Wolbachia is a maternally inherited α-proteobacteria that lives an obligate intracellular lifestyle in its eukaryotic hosts. Wolbachia pipientis was first identified in the 1920’s in the mosquito Culex pipiens; Wolbachia has since been detected in a broad range of hosts. Wolbachia induces a number of diverse reproductive manipulations in many of its hosts, implicating Wolbachia in control strategies for target species. However, changes in host bacterial interactions can evolve toward mutualism, and this requires investigation in target systems. / This first part of this work examines changes in the Drosophila simulans-Wolbachia Riverside system in California. This system, studied for a period of more than two decades, provides a rare example in nature of a symbiotic relationship shifting from parasitism to mutualism. In my study, no changes in overall estimates of infection frequency, maternal transmission or cytoplasmic incompatibility were found, however there appears to be heterogeneity in maternal transmission rates and the ability of males to induce cytoplasmic incompatibility (CI). The source of CI variation in one isofemale line was subsequently investigated through reciprocal backcrossing with an old Wolbachia-infected strain, Riv88, and the variation was attributed to the Wolbachia genome. Further investigations are required to determine the extent of CI variation in the wild. These findings significant implications for the many applied projects that intend to exploit Wolbachia for its ability to manipulate host reproductive systems. / The second part of this work investigates the extent to which evolution of a host-bacterial symbiosis can influence the effectiveness of control strategies using Wolbachia. A particular strain of Wolbachia, named popcorn (wMelPop), has been isolated for its ability to reduce host longevity. This bacterium has the capacity to alter the age structure of the target host populations. As many vector-borne diseases (eg: Dengue Fever, Malaria) require an incubation period within the vector prior to transmission to the final host, a reduction in the lifespan of vector populations has the potential to lower transmission levels. The long term stability of this bacterial strain has been investigated in its native host (Drosophila melanogaster), and a novel host (D. simulans). The longevity-shortening phenotype and several life-history traits that might influence the effectiveness of control strategies have been examined. Host genetic background and the indirect selection on the longevity phenotype (via early or late fecundity selection) were found to influence multiple life-history traits in these species. The source of this variation in D. melanogaster is attributed primarily to the host, but can also be influenced by Wolbachia. Strong host background effects were noted in D. simulans, which highlights the importance of testing multiple backgrounds for suitability of use in applied projects. / This work has allowed for greater understanding of the potential for evolution within host-symbiont systems, and can be used to provide a framework for undertaking projects that will use Wolbachia as biological control agents. Future projects should consider the potential for evolution in detail under laboratory conditions before control strategies are implemented in the wild.

Submitted by Nuzia Santos (nuzia@cpqrr.fiocruz.br) on 2015-04-16T15:19:17Z No. of bitstreams: 1 Dissertacao_BCM_Daniela da Silva Gonçalves.pdf: 3089652 bytes, checksum: 385ead67db7f264f48369a8a80a7040e (MD5) / Approved for entry into archive by Nuzia Santos (nuzia@cpqrr.fiocruz.br) on 2015-04-16T15:19:26Z (GMT) No. of bitstreams: 1 Dissertacao_BCM_Daniela da Silva Gonçalves.pdf: 3089652 bytes, checksum: 385ead67db7f264f48369a8a80a7040e (MD5) / Approved for entry into archive by Nuzia Santos (nuzia@cpqrr.fiocruz.br) on 2015-04-16T15:19:35Z (GMT) No. of bitstreams: 1 Dissertacao_BCM_Daniela da Silva Gonçalves.pdf: 3089652 bytes, checksum: 385ead67db7f264f48369a8a80a7040e (MD5) / Made available in DSpace on 2015-04-16T15:19:35Z (GMT). No. of bitstreams: 1 Dissertacao_BCM_Daniela da Silva Gonçalves.pdf: 3089652 bytes, checksum: 385ead67db7f264f48369a8a80a7040e (MD5) Previous issue date: 2014 / Fundação Oswaldo Cruz. Centro de Pesquisa René Rachou. Belo Horizonte, MG, Brasil / Wolbachia pipientis é uma bactéria intracelular que infecta cerca de 