Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-04T14:29:38Z No. of bitstreams: 1 caiomarciodeoliveiramonteiro.pdf: 1857142 bytes, checksum: 6df29461b8db39b06498cf5c935d15f1 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-04T15:38:45Z (GMT) No. of bitstreams: 1 caiomarciodeoliveiramonteiro.pdf: 1857142 bytes, checksum: 6df29461b8db39b06498cf5c935d15f1 (MD5) / Made available in DSpace on 2017-04-04T15:38:45Z (GMT). No. of bitstreams: 1 caiomarciodeoliveiramonteiro.pdf: 1857142 bytes, checksum: 6df29461b8db39b06498cf5c935d15f1 (MD5) Previous issue date: 2009-02-18 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / Em vista do atual quadro de resistência do carrapato dos bovinos aos carrapaticidas comerciais, somando-se ainda a necessidade de preservação ambiental e de alimentos livres de resíduos, novas alternativas no controle deste artrópode vem ganhando maior atenção. Entre estas podemos destacar a utilização de nematóides entomopatogênicos como promissores agentes de controle biológico de ixodídeos e, desta forma, a Embrapa Gado de Leite vem desenvolvendo uma linha de pesquisa que investiga interações entre este ixodídeo e estes nematóides. Com objetivo de avaliar a eficiência de duas espécies de nematóides no controle do carrapato dos bovinos, o presente trabalho foi dividido em três experimentos que avaliaram o potencial “in vitro” de Heterorhabditis bacteriophora HP88 e Heterorhabditis amazonensis RSC-5 como controladores biológicos de Rhipicephalus (Boophilus) microplus. O estudo foi desenvolvido no Laboratório de Parasitologia da Embrapa Gado de Leite, Juiz de Fora, Minas Gerais. No primeiro experimento foi avaliada a eficiência de diferentes dosagens de juvenis infectantes de H. bacteriophora HP88 no controle do carrapato dos bovinos. A eficácia dos tratamentos foi superior a 90% em todas as concentrações utilizadas, demonstrando que este isolado foi altamente eficaz na redução da prole de R. (B.) microplus em condições de laboratório. No segundo experimento, foi feita a mesma avaliação, xiv entretanto foi empregado o nematóide H. amazonensis RSC-5. Os resultados alcançados com H. amazonensis RSC-5 foram inferiores aos obtidos com H. bacteriophora HP88, sendo que a melhor eficácia foi de 67% no tratamento com 300 NEPs/fêmea. Por ter sido mais eficiente, H. bacteriophora HP88 foi à espécie selecionada para o desenvolvimento do terceiro experimento, que buscou avaliar o efeito de diferentes tempos de exposição de fêmeas ingurgitadas de R. (B.) microplus a juvenis infectantes deste nematóide. Os resultados alcançados mostram que tempos de exposição inferiores a 24h não são suficientes para que o nematóide exerça controle eficiente sobre este ixodídeo. Entretanto, a partir de 24h de exposição o percentual de controle foi de 82%, e com 48 e 72h esta eficácia chegou a 100%. Os resultados alcançados no presente estudo demonstram que “in vitro” estes nematóides são eficientes no controle do carrapato dos bovinos, entretanto, ainda é necessária a realização de estudos futuros para investigar o potencial destes agentes de controle biológico em condições de campo e os possíveis impactos que esta utilização possa causar. / Because of the widespread resistance of cattle ticks to commercial carrapaticides and the need to protect the environment and food supply from chemical residues, there is increasing interest in finding new control alternatives. Among these is the use of entomopathogenic nematodes as biological control agents. In this effort, the Embrapa Dairy Cattle Research Center (Embrapa Gado de Leite) has been conducting a line of research investigating the interactions between cattle ticks and these nematodes. The present work examines the efficiency of two nematode species in the control of cattle ticks. We conducted three experiments to evaluate the in vitro potential of Heterorhabditis bacteriophora HP88 and Heterorhabditis amazonensis RSC-5 as biological controls of Rhipicephalus (Boophilus) microplus. The study was conducted in the Parasitology Laboratory of Embrapa Gado de Leite in Juiz de Fora, Minas Gerais, Brazil. In the first experiment the efficiency was evaluated of different concentrations of infective juveniles of H. bacteriophora HP88 to control the ticks. The efficiency of the treatment was greater than 90% at all the concentrations tested, demonstrating this isolate is highly effective in reducing the reproductive capacity of R. (B.) microplus in laboratory conditions. In the second experiment, the same evaluation was carried out employing different concentrations of the nematode H. amazonensis RSC-5. The results were inferior to those obtained with H. bacteriophora HP88. The best efficacy xvi was 67% in the treatment with 300 EPNs/female. Because it was more efficient, we chose H. bacteriophora HP88 for the third experiment, which evaluated the effect of different exposure times of engorged females of R. (B.) microplus to infective juveniles of this nematode. The results obtained show that exposure times shorter than 24 hours are not sufficient for the nematode to have a significant control effect on this tick. However, with exposure for longer than 24 h the control percentage rose to 82%, and at 48 and 72h it reached 100%. The results obtained in this study show that in vitro these nematodes are efficient in controlling cattle ticks, but further studies are necessary to investigate the of these biological control agents under field conditions and the possible impacts this can cause.

