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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Biological and non-biological factors in the spatio-temporal changes of tick-borne encephalitis (TBE) in the Baltic States

Sumilo, Dana January 2006 (has links)
No description available.
72

Klasifikace vegetačního pokryvu z dat DPZ pro účely vyhodnocení rizika nákazy klíšťovou encefalitidou / Tick-borne encephalitis risk assessment based on classification of vegetation from remote sensing data

Červená, Lucie January 2012 (has links)
Tick-borne encephalitis risk assessment based on classification of vegetation from remote sensing data Abstract The main aim of this thesis has been to find out how to classify various categories of forest vegetation with a different risk of exposure to the tick-borne encephalitis based on the Landsat imagery. The legend used here is derived from the one used in the projects by Daniel, Kolář, Zeman (1995) and Daniel, Kolář, Beneš (1999) but has been reduced to only five classses with no overlaps in their definitions (I. coniferous stands, II. mixed stands, III. young deciduous stands and stand ecotones with a highly heterogeneous structure, IV. deciduous stands with a homogeneous structure, V. deciduous stands with a heterogeneous structure). The supervised classification with the Maximum Likelihood Classifier has been used on the Landsat imagery from various seasons. Difficulties concerned with the presence of clouds and varying Sun elevation across the imagery had to be adressed in the course of the work. The training sites and the control points have been defined by the field research and interpretation of the relevant orthophotomaps and Landsat imagery in 5-4-3 RGB composite. The mask of the forest has been created on the ZABAGED data basis. The time horizon of 2006 - 2010 has been the primary focus....
73

Imunobiologia das infestações de bovinos pelo carrapato Rhipicephalus (Boophilus) microplus: estudo dos correlatos imunes de resistência e de susceptibilidade / The immunobiology of infestations with the cattle tick Rhipiceplahus (Boophilus) microplus: comparative immunologic and molecular studies of the tick-host interface in susceptible and resistant bovine hosts.