40% dos artrópodes e alguns nematódeos, causando alterações reprodutivas em seus hospedeiros. Recentemente, duas cepas de Wolbachia (wMelPop e wMel) foram inseridas individualmente em Aedes aegypti (não infectado naturalmente) e os mosquitos adultos contendo a Wolbachia foram menos suscetíveis a diferentes arboviroses (Dengue e Chikungunya) bem como ao Plasmodium sp. Atualmente, mosquitos A. aegypti contendo Wolbachia (wMel) estão sendo liberados a campo em diversos países, pelo Programa Eliminate Dengue, como possível agente de controle biológico de Dengue. Durante o processo de invasão de mosquitos contendo Wolbachia no campo, há a necessidade de realização de coletas e screening semanal de grandes quantidades de mosquitos para detecção de Wolbachia, via PCR quantitativo, técnica ainda bastante onerosa. Diante disto, é imprescindível o desenvolvimento de um método rápido, específico e de baixo custo para detecção de mosquitos infectados com a bactéria, para levantamento e monitoramento da disseminação da Wolbachia em campo. No presente trabalho, desenvolvemos com sucesso um método rápido de detecção através do LAMP (Amplificação isotérmica mediada por loop) que utiliza 3 pares de primers que se ligam em 8 regiões distintas do DNA alvo, o que torna a reação bastante específica. Em nosso caso, desenhamos iniciadores baseando-se na sequência alvo do gene 16S rRNA da bactéria. Para padronização, foram utilizados mosquitos da colônia do Insetário do Laboratório de Malária do CPqRR, infectados e não infectados por Wolbachia, além de insetos de campo (mosquitos e insetos de diferentes ordens) doados por colaboradores. O tempo de incubação estabelecido para a amplificação foi de 90 minutos à 63oC, sendo possível a realização da reação tanto em termociclador, como em banho seco. Para análise da sensibilidade, foi feita a diluição seriada de plasmídeo contendo a sequência alvo de 109 à 100 cópias, sendo possível a amplificação utilizando apenas 1 cópia do DNA. Para verificar a especificidade, foram utilizadas amostras de diferentes espécies de bactérias e em nenhuma delas ocorreu a amplificação, confirmando que o LAMP é bastante específico. Uma maneira de reduzir os custos foi através da redução da concentração da enzima Bst DNA polimerase por reação e, com apenas 1 unidade, a amplificação ocorreu de maneira eficiente. Para visualização dos resultados, foram utilizados dois corantes, o azul de hidroxinaftol (HNB) e SYBR Green I. Em ambos foi possível diferenciar as amostras positivas das negativas sem a necessidade de géis de agarose, sendo que, com o HNB, não há manipulação de produto amplificado pois é adicionado antes da reação, o que evita possíveis contaminações, e também é possível observar a diferença de cores a olho nu, sem o uso de luz UV. Comparando os custos, em reais, para realização da técnica de PCR e LAMP, esta apresentou um custo de 53,92% menor em relação ao PCR, o que confirma ser uma técnica de baixo custo, já que não requer equipamentos sofisticados e nem eletroforese em gel de agarose para análise dos resultados. Desenvolvemos, neste trabalho, uma técnica para detecção de Wolbachia bastante especifica, rápida, sensível e de baixo custo a qual possibilita seu uso em larga escala para monitoramento de diversas espécies de insetos infectadas no campo. / Wolbachia pipientis is an intracellular bacterium that infects about 40% of arthropods and some nematodes, causing reproductive alterations in their hosts. Recently, two strains of Wolbachia (wMelPop and wMel) were individually introduced into Aedes aegypti (naturally uninfected) and the adult mosquitoes containing Wolbachia were less susceptible to different arboviruses (Dengue and Chikungunya) and Plasmodium sp. Currently, A. aegypti mosquitoes containing Wolbachia (wMel) are being released in the field in many countries, through the Eliminate Dengue Program, as a possible biological control agent for Dengue. During the invasion of mosquitoes containing Wolbachia in the field there is the need to weekly screen large numbers of mosquitoes to detect Wolbachia via quantitative PCR, a technique still quite costly. Due to this fact, it is essential to develop a rapid, specific and inexpensive method to detect mosquitoes infected with this bacterium, to survey and monitor the spread of Wolbachia in the field. In the present study we successfully developed a rapid detection method