Thesis (MSc. (Veterinary Tropical Diseases)--University of Pretoria, 2008. / Includes bibliographical references. Also available in print format.

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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.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-06-22T11:15:51Z No. of bitstreams: 1 marcioscoralickgoldner.pdf: 1368658 bytes, checksum: 524048ed973021e443fbeb565aadcf5d (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-06-24T13:12:02Z (GMT) No. of bitstreams: 1 marcioscoralickgoldner.pdf: 1368658 bytes, checksum: 524048ed973021e443fbeb565aadcf5d (MD5) / Made available in DSpace on 2017-06-24T13:12:02Z (GMT). No. of bitstreams: 1 marcioscoralickgoldner.pdf: 1368658 bytes, checksum: 524048ed973021e443fbeb565aadcf5d (MD5) Previous issue date: 2011 / O uso indiscriminado de carrapaticidas sintéticos e o quadro de resistência aos produtos utilizados no mercado impulsionaram novas pesquisas e alternativas ao combate aos parasitos hematófagos. Dentre as alternativas mais promissoras, pode-se evidenciar o uso de substâncias e seus derivados provenientes de plantas com objetivo de implementar de carrapaticidas de origem natural que podem ser menos prejudiciais ao meio ambiente. O presente trabalho teve por objetivo potencializar ‘’in vitro’’ a eficácia carrapaticida do timol frente a larvas de R. (B.) microplus. No primeiro experimento, foram elaboradas três formulações, visando à escolha do preparado com melhor custo-benefício sem que os diferentes componentes das formulações interferissem na eficácia carrapaticida. A formulação de escolha demonstrou a mortalidade de 96,65% das larvas mantendo a eficácia carrapaticida do timol a 2% acima dos limites preconizados pelo Ministério da Agricultura de 95% para produtos comerciais. No segundo experimento, foram testadas, na formulação eleita, as concentrações de 0,25%%, 0,5% e 1% de timol sobre larvas de R. (B.) microplus, sendo que a taxa de mortalidade obtida com 0.25% foi de 94%, demonstrando que mesmo com baixa concentração de timol a eficácia carrapaticida foi considerável. Os resultados alcançados mostram que, in vitro, a eficácia carrapaticida do timol pode ser não somente mantida, como potencializada se for levada em consideração a metodologia de preparo da formulação, bem como características físico-químicas dos seus componentes, visando minimizar perdas do princípio ativo. Entretanto, são necessárias pesquisas futuras para ratificar o potencial acaricida do timol em ambiente de campo, modificando e testando diferentes apresentações. / The indiscriminate use of synthetic acaricides and the picture of resistance to products used in the market spurred new research and alternatives to combat these hematophagous parasites. Among the most promising alternatives, it can be highlight the use of substances and their derivatives from plants, aiming to implement the carrapaticide products of natural origin that may be less harmful to the environment. This study aimed to ''enhance'' the in vitro acaricide efficacy of thymol against the larvae of R. (B.) microplus. In the first experiment, three formulations were prepared, in order to choose the most cost-prepared without any of the different components interfere with the efficacy of insecticide formulations. The formulation of choice showed 96.65% mortality of larvae still remain effective insecticide of the thymol 2% above the limits established by the Ministry of Agriculture of 95% for commercial products. In the second experiment, were tested in the formulation choice, the concentrations of 0.25%, 0.5% and 1% of thymol on larvae of R. (B.) microplus, with a mortality rate of 94% with 0.25% of thymol, demonstrating that even in low concentrations of thymol acaricide efficacy was considerable. The results show that in vitro, acaricide efficacy of thymol can be not only maintained, as increased if it is taken into account the preparation method of the formulation and the physicochemical characteristics of its components in order to minimize losses of active. However, further research is needed to ratify the acaricidal potential of thymol in a field environment, modifying and testing different presentations and to assess its impact on the environment.