Franzin, Alessandra Mara 31 August 2009 (has links)
A pele dos vertebrados é alvo da maioria das 15.000 espécies de artrópodes hematófagos existentes e pouco se sabe sobre as estratégias imunológicas utilizadas pelos hospedeiros para expulsar esse tipo de ectoparasitos. É fato que carrapatos, como artrópodes hematófagos, são capazes também de induzi-las. Entre a grande variedade de hospedeiros, os bovinos, que apresentam fenótipos variáveis de resistência ao Ripicephalus (Boophilus) microplus, constituem o único modelo no qual é possível correlacionar as respostas imunológicas entre os fenótipos contrastantes na mesma espécie hospedeira. Para tal, as populações celulares do infiltrado induzido na pele pelo carrapato foram quantificadas nos bovinos resistentes, Bos taurus indicus e nos suscetíveis, Bos taurus taurus. Como esperado, o carrapato induziu inflamação cutânea local nos bovinos estudados e a composição celular do infiltrado apresentou diferenças que variaram entre os fenótipos contrastantes de infestação. A pele resistente apresentou maior número de basófilos em comparação a pele suscetível infestada pelo carrapato adulto (P < 0,05) o que sugere a participação desse tipo de granulócito na resposta imune, prejudicando a hematofagia do carrapato. Eosinófilos não foram observados na pele naïve, mas sim na pele normal e infestada, apresentando maiores quantidades (P < 0,05) na pele resistente infestada por ninfa e por adulto. Esse granulócito também se mostrou importante para a aquisição de resistência a carrapatos, a cinética observada na pele dos animais sugere um efeito sistêmico de eosinófilos na infestação. Já mastócitos se mostraram reduzidos de forma semelhante na pele resistente e suscetível infestada por ninfa e adulto em comparação a pele não infestada das mesmas (P < 0,05), sugerindo desgranulação induzida pela saliva do carrapato. As citocinas e mediadores inflamatórios liberados por mastócitos poderiam desencadear e até modular as respostas imunes de contra o carrapato. Neutrófilos estavam em 9 quantidades semelhantes na pele infestada de ambas as raças, apresentando maior quantidade na fase de adulto em relação à fase de ninfa (P < 0,05). Esse fato sugere que a saliva da ninfa expressa desintegrinas contendo RGD, que possivelmente são específicas para esse granulócito. Em contrapartida, as células mononucleares foram mais abundantes na pele resistente e suscetível infestadas por ninfa em relação às infestadas por adulto (P = 0,001). Entre as populações mononucleares fenotipadas, as células T CD3+ foram recrutadas em maior número na pele resistente infestada por ninfa e adulto que na pele suscetível nas mesmas fases (P < 0,05), indicando sua importância na regulação da resposta imune de resistência ao ectoparasito. Células CD4+ foram mais numerosas na pele resistente infestada por adulto que a pele suscetível infestada pela mesma fase (P < 0,05); já as células CD8+ estavam em maior número na pele resistente infestada por ninfa do que na pele suscetível na mesma fase de infestação (P < 0,05). Células T gd/WC1+ foram mais abundantes (P < 0,05) na pele resistente infestada por adulto que a mesma não infestada, indicando que esses linfócitos podem desempenhar papel importante na aquisição de resistência. Já os linfócitos B estiveram em número reduzido na pele suscetível infestada por ninfa e por adulto em comparação à mesma não infestada (P < 0,05). Entretanto, na pele resistente infestada por adulto, o número desses linfócitos foi maior (P < 0,05) em comparado ao encontrado na pele suscetível infestada pela mesma fase, sugerindo a participação de anticorpos na aquisição de resistência a carrapatos. Embora não significativa, o maior número de células Natural Killers na pele resistente, sugere seu envolvimento na proteção contra doenças transmitidas por carrapatos. Em suma, os resultados obtidos sugerem que a resposta imune local envolve células residentes e recrutam outras que, em conjunto, atuam na imunorregulação e na elaboração de respostas imunes efetoras e de memória eficazes contra carrapatos. / The skin of vertebrates is the largest for over 15,000 species of hematophagous arthropods. Among them are ticks, which are long-term feeders and interact with host defenses for days to weeks. Little is known about specialized strategies for eliminating ectoparasites, but ticks can induce immune responses in host. Bovines present variable and heritable levels of resistance to the Ripicephalus (Boophilus) microplus and are the only model in which distinct outcomes of infestation can be examined in the same species of host. In order to obtain some of the immune correlates of these outcomes, we quantified populations of leukocytes and lymphocytes present in the inflammatory infiltrates elicited by tick bites in skin of resistant and susceptible bovine breeds, respectively, Bos taurus indicus and Bos Taurus taurus. As expected, ticks induce cutaneous inflammatory infiltrates around their mouthparts. However the composition of infiltrate presented with significant differences that varied according to the phenotype of infestation. Inflammation of resistant breed contained significantly more basophils than in susceptible adult-infested skin (P<0.05). Eosinophils were absent in skin from naïve animals, but were present in normal and infested skin. They were present in infested skin of both breeds and more significantly so in nymph and adult-infested skin of resistant breed (P<0.05). However, mast cell numbers were equally diminished in nymph and adult-infested skin of both breeds when compared with non-infested skin (P<0.05). The neutrophils were equally present in infested skin of both breeds, but they are more numerous in skin infested with adults than with nymphs (P<0.05). Conversely, mononuclear cells were more abundant in skin infested with nymphs than with adults (P=0.001). Bites by nymphs and adults recruit more CD3+ T cells in skin of resistant breeds than in that of susceptible ones (P<0.05). The CD4+ populations of cells 11 were more numerous in adult-infested skin of resistant than in that of susceptible (P<0.05); CD8+ cells were increased in nymph-infested skin of resistants relative to that of susceptibles (P<0.05). The population of gd/WC1+ T cells were more abundant (P<0.05) in adult-infested skin of resistant when compared with those found in control skin of the same animals. The numbers of B lymphocytes were diminished in nymph and adult-infested skin of susceptibles when compared with those found in control skin (P<0.05); in adult-infested skin of resistants, B lymphocytes were more numerous (P < 0,05) than in skin of susceptibles. Bites by nymph and adult tends to recruited more Natural Killers cells to skin in resistant breed than in susceptible one (P > 0,05). The results suggest that mast cells are source of cytokines and inflammatory mediators that play effectors and modulator roles in immune responses, their reduction possibly due to degranulation by tick saliva. Amount of neutrophils in infested skin may reflect the fact that only nymphs express RGD-containing disintegrins, which are possibly neutrophils-specific. Eosinophils, as well as basophils, are important to ticks resistance, their skin kinetic suggesting a systemic effect of tick infestations. Basophils resistant host increasing suggesting that they are the pivotal cells that impair haematophagy. The observed increase of CD3+ T cells in nymph and adult-infested skin of resistants suggests their importance to regulate anti-tick immune responses. The diminished numbers of B cells in susceptible breed indicate that antibodies are important in acquired resistance to ticks. On the other hand, the reduction of gd/WC1+ T cells seen in the infested skin of susceptible bovines indicates that these cells may play a role in resistance to ticks. Natural Killers cells could help the development of efficacious immune responses to ticks-borne diseases. In conclusion, these results reflect the fact that local responses involve resident and infiltrating leukocytes and lymphocytes that are sources of immunoregulatory, effectors and memory responses elicited against ticks.
74