through LAMP (loop-mediated isothermal amplification) using 3 pairs of primers that bind to 8 distinct regions of the target DNA, increasing the specificity of the reaction. In our case, we designed primers based on the sequence of the Wolbachia 16S rRNA gene. During the optimization process we used colony mosquitoes reared at the Insectary of the Malaria Laboratory (CPqRR), either infected or uninfected with Wolbachia. We also used field insect samples (mosquitoes and insects belonging to different orders). The incubation time allowing amplification was set to 90 minutes at 63oC, being possible to perform the reaction either in a thermocycler or on a heat block. For sensitivity analysis, we performed serial dilutions of plasmid DNA (109 to 100 copies) containing the target sequence and the amplification was still possible by using only one copy of the plasmid DNA. To verify the specificity, samples of different bacterial species were used and in none of them the amplification occurred, confirming that the LAMP is very specific. To reduce the reaction cost we were able to reduce the amount of the Bst DNA polymerase down to 1 unit and we can see clearly a great amplification. To visualize the results, two dyes were used, the Hydroxy Naphtol Blue (HNB) and SYBR Green I. In both cases it was possible to differentiate positive from negative samples without the need to run agarose gels. An advantage of using the HNB is that there is no need to manipulate amplified products as this dye is added before the reaction, avoiding possible contamination, and it is also possible to see the difference in color by naked eye without the need of UV light. When comparing the costs, in Brazilian Reais, to perform PCR or LAMP, the latter had a cost 53.92% lower than the PCR, and it does not require sophisticated equipment or electrophoresis agarose gel to analyze the results. In the present study, we develop a technique for Wolbachia detection which is very specific, rapid, sensitive and with low cost enabling its use in large-scale monitoring of Wolbachia infection status of several insect species.

Made available in DSpace on 2015-06-12T13:55:09Z (GMT). No. of bitstreams: 2 451.pdf: 4164866 bytes, checksum: 0033f939c37f8329071090089fd91e05 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2011 / Fundação Oswaldo Cruz. Centro de Pesquisas Aggeu Magalhães. Recife, PE, Brasil / A bactéria endossimbionte Wolbachia tem sido sugerida como mecanismo de controle de insetos vetores e alvo para o tratamento das filarioses. Nesse contexto, estudos sobre a prevalência de Wolbachia em populações de vetores de campo, a análise da sua densidade em insetos sob diferentes condições fisiológicas e a investigação da diversidade genética da bactéria dentro e entre diferentes populações de vetores e em pacientes filarêmicos são relevantes. O presente estudo teve como objetivos: determinar o percentual de infecção em Culex quinquefasciatus e Aedes albopictus coletados em diferentes áreas da RMR - PE BR; descrever a diversidade dos genes ftsZ e wsp nas linhagens de Wolbachia encontradas tanto nos vetores citados quanto nos vermes filariais coletados de pacientes microfilarêmicos da região; como também comparar a densidade da bactéria em duas populações de C. quinquefasciatus do estado de PE, uma susceptível e outra resistente a temefós. Nossos resultados mostraram que o simbionte Wolbachia está presente em 100 por cento dos vetores analisados quando diagnosticados pelo método de PCR seminested, o qual se mostrou mais eficiente que a PCR convencional. Quanto à densidade do endossimbionte, as fêmeas de C. quinquefasciatus resistentes a organofosforados de Santa Cruz do Capibaribe, Sertão PE, apresentaram a densidade média, cerca de sete vezes maior que às fêmeas susceptíveis de Peixinhos, RMR PE, confirmando dados encontrados na literatura. Isto sugere que mosquitos resistentes apresentam maior dificuldade para controlar a densidade do endossimbionte provavelmente pelo custo biológico associado à resistência. / Em relação à diversidade genética, os dois genes estudados não mostraram nenhuma variação nas populações observadas. A análise de outros marcadores pode ajudar a esclarecer a relação entre hospedeiros e endossimbionte dando maior suporte ao uso de Wolbachia no desenvolvimento de novas estratégias de controle e tratamento de doenças transmitidas por vetores