Made available in DSpace on 2014-08-20T14:38:46Z (GMT). No. of bitstreams: 1 dissertacao_patricia_biegelmeyer.pdf: 576535 bytes, checksum: 210ef4efc6311207454f251dd80d5018 (MD5) Previous issue date: 2012-02-29 / The overall aim of this study was to analyze different perspectives of Rhipicephalus (Boophilus) microplus genetic resistance. Therefore, the present study was divided into three manuscripts. Firstly, a literature review was conducted to present some aspects of tick resistance, like results of previous studies of bovine resistance, environmental effects on this triat, and some findings in molecular biology that will help to identify resistant animals. The second trial was conducted to estimate genetic parameters for tick resistance measured by two assessment methods in Hereford and Braford cattle, and genetic correlations between tick resistance and growth of animals. The animals belonging to the Delta G Connection genetic improvement consortium, were raised on nature and artificial pastures in Southern Brazil, and the age at the evaluation period was about 18 months. Data were analyzed from 6,462 bovines naturally exposed to ticks. The number of ticks was counted at inner hind legs region (IHL) of 3,413 animals between 2001 and 2008, and was recorded up to three consecutive counts at one side of body (LAT) in 3,049 bovines between 2009 and 2010, a total of 7,813 records. In addition, the database contained data of 109,566 birth weights (BW), 112,815 records of weight gain from birth to weaning (ADG) and 54,843 data of weight gain from weaning to yearling (PWG). For the analyses, tick count data was transformed using a logarithmic function. Heritability estimates obtained by bivariate analysis were IHL = 0.152 ± 0.043 and LAT = 0.235 ± 0.063 and genetic correlation between both methods was 0.575 ± 0.220. Single-trait analysis of LAT indicated a repeatability of 0.312 ± 0.014. Genetics association analysis between IHL and LAT and the development characteristics evaluated indicated significant associations between IHL and BW (0.220 ± 0.102), and favorable negative correlations between LAT and ADG (-0.211 ± 0.099) and LAT and PWG (-0.650 ± 0.125) (P<0.05). The objective of third trial was to analyze the bovine genetic resistance effect on tick biological traits. The engorged female ticks analyzed were collected from 40 Braford heifers classified as genetically resistant (R) or susceptible (S), according to the breeding values for tick count, calculated based on a database with 9,036 records of Hereford and Braford bovines. After classification, the selected heifers were moved to an experimental area in Embrapa Pecuária Sul, located in the city of Bagé, in the Brazilian state of Rio Grande do Sul, and subjected to four artificial infestations, 14 days apart each one. Weights of engorged female ticks and of female ticks after oviposition did not differ between resistant and susceptible heifers. Female ticks engorged in genetically susceptible heifers showed higher capacity of posture (R = 0.097 ± 0.021g and S = 0.109 ± 0.030g) and higher values of reproductive efficiency index (R = 47.23 ± 5.85% and S = 53.27 ± 3.74%) The overall aim of this study was to analyze different perspectives of Rhipicephalus (Boophilus) microplus genetic resistance. Therefore, the present study was divided into three manuscripts. Firstly, a literature review was conducted to present some aspects of tick resistance, like results of previous studies of bovine resistance, environmental effects on this triat, and some findings in molecular biology that will help to identify resistant animals. The second trial was conducted to estimate genetic parameters for tick resistance measured by two assessment methods in Hereford and Braford cattle, and genetic correlations between tick resistance and growth of animals. The animals belonging to the Delta G Connection genetic improvement consortium, were raised on nature and artificial pastures in Southern Brazil, and the age at the evaluation period was about 18 months. Data were analyzed from 6,462 bovines naturally exposed to ticks. The number of ticks was counted at inner hind legs region (IHL) of 3,413 animals between 2001 and 2008, and was recorded up to three consecutive counts at one side of body (LAT) in 3,049 bovines between 2009 and 2010, a total of 7,813 records. In addition, the database contained data of 109,566 birth weights (BW), 112,815 records of weight gain from birth to weaning (ADG) and 54,843 data of weight gain from weaning to yearling (PWG). For the analyses, tick count data was transformed using a logarithmic function. Heritability estimates obtained by bivariate analysis were IHL = 0.152 ± 0.043 and LAT = 0.235 ± 0.063 and genetic correlation between both methods was 0.575 ± 0.220. Single-trait analysis of LAT indicated a repeatability of 0.312 ± 0.014. Genetics association analysis between IHL and LAT and the development characteristics evaluated indicated significant associations between IHL and BW (0.220 ± 0.102), and favorable negative correlations between LAT and ADG (-0.211 ± 0.099) and LAT and PWG (-0.650 ± 0.125) (P<0.05). The objective of third trial was to analyze the bovine genetic resistance effect on tick biological traits. The engorged female ticks analyzed were collected from 40 Braford heifers classified as genetically resistant (R) or susceptible (S), according to the breeding values for tick count, calculated based on a database with 9,036 records of Hereford and Braford bovines. After classification, the selected heifers were moved to an experimental area in Embrapa Pecuária Sul, located in the city of Bagé, in the Brazilian state of Rio Grande do Sul, and subjected to four artificial infestations, 14 days apart each one. Weights of engorged female ticks and of female ticks after oviposition did not differ between resistant and susceptible heifers. Female ticks engorged in genetically susceptible heifers showed higher capacity of posture (R = 0.097 ± 0.021g and S = 0.109 ± 0.030g) and higher values of reproductive efficiency index (R = 47.23 ± 5.85% and S = 53.27 ± 3.74%) / O objetivo geral do presente estudo foi abordar diferentes perspectivas sobre a resistência genética de bovinos ao carrapato Rhipicephalus (Boophilus) microplus. Para tanto, foi dividido em três trabalhos. Primeiramente, foi realizado um estudo de revisão que abrangeu alguns aspectos relacionados à resistência, como resultados de trabalhos que avaliaram a resistência de bovinos, fatores ambientais capazes de afetar os fenótipos de resistência e algumas descobertas na área da biologia molecular que poderão ser úteis no processo de identificação de animais geneticamente resistentes. O segundo trabalho objetivou estimar parâmetros genéticos para a resistência mensurada por dois métodos de avaliação em bovinos Hereford e Braford, e as correlações genéticas entre a resistência e características de crescimento dos animais. Os bovinos que participaram das avaliações foram provenientes de rebanhos controlados pelo programa de melhoramento da Conexão Delta G, localizados no estado do Rio Grande do Sul e criados a campo sobre pastagens naturais e artificiais. Foram avaliados dados de 6.462 bovinos com idade média de 18 meses, naturalmente infestados, sendo as contagens realizadas na região do entrepernas (ENT) em 3.413 animais entre 2001 e 2008, e 7.813 registros de contagens na lateral do corpo (LAT) de 3.049 bovinos realizadas entre 2009 e 2011. Foram utilizados também 109.566 dados de peso ao nascimento (PN), 112.815 registros de ganho de peso do nascimento à desmama (GPD) e 55.843 dados de ganho da desmama ao sobreano (GDS). Para as análises, os dados de contagens sofreram transformação logarítmica. As estimativas de herdabilidade dos métodos de avaliação obtidas por análise bicaracterística foram ENT = 0,152 ± 0,043 e LAT = 0,235 ± 0,063, e a correlação genética entre ambos foi de 0,575 ± 0,220. A análise unicaráter da LAT apontou uma repetibilidade de 0,312 ± 0,014. As associações genéticas entre a ENT e a LAT e as características de desenvolvimento avaliadas apontaram associações significativas entre ENT e PN (0,220 ± 0,102), e favoráveis correlações negativas e entre LAT e GPD (-0,211 ± 0,099) e LAT e GDS (-0,650 ± 0,125) (P<0,05). O terceiro trabalho objetivou analisar o efeito da resistência dos bovinos sobre características biológicas dos carrapatos. As teleóginas analisadas foram coletadas em 40 novilhas Braford classificadas como geneticamente resistentes (R) ou suscetíveis (S), de acordo com os valores genéticos obtidos para a característica de contagem de carrapatos, calculados com base em um banco de dados com registros de 9.036 animais das raças Hereford e Braford. Após a classificação, as novilhas selecionadas foram encaminhadas à Embrapa Pecuária Sul (Bagé, RS), onde foram submetidas a quatro infestações artificiais, com intervalos de 14 dias. Os pesos médios iniciais das teleóginas e os pesos das quenóginas não diferiram entre os grupos de novilhas resistentes e suscetíveis. Fêmeas ingurgitadas em novilhas geneticamente suscetíveis apresentaram maior capacidade de postura (R = 0,097 ± 0,021g e S = 0,109 ± 0,030g) e maiores índices de eficiência reprodutiva (R = 47,23 ± 5,85% e S = 53,27 ± 3,74%) e nutricional (R = 54,33 ± 4,36% e S = 65,62 ± 8,84%) que teleóginas ingurgitadas em novilhas resistentes.