) [95%CI] = 0.79 [0.75, 0.83]) over 6 months. The EC formulation of PM provided incremental protection for the first three months (IPE [95%CI] = 0.23 [0.15, 0.31]) that was approximately equivalent to the two pyrethroid formulations (LC-CS, IPE [95%CI] = 0.31 [0.10, 0.47] and DM-WG, IPE [95%CI] = 0.19 [-0.01, 0.35]) but the additional protection provided by the former, apparently lasted an entire year. There were no obvious differences in the densities of An. funestus during the first three months post-spraying for both pyrethroid formulations (DM-WG (IPE[95%CI]=0.01[-0.56,0.37],P=0.103) and LC-CS (IPE[95%CI]=-0.03[-0.88,0.44],P=0.195) and PM-EC (IPE[95%CI]=-0.04[-0.30,0.17], P=0.103). However, where PM-CS was applied, mosquito densities were dramatically reduced during the same period (IPE [95%CI] =0.93[0.87, 0.97], P<0.001). Between the fourth and the sixth month after spraying with DM-WG, there was an apparent, but presumably spurious, three-fold increase in An. funestus densities while LC-CS, PM-EC and PM-CS achieved 5, 3 and 71-fold reductions, respectively. However, from the seventh to twelfth months after spraying, DM-WG and PM-EC had no obvious effect on the An. funestus densities while insufficient data was available to examine the incremental impact of LC-CS or PM-CS. When applied at this pilot scale, this CB mosquito-trapping scheme provided entomological evidence that complements epidemiological monitoring data to demonstrate how supplementing LLINs with IRS can reduce malaria transmission beyond levels achieved with LLINs alone in this setting where physiological resistance to pyrethroids occurs, especially when a non-pyrethroid organophosphate insecticide is used. Overall, it appears that CB trapping schemes are affordable, cost-effective, and epidemiologically relevant. It also appears, based on the evidence from this pilot scale evaluation, that they may be applicable to routine programmatic monitoring of vector population dynamics on unprecedented national scales.
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Spenassatto, Carine [UNESP]. "Desenvolvimento de metodologia high-throughput para estudo populacional do mosquito Aedes aegypti e comparação de dados de genes mitocondriais." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/92451.
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spenassatto_c_me_botib.pdf: 1377275 bytes, checksum: 6cf6a389dd380de975e39f9fc9268330 (MD5)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O Aedes aegypti, culicídeo de hábitos diurnos, é originário do continente africano e está globalmente distribuído pelos trópicos em associação com as populações humanas. É considerado de grande importância epidemiológica por ser o principal vetor dos quatro sorotipos do vírus da dengue e da febre amarela. Uma das primeiras detecções da presença do mosquito no Estado de São Paulo aconteceu na década de 80 na cidade de Santos. Atualmente não há disponível nenhuma vacina ou medicamento eficiente contra a dengue, assim o controle da doença está restrito ao controle do vetor. Uma das alternativas de controle e entendimento das relações vetor-patógeno-homem se baseiam no desenvolvimento de ferramentas moleculares que utilizam técnicas baseadas em PCR, as quais têm possibilitado o estudo genético das populações do Ae. aegypti. Em tais estudos, vários marcadores foram envolvidos, tais como os SNPs (Single Nucleotide Polymorphisms) e marcadores mitocondriais. Nós desenvolvemos ensaios utilizando metodologia TaqMan® para o estudo genético populacional de duas populações do mosquito Aedes aegypti de cidades portuárias do Estado de São Paulo, utilizando nove marcadores SNPs. Verificamos que esta metodologia é reprodutível, rápida, de baixo custo e eficiente para estudos em larga escala. Pela análise AMOVA encontramos uma baixa, mas significativa diferenciação genética entre as populações do estudo (FST = 0,0324; P < 0,01), e uma alta taxa de migrantes por geração (8,72 entre as populações 2007 e 5,39 entre as populações 2008), indicando fluxo gênico entre as populações. A análise implementada no software Structure 2.3.1, evidenciou a existência de três clusters baseados em semelhanças genotípicas, distribuídos em dois grupos, confirmando uma moderada estruturação populacional. Verificamos através da análise de fragmentos...
Aedes aegypti, is a diurnal mosquito, originated from the African continent and is globally distributed through the tropics in association with human populations. It is considered of great epidemiological importance for being the main vector of the four serotypes of Dengue and Yellow Fever. One of the first detections of the presence of the mosquito in the State of São Paulo happened in the 80's, in the city of Santos. Currently there is no available vaccine or effective medicine against dengue fever, and disease control is restricted to vector control. An alternative to control and understanding of vectorpathogen- man relationships are based on the development of molecular tools that use PCR-based techniques, which have enabled the genetic study of populations of Ae. aegypti. In such studies, several markers were involved, such as SNPs (Single Nucleotide Polymorphisms) and mitochondrial ones. We have developed assays using TaqMan® methodology for population genetic studies of two populations of Aedes aegypti from the port cities of São Paulo, using nine SNPs markers. We found that this methodology is reproducible, fast, inexpensive and efficient for large-scale studies. AMOVA analysis found a low but significant genetic differentiation between the studied populations (FST = 0.0324, P <0.01), and a high rate of migrants per generation (8.72 among populations in 2007 and 5.39 among populations in 2008), indicating gene flow between populations. The analysis implemented in software Structure 2.3.1, revealed the existence of three clusters based on genotypic similarities, divided into two groups, confirming a moderate population structure. We verified through the analysis of the mitochondrial gene fragments NADH dehydrogenase subunit 4 (ND4) a high genetic differentiation between the two study populations (FST = 0.18034, P <0.01), and a rate of migrants per generation considered high... (Complete abstract click electronic access below)
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Spenassatto, Carine. "Desenvolvimento de metodologia high-throughput para estudo populacional do mosquito Aedes aegypti e comparação de dados de genes mitocondriais /." Botucatu : [s.n.], 2011. http://hdl.handle.net/11449/92451.
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Resumo: O Aedes aegypti, culicídeo de hábitos diurnos, é originário do continente africano e está globalmente distribuído pelos trópicos em associação com as populações humanas. É considerado de grande importância epidemiológica por ser o principal vetor dos quatro sorotipos do vírus da dengue e da febre amarela. Uma das primeiras detecções da presença do mosquito no Estado de São Paulo aconteceu na década de 80 na cidade de Santos. Atualmente não há disponível nenhuma vacina ou medicamento eficiente contra a dengue, assim o controle da doença está restrito ao controle do vetor. Uma das alternativas de controle e entendimento das relações vetor-patógeno-homem se baseiam no desenvolvimento de ferramentas moleculares que utilizam técnicas baseadas em PCR, as quais têm possibilitado o estudo genético das populações do Ae. aegypti. Em tais estudos, vários marcadores foram envolvidos, tais como os SNPs (Single Nucleotide Polymorphisms) e marcadores mitocondriais. Nós desenvolvemos ensaios utilizando metodologia TaqMan® para o estudo genético populacional de duas populações do mosquito Aedes aegypti de cidades portuárias do Estado de São Paulo, utilizando nove marcadores SNPs. Verificamos que esta metodologia é reprodutível, rápida, de baixo custo e eficiente para estudos em larga escala. Pela análise AMOVA encontramos uma baixa, mas significativa diferenciação genética entre as populações do estudo (FST = 0,0324; P < 0,01), e uma alta taxa de migrantes por geração (8,72 entre as populações 2007 e 5,39 entre as populações 2008), indicando fluxo gênico entre as populações. A análise implementada no software Structure 2.3.1, evidenciou a existência de três clusters baseados em semelhanças genotípicas, distribuídos em dois grupos, confirmando uma moderada estruturação populacional. Verificamos através da análise de fragmentos... (Resumo completo, clicar acesso eletrônico abaixo)Abstract: Aedes aegypti, is a diurnal mosquito, originated from the African continent and is globally distributed through the tropics in association with human populations. It is considered of great epidemiological importance for being the main vector of the four serotypes of Dengue and Yellow Fever. One of the first detections of the presence of the mosquito in the State of São Paulo happened in the 80's, in the city of Santos. Currently there is no available vaccine or effective medicine against dengue fever, and disease control is restricted to vector control. An alternative to control and understanding of vectorpathogen- man relationships are based on the development of molecular tools that use PCR-based techniques, which have enabled the genetic study of populations of Ae. aegypti. In such studies, several markers were involved, such as SNPs (Single Nucleotide Polymorphisms) and mitochondrial ones. We have developed assays using TaqMan® methodology for population genetic studies of two populations of Aedes aegypti from the port cities of São Paulo, using nine SNPs markers. We found that this methodology is reproducible, fast, inexpensive and efficient for large-scale studies. AMOVA analysis found a low but significant genetic differentiation between the studied populations (FST = 0.0324, P <0.01), and a high rate of migrants per generation (8.72 among populations in 2007 and 5.39 among populations in 2008), indicating gene flow between populations. The analysis implemented in software Structure 2.3.1, revealed the existence of three clusters based on genotypic similarities, divided into two groups, confirming a moderate population structure. We verified through the analysis of the mitochondrial gene fragments NADH dehydrogenase subunit 4 (ND4) a high genetic differentiation between the two study populations (FST = 0.18034, P <0.01), and a rate of migrants per generation considered high... (Complete abstract click electronic access below)
Orientador: Paulo Eduardo Martins Ribolla
Coorientador: Karina dos Santos Paduan
Mestre
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Quinn, Megan, Timothy Joyner, and Julie Obenauer. "The Importance of Human Population Characteristics in Modeling Mosquito Vectors: A Comparative Analysis of Model Components." Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/etsu-works/6803.