Made available in DSpace on 2015-09-17T15:25:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-03-06. Added 1 bitstream(s) on 2015-09-17T15:48:35Z : No. of bitstreams: 1 000845669_20160306.pdf: 285697 bytes, checksum: 31a6836e707fa9458fac599525f577da (MD5) Bitstreams deleted on 2016-03-07T11:06:14Z: 000845669_20160306.pdf,. Added 1 bitstream(s) on 2016-03-07T11:07:06Z : No. of bitstreams: 1 000845669.pdf: 1141164 bytes, checksum: 3bf7c568fe9454678b74118810132337 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Mecanismos de isolamento reprodutivo são agentes que impedem ou diminuem a troca de genes entre duas espécies ou populações de uma mesma espécie que se encontram em processo de especiação. Esses mecanismos são compreendidos por uma serie de processos que atuam em diferentes níveis da reprodução, incluindo desde barreiras pré-zigóticas até barreiras pós-zigóticas. Nas ultimas décadas, muitos estudos têm indicado que a ausência de híbridos pode também ser promovida por interações entre microorganismos simbiontes e seus hospedeiros. Um dos principais simbiontes capazes de interagir com os insetos, levando a modificações do processo reprodutivo, são as alfaproteobactérias do gênero Wolbachia. No presente estudo, foram analisados os efeitos da infecção pela Wolbachia causados no parâmetro produtividade (número de descendentes), em intra e intercruzamentos de linhagens de Drosophila. saltans, D. prosaltans (espécies próximas pertencentes ao subgrupo saltans) e mais duas linhagens, obtidas por introgressão a partir de híbridos F1 do intercruzamento dessas duas espécies. Análises preliminares para detecção da infecção pela Wolbachia nas linhagens de Drosophila mostraram que cada uma das seis linhagens estava infectada com uma linhagem do simbionte. Os resultados quanto à produtividade foram obtidos de intra e intercruzamentos das linhagens nas condições infectadas e não infectadas A eliminação do simbionte foi realizada por tratamento com o antibiótico tetraciclina. O principal mecanismo resultante da interação simbionte-hospedeiro mencionado na literatura é chamado incompatibilidade citoplasmática (IC) e ocorre nos intercruzamentos de fêmeas não infectadas com machos infectados. Considera-se que nos machos infectados ocorrem alterações nos espermatozoides que somente os ovócitos de fêmeas infectadas podem reverter, reestabelecendo a produtividade. Os resultados obtidos, neste trabalho, sobre a... / Reproductive isolation mechanisms are agents that prevent or decrease the exchange of genes between species or populations of the same species that are in process of speciation. These mechanisms are comprised of a series of processes operating at different levels of reproduction, ranging from pre-zygotic to post-zygotic barriers. In recent decades, studies have indicated that the absence of progeny can also be promoted by interactions of symbiont microorganisms and their hosts. Presently, the most known endosymbionts capable of interact with the insects, interfering in the reproductive process, are the alphaproteobacteria of the genus Wolbachia. In the present study, we investigated the Wolbachia effects on reproduction, focusing the parameter productivity (number of progeny) in crosses involving four strains of Drosophila saltans and D. prosaltans (close species belonging to the saltans group, Sophophora subgenus) and two introgressed strains started with F1 hybrids of these two species. Preliminary tests for screening Wolbachia showed that each of the six strains was infected with one strain of the symbiont. The results on productivity were obtained from intra and intercrosses of the strains in the conditions infected or uninfected. The elimination of Wolbachia was performed by treatment of the strains with the antibiotics tetracycline. The main mechanism resulting from the interaction symbiont-host described in the literature is called cytoplasmatic incompatibility (CI) and occurs in the intercrosses of uninfected females with infected males. It is considered that, in infected males, there are changes in the sperm that only the oocytes of infected females are able to correct, reestablishing the productivity. The present results on Wolbachia infection of the species from the saltans group were variable. In several crosses of the strains, the combinations that are sterile or almost sterile when CI effect occurs, were the most productive ...

