Thesis (Ph. D.)--University of Florida, 1980. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 157-167).

Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 113-137).

Thesis (Ph.D.)--Ohio University, November, 2005. / Includes bibliographical references (leaves 147-154)

Se por um lado as usinas hidrelétricas suprem as necessidades de energia do país, essas também são responsáveis pela proliferação de doenças cujos agentes são transmitidos, em sua grande maioria, por mosquitos que utilizam as áreas inundadas dessas usinas como criadouros. Pode-se observar tal cenário na UHE de Ourinhos, que está localizada no rio Paranapanema entre as cidades de Ourinhos, SP, e Jacarezinho, PR, onde foram definidas três estações de coleta usadas para a avaliação da dinâmica de população nos períodos pré e pós inundação do reservatório, a partir dos dados coletados descreveu-se as alterações ocorridas na população de culicídeos da UHE Ourinhos, diante dos impactos da inundação e calculou-se riqueza, dominância, diversidade e , IAEP e similaridade. Sendo que para captura de adultos utilizou-se armadilha de Shannon e aspirador à bateria, e para os imaturos conchas entomológicas em coleções de água estagnada. Entre as espécies de importância epidemiológica coletadas e identificadas temos: Aedes albopictus, Aedes scapularis, Anopheles albitarsis, Anopheles darlingi, Culex quinquefasciatus, Culex nigripalpus, Haemagogus leucocelaenus e Psorophora ferox. Destaca-se a redução do número de espécies no período pós enchimento, juntamente com a recolonização do nicho por novas espécies ou espécies antes raras, como exemplificado pelo surgimento do An. darlingi, e ascensão do An. albitarsis, espécies consideradas vetores primário e secundário da malária, no Brasil, respectivamente. Como conclusão, depreende-se que o lago formado pela represa de Ourinhos alterou a dinâmica de culicídeos do local, fato que pode representar menor contato desses hematófagos com a população no entorno do lago recém formado / If the hydroelectric power plants supply the needs of the country, they are also responsible for the proliferation of diseases whose pathogens are transferred, in most of time, by mosquitoes that using the flooded areas such as breeding. It can be observed this scenario in the HPP of Ourinhos, which is located on the Paranapanema river between the cities of Ourinhos, SP, and Jacarezinho, PR, where three stations were established to collect used for assessing the diversity of populations in the pre and post flooding of the reservoir from the data collected described the changes occurring in the population of Culicidae of Ourinhos HPP, before the impacts of flooding and it was estimated richness, dominance, and diversity, standardized index of abundance of species and similarity. Where to catch the adult was used the Shannons trap and vacuum, and for the immature forms \"entomological ladle\" in collections of stagnant water. Among the species of epidemiological importance have collected and identified: Aedes albopictus, Aedes scapularis, Anopheles albitarsis s.l, Anopheles darlingi, Culex quinquefasciatus, Culex nigripalpus, Haemagogus leucocelaenus and Psorophora ferox. It is reducing the number of species in the period after filling, together with the recolonization of the niche for new species or rare species before, as exemplified by the emergence of Anopheles(Nys.) darlingi and Anopheles albitarsis s.l rise of species, as primary and secondary vectors malaria in Brazil, respectively. In conclusion, it appears that the lake formed by the dam of Ourinhos changed the diversity of the mosquitoes in site, which may represent less contact with the blood of people around the newly formed lake

Weekly collections were conducted from May to December, 2007 (153 trap nights, total) in Denton, Texas, in and around large storm drains and overpass drainage facilities in residential and non-residential areas, using Centers for Disease Control (CDC) light traps and gravid traps. A total of 1964 mosquitoes were collected, representing 24 species within 6 genera: Aedes, Anopheles, Culiseta, Culex, Psorophora, and Uranotaenia. Culex was the most abundant genus, representing 75% of all mosquitoes collected; Aedes was the second most abundant, representing 12 % of all mosquitoes collected. Cx. quinquefasciatus was the dominant species collected via gravid traps; Cx. (Melanoconion) species were the dominant species collected via CDC light traps. Data of gravid traps and light traps were analyzed separately using nonparametric correlation analysis, comparing environmental data and physical characteristics to total abundance of mosquitoes. There was no significant correlation found when comparing the three dominant species collected in light traps (unidentified Cx. (Melanoconion) sp, Cx. quinquefasciatus, and Ae. vexans) to environmental characteristics and physical characteristics. Analysis of Cx. quinquefasciatus collected in gravid traps indicated no significant correlation between abundance, environmental data, and physical characteristics. Linear regression models were analyzed to determine if either environmental variables or physical characteristics of the drainage system explained the species abundance collected; no individual variable showed an association of significance. Analysis of Cx. quinquefasciatus collected in storm drains via gravid traps determined temperature to be the most important variable in determining population abundance and explained 99% of the population variability.