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The current Zika virus epidemic in the Western hemisphere is representative of the confluence of global climate change and infectious disease expansion, and vector modeling represents a pertinent and timely method to analyze the environment associated with Zika-carrying mosquitoes. Among many mosquito species distribution models, there are varying opinions on which variables are most predictive and, consequently, should be included in modeling efforts. While climate variables (e.g.,mean temperature, mean precipitation) are routinely included, some argue that human population dynamics, in the form of population density and socioeconomic status, should also be included. This project aimed to test the importance of including human population characteristics by modelling the Zika virus vector Aedes aegypti in the Southeastern United States with climate variables, population density, and poverty characteristics. A. aegypti occurrences, global climate data, and population characteristics were obtained from publicly available sources and sampled at a resolution of 2.5 arc-minutes. Data pre and post-processing was completed in ArcMap 10.3 and models were created in Maxent v.3.3.3k. Four models were developed for this project: a climate-only model, a climate and population density model, a climate and poverty model, and a combined model with climate, population density, and poverty. Models were evaluated by comparing test and training area under the curve metrics, omission and commission errors, and variable jackknifing results. The climate-only model performed poorly compared to models with human population characteristics. The combined model was the best fit, though the model with climate and population density had a lower commission rate (21.0% and 20.6%, respectively). Jackknife results for the full model showed that population density was the most significant contributor to the model. This research indicates that more consideration should be given to human population characteristics when modelling mosquito habitats.
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Yamashita, William Massayuki Sakaguchi. "Modelagem física e computacional da dinâmica populacional do mosquito Aedes aegypti." Universidade Federal de Juiz de Fora (UFJF), 2018. https://repositorio.ufjf.br/jspui/handle/ufjf/8022.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
A incidência global dos vírus da Dengue e, mais recentemente, do Zika, Chikungunya e Febre Amarela, tem aumentado o interesse em estudar e compreender a dinâmica populacional do mosquito. Essas doenças são predominantemente disseminadas pelo Aedes aegypti nos países tropicais e subtropicais do mundo. Compreender essa dinâmica é importante para a saúde pública nos países, onde as condições climáticas e ambientais são favoráveis para a propagação destas doenças. Por essa razão, modelos que estudam a dinâmica populacional em uma cidade são de suma importância. Este trabalho discute a modelagem numérica da dinâmica populacional do mosquito Aedes aegypti em uma vizinhança urbana de uma cidade. Em um primeiro momento, apresentamos os resultados teóricos preliminares de modelos unidimensionais. Em seguida, propomos um modelo bidimensional utilizando equações diferenciais parciais. Este modelo permite incorporar fatores externos (vento e inseticidas químicos) e dados topográficos (ruas, blocos de construção, parques, florestas e praias). O modelo proposto foi testado em exemplos envolvendo duas cidades brasileiras (o centro da cidade de Juiz de Fora e a Praia de Copacabana no Rio de Janeiro).
The global incidence of the Dengue virus and, more recently, the Zika, Chikungunya and Yellow Fever, has increased interest in studying and understanding the population dynamics of the mosquito. These diseases are predominantly disseminated by Aedes aegypti in the tropical and subtropical countries of the world. Understanding this dynamics is important for public health in countries, where climatic and environmental conditions are favorable for the spread of these diseases. For this reason, models that study the population dynamics in a city are of short importance. This work discusses the numerical modeling of the population dynamics of the mosquito Aedes aegypti in an urban neighborhood of a city. First, we present the preliminary theoretical results of one-dimensional models. Next, we propose a two-dimensional model using partial differential equations. This model allows incorporating external factors (wind and chemical insecticides) and topographic data (streets, building blocks, parks, forests and beaches). The proposed model was tested in examples involving two Brazilian cities (the city center of Juiz de Fora and Copacabana Beach in Rio de Janeiro).
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Donnelly, Martin James. "Population structure and gene flow in mosquitoes of the Anopheles gambiae complex." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365912.
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Crain, Philip R. "Putting theory into practice: Predicting the invasion and stability of Wolbachia using simulation models and empirical studies." UKnowledge, 2013. http://uknowledge.uky.edu/entomology_etds/2.
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A new strategy to fight mosquito-borne disease is based on infections of the maternally-transmitted, intracellular bacterium Wolbachia pipientis. Estimates predict that Wolbachia infects nearly half of all insect species, as well as other arthropods and some nematodes. Wolbachia manipulates the reproduction of its host to promote infection, most commonly causing a form of conditional sterility known as cytoplasmic incompatibility. Generally, Wolbachia infections are benign and do not inflict significant costs upon its host. However, studies demonstrate that some infections are associated with substantial costs to its host. These same infections can also induce pathogen interference and decrease vector competency of important disease vectors. Theory predicts that organisms that incur costs relative to conspecifics are less competitive and their competitive exclusion is expected. In the case of Wolbachia, the bacterium can influence reproduction such that phenotypes with lower fitness may still reach fixation in natural populations.
In this dissertation, I describe theoretical and empirical experiments that aim to understand the invasion and stability of Wolbachia infections that impose costs on their host. Particular attention is paid to immature insect lifestages, which have been previously marginalized. These results are discussed in relation to ongoing vector control strategies that would use Wolbachia to manipulate vector populations. Specifically, I discuss the cost of novel Wolbachia infections in Aedespolynesiensis, which decreases larval survival and overall fitness relative to wild-type mosquitoes. Then, a theoretical framework was developed to determine the significance of reductions in larval viability in relation to the population replacement disease control strategy. Further theoretical studies determined that Wolbachia infections, once established, resist re-invasion by uninfected individuals despite relatively high costs associated with infection so long as the infection produces reproductive manipulations. Additional studies determined that larvae hatched from old eggs experience reduced survival in mosquito strains with novel Wolbachia infections when compared to the wild-type. To validate the theoretical studies, model predictions were tested empirically to determine the importance of the larval viability. Finally, a COPAS PLUS machine was evaluated and its role in understanding early larval development in mosquitoes is discussed. The importance of integrated research in disease control is highlighted.
