A dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, South Africa in fulfilment of the requirements for the degree of Master of Science. 2016 / This project explored the ecological conditions of aquatic breeding sites of Anopheles gambiae sensu lato immatures in the Lowveld region of eastern Mpumalanga Province, South Africa. The aim was to determine the environmental conditions influencing anopheline abundance as well as abiotic parameters which associated with vector productivity. In addition to this, the levels of insecticide resistance to the three dominant compounds used in vector control in the region were assessed. Taking into account the sympatric occurrence of the major malaria vector in South Africa (An. arabiensis Patton) and its sibling, non-vector species (An. quadriannulatus Theobald), a laboratory study was devised which investigated the outcome of intra- and inter-specific competition under constant and fluctuating temperature regimes. There was a heterogenous distribution of anophelines across aquatic habitats in Mpumalanga with small-scale variation in salinity and Total Dissolved Solids (TDS) influencing species composition and Anopheles arabiensis was found in all sites surveyed with low numbers occurring where salinity levels were elevated. Anopheles merus associated with high salinity and TDS (Pearson’s Product Moment, r = 0.922, p < 0.05) whilst An. quadriannulatus dominated in breeding sites within 50m of a building or road. Anopheles gambiae complex members were susceptible to the insecticides tested with possible resistance (97%) to DDT in An. merus. Under laboratory conditions, temperature and competitive scenarios affected the life-history traits of both species studied here. The treatment 18 - 35°C generally reduced survivorship except for An. arabiensis in mixed, larval species treatments where it was similar to values reported for 25°C. Survivorship of both species at 20 - 30°C was not significantly impacted and the adult production was high across species treatments. The development rates at 25°C and 20 - 30°C were significantly different between species when reared alone and in mixed species treatments from larvae and from eggs. The effect of temperature was more pronounced at 18 - 35°C with An. arabiensis developing faster under both competitive scenarios and An. quadriannulatus slower, notably when in the presence of its competitor (p < 0.05). In the field component of this study, Anopheles arabiensis exploited all the habitats surveyed. It is therefore recommended that larval control operations should include all available breeding sites, focusing efforts during the dry season when these sites are limited and discreet within the landscape. In the laboratory component, it was possible to test whether or not community composition of anophelines at the adult stage was regulated by different temperature and competitive conditions at the larval stage to better understand the ecological conditions that determine anopheline composition and relative abundance. Taken together, the results of each component emphasize the need for local scale studies, especially under conditions of changing temperatures and rainfall patterns. The results of responses to temperatures and biotic interactions are necessary data for use in models predicting the impact of climate change on malaria vector mosquitoes. / MT2016

Thesis advisor: Marc A.T. Muskavitch / The protozoan Plasmodium falciparum, the mosquito-borne pathogen that causes human malaria, remains one of the most difficult infectious parasites to combat and control. Campaigns against malaria eradication have succeeded, in most instances, at the level of vector control, rather than from initiatives that have attempted to decrease malaria burden by targeting parasites. The rapid evolution and spread of insecticide-resistant mosquitoes is threatening our ability to combat vectors and control malaria. Therefore, the development, procurement and distribution of new methods of vector control are paramount. Two aspects of vector biology that can be exploited toward these ends are vector behaviors and vector-specific insecticide targets. In this thesis, I describe three aspects of vector biology with potential for the development of improved means of vector control: photopreference behavior, long non-coding RNA (lncRNA) targets and epigenetic gene ensemble targets. My studies of photopreference have revealed that specific mosquito species within the genus Anopheles, An. gambiae and An. stephensi, exhibit different photopreference behaviors, and that each gender of mosquito in these species exhibits distinct light-dependent resting behaviors. These inter-specific behavioral differences may be affected by differing numbers of long-wavelength sensing Opsin genes in each species, and my findings regarding species-specific photopreferences suggest that some behavioral interventions may need to be tailored for specific vector mosquito species. Based on the advancement of next-generation sequencing technologies and the generation by others of assembled genomes of many anopheline mosquito species, I have identified a comprehensive set of approximately 3,000 lncRNAs and find that RNA secondary structures are notably conserved within the gambiae species complex. As lncRNAs and epigenetic modifiers cooperate to modulate epigenetic regulation, I have also analyzed the conservation of epigenetic gene ensembles across a number of anopheline species, based on identification of homologous epigenetic ensemble genes in An. gambiae compared to Drosophila melanogaster. Further analyses of these ensembles illustrate that these epigenetic genes are highly stable among many anopheline species, in that I detect only eight gene family expansion or contraction events among 169 epigenetic ensemble genes within a set of 12 anopheline species. My hope is that my findings will enable deeper investigations of many behavioral and epigenetic processes in Anopheles gambiae and other anopheline vector mosquitoes and thereby enable the development of new, more effective means of vector and malaria control. / Thesis (PhD) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Biology.