Les Nématodes Entomopathogènes (NEP) de la famille des Steinernematidae et Heterorhabditidae sont des parasites pour les insectes. Ils hébergent dans leur intestin un symbiote bactérien (genres Xenorhabdus et Photorhabdus) essentiel au succès parasitaire. Les NEP sont présents dans les sols des cinq continents de la planète. Leur diversité génétique et leurs propriétés biologiques constituent une intéressante ressource biologique. Grâce à leur entomotoxicité, les NEP sont de bons outils de lutte biologique en agriculture et en culture ornementale un peu partout dans le monde. La diversité et la biogéographie des NEP dans les cinq continents de la Terre (à l'exception de l'Antarctique) ont été étudiées partout dans le monde mais le Liban est parmi les rares pays du moyen orient où aucune prospection de ces nématodes n'a été réalisée alors que des NEP en Turquie, Syrie, Jordanie, Palestine et Egypte ont déjà été trouvés et caractérisés. L'objet de la thèse est de procéder à une étude biogéographique dans le but de connaître la diversité des NEP au Liban. L'enjeu scientifique est donc de combler un « vide » dans la connaissance de la répartition et de la biodiversité mondiale des NEP. Pour cela, un échantillonnage à l'échelle des étages de végétation est mené au Liban. Des échantillons de sol sont ainsi prélevés, mis en contact avec des larves de Galleria mellonella pour isoler les nématodes entomopathogènes et leurs symbiotes. Les nématodes et leurs symbiotes sont par la suite identifiés morphologiquement et moléculairement. Par la suite, une approche à l'échelle de l'habitat fait l'objet de cette thèse également pour étudier les interactions biotiques et abiotiques influençant la présence des nématodes entomopathogènes dans le sol. Les enjeux technologiques, exposés au second volet de la thèse, sont liés aux propriétés biologiques des nématodes et de leurs symbiotes afin de valoriser leur entomotoxicité en lutte biologique. Dans ce cadre, la sensibilité des Cephalcia tannourinensis, ravageur des cédraies au Liban, par rapport aux nématodes entomopathogènes est exploitée in vitro ; différentes espèces de nématodes entomopathogènes sont testées pour suivre leur cycle à l'intérieur des Cephalcia. / Entomopathogenic nematodes (EPNs) are parasites of soil-dwelling insects that occur in natural and agricultural soils around the world. Thanks to their entomotoxicity, EPNs are good tools for biological control in agriculture almost everywhere in the world. They are ubiquitous, having been isolated from every inhabited continent (except Antartica) from a wide range of ecologically diverse soil habitats including cultivated fields, forests, grasslands, deserts, and even ocean beaches. Biogeographic assessments of EPNs in the Eastern Mediterranean basin have been conducted in several countries such as Turkey, Syria, Jordan, Israel, Palestine and Egypt. Lebanon is among the few countries of the Middle East for which no survey of EPNs has been done. The scientific stake is thus to fill a gap in our knowledge of EPNs distribution in the Mediterranean basin. Survey of EPNs was conducted in this framework to cover the different vegetation levels defined in Lebanon. Soil samples were removed placed in contact with Galleria mellonella to isolate entomopathogenic nematode and their symbiotic bacteria. EPNs and their bacteria were then identified morphologically and molecularly. On the other hand, despite the different national surveys conducted on EPNs distribution around the world, habitat preferences remain inadequately known for entomopathogenic nematodes. Therefore, a comprehensive understanding of their distribution and the various biotic and abiotic factors influencing their presence is also a second object of our work. Beside a technological approach related to the biological properties of the nematodes and their symbiotics: valorisation of the entomotoxicity in biological control will be part of the third shutter of the thesis. In this framework, the sensibility of cedar pests, Cephalcia tannourinensis against entomopathogenic nematodes is exploited in vitro; different EPNs species were tested to study their life cycle inside Cephalcia larvae.