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Bradford, Jessica. "Examining Culex tarsalis (Diptera: Culicidae) population changes with satellite vegetation index data." Kansas State University, 2014. http://hdl.handle.net/2097/17139.
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Master of Public HealthDepartment of Diagnostic Medicine/Pathobiology
Michael W. Sanderson
A zoonotic disease is any disease or infection that is naturally transmissible from vertebrate animals to humans. Over 200 zoonoses have been described (Zoonoses and the Human-Animal-Ecosystems Interface, 2013). Many zoonotic viruses are arboviruses, viruses transmitted by an infected, blood-sucking, arthropod vector (Hunt, 2010). There are several endemic arboviruses in the United States; some foreign arboviruses, such as Rift Valley fever (RVF) virus, are potential bioterrorism agents (Dar, 2013). Arboviruses, both endemic and foreign, threaten public health (Gubler, 2002) and therefore disease surveillance, vector control and public education are all vital steps in minimizing arboviral disease impact in the United States. Mosquito-borne disease threats, such as West Nile virus and Rift Valley fever, are constant concerns in the United States and globally. Current strategies to prevent and control mosquito-borne diseases utilize vector distribution, seasonal and daylight timing, and variation in population numbers. Climate factors, such as availability of still water for development of immature mosquitoes, shade, and rainfall, are known to influence population dynamics of mosquitoes. Using 1995-2011 mosquito population surveillance data from Fort Riley, Kansas, we compared population numbers of Culex tarsalis (Diptera: Culicidae), a vector of several arboviruses including West Nile virus and potentially Rift Valley fever, to a satellite-derived index of climate, the Normalized Difference Vegetation Index (NDVI) anomaly. No correlation between the population numbers and NDVI anomaly was observed, which contrasts with results from similar analyses in other locations. These findings suggest a need for continued investigation into mosquito population dynamics in additional ecological regions of the United States to better describe the heterogeneity of environment-population relationships within and among mosquito species.
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Hlaing, Thaung. "Genetic population structure and gene flow in Aedes aegypti mosquitoes in southeast Asia." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.495746.
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Aedes aegypti mosquito is the principle vector for dengue virus transmission. It is the day-biting mosquito which natually breeds in different water containers in and around houses. Dengue/dengue haemorrhagic fever (DF/DHF) is a re-emerging public health problem with > 2.5 billkm people at risk in th world with the greatest disease bilrden in Southeast Asia and the c. An understanding of genetic population structure and dispersal ability in vector populations is important basic Knowledge for effective vector control using both inventional methods and novel strategies such as genetic modification of the vectors.
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MENDES, Cristina Isabel Rodrigues. "Population diversity and transmission dynamics of Plasmodium sp." Doctoral thesis, Instituto de Higiene e Medicina Tropical, 2014. http://hdl.handle.net/10362/19310.
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Apesar dos esforços desenvolvidos nas últimas décadas, a malária continua a ser um dos maiores problemas de saúde pública no mundo, sendo a principal causa de morbilidade e mortalidade principalmente na África Subsaariana.
Fazer uma análise global, que integre todos os intervenientes deste sistema complexo, que engloba três entidades biológicas, fatores socioeconómicos e ambientais, não é fácil, mas pensamos ser um ponto fulcral para um maior conhecimento sobre esta doença. Neste estudo, utilizando um conjunto completo de amostras – sangue periférico e mosquitos – pretendeu-se analisar este complexo sistema de forma abrangente.
Deste modo, este trabalho teve como principais objetivos: 1) Caraterizar as populações parasitárias circulantes nos dois hospedeiros – humano e mosquito vetor - através da identificação das espécies de Plasmodium presentes; marcadores moleculares
de diversidade (Pfmsp2) e marcadores moleculares associados a resistência a fármacos (mutações pontuais nos genes Pfdhps, Pfdhfr, Pfcrt e Pfmdr1); 2) Analisar as pressões seletivas atuantes sobre os genes associados a resistência a fármacos e 3) Analisar a diversidade de genes do mosquito vetor - AgTG1 e AgTG2 - tentando relacioná-los com a presença/ausência de infeção.
As amostras biológicas utilizadas para este trabalho foram recolhidas em três países diferentes: na Guiné Equatorial continental foram colhidas amostras de sangue e mosquitos adultos em duas localidades, Miyobo e Ngonamanga. Em Angola obtiveramse as amostras de sangue em quatro localidades diferentes (Gabela, Porto Amboim, Kissala – Sumbe e Praia – Sumbe) e foram ainda usados neste estudo mosquitos adultos provenientes de Antula, Guiné-Bissau.
Em relação ao primeiro e segundo objetivos deste trabalho, foi possível constatar a presença das quatro espécies de Plasmodium em ambos os hospedeiros, com prevalências superiores às reportadas oficialmente, incluindo P. vivax, espécie que ainda não tinha sido detetada na Guiné Equatorial continental. Detetou-se igualmente
indivíduos Duffy negativos infetados com duas estirpes diferentes de Plasmodium vivax (P. vivax clássico e o P. vivax VK247). Relativamente às mutações pontuais associadas à resistência aos antimaláricos, constatou-se que de um modo geral estas ocorriam em elevada prevalência. Verificou-se igualmente que a resistência à pirimetamina encontrase bem estabelecida neste país, enquanto a resistência à sulfadoxina terá tido uma introdução mais recente. Relativamente ao terceiro e último objetivo deste trabalho, constatou-se que os dois genes estudados - AgTG1 e AgTG2- apresentam fortes sinais de
seleção positiva, podendo estar envolvidos no reconhecimento de organismos patogénicos, e por conseguinte envolvidos numa resposta contra a infeção.
Por fim, este trabalho permitiu concluir que na Guiné Equatorial continental existem as quatro espécies de Plasmodium, incluindo a espécie P. vivax que até à data não estava descrita no país. Foi encontrada uma elevada prevalência de mutações associadas à resistência à sulfadoxina-pirimetamina, pelo que se recomenda uma
contínua monitorização destas mutações. Por fim constatou-se que os genes AgTG1 e AgTG2 apresentam fortes sinais de de seleção positiva, podendo estar envolvidos no reconhecimento de organismos patogénicos, e por conseguinte envolvidos numa resposta contra a infeção. Por fim, este trabalho permitiu concluir que na Guiné Equatorial continental existem as quatro espécies de Plasmodium, incluindo a espécie P.vivax que até à data não estava descrita no país. Foi encontrada uma elevada prevalência de mutações associadas à resistência à sulfadoxina-pirimetamina, pelo que se recomenda uma contínua monitorização destas mutações. Por fim constatou-se que os genes AgTG1 e AgTG2 apresentam fortes sinais de seleção positiva, podendo estar envolvidos na resposta à infeção por Plasmodium.Despite all efforts made over the past decades, malaria remains a major public health problem in the world, affecting mainly the Sub-Saharan Africa. A comprehensive analysis that integrates all factors in this complex system, which consists of three biological entities, socio-economic and environmental factors, is not easy, but it is crucial for a better understanding of this disease. In this study, using a complete set of peripheral blood samples and mosquitoes, we intended to analyse this complex system. So, the main objectives of this study were to: 1) Characterise the circulating parasite populations in the two hosts – human and mosquito vector - through the identification of Plasmodium species; molecular marker diversity (Pfmsp2) and drug resistance-associated markers (mutations in the genes Pfdhps , Pfdhfr , Pfcrt and Pfmdr1; 2) analyse the selective pressures acting on genes associated with drug resistance and 3 ) analyse the diversity of genes in the mosquito vector - AgTG1 and AgTG2 - trying to relate them to the presence / absence of infection. The biological samples used in this study were collected in three different countries: blood samples were collected in mainland Equatorial Guinea (in two villages: Miyobo and Ngonamanga) and in Angola (in four different villages: Gabela, Porto Amboim, Kissala - Sumbe and Praia - Sumbe); mosquitoes were collected, also, in the two villages of Equatorial Guinea and in Antula, Guinea Bissau. Regarding the first and second objectives of this study, it was possible to detect the presence of the four Plasmodium species in both hosts, with prevalence higher than officially reported, including Plasmodium vivax, a species that had not been previously described in this country. Duffy negative individuals infected with two different strains of P. vivax (VK247 and classic strains) were also found. Concerning the molecular markers associated to drug resistance, high prevalence was found. Results also demonstrated that pyrimethamine resistance has been established for a while in mainland Equatorial Guinea as shown by several selection signatures in the parasite genome, while sulphadoxine had a more recent introduction in this country.Finally and regarding the third and final objective of this study, it was found that the both genes studied - AgTG1AgTG2 - showed strong signs of positive selection. This study revealed that the four Plasmodium species are present in mainland Equatorial Guinea, including P. vivax, specie that had not been described yet in this country. High prevalence of mutation in genes associated with resistance to the sulphadoxine-pyrimethamine combination were found, so it is recommended a close and continuous monitoring of these mutations frequency, since there is the danger of an eventual reduction in the efficacy of combined therapy. Finally it was found that the AgTG1 and AgTG2 genes show strong positive selection signals, which may be involved in recognition and immune response triggered by the mosquito against the invading pathogens, like Plasmodium.