O objetivo do estudo foi confirmar se a redução da fecundidade dos mosquitos Aedes aegypti infectados por Plasmodium gallinaceum ocorre por morte das células foliculares dos ovários. Mosquitos infectados produzem menos ovos quando comparado aos mosquitos sadios. Uma explicação é a redução da viabilidade celular que ocorre nos ovários de fêmeas 18, 22 e 24 horas após o repasto sanguíneo infectado (RSI) como foi observado pela técnica MTT. Utilizando o acridine orange, não foi possível observar a morte das células foliculares no intervalo de 18 horas, mas 22 e 24 horas após o RSI essas células estão em morte em relação ao mesmo intervalo do repasto sanguíneo controle (RSC). A análise do DNA fragmentado foi realizada através do TUNEL. Ovários de 22 e 24 horas após RSC e RSI foram negativos nas regiões dos cortes histológicos examinados. Sendo assim, podemos concluir que, utilizando esses ensaios foi possível identificar a morte das células foliculares como uma resposta a redução da fecundidade, porém não foi possível determinar que o tipo de morte é apoptose. / The objective of this study was to confirm the hypothesis that the fertility reduction in Plasmodium gallinaceum-infected Aedes aegypti occurs by follicular cells death. A significant reduction in the number of eggs laid by infected mosquitoes was confirmed. It was observed a reduction of viable cells in 18, 22 and 24 hours PBM infected by MTT assay. It was not possible to observe cell death in ovary tissue 18 hours PBM infected, but the follicular cells showed orange color 22 and 24 hours indicating they are in death in relation to the same interval of PBM control. To determine if these cells exhibit apoptosis, we use the TUNEL which mark the fragmented DNA, a characteristic of the apoptosis process. Ovaries 22 and 24 hours PBM infected and control were negative for TUNEL marker from ovary histological preparations. Thus, we conclude that fecundity reduction occurs as a response to follicular cells death caused by P. gallinaceum infection but it was not possible to affirm if the type of follicular cells death is apoptosis.

The development of pyrethroid resistance in mosquitoes threatens the goal of malaria elimination in Africa. Alternative insecticides, e.g. organophosphates, can be considered to control pyrethroid resistant mosquitoes. The problem associated with the deployment of organophosphate-based insecticides is their high volatility. Conventional application forms have a fairly short residual efficacy. This study aimed at extending the residual efficacy of an organophosphate insecticide by using a polymer matrix as a slow release device. A multilayer film blower was used to produce a trilayer film. The middle layer comprised poly(ethylene-co-vinyl acetate), i.e. EVA polymer, impregnated with malathion. This was sandwiched by two low density polyethylene (LDPE) outer layers. These acted as semi-permeable membrane-like barriers that slowed down the release of the contact insecticide to the surfaces of the film. In theory, such a film could be deployed as a long-lasting insecticide-treated wall lining in pyrethroid resistant settings. Scanning electron microscopy (SEM) confirmed the trilayer film structure of the blown film. The malathion release from the film was tracked with Fourier transform infrared spectroscopy (FTIR). The malathion absorption band in the FTIR spectra disappeared gradually over time. Confocal Raman analysis showed a malathion concentration gradient across the thickness of the polyethylene layers. These results suggested diffusion-controlled transport through the LDPE membranes. Bioassays indicated that the residual efficacy of the malathion, against mosquitoes, was increased to about six months. This means that trilayer films, impregnated with an organophosphate, may have potential as alternative mosquito control interventions in pyrethroid resistant settings. / Dissertation (MEng)--University of Pretoria, 2017. / Chemical Engineering / MEng / Unrestricted