A central concept in evolutionary biology is to understand how new species arise and are maintained. Studying the temporal and spatial distribution of genealogical lineages provides insight into evolutionary processes which govern diversification while the study of disease vectors has additional implications for human health. Within Africa, medically important Aedes mosquitoes provide an interesting case in which to study evolutionary processes because they are behaviourally and morphologically diverse. These mosquitoes are also inherently dependent of forests and so provide an ideal study organism in which to test the refuge hypothesis of historical climate change, which has been suggested as a pivotal force in species evolution. Before their evolutionary history can be determined, reliable identification of target species is required. In Chapter 3, we have developed a PCR mediated method to distinguish between isomorphic species of the Simpsoni Complex and use this method to provide inferences on ecology and species distributions; findings reveal an east-west difference in the distribution of the yellow fever vector Ae. bromeliae and non-vector Ae. lilii across the African continent, while these species meet in Uganda where they use the same larval habitats. In Chapters 4 and 5 we use a standard phylogeographic approach coupled with Approximate Bayesian Computation to uncover the evolutionary history of Aedes mosquitoes. Analysis reveals common phylogeographic signals within Aedes species which show populations have been subject to historical lineage diversification, admixture and recent demographic structure, in accordance with the refuge hypothesis of climate induced vicariance and secondary contact. Findings suggest that recent climate change throughout the late Pleistocene and early Holocene was important in generating African biodiversity. We find additional differences in the population structure of species between East and West Africa which could reflect more general biodiversity patterns within Africa. As the region connecting East and West African populations, Central Africa could be an important area regarding the diversification of species, including diseases and their vectors. We have identified a putative role for ecological speciation; for example in Chapter 4 we have provided additional evidence that worldwide populations of Ae. aegypti stem from a particularly successful source, indicating these mosquitoes possessed a trait integral for range expansion. In Chapters 4 and 5 we find that historical admixture within Africa characterises populations of Aedes mosquitoes and so may have played a key role in their evolutionary success. Since admixture can combine novel combinations of genetic material and raise adaptive potential, admixture may have been selectively advantageous for Aedes mosquitoes. Similarly, climate related secondary contact is likely to have been an important force for the evolution of other forest dependent species within Africa.

Les moustiques anophèles sont les vecteurs du parasite Plasmodium l’agent du paludisme. Le parasite subit des pertes massives pendant son cycle de développement chez l’anophèle, ce qui suggère que les moustiques sont capables de développer une réaction immunitaire efficace contre le parasite. La connaissance de l’immunité et de la résistance des moustiques au genre Plasmodium provient principalement de systèmes de laboratoire qui utilisent des espèces de parasites de rongeurs ou d’oiseaux comme modèles du paludisme humain. Les observations présentées dans cette thèse suggèrent que certains gènes comme Tep1 et LRIM1 sont des médiateurs de réponses antiparsitiques contre différents Plasmodiums dans différents vecteurs. Cependant, le degré d'efficacité avec laquelle un moustique est capable de réduire le nombre de parasites peut être variable surtout entre combinaison de souche de moustique et de souche de parasite différentes, selon que la paire soit hautement compatible ou non.

Abstract The objective of this thesis is to study the biological effects of larvae of Aedes albopictus induced by ultrasound exposure. Ultrasound is widely used in medical and biological techniques, most of them are cell killing or tumor eliminating by high-intensity ultrasound. In order to analyse the influences of ultrasound biological effects in vivo, the larvae of mosquito, in this research, were exposed to continuous-wave ultrasound. Some preliminary observations were made with 0-day larvae. The oscillation of the trachea in larvae in response to the ultrasound radiation is simulated using Miller¡¦s cylindrical-bubble activation theory. Dimensions of tubes in the respiratory system of larvae were measured by microscope. The resonant frequency of the tracheae were calculated, and its range is about 0.6¡ã1.5 MHz. It was observed that the tracheae in 0-day larvae were ruptured by ultrasound exposure, and the larvae were dead in the duration of growth, some fourth instar larvae failed to mature into pupae. The maximum mosquito larvae mortality was with 1 MHz irradiation, and it¡¦s in good agreement with the resonant frequency calculated in this paper.

Thesis (M.P.H.)--University of Michigan, 1946.

Thesis (M.P.H.)--University of Michigan, 1946.

No description available.