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Zielke, Dorothee Ellen [Verfasser]. "Population genetics and distribution of the invasive mosquito Aedes japonicus japonicus (Diptera: Culicidae) in Germany and Europe / Dorothee Ellen Zielke." Greifswald : Universitätsbibliothek Greifswald, 2016. http://d-nb.info/1102162639/34.
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Rono, Evans Kiplangat. "Variation in the Anopheles gambiae TEP1 Gene Shapes Local Population Structures of Malaria Mosquitoes." Doctoral thesis, Humboldt-Universität zu Berlin, 2017. http://dx.doi.org/10.18452/18573.
Full textAbstract:
Die Allele (*R1, *R2, *S1 und *S2) des A. gambiae complement-like thioester-containing Protein 1 (TEP1) bestimmen die Fitness der Mücken, welches die männlichen Fertilität und den Resistenzgrad der Mücke gegen Pathogene wie Bakterien und Malaria-Parasiten. Dieser Kompromiss zwischen Reproduktion und Immunnität hat Auswirkungen auf die Größe der Mückenpopulationen und die Rate der Malariaübertragung. Wie die genetische Diversität von TEP1 die genetische Struktur natürlicher Vektorpopulationen beeinflusst, ist noch unklar. Die Zielsetzung dieser Doktorarbeit waren: i) die biogeographische Kartographierung der TEP1 Allele und Genotypen in lokalen Malariavektorpopulationen in Mali, Burkina Faso, Kamerun, und Kenia, und ii) die Bemessung des Einflusses von TEP1 Polymorphismen auf die Entwicklung humaner P. falciparum Parasiten in der Mücke. Die Analysen der TEP1 Polymorphismen zeigten, dass die natürliche Selektion auf Exone, sowie Introne wirkt, was auf eine starke funktionale Beschränkung an diesem Lokus hindeutet. Außerdem zeigen unsere Daten die strukturierte Erhaltung natürlicher genetischer Variation im TEP1 Lokus, in welchem die Allele und Genotypen spezifische evolutionäre Wege verfolgen. Diese Ergebnisse weisen auf die Existenz von arten- und habitatspezifischen Selektionsdrücken hin, die auf den TEP1 Lokus wirken. Resultate haben gezeigt, dass TEP1*S1 und *S2 Mücken gleichermassen empfänglich für Plasmodium-Infektionen sind. Insgesamt tragen die Resultate der biogeographischen Kartographierung des TEP1 Lokus und der Züchtungs- und Infektionsexperimente zu einem besseren Verständnis über den Einfluss der verschiedenen Vektorarten und lokale Umwelteinflüsse auf die Vektorpopulationen und Malariaübertragung bei. Des weiteren kann die hier beschriebene hochdurchsatz-genotypisierungs Methode, zur Studie lokaler A. gambiae Mückenpopulationen, in der Feldforschungsarbeit eingesetzt werden. Dieser neue Ansatz wird die epidemiologisch relevante Überwachung und Vorhersage dynamischer Prozesse in lokalen Malariavektorpopulationen unterstützen, welche die Entwicklung neuer Strategien der Vektorkontrolle ermöglichen könnten.The alleles (*R1, *R2, *S1 and *S2) and genotypes of A. gambiae complement-like thioester-containing protein 1 (TEP1) determine the fitness in male fertility and the degree of mosquito resistance to pathogens such as bacteria and malaria parasites. This trade-off between the reproduction and the immunity impacts directly on mosquito population abundance and malaria transmission respectively. How TEP1 genetic diversity influences the genetic structure of natural vector populations and development of human malaria parasites is unclear. The aims of this thesis were to: i) map distribution of TEP1 alleles and genotypes in local malaria vector populations in Mali, Burkina Faso, Cameroon and Kenya, and ii) assess the impact of TEP1 polymorphism on development of human P. falciparum parasites in mosquitoes. Analyses of TEP1 polymorphism revealed that natural selection acts in concert on both exons and introns, suggesting strong functional constrains acting at this locus. Moreover, our data demonstrate a structured maintenance of natural TEP1 genetic variation, where the alleles and the genotypes follow distinct evolutionary paths. These findings suggest the existence of species- and habitat-specific selection patterns that act on TEP1 locus. Results revealed that the TEP1*S1 and *S2 mosquitoes are equally susceptible to Plasmodium infections. Collectively, results of my thesis on the biogeographic TEP1 mapping, and on the breeding and infection experiments contribute to a better understanding of how the vector species and local environmental factors, shape vector population structures and malaria transmission. Furthermore, the high throughput TEP1 genotyping approach reported here could be used for field studies of local A. gambiae mosquito populations. This new approach will benefit surveilance and prediction of dynamics in local malaria vector populations that may have epidemiological significance, and therefore inform the development of novel vector control measures.
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Milligan, Janine Marie. "Temporal variation of esterase activity associated with three amplified esterase genes in a field population of Culex quinquefasciatus." CSUSB ScholarWorks, 1995. https://scholarworks.lib.csusb.edu/etd-project/1113.
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Bustamante, Zamora Dulce Maria. "Culex nigripalpus (Diptera: Culicidae) population age structure under heterogeneous environments and sources of error on the estimation of mosquito infection rates." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0041128.
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Fabrigar, Danica Joy. "A genomic approach to investigate the evolution of exophagy in Anopheles mosquitoes." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:1e65b4bf-48fb-4921-a20b-8d8f7d0bdd12.
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The development of behavioural resistance in Anopheles mosquitoes is an important threat to the sustainability of current vector interventions, which selectively target mosquitoes that are found indoors. Changes in the following behaviour have been reported in several Anopheles vectors: biting time, host preference, biting and resting behaviour. However, a critical review of the published literature reveals that behavioural resistance has not been demonstrated clearly in Anopheles, highlighting important limitations in using entomological data to investigate the evolution of behaviour. The availability of next generation sequencing and low-cost custom genotyping technologies makes it possible to investigate behavioural resistance using genetic information as an alternative approach. Using such technologies, this thesis aims to investigate whether Anopheles vectors are evolving towards outdoor-biting behaviour ('exophagy') by examining the genetic difference between the indoor- and -outdoor population of the main African malaria vectors, An. coluzzii and An. gambiae from The Gambia and Uganda, respectively. We also investigated the role of olfactory-related genes in driving the potential genetic difference between the two populations. We found limited divergence between the two populations overall, however close inspection identified SNPs potentially associated with outdoor-biting behaviour as well as genomic regions displaying elevated levels of differentiation between the two populations. Most notably, gustatory receptors, Gr11 and Gr12 and the odour receptor, OR1 were identified as well as, genes related to transcription, signal transduction and catalysis. We discuss the potential role of these genes in determining biting behaviour and suggest that further investigation of these genomic regions is required to confirm the early-stage divergence of indoor- and outdoor-biting Anopheles populations.