Orientador: Celso Luis Marino / Banca: Maoel Victor Franco Lemos / Banca: Carlos Frederico Wilcken / Resumo: Wolbachia é uma bactéria endossimbionte comumente encontrada nos tecidos reprodutores de invertebrados, sendo herdada vertical e horizontalmente. Esta bactéria é desencadeadora de inúmeras alterações reprodutivas, dentre elas a incompatibilidade citoplasmática. Bactéria Wolbachia apresenta oito diferentes tipos de genoma, identificados de A a H. Dentre os hospedeiros da Wolbachia estão as moscas-das-frutas do gênero Anastrepha, que são um importante inseto-praga causador de inúmeras perdas na fruticultura de vários países na América. Neste estudo, foram utilizados os primers 16S rDNA, ftsZ e wsp na detecção da Wolbachia e identificação do supergrupo em três populações de Anastrepha do complexo fraterculus, de diferentes regiões do estado de São Paulo. Em todas as amostras de moscas foi detectada a presença da Wolbachia do supergrupo A, através da utilização dos primers 16S rDNA e wsp, visto que o ftsZ apresentou baixa sensibilidade na detecção desta bactéria em Anastrepha. Comparações das sequências do gene wsp dos 62 indivíduos no Genebank possibilitaram a identificação de duas linhagens de Wolbachia, uma pertencente a Anastrepha sp. 2 (wAsp2B) e a outra ao nematóide Brugia pahangi (Bp-1-1001). Com isso, sugere-se a ocorrência de transferência horizontal da linhagem Bp-1-1001 em Anastrepha através das vespas parasitas de dípteros. A partir de comparações entre as sequências geradas com o gene wsp, observou-se a ocorrência de quatro diferentes sequências pertencentes a novas linhagens de Wolbachia, denominadas wAsc, wAnc, wBjc e wBsp. Essas linhagens estão distribuídas nas diferentes populações de moscas-das-frutas do gênero Anastrepha / Abstract: Wolbachia is a endosymbiont bacteria commonly found in reproducer tissue of invertebrates, being vertically and horizontally inherited. This bacteria cause innumerable reproductive alterations, among them a cytoplasmic incompatibility. Wolbachia have eight different types of genome, designated from A to H. Among Wolbachia host there are the fruit flies of genus Anastrepha. These arthropods are important pest insect that causes many losses in fruit production of many countries of America. In this work, were used the primers 16S rDNA, ftsZ and wsp to detect Wolbachia and to identify the supergroups of three Anastrepha populations the different regions of São Paulo state, Brazil. In all fruit flies samples, it was detected the presence of Wolbachia of the A supergroup, through the use of primers 16S rDNA and wsp, since ftsZ has low sensitivity in detecting this bacteria in Anastrepha. Comparisons of the wsp gene sequences of 62 samples in GeneBank, allowed the identification of two Wolbachia lineages, one relating to Anastrepha sp. 2 (wAsp2B) and other in Brugia pahangi nematode (Bp-1-1001). Therefore it is propose the occurrence the horizontal transference of Wolbachia lineages Bp-1- 1001 into Anastrepha through the did parasite wasps of dipterous. The comparisons among the wsp gene sequences showed the occurrence of four different sequences, possibly belonging to the news lineages of Wolbachia, which were named wAsc, wAnc, wBjc and wBsp. These lineages are distributed in different fruit flies of populations of the Anastrepha genus / Mestre

Over the past 20 years numerous major arbovirus outbreaks including Yellow Fever virus, West Nile virus, dengue virus, Chikungunya virus, and most recently Zika virus, have highlighted the need for novel methods of control for these diseases. Wolbachia are maternally transmitted endosymbionts that inhabit a large portion of arthropods, including Aedes aegypti, Aedes albopictus, and Culex pipiens, which are three mosquito vectors that transmit these viruses. Wolbachia have been shown to reduce vector competency in these mosquitos. However, the molecular pathways at the Wolbachia-host cell interface are mostly unknown. For fundamental biological questions and for vector control approaches, there is a need to further our understanding of host-symbiont interactions at the molecular level. From this, autophagy has been suggested as one possible mechanism at this interface. Autophagy is a conserved, cellular, homeostasis process that involves degrading cytoplasmic contents, including organelles and protein aggregates. Canonical autophagy can be a large, bulky process, or a more targeted, selective one. There is the potential for Wolbachia to both benefit from the nutrients generated from bulk autophagy, but