Uso do geoprocessamento na identificação de áreas de risco para infestação humana pelo Amblyomma cajennense (Acari: Ixodidae) no Município de Piracicaba, SP / Use of geoprocessing techniques to identify risk areas for human infestation by Amblyomma cajennense in Piracicaba, SP

Ferreira, Patricia Marques 29 March 2006 (has links)
Utilizou-se técnicas de geoprocessamento e imagens geradas pelo Sistema Landsat 7 - ETM+, para identificar áreas favoráveis ao crescimento das populações de Amblyomma cajennense e, conseqüentemente, o risco de infestação humana pelo carrapato no Município de Piracicaba, São Paulo, Brasil. As imagens de satélite permitiram determinar os valores de temperatura e do Índice de Vegetação por Diferença Normalizada (NDVI) que, em associação com as variáveis, densidade de eqüinos e modelo preditivo de distribuição de capivaras (Hydrochoerus hydrochaeris), foram utilizadas para construir um modelo de risco multivariado identificando assim áreas favoráveis ao crescimento de populações do carrapato. Verificou-se que a população humana exposta às regiões altamente desfavoráveis ou desfavoráveis ao crescimento de populações de A. cajennense é de, no mínimo, 70,14% podendo chegar a 96,16%. Por outro lado, de 0,04% a 15,23% da população está exposta a áreas favoráveis ou altamente favoráveis ao longo do ano. / Geoprocessing techniques and Landsat 7 - ETM+ images were used to identify suitable areas for the development of Amblyomma cajennense populations and the resulting risk of human infestation by that tick in Piracicaba, São Paulo, Brazil. Temperature and Normalized Difference Vegetation Index (NDVI) were calculated based on satellite images, and those data were later associated with horse density and a predictive model of spatial distribution of capybaras (Hydrochoerus hydrochaeris) to build a multi-variant risk model. It was observed that the human population exposed to extremely unsuitable or unsuitable areas ranges from 70.14% to 96.16%. On the other hand, 0.04% to 15.23% of the human population is exposed to suitable or extremely suitable areas throughout the year.
75

Imunobiologia das infestações de bovinos pelo carrapato Rhipicephalus (Boophilus) microplus: estudo dos correlatos imunes de resistência e de susceptibilidade / The immunobiology of infestations with the cattle tick Rhipiceplahus (Boophilus) microplus: comparative immunologic and molecular studies of the tick-host interface in susceptible and resistant bovine hosts.