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Endo, Noriko Ph D. Massachusetts Institute of Technology. "Simulation of hydrology and population dynamics of Anopheles mosquitoes around the Koka Reservoir in Ethiopia." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/88393.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 89-96).
This thesis applies the HYDRology, Entomology and MAlaria Transmission Simulator (HYDREMATS) to the environment around a water resources reservoir in Ethiopia. HYDREMATS was modified to simulate the local hydrology and the mosquito population dynamics influenced by the reservoir system. The hydrology component of HYDREMATS including a representation of the groundwater was coupled with a reservoir model to describe the spatiotemporal variability of the groundwater table, and the variability in shoreline locations. The entomology component was modified to match the relatively humid environment. HYDREMATS was applied to two villages around the Koka Reservoir in Ethiopia, one adjacent to the reservoir, Ejersa, and the other located 12 km away from it, Gudedo. Meteorological data were collected from July 2011 to February 2013. Entomological data collection started in July 2012 and continued until February 2013. Adult mosquitoes were sampled from the two field sites and classified at the genus level, i.e., Anopheles or Culex. Because of their geographical proximity, the climatology in Ejersa and the climatology in Gudedo were comparable; however, entomological conditions in the two villages were distinct. Ejersa experienced an enhanced and prolonged mosquito season. HYDREMATS was able to simulate the hydrology and the population dynamics of Anopheles mosquitoes at both sites for the period, from January 2012 to February 2013. The model applied to Ejersa simulated a large mosquito population and a prolonged mosquito breeding season because of the existence of the reservoir, in agreement with observations. Especially, a large mosquito population in the post-rainy season was sustained in the simulation due to a large shoreline breeding area. The model applied to Gudedo simulated smaller mosquito population, but it failed to reproduce observed adult mosquito population dynamics correctly. However, the simulated adult mosquito population dynamics in Gudedo resembled those of the observed larvae samples. Further model calibration and validation will be conducted as more data become available. This study demonstrates that HYDREMATS can serve as an effective tool to simulate local hydrology and mosquito population dynamics at a reservoir environment, given hydrological and entomological parameters specified for the given field site.
by Noriko Endo.
S.M.
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Honnen, Ann-Christin [Verfasser]. "Evolutionary implications of artificial night-time lighting for the mosquito Culex pipiens : insights from genetics, physiology, behaviour and population structure / Ann-Christin Honnen." Berlin : Freie Universität Berlin, 2015. http://d-nb.info/1065670257/34.
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Carvalho, Gabriela Cristina de. "Análise da estrutura populacional de mosquitos Culex quinquefasciatus e Culex nigripalpus (Diptera: Culicidae) utilizando marcadores de microssatélites e análise de morfometria geométrica alar." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/6/6132/tde-27112017-163521/.
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Introdução: Parques inseridos na malha urbana de grandes metrópoles possuem potencial para manter o ciclo biológico de diversas espécies vetoras de patógenos, como as espécies Culex quinquefasciatus e Culex nigripalpus. Consideradas antropofílicas, essas espécies têm importância epidemiológica e são abundantemente encontradas na cidade de São Paulo. Porém, pouco se sabe sobre as características genéticas dessas espécies em escala microgeográfica. Visando o melhor entendimento sobre a estrutura populacional dessas espécies, foi analisado os padrões da forma alar e a caracterização genética por marcadores de microssatélites, afim de se obter informações que contribuam para o entendimento da situação populacional desses vetores dentro do município. Objetivos: (1) Analisar a variabilidade da forma alar nas populações de Cx. quinquefasciatus e Cx. nigripalpus; (2) Analisar a variabilidade genética e o fluxo gênico nas mesmas populações; (3) Testar a funcionabilidade de primers desenvolvidos para regiões de microssatélites nas populações de Cx. nigripalpus. Material e Métodos: No total, foram estudadas cinco populações de Cx. quinquefasciatus e sete populações de Cx. nigripalpus, coletados em parques urbanos da cidade de São Paulo. Análises discriminantes, como variável canônica, teste de reclassificação cruzada e dendrograma de Neighbor-joining, utilizando os software Morpho J e Past, foram realizadas para a compreensão do formato e tamanho da asa direita nas populações. Em relação ao estudo da estruturação genética, foram testados 12 pares de primers de microssatélites em mosquitos Cx. quinquefasciatus e 33 pares de primers em mosquitos Cx. nigripalpus. Resultados: Análise da morfometria geométrica alar nas populações de Cx. quinquefasciatus demonstrou homogeneidade nos formatos alares, sendo um caracter preservado nessa espécie pela cidade, contudo, há tênues diferenças na população coletada em ambiente mais silvestre. O mesmo foi observado para as populações de Cx. nigripalpus, onde foi possível visualizar uma subestruturação na forma alar dentro da população Shangrilá. Dos primers testados, 12 amplificaram de forma consistente em todas as populações de Cx. quinquefasciatus e seis primers nas populações de Cx. nigripalpus. Os resultados encontrados sugerem que ambas as espécies possuem baixa estruturação genética, com fluxo gênico moderado entre as populações de Cx. quinquefasciatus e baixo entre as de Cx. nigripalpus, apresentando alto índice de heterozigosidade, onde as únicas populações que estão em expansão são as que foram coletadas em ambientes onde a urbanização está avançando. Discussão: Processos de urbanização, somados às mudanças causadas no ambiente, beneficiam e tendem a elevar a abundância dessas espécies em ambientes antropizados. A baixa estruturação genética e morfométrica das asas dessas espécies indicam a adaptação delas na cidade, havendo segregação devido à heterogeneidade do ambiente em que as populações se encontram. Conclusão: Evidências de baixa estruturação entre as populações e indícios de expansão em populações de ambientes mais silvestres indicam que essas espécies estão atreladas ao processo de urbanização da cidade de São PauloIntroduction: Urban parks have the potential to harbor and maintain the life cycle of several mosquitoes such as Culex quinquefasciatus and Culex nigripalpus, both are anthropophilic species with epidemiological importance and very abundant in São Paulo city. However, their genetics characteristics are poorly know. Aiming the better understanding of the population structure of these species in microregion, was evaluated the wing shape variation and selected microsatellite loci. In this way, the information obtained can contribute to the understanding of the population situation of these vectors in São Paulo city. Objectives: (1) To evaluate the wing shape variability in populations of Cx. quinquefasciatus and Cx.nigripalpus; (2) To evaluate the genetic variability and gene flow in the Cx. quinquefasciatus and Cx.nigripalpus populations (3) Test microsatellite markers functionality parameters in Cx. nigripalpus, previously used successfully in other Culex species. Material and Methods: Were studied, five populations of Cx. quinquefasciatus and seven population of Cx. nigripalpus collected in urban parks in São Paulo city. Discriminant analysis was made to evaluate the wing shape patterns, such as Canonical variate analysis, cross validated test and Neghbor-joninin dendrogram using Morpho J and Past softwares, were perfomed to understand the size and shape of the right wing in these populations. For the study of genetic structuring, there were tested 12 pairs of microsatellite loci in Cx. quinquefasciatus samples and 33 pairs of microsatellite loci in Cx. nigripalpus samples. Results: The wing shape patterns in Cx. quinquefasciatus population were homogeneous, showing a preserved character in this population, however, has been tenuous differences in the more sylvatic population. The same pattern was observed in Cx. nigripalpus populations and was observed substructuring in the Shangrilá population. From the tested primers, 12 were functional and amplified consistently in the all five Cx. quinquefasciatus population and for Cx. nigripalpus, six primers were amplified. The results suggest both species having low genetic structure, moderate gene flow and the only populations which are expading were collected in areas that the urbanization is increasing. Discussion: Urbanization processes added to the environmental changes benefit and tend to raise the abundance of these species in anthropized locals. The low genetic structure and alar morphometry indicates the adaptation of these species in São Paulo city, there being segregated due to the environment heterogeneity which the population inhabit. Conclusion: Evidence of low structure between populations studied and signs of expansion in populations of more sylvatic environments indicate that these species are linked to urbanization process
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Johnson, Todd. "Population composition and seasonal dynamics of mosquito communities across landscape gradients in southern Africa, with emphasis on selected arbovirus vector species and their role in disease transmission." Thesis, University of Pretoria, 2020. http://hdl.handle.net/2263/73323.