also be targeted in the host’s immune response, as selective autophagy has been shown to aid in removal of intracellular pathogens. Here we describe how autophagy plays a role in regulating Wolbachia in Drosophila melanogaster as a model for mosquitos. Using antibody and FISH staining we visualized differences in Wolbachia density after knocking down autophagy genes. Knocking down Atg1, an important factor in initiating autophagy, was sufficient for increasing Wolbachia density in polar cells, but other components like Atg7 and Ref(2)p were not. Results varied based on the Wolbachia strain infection, showing that autophagy differentially affects Wolbachia according to the strain. These findings further our understanding of molecular host-symbiont interactions and provide additional tools to Wolbachia based vector control strategies. / 2021-10-09T00:00:00Z

Wolbachia is a vertically transmitted, obligate intracellular bacterium infecting ~40% of all known species of arthropods, as well as filarial nematodes. The nature of Wolbachia-host interactions ranges from reproductive parasitism to increased fecundity and pathogen protection. Wolbachia reduces the ability of mosquitoes to transmit human pathogens, which is being explored as a novel method for the control of vector-borne diseases like Dengue and Zika. The mechanisms of Wolbachia blocking the transmission of these diseases are not fully understood. There are studies indicating that Wolbachia-induced changes in the insect immunity could block the virus, however there is no consensus in the literature. A necessary step in the transmission of these diseases is the viral entry into the insect vector. This occurs trough the gut epithelium, highlighting the importance of understanding the interaction of this tissue with microorganisms. We have recently shown that Wolbachia colonizes the Drosophila gut epithelium and affects the gut microbiome composition. Wolbachia’s presence did not affect the gene expression of immune effector molecules from the main regulators of gut immunity, Imd and ROS pathways. Our understanding of the mechanisms of Wolbachia’s colonization of the gut epithelium and modulation of gut microbiome are still very limited. This work characterizes Wolbachia’s kinetics of colonization in Drosophila midguts. Imaging analysis revealed that Wolbachia colonizes adult and larval midguts in different patterns. We have also characterized a preferential colonization in specific adult midgut sub-regions. We observed that Wolbachia patches are confined to specific midgut subregions, in a pattern similar to the arrangement of intestinal stem cell (ISC) clones. These results led us to hypothesize that Wolbachia colonizes Drosophila midguts by infecting intestinal progenitor cells and spreading vertically to their progeny with limited lateral transmission between neighboring cells. We provide evidence to support this hypothesis by showing that Wolbachia is present in intestinal progenitor cells in all stages of the fly’s life cycle as well as by analyzing the infection status of ISC clones and differentiated cells surrounding ISCs. Finally, we found that ISC proliferation is reduced by the intracellular presence of Wolbachia, which also decreases ISC tumor incidence triggered by the downregulation of Notch signaling specifically in ISCs. These findings will aid in our understanding of Wolbachia tropisms and its phenotypic consequences. It has been shown that in the Wolbachia wMelPop strain excessive growth of intracellular bacteria leads to damage to the host cell, suggesting a mechanism of controlling intracellular growth in other strains. To better understand the molecular mechanisms behind Wolbachia-Drosophila interactions, we turned to the gonads, as Wolbachia colonization of these tissues has been well characterized. We chose to investigate the interplay between Reactive Oxygen Species (ROS) and Wolbachia, as intracellular ROS could regulate bacterial density but also be affected by Wolbachia and play a role in symbiont-related phenotypes. Using direct and indirect measurements of ROS, we show that the pathogenic strain wMelPop increases ROS in the germarium, while the symbiotic strains wMel and wMelCS reduce ROS in the terminal filaments. None of the Wolbachia strains tested affected ROS levels in the testes. In addition, genetically altering ROS levels in the germline or systemically in the fly did not affect Wolbachia levels in the ovaries. We conclude that ROS does not significantly affect Wolbachia in the fruit fly gonads.