Virtually all organisms exhibit circadian rhythms, this includes mosquitoes. Many aspects of their biology are under the control of their circadian clocks like their vision, olfaction, host-seeking, mating, oviposition, metabolism, locomotion, and more. However, how the circadian clock regulates mosquito-host interactions and adapts to specific environmental conditions remains largely unknown, despite its importance to vector disease control. Here, we relied on a multidisciplinary, integrative, and comparative approach to shed light on the mechanisms underlying mosquitoes adaptations to various temporal niches. We use CRISPR/Cas9 to knockout timeless in Aedes aegypti and show this mutation causes an increase in their free running periods under continuous darkness conditions. External factors can also influence a vector's activity pattern like climate, light pollution, as well as host preference and availability. To investigate the influence these factors have on activity patterns, we compare the activity patterns of multiple lab rear strains of Aedes albopictus as well as two field collected populations of Aedes japonicus. Our results suggest host availability and light pollution could cause the differences in activity profiles that we observed. With vision playing an important role in both circadian rhythms, host seeking, and threat detection, we compared a nocturnal mosquito (Aedes japonicus) and a diurnal mosquito (Aedes aegypti). We introduced a looming visual stimulus in an LED arena and found Aedes aegypti to be more responsive to the looming stimulus than Aedes japonicus. Finally, the underlying mechanisms that mediate this threat detection and escape behavior were examined, revealing a possible candidate for a giant fiber neuron in Aedes aegypti. Overall these results provide novel insights into mosquito biology that have the potential to be applied towards vector control methods. / Doctor of Philosophy / Most living things, including mosquitoes, follow a daily pattern called a circadian rhythm. This rhythm affects many parts of their lives including their vision, smell, and activity. Understanding how their circadian clock functions can help us control populations of mosquitoes and prevent the transmission of diseases they may carry. By studying different species and populations of mosquitoes in the lab and from the wild, we have found that factors like light pollution and host availability could affect when mosquitoes are active. In addition to these results we have also demonstrated that mosquitoes that are active during the day and mosquitoes that are active during the night will respond differently to a looming visual stimulus. We examined the brain of the mosquitoes that were most responsive to the looming stimulus and found a system of large neurons that could potentially be responsible for eliciting their escape behaviors. Overall these results provide new and important information about mosquito biology and can be applied to mosquito control.

Understanding the factors that make non-native species successful invaders is an important step towards mitigating spread. At the same time, species invasions can serve as natural experiments to test range-limit theory. Range-limit theory postulates declines in local abundance (abundant center model) and genetic diversity (central-peripheral hypothesis) towards range edges because of underlying environmental gradients. Such declines constrain adaptation to marginal habitats via gene swamping. However, broader evolutionary theory predicts intermediate rates of immigration into range-edge populations can relieve genetic drift and improve adaptive potential. I tested hypotheses generated from theory while illuminating aspects affecting of the invasion of the Asian tiger mosquito (Aedes albopictus Skuse) into the US. Using reciprocal distribution modeling, I found US populations occupied significantly different climate and habitat than in their native range (SE Asia). Most inconsistencies were found in the northern US range, where Ae. albopictus has recently crept northward, providing an opportunity to test range-limit theory as the range reaches its limit. Because of its limited natural dispersal ability, rapid spread after the 1985 US introduction pointed to human-aided dispersal. I tested the current role of human-aided versus natural dispersal using a landscape genetics framework, and found that natural dispersal dominated current patterns. Some distant localities were highly genetically similar, indicating potential human-aided transport in limited cases. Asymmetric gene flow from core to edge localities supported the abundant center model, but uniformly high genetic diversity contrasted with the central-marginal hypothesis. I detected a significant signature of local adaptation by overwintering diapause-induced eggs in multiple field sites using reciprocal transplants. Surprisingly, most genotypes from throughout the range produced large offspring when overwintered at the range edge. Relative offspring mass between home and away winters peaked at an intermediate immigration rate. These results show that rapid adaptation has occurred in US populations of Ae. albopictus and highlight the potential for further spread. Genetic admixture from multiple introductions may explain high genetic diversity throughout the US range and contribute to high offspring size for all genotypes overwintered at the range edge. Finally, my work highlights the need for a better understanding of contemporary ecological and evolutionary processes leading to range-limits (or expansion) to more accurately reflect processes occurring in a human-dominated world.

Diseases vectored by mosquitoes cause millions of deaths each year. In modern times Florida*s disease risk has been reduced due to efforts to lessen the prevalence of mosquitoes through habitat modification of non-adults. With emerging diseases (i.e. Dengue and Chikunguya) encroaching into Florida from the Caribbean, this traditional approach may not be enough. Alternatively, we can better understand the ecology of how disease works in an ecosystem. One possible way is through the Dilution Effect, which states that the more species that are in a system the lower the chance for zoonosis. This project models mosquito diversity across regions, land use, and vegetation height in South-Central Florida, for the purpose of identifying predictors that indicate a higher disease risk using information theory (AICc). The plains and coastal regions as well as the developed areas have a relatively higher risk of disease. Florida is a fire maintained habitat, but has been fire suppressed for the last century. Archbold Biological Station (ABS) has used prescribed fires since the early 1980s to try and restore a more natural system. This has created a mosaic of different fire histories. Fire affects the structures that mosquitoes rest under during the day (they are vulnerable to desiccation during the day and hide in darker/shady places), therefore there is a high likelihood that fire will have some effect on mosquito assemblages. This project used model selection to determine the most plausible set of predictors that describe the effect of fire on mosquito assemblages at ABS, using information theory (AICc). In general, time of season accounted for the largest proportion of the variation in the data and TSF had negligible effect on adult mosquito assemblages measured as abundance, speices richness, and Jost D.