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Mosquito-borne arboviruses are of considerable public health importance as they cause some of the most important emerging and re-emerging infectious diseases affecting humans and animals in many parts of the world including southern Africa. The threat of large epidemics of mosquito-borne arboviruses are often associated with climatic conditions, global warming, animal migrations, surface water, wind, topography, harbourage, vegetation, food supply and abundance of competent mosquito vectors. The goal of this project is to provide an in depth understanding of mosquito community dynamics and the importance of mosquito vector populations in the maintenance and transmission of mosquito-borne diseases in southern Africa.
Firstly, a review of past and current literature was conducted to highlight: (a) the current state of knowledge regarding the most important mosquito-borne viruses of medical significance in southern Africa (b) lesser known mosquito-borne arboviruses with the potential of causing zoonotic health threats for humans in southern Africa. (c) key aspects of the ecology of mosquito vectors of medically significant mosquito-borne viruses in southern Africa. d) gaps in knowledge regarding southern African arbovirus mosquito vectors. Most of the studies on mosquito-borne viruses in southern Africa can be clustered into specific programmes led by Kokernot and Smithburn in the 1950s, McIntosh in the 1970s and 1980s, Swanepoel in the 1970s, Venter and others in more recent years, and have largely been restricted to South Africa, Mozambique and Zimbabwe. Twenty-six (26) arboviruses have been isolated from mosquitoes in southern Africa. Of these, Chikungunya (CHIK), Sindbis (SIN), West Nile (WN), Wesselsbron (WES), Spondweni (SPO), Banzi (BAN), Dengue (DEN), Bunyamwera (BUN), Germiston (GER) and Rift Valley fever (RVF) viruses are known to cause human illness. Middelburg (MID) and Shuni (SHUN) viruses are also important, causing neurological symptoms in animals with zoonotic potential for humans in South Africa. There are eight mosquito-borne arboviral infections most likely to impact humans in southern Africa (CHIK, MID, SIN, DEN, WES, WN, SHUN and RVF viruses). Mosquitoes in the subfamily Culicinae (mostly Aedes and Culex mosquitoes) are the most frequently associated with arbovirus transmission (115 and 105 types of arbovirus, respectively). Understanding the role of mosquito vector species in arbovirus transmission is vital for the development of new strategies to control the spread of arboviral diseases. In southern Africa, a few species in the genera Anopheles, Coquillettidia and Mansonia have also been implicated as vectors of arboviruses. Surveys over multiple decades across southern Africa have provided an insight regarding which species of mosquitoes are involved in the transmission of at least the most common of the mosquito-borne zoonotic arboviruses. These cluster within the genera Aedes and Culex, each representing a different transmission strategy. Aedes-borne viruses such as CHIK, DEN and WES tend to have primate or human reservoir hosts (McIntosh, 1986), while Culex-borne viruses often use birds as reservoir hosts, and these factors influence the distribution and epidemiology of the diseases they cause in humans and animals. Aedes and Culex have different breeding strategies and preferences which also represent fundamental differences. These mosquitoes are Aedes aegypti, Aedes furcifer/cordellieri, Aedes circumluteolus, Aedes unidentatus, Aedes mcintoshi, Aedes caballus, Aedes juppi, Culex theileri, Culex zombaensis, Culex univittatus, Culex neavei and Culex rubinotus.
To determine mosquito community dynamics and mosquito vector distributions, sampling mosquito vectors at six sentinel sites in three provinces in the northern part of South Africa where recent cases had been detected in animals. Adult mosquitoes were collected from two horse properties in Gauteng Province; two wildlife reserves in Limpopo Province and at Orpen Gate in Kruger National Park and Mnisi Area in Mpumalanga Province between 2014–2017, using carbon dioxide-baited light and tent traps. Culex poicilipes, was the most abundant species caught during the study period. Highest diversity and species richness were found at Lapalala Wilderness Reserve, while the lowest diversity and abundances were at Orpen in Kruger National Park. Aedes aegypti, Ae. mcintoshi, Ae. metallicus, Ae. vittatus, Cx. pipiens sensu lato, Cx. theileri and Cx. univittatus, which are potential arbovirus vectors, had the widest geographical distribution in northern South Africa. Also collected were Anopheles arabiensis and An. vaneedeni, both known malaria vectors in South Africa. Therefore, arbovirus surveillance and vector control programs should be augmented in peri-urban and mixed rural settings where there is greater risk for arbovirus transmission to humans and domestic stock.
Since climate has reportedly been associated with disease transmission, it’s important to understand the extent of its influence on mosquito abundance and distribution in northern South Africa. Thus, population composition, abundance and diversity of mosquitoes collected over a three-year period were determined and correlated to diverse climatic conditions during those years in order to determine seasonal trends in occurrence, abundance and distribution. Marked differences in the temporal distribution and seasonal abundances of the seven medically important mosquito vectors encountered from the two distinct geographic regions and climates. Statistical models have shown that climatic factors play a crucial role in shaping the population dynamics of Ae. mcintoshi, Ae. vittatus, An. arabiensis, Cx. pipiens s.l., Cx. poicilipes, Cx. theileri and Cx. univittatus both in Highveld Grassland and Middleveld Bushveld regions of northern South Africa. High summer temperatures and rainfall lead to increased vector density which might trigger outbreaks of RVF, SIN and WN viruses on the inland plateau of South Africa. This study also showed that abundances of RVF and WN virus vectors are related to elevation. These findings will be important in predicting the timing of onset and spread of future epidemics such as WN and RVF viruses, in southern Africa and other geographical settings with similar climates.Thesis (PhD)--University of Pretoria, 2020.
University of Pretoria US Centers for Disease Control and Prevention
Medical Virology
PhD
Unrestricted
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Silva, Ramon Wilk da. "Análise da estrutura populacional de mosquitos Aedes aegypti(Diptera: Culicidae) em diferentes estratos urbanos na cidade de São Paulo, utilizando morfometria geométrica alar e marcadores microssatélites." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/6/6132/tde-18072017-151547/.