Plum curculio, Conotrachelus nenuphar (Herbst), is an endemic pest of stone and pome crops of the eastern United States. Two morphologically identical strains of plum curculio have been described and documented in Virgina: a univoltine strain and a multivoltine strain. Because of the cryptic coloring and behaviours of the plum curculio adults, monitoring in orchards is difficult and often ineffective. RAPD-PCR assay was an effective method for separation of the geographical strains. Of the tested primers four, OPE 01, OPE 03, OPE 04, and OPE 07, gave 21 amplimers that are useful for distinguishing individuals from the univoltine and multivoltine populations. Gene targeted PCR revealed the presence of Wolbachia in both populations. Analysis of the wsp gene sequence showed the univoltine population of plum curculio is associated with a strain of Wolbachia in supergroup B, most closely related to a strain identified from Perithemis tenera (Say) (Odonata). The multivoltine populations of plum curculio are associated with strains of Wolbachia which are in supergroup A, and most closely related to Wolbachia strains associated with Dacus destillatoria, Bactrocera sp., and Callosobruchus chinensis Linn. Three different trap designs baited with grandisoic acid, plant volatiles, and a combination of pheromone and plant volatiles were tested. In 1999, significantly more plum curculios were captured with Tedders traps baited with grandisoic acid and unbaited control in traps baited with limonene, plum essence or ethyl isovalerate. In 2000, Circle traps baited with plum essence, sour cherry essence and grandisoic acid yielded no results. In 2001, branch mimic traps yielded no significant differences among three release rates of a blend of benzaldehyde, ethyl isovalerate, trans-2-hexenal, and limonene; although, there was a significant interaction between the pheromone and the host plant volatiles. Overall however, all three of the traps were not effective. / Master of Science

This research focused on the reproductive incompatibility and genetic differences between the two strains of plum curculio, Conotrachelus nenuphar (Herbst). Two molecular markers served as the basis for the strain distribution analysis of plum curculio and Wolbachia symbiont. One marker is the partial mitochondrial cytochrome oxidase gene subunit I (mtCOI) of plum curculio. Another marker is the Wolbachia Surface Protein (wsp) gene of Wolbachia associated with plum curculio. First, the reproductive compatibility of cross-populations mating in plum curculio was studied during the summers of 2004 and 2006. The results confirmed the reproductive incompatibility among plum curculio geographic populations. A unidirectional incompatibility was revealed in an approximate north and south transect of the range of plum curculio (4 x 4 two factorial design: NY, VA, FL, and WV): there was a significant low fertility in WV males mated with NY (40%) and VA (29%) females. The Florida population showed a different pattern: FL males have a significantly lower fertility with VA (46%) and WV (37%) females while FL females were compatible with all males from the four populations. The results of experiment 2 indicated that within the northern geographic area populations (3 x 3 two factorial design: NY, MA, and NJ) were compatible with each other. An opposite unidirectional reproductive incompatibility was revealed in the combination of NJ males with FL females, which showed a significant low fertility (47%). A bi-directional incompatibility occurred between FL and WV reciprocal cross mating. FL males mated with WV females (26%) and WV males mated with FL females (21%) both have the significant low fertility compared to fertility of within their population matings. The genetic diversity among plum curculio populations from different geographic locations was investigated using the partial mtCOI gene. A total of 50 samples from 10 populations were sequenced. PCR products were 863 bp in length. A total of 23 unique sequence haplotypes were found in the 50 samples tested. Haplotype G (n = 5), L (n = 12) and T (n = 13) comprised 60% of 50 samples. The nucleotide distances between those haplotypes ranged from 0.12% to 4.87%. Genetic distances between northern and southern group plum curculios range from 4.17% to 4.87%. Two distinct major clades were found, using three different phylogenetic analyses: 1) neighbor joining (NJ), 2) maximum-parsimony (MP), and 3) maximum-likelihood (ML). 100% bootstraps support the northern clade and the southern clade was strongly supported (100/100/86, NJ/MP/ML) as well. The mid-southern subclade within the southern clade was also strongly supported (70/82/71, NJ/MP/ML) and the far-southern subclade was supported in NJ tree (81%) but was not resovled in MP and ML trees. The mid-southern subclade included haplotypes from two NJ, Washington, VA (Ra), Blacksburg, VA (BL) and 50% of WV populations and the far-southern subclade included haplotypes from FL, GA, Whitethorne, VA (Ke), Troutville, VA (Bo) and another 50% of WV populations. The results suggested that the northern and the southern clade could correspond with the northern and southern strains, respectively, of plum curculio. In this study, the mtCOI sequence was highly informative as a molecular marker in that it was useful to distinguish C. nenuphar from northern and from southern geographic locations in the eastern United States. However, the number of generations per year of several geographic populations within the southern clade still needs to be determined. The distribution of Wolbachia infection associated with plum curculio strains was investigated. 91 of 93 samples were infected by Wolbachia. Three unique Wolbachia strains were identified. The strains wCne1 and wCne2 (593 bp) were 97% identical, and their sequences were both 84% identical with wCne3 (590 bp). The wsp sequence of wCne1 was 99% identical to Wolbachia sequenced from the neotropical beetle, Chelymorpha alternans Boheman (Keller et al. 2004). The wCne2 sequence was 98.5% identical to the flower bug, Orius nagaii Yasunaga (Miura and Tagami, unpublished). The wCne3 sequence was 100% identical to Wolbachia sequenced from the tephritid fruit fly, Dacus destillatoria (Jamnongluk et al. 2000) and the ant, Formica exsecta (Reuter and Keller 2003). PCR - Restriction Fragment Length Polymorphism (RFLP) was used for superinfection detection. Of 93 samples, 15 (16.1%), 21 (22.6%), 19 (20.4%), 36 (38.7%) samples were infected by wCne1, wCne2, wCne1 plus wCne2, and wCne3, respectively. Only two (2.2%) samples had no infection. The wCne3 strain was always present as a single infection. Therefore, current results suggest that Wolbachia strains approximate the distribution of plum curculio strains: the northern strain is infected with wCne1 and wCne2 strains in supergroup B, the southern strain is infected with wCne3 strain in supergroup A and the mid-Atlantic region is the convergence area. Compared with the haplotype distribution of plum curculio mtCOI gene, there was a closer relation of the mid-southern PC clade to the far-southern clade than to the northern clade. However, Wolbachia symbionts in mid-southern PC are more closely related to those in northern PC than to those in far-southern PC. The relationship of Wolabchia infection with reproductive incompatibility between plum curculio populations is also discussed. / Ph. D.