Submitted by Romulus Lima (romulus.lima@ufpe.br) on 2015-03-10T19:06:13Z No. of bitstreams: 2 DISSERTAÇÃO Cristina Maria Torres.pdf: 1528914 bytes, checksum: c901ce48fda5bcb9f1e07e164ccadb13 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-10T19:06:13Z (GMT). No. of bitstreams: 2 DISSERTAÇÃO Cristina Maria Torres.pdf: 1528914 bytes, checksum: c901ce48fda5bcb9f1e07e164ccadb13 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2014-02-18 / CNPq / Estudos de campo foram realizados para avaliar o desempenho do larvicida spinosad (Natular® DT) nas formulações líquida (6,3nL/L e 18,9nL/L) e em pastilha (100mg/L, 50mg/L e 25mg/L), como alternativa para o uso em ovitrampas. Além disso, foram avaliados a influência do spinosad sobre a escolha da armadilha como sítio de oviposição e o potencial de inibição de eclosão de larvas em ovos expostos ao spinosad pastilha. O biolarvicida Bacillus thuringiensis israelensis (Bti) na concentração de 4mg/L (VectoBacWG®) foi usado como parâmetro para comparação da ação larvicida e a persistência do spinosad. A presença de larvas e pupas foi analisada semanalmente em 210 ovitrampas instaladas no campus da UFPE. A positividade e a densidade de ovos postos nas ovitrampas foram consideradas para avaliar a influência do spinosad sobre a escolha da armadilha como sítio de oviposição. O percentual de ovos intactos e murchos foi considerado na avaliação da taxa de inibição de eclosão. O período de controle total de larvas sofreu influencia da concentração e exposição das ovitrampas ao sol, tendo sido mais prolongado (17 semanas) na formulação pastilha em armadilhas sombreadas. O registro de larvas vivas nas ovitrampas contendo a formulação líquida do spinosad ocorreu desde a primeira semana de tratamento. A atividade de controle do Bti em condições similares foi de duas semanas. Não foi observado efeito repelente do spinosad em nenhuma das condições testadas nesse trabalho, com percentual de colonização >90% das ovitrampas. A eclosão das larvas em ovitrampas foi elevada (>70%) mesmo nas altas concentrações testadas da formulação pastilha. Esses dados proveem evidências de que a formulação pastilha apresenta uma elevada atividade larvicida e melhor persistência sob condições adversas de exposição solar, quando comparada com a formulação líquida e com o Bti. Além disso, o produto não influencia na escolha da ovitrampa pelas fêmeas de Aedes sp nem na eclosão das larvas.

Aedes aegypti mosquitoes are the vectors of many significant arboviruses that cause tremendous social and economic impact. RNA interference (RNAi) plays a crucial role in the vector competence of mosquitoes and is often targeted in studies involving mosquito innate immunity, genetics-based vector control strategies, and the development of viral-resistant transgenic mosquitoes. In general, RNA interference is induced by double stranded RNA (dsRNA) and results in the inhibition of cognate gene expression. There are several different RNA interference pathways, with distinct functions and mechanisms. The micro RNA pathway is important for endogenous gene regulation and development. The endogenous small interfering RNA (endo-siRNA) pathway functions in gene regulation and protection of the genome from the deleterious effects of transposable elements. The exogenous siRNA (exosiRNA) pathway is a major contributor to mosquito innate immunity and vector competence by limiting viral replication during infection. Lastly, the piwi RNA (piRNA) pathway primarily functions in protecting the genome from the deleterious effects of transposable elements. While the structure and function of many genes involved in Drosophila RNAi have been characterized, the corresponding mosquito orthologs have only been peripherally described or remain unknown. Thus, the overall purpose of this study is to improve the understanding of mosquito RNAi mechanisms by identifying and analyzing genetic factors involved in the various pathways. This research especially focuses on characterizing and analyzing putative doubleiii stranded RNA binding proteins (dsRBPs) important to the function of the RNAi initiator and effector complexes. Two genes, r2d2 and r3d1 are orthologs of Drosophila genes known to have important roles in the RNAi initiator complex. A third member of the same family, which we refer to as extra loquacious (exloqs), appears to have no known orthologs outside of the Aedes genus. Structural characterization of these genes included identification of single nucleotide polymorphisms (SNPs), novel exons and alternative splice variants. RT-PCR assays were utilized to examine differential expression of all three genes in specific tissues and developmental stages. Sub-cellular fractionation assays enabled intracellular localization of the RNAi proteins within Ae. aegypti cells. Co-immunoprecipitation of tagged dsRBPs revealed protein-protein interactions between specific dsRBPs and known RNAi factors. In addition, an exo-siRNA sensor was designed and tested in-vivo and in-vitro with the purpose of facilitating the identification of novel genetic factors involved in this anti-viral pathway. Lastly, TALENbased gene disruption was successfully employed to knockout the exloqs gene in Ae. aegypti mosquitoes, enabling further analysis into the function of this gene. The research described in this document provides further insight into mosquito innate immunity and gene regulation, which is important to the advancement of genetics-based vector control strategies. / Ph. D.