Full textAbstract:
O mosquito Aedes aegypti é reconhecido como o principal vetor do vírus da Dengue, além de transmitir outros arbovírus de importância médica, como os causadores da Febre Amarela urbana, Chikungunya e Zika. A ecologia deste vetor está intimamente associada ao homem, sendo provavelmente, a única espécie de culicídeo a conseguir completar todo seu ciclo de vida dentro das habitações humanas, com sua dinâmica populacional fortemente relacionada aos processos decorrente da urbanização. Assim como outras metrópoles, a cidade de São Paulo apresenta estresse ambiental, em função da elevada densidade populacional e urbanização não planejada, o que contribui para a proliferação do Ae. aegypti e, consequentemente, o aumento no número de casos de Dengue. Embora, vacinas como a da Febre Amarela e Dengue já tenham sido desenvolvidas, esta última mais recentemente e, ainda não empregada em larga escala, o controle do vetor ainda permanece como a principal estratégia para a disruptura dos padrões epidemiológicos das arboviroses causadas por seus patógenos. Estruturação populacional, geralmente é um resultado de combinações decorrentes de processos históricos e contemporâneos envolvendo determinada espécie, como a sua capacidade de dispersão, padrões de cópula, barreiras físicas e ambientais, além de padrões demográficos. Desse modo, determinar os diferentes papéis destes processos na estruturação de populações torna-se útil no controle de vetores de importância médica. Um bom exemplo é a propagação da resistência a inseticidas, em decorrência do fluxo gênico entre as populações. Portanto, um melhor conhecimento da estruturação populacional do Ae. aegypti é crucial para auxílio e desenvolvimento de novas estratégias de controle. Dessa forma, visando elucidar seu padrão de estruturação, o presente estudo utilizou-se da morfometria geométrica alar e de marcadores microssatélites, para investigação de 11 populações de mosquitos Ae. aegypti coletados em áreas com diferentes graus de urbanização, localizadas no município de São Paulo. Os resultados encontrados sugerem um padrão de estruturação de acordo com o gradiente de urbanização no qual os espécimes foram coletados. As distâncias de Mahalanobis, obtidas pela morfometria geométrica alar, apresentaram significância estatística em 54 dos 55 testes conduzidos, com as populações exibindo um claro padrão de segregação nas Análises de Variáveis Canônicas e Neighbor-Joining, tanto para as populações agrupadas na forma de seus estratos urbanos, como por seus respectivos locais de coleta, enquanto que o teste de reclassificação dos espécimes alcançou relativo grau de precisão de reconhecimento. Os microssatélites indicaram uma baixa estruturação genética (Fst = 0,057), com 93 por cento de seus valores apresentando significância estatística. Contudo, em conformidade com o gradiente de urbanização dos estratos, com moderado fluxo gênico, déficit de heterozigosidade e indícios de expansão populacional, principalmente nas áreas com maior grau de urbanização. A intensificação dos processos decorrentes da urbanização tem como causa a diminuição dos espaços verdes encontrados nas cidades, de modo a contribuir para a elevação da temperatura e, consequentemente, favorecer a proliferação do Ae. aegypti. Adicionalmente, a perda destes espaços implica no processo de homogeneização biótica, fenômeno que atua como adjuvante a plasticidade ecológica do vetor, de maneira a beneficia-lo. Hipótese, corroborada pela sua expansão populacional, exibida principalmente nos ambientes mais antropizados. A estruturação observada nas populações de Ae. aegypti no presente estudo indica que os processos de urbanização desempenham um importante papel na sua conformação, e fatores como o moderado fluxo gênico e déficit de heterozigosidade podem estar refletindo nos seus padrões epidemiológicosAedes aegypti is recognized as the main vector of Dengue, in addition to transmit other arboviruses of medical importance, as the agents of Yellow Fever, Chikungunya and Zika. The ecology of this vector is closely associated with the human, being probably the only kind of mosquito to be able to complete all their life cycle inside the human habitations, with their population dynamics strongly related to processes arising from urbanization. Like other cities, the city of São Paulo suffers from environmental stress due to the high population density and unplanned urbanization, which contributes to the proliferation of Ae. aegypti mosquitoes and consequently the increase in the number of cases of dengue fever. Although vaccines such as Yellow Fever and Dengue have already been developed, the latter, more recently, and not yet used on a large scale, vector control remains the main strategy for the disruption of epidemiological patterns of arboviral diseases caused by their pathogens. Structure of the population, is generally the result of combinations resulting from historical and contemporary processes involving certain species, such as their ability to disperse, copulation pattern, physical and environmental barriers and demographic trends, and to determine the different roles of these processes in structuring the population becomes very useful for the medical importance of vector control. A good example is the spread of insecticide resistance, due to gene flow between populations. Therefore, a better understanding of the population structure of Ae. Aegypti is crucial to support and develop new strategies for control programs. Thus, in order to elucidate its pattern of structuring this study utilized wing geometric morphometric and microsatellite markers, for investigation of 11 Ae. aegypti populations collected in areas with different degrees of urbanization, located in the municipality of São Paulo. The results suggest a pattern of structuring according to the urbanization gradient in which the specimens were collected. The distances of Mahalanobis obtained by wing geometric morphometry, statistically significant in 54 of the 55 tests performed, with populations showing a clear trend of segregation in the Canonical Variables analysis and Neighbor-Joining, both for the populations grouped in the form of their urban strata as per their respective collection locations, while the reclassification of test specimens reached relative degree of recognition accuracy. Microsatellites indicated a low genetic structure (Fst = 0.057), with 93 per cent of their statistically significant values. However, in accordance with the gradient of urbanization of the strata, with moderate gene flow, heterozygosity and evidence of population expansion, especially in the areas with the highest degree of urbanization. The intensification of the processes resulting from urbanization Implies in the reduction of the green spaces found in the cities, in order to contribute to the increase of the temperature and thus the proliferation of the Ae. Aegypti. In addition, the loss of these spaces involves biotic homogenization process, a phenomenon that acts as an adjuvant ecological plasticity of the vector, in order to benefit it. Hypothesis, corroborated by its population expansion, displayed mainly in anthropic environments. The structure observed in populations of Ae. aegypti in this study indicates that the urbanization processes play an important role in their conformation, and factors such as moderate gene flow and deficit of heterozygosity can be reflected in their epidemiological patterns
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Rono, Evans Kiplangat [Verfasser], Elena A. [Gutachter] Levashina, Arturo [Gutachter] Zychlinski, and Susanne [Gutachter] Hartmann. "Variation in the Anopheles gambiae TEP1 Gene Shapes Local Population Structures of Malaria Mosquitoes / Evans Kiplangat Rono ; Gutachter: Elena A. Levashina, Arturo Zychlinski, Susanne Hartmann." Berlin : Humboldt-Universität zu Berlin, 2017. http://d-nb.info/1189328771/34.
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Jaonalison, Henitsoa. "Les premiers stades de vie des poissons dans le SO de Madagascar : éléments pour une meilleure connaissance de la biodiversité et une meilleure gestion des ressources exploitées." Thesis, La Réunion, 2019. http://www.theses.fr/2019LARE0030.