On assiste actuellement à l'émergence et la ré-émergence mondiale d'arboviroses comme le chikungunya, la dengue ou la fièvre de la vallée du Rift. Ces maladies, responsables d'environ 30 000 décès par an, sont dues à des virus principalement transmis à l'homme par des moustiques vecteurs. En l'absence de vaccins efficaces et face aux limites de l'utilisation d'insecticides, nocifs pour les écosystèmes et entrainant des résistances chez les vecteurs, il est nécessaire de développer des moyens alternatifs de lutte. La découverte récente du potentiel antiviral de certaines bactéries symbiotiques du moustique, comme le genre Wolbachia, représente un outil de lutte biologique prometteur face aux arboviroses. Ce projet de thèse porte sur la relation tripartite moustique-bactéries endosymbiotiques-arbovirus, en prenant pour modèle le moustique-tigre, Aedes albopictus. Cette espèce originaire d'Asie envahit progressivement l'Europe. Elle transmet notamment le virus de la dengue et du chikungunya, et est naturellement infectée par Wolbachia. Les résultats obtenus ont permis d'observer un phénotype antiviral chez les moustiques infectés par Wolbachia, contrairement aux moustiques aposymbiotiques. L'utilisation d'une méthode de transcriptomique haut-débit (RNAseq) a permis de déterminer certains mécanismes cellulaires et moléculaires majeurs du moustique spécifiquement impliqués dans l'interaction avec les arbovirus, Wolbachia, et les deux partenaires simultanément. Le développement d'une lignée cellulaire d'Ae. albopictus stablement infectée par Wolbachia a permis de mettre en évidence le rôle central de l'autophagie dans l'interaction Wolbachia-arbovirus chez Ae. Albopictus / Arthropod-borne virus (arbovirus) are important cause of human diseases worldwide, leading to nearly 30.000 deaths every year. Many arboviruses like dengue virus (DENV), chikungunya virus (CHIKV) or Rift valley Fever virus (RVFV) are transmitted by mosquitoes, and global changes like climate warming or international trade increase vectors geographic range, thus facilitating the emergence of arbovirosis. Very few vaccines are currently available, and the use of insecticides remains the only way to prevent arbovirosis but cause adverse effects on ecosystems, and lead to resistance phenotypes in vector populations. Recent work showed that mosquito bacterial flora, especially bacteria from the genus Wolbachia, can modulate viral infection, a phenotype called microbial interference. These results provide a promising tool to limit transmission of arboviruses, but little is known about mosquito-Wolbachia-arbovirus interaction especially at the cellular level. We characterized for the first time this multipartite interaction in Aedes albopictus, an important mosquito vector of DENV and CHIKV, which is naturally infected by Wolbachia. Results showed an antiviral phenotype in Wolbachia-infected mosquitoes, compared to aposymbiotic insects. We used RNAseq to decipher the major mosquito pathways implemented during mono-infection by virus, bacteria or during bi-infection. Moreover, we developed an Ae. albopictus cell line stably infected by Wolbachia to go further in mechanical aspects, and showed that autophagy is a major pathway involved in Wolbachia-arbovirus interaction in Ae. albopictus