Full textAbstract:
Les écosystèmes marins qui fournissent de multiples services écosystémiques indispensables au bien-être de l’humanité sont actuellement menacés par la surexploitation des ressources et l’utilisation d’engins destructifs. Ceci conduit à une perte à l’échelle globale de 20% des mangroves, 19% des récifs coralliens et 110 km2 par an des herbiers. Les habitats côtiers qui soutiennent jusqu’à 20% de la production globale de la pêche sont les plus touchés, notamment dans les pays les moins avancés comme Madagascar. Dans ce pays, 87% des écosystèmes récifaux sont menacés, notamment dans le sud-ouest où les petits pêcheurs utilisent des engins prohibés capturant les juvéniles. Une meilleure connaissance de l’écologie des jeunes poissons est donc un point clé pour la mise en place des mesures de gestion efficaces et robustes. D’où l’objet de ce présent travail centré sur les jeunes stades de développement des poissons, identifiés en utilisant le barcoding ADN. Les identifications à l’espèce ont permis de prédire l’approvisionnement en post-larves et de découvrir la variabilité du recrutement en juvéniles qui semble liée à l’altération des apports en post-larves. Au total, 387 espèces ont été observées avec 9 nouvelles espèces pour Madagascar. L’intérêt et les limites du barcoding ADN sont largement discutés (chapitre 1). L’approvisionnement en post-larves a été mieux prédit par les conditions océaniques obtenues par télédétection avec une précision de 60% pour la richesse et 50% pour l’abondance. Pourtant, la performance des modèles pour prédire l’abondance semble influencée par les caractéristiques des masses d'eau qui sont différentes entre les deux sites, tandis que la performance pour prédire la richesse parait similaire entre ces deux sites (chapitre 2). Les conditions océaniques obtenues par télédétection expliquent mieux les assemblages de post-larves. Pourtant, ces conditions océaniques structurent davantage les assemblages de post-larves dans les masses d'eau présentant des caractéristiques d’eaux côtières que ceux dans les eaux présentant des caractéristiques océaniques (chapitre 3). La période de recrutement et les assemblages de juvéniles diffèrent entre les années. Ces variabilités interannuelles ont été aussi observées dans l’approvisionnement en post-larves qui semble conditionné par les variations des conditions océaniques. Ce qui suggère que les altérations des apports en post-larves influencent la distribution temporelle des juvéniles (chapitre 4). Le cas du recrutement des juvéniles de Siganidae, qui semble être fortement en lien avec les apports en post-larves, est développé dans la discussion générale. De même, la localisation des zones de nourriceries a permis de proposer des mesures de gestion tenant compte du contexte local qui sont aussi discutéesMarine ecosystems which provide multiple ecosystem services essential to human well-being are currently threatened by resources overexploitation and the use of destructive fishing gears. This leads to a global loss of 20% of mangroves, 19% of coral reefs, and 110 km2 per year of seagrass meadows. The coastal habitats that support up to 20% of global fisheries production are the most affected, particularly in least developed countries such as Madagascar. In this country, 87% of coral reef are threatened, particularly in the southwestern part of the island where small-scale fishermen practice juveniles fishing. A better knowledge of the ecology of young fishes is thus a key point for the implementation of effective and robust measures. The present work was centred on early developmental stages of fish identified using DNA barcoding. Identifications to the species level were used to predict the post-larvae supply and to discover the variability in juveniles recruitment that appears to be related to the alteration of post-larvae supply. In total, 387 species have been observed with nine new species for Madagascar. The interests and limitations of DNA barcoding are widely discussed in Chapter 1. Post-larvae supply was better predicted by the remotely sensed oceanic conditions with an accuracy of 60% for species richness and 50% for abundance. However, the performance of models for predicting abundance appears to be influenced by the characteristics of water masses that are different among sites, while the performance of models for predicting species richness appears similar between the sites (discussed in Chapter 2). The remotely sensed oceanic conditions better explained the post-larval fish assemblages. However, these oceanic conditions structure mostly the post-larval fish assemblages in water masses with coastal water characteristics than those in waters with ocean characteristics (discussed in Chapter 3). The period of juvenile recruitment as well as juvenile assemblages differ among years. These interannual variabilities were also observed on post-larvae supply which were conditioned by the interannual variation of oceanic conditions. This suggests that alterations in post-larvae supply influence the temporal distribution of juvenile fish, which is a subject discussed in Chapter 4. The case of Siganidae recruitment, which seems to be strongly linked to post-larvae supply, is developed in the final discussion of this thesis. Likewise, the identification of nursery areas allows to propose management measures to deal with the local context that are also discussed
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Jian, Yun. "Prediction of Mosquito Abundance in Temperate Regions, Using Ecological, Hydrological and Remote Sensing Models." Diss., 2014. http://hdl.handle.net/10161/9436.
Full textAbstract:
New and old mosquito-borne diseases have emerged and re-emerged in temperate regions over the recent past, but an understanding of mosquito population dynamics, a fundamental step toward disease control, remains elusive. In particular, we are still lacking reliable predictive models of mosquito abundance in temperate areas due to the subtle links between the fluctuation of mosquito population and highly heterogeneous environmental drivers. Hence, this doctoral dissertation presents an interdisciplinary approach towards an improved understanding and prediction of the fluctuations in mosquito abundance in temperate regions. In the first part of this dissertation a hierarchical Gompertz-based model is used to assess the relative importance of endogenous (density dependence) and exogenous (environmental forcings) controls and their interactions in regulating the dynamics of a West Nile Virus vector (Culex pipiens) in the Po River delta in Italy. The results clearly detect the effects of density-dependence in the observed population dynamics for the mosquito species analyzed and highlight the controls exerted by environmental forcings and habitat conditions. Subsequently, the characteristic scales of temporal variability in mosquito populations, and the representativeness of observations at different sampling resolutions, are investigated using a 10 year daily mosquito sample from Brunswick County, North Carolina. The species present in the sample (among which Aedes vexans and Culiseta melanura are addressed in greater detail, as vectors of East Equine Encephalitis and West Nile Virus) are investigated using a combination of time series analysis, individual based simulations, and density-dependent modeling approaches. Significant population fluctuations with characteristic periodicity between 2 days and several years are found in response to different regulation mechanisms. In particular, the observed fast fluctuations are importantly determined by a varying mosquito activity, rather than by reproduction/mortality processes, driven by rapid changes in meteorological conditions. Finally, in the third part of this study, a state space reconstruction (SSR) approach is used to understand how the predictability of mosquito abundance varies with aggregation time scale and with the prediction horizon, and how much can the prediction of mosquito abundance be improved by using daily observations compared to the commonly used once-per-week samples. The results show that the predictability of mosquito abundance decreases as the time scale of the models increases from one week to one month, while the predictability of per capita growth rate increases together with the modeling scale. It is also shown that the prediction of mosquito per capita growth rate can be improved using daily abundance observations. Furthermore, many mosquito models compare the observed and predicted abundance as a measure of model performance. However, my results suggest that short term forecasts of mosquito abundance may appear to have a significant capability due to the positive autocorrelation between abundance in subsequent time steps, even when the model's ability to predict the abundance change is low. Model capability should thus be evaluated comparing observed and modelled per capita rates of change.
Dissertation
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Johnsen, Mark Miller. "The status of resistance in Culex quinquefasciatus say (Diptera: culicidae) populations in Brazos and Harris Counties, Texas." 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1298.
Full textAbstract:
In 2002, West Nile virus was isolated for the first time in Harris County, Texas.
The subsequent epidemic led the Harris County Mosquito Control Division to initiate an
extensive spraying operation to suppress infected adult mosquitoes. The control
program was aimed at the predominate disease-carrying mosquito for the southern
United States, Culex quinquefasciatus Say. With the increase of insecticide pressure on
the mosquito populations, the possibility of resistance was brought into question. A
three year study using a vial bioassay test was conducted in Harris (2004-2005) and
Brazos (2005-2006) counties to determine the resistance status of Cx. quinquefasciatus
to the six chemicals (malathion, naled, resmethrin, permethrin, sumithrin, and
pyrethrum) used most frequently in adult mosquito control programs.
The resistance ratios acquired from the vial bioassay tests were mapped onto
shapefiles for Harris and Brazos counties, which revealed clustering of areas with
pyrethroid resistance mosquito populations in the northeastern, southeastern, and
southwestern corners of Loop 610 in Harris County. An additional six-month
preliminary study, involving six operational areas in Harris County and three in Brazos County, was conducted, demonstrating only minor fluctuations in the monthly resistance
ratios occurring in both counties in 2005.
A significant correlation was documented between the two years of resistance
ratios for mosquitoes to the three pyrethroids in Harris County and all the insecticides
except pyrethrum in Brazos County. A significant relationship was also found between
the resmethrin resistance ratios and the number of spray events performed during the
previous year and the malathion resistance ratios with the insecticide treatments
conducted in the same year. The correlation analyses provide data used to predict areas
where resistance can develop in the mosquito population, thus providing the control
agency more data to plan future control tactics.
The overall analysis indicated that Harris County has localized pockets of
resistant mosquitoes; but, on a whole, it does not seem to have widespread resistance in
its mosquito populations. The only resistance that was detected was in the mosquitoes
tested against the three pyrethroids. Mosquitoes in Brazos County, which has no
organized mosquito control, demonstrated county-wide susceptibility to all six
insecticides tested.