Alessandra Mara Franzin 31 August 2009 (has links)
A pele dos vertebrados é alvo da maioria das 15.000 espécies de artrópodes hematófagos existentes e pouco se sabe sobre as estratégias imunológicas utilizadas pelos hospedeiros para expulsar esse tipo de ectoparasitos. É fato que carrapatos, como artrópodes hematófagos, são capazes também de induzi-las. Entre a grande variedade de hospedeiros, os bovinos, que apresentam fenótipos variáveis de resistência ao Ripicephalus (Boophilus) microplus, constituem o único modelo no qual é possível correlacionar as respostas imunológicas entre os fenótipos contrastantes na mesma espécie hospedeira. Para tal, as populações celulares do infiltrado induzido na pele pelo carrapato foram quantificadas nos bovinos resistentes, Bos taurus indicus e nos suscetíveis, Bos taurus taurus. Como esperado, o carrapato induziu inflamação cutânea local nos bovinos estudados e a composição celular do infiltrado apresentou diferenças que variaram entre os fenótipos contrastantes de infestação. A pele resistente apresentou maior número de basófilos em comparação a pele suscetível infestada pelo carrapato adulto (P < 0,05) o que sugere a participação desse tipo de granulócito na resposta imune, prejudicando a hematofagia do carrapato. Eosinófilos não foram observados na pele naïve, mas sim na pele normal e infestada, apresentando maiores quantidades (P < 0,05) na pele resistente infestada por ninfa e por adulto. Esse granulócito também se mostrou importante para a aquisição de resistência a carrapatos, a cinética observada na pele dos animais sugere um efeito sistêmico de eosinófilos na infestação. Já mastócitos se mostraram reduzidos de forma semelhante na pele resistente e suscetível infestada por ninfa e adulto em comparação a pele não infestada das mesmas (P < 0,05), sugerindo desgranulação induzida pela saliva do carrapato. As citocinas e mediadores inflamatórios liberados por mastócitos poderiam desencadear e até modular as respostas imunes de contra o carrapato. Neutrófilos estavam em 9 quantidades semelhantes na pele infestada de ambas as raças, apresentando maior quantidade na fase de adulto em relação à fase de ninfa (P < 0,05). Esse fato sugere que a saliva da ninfa expressa desintegrinas contendo RGD, que possivelmente são específicas para esse granulócito. Em contrapartida, as células mononucleares foram mais abundantes na pele resistente e suscetível infestadas por ninfa em relação às infestadas por adulto (P = 0,001). Entre as populações mononucleares fenotipadas, as células T CD3+ foram recrutadas em maior número na pele resistente infestada por ninfa e adulto que na pele suscetível nas mesmas fases (P < 0,05), indicando sua importância na regulação da resposta imune de resistência ao ectoparasito. Células CD4+ foram mais numerosas na pele resistente infestada por adulto que a pele suscetível infestada pela mesma fase (P < 0,05); já as células CD8+ estavam em maior número na pele resistente infestada por ninfa do que na pele suscetível na mesma fase de infestação (P < 0,05). Células T gd/WC1+ foram mais abundantes (P < 0,05) na pele resistente infestada por adulto que a mesma não infestada, indicando que esses linfócitos podem desempenhar papel importante na aquisição de resistência. Já os linfócitos B estiveram em número reduzido na pele suscetível infestada por ninfa e por adulto em comparação à mesma não infestada (P < 0,05). Entretanto, na pele resistente infestada por adulto, o número desses linfócitos foi maior (P < 0,05) em comparado ao encontrado na pele suscetível infestada pela mesma fase, sugerindo a participação de anticorpos na aquisição de resistência a carrapatos. Embora não significativa, o maior número de células Natural Killers na pele resistente, sugere seu envolvimento na proteção contra doenças transmitidas por carrapatos. Em suma, os resultados obtidos sugerem que a resposta imune local envolve células residentes e recrutam outras que, em conjunto, atuam na imunorregulação e na elaboração de respostas imunes efetoras e de memória eficazes contra carrapatos. / The skin of vertebrates is the largest for over 15,000 species of hematophagous arthropods. Among them are ticks, which are long-term feeders and interact with host defenses for days to weeks. Little is known about specialized strategies for eliminating ectoparasites, but ticks can induce immune responses in host. Bovines present variable and heritable levels of resistance to the Ripicephalus (Boophilus) microplus and are the only model in which distinct outcomes of infestation can be examined in the same species of host. In order to obtain some of the immune correlates of these outcomes, we quantified populations of leukocytes and lymphocytes present in the inflammatory infiltrates elicited by tick bites in skin of resistant and susceptible bovine breeds, respectively, Bos taurus indicus and Bos Taurus taurus. As expected, ticks induce cutaneous inflammatory infiltrates around their mouthparts. However the composition of infiltrate presented with significant differences that varied according to the phenotype of infestation. Inflammation of resistant breed contained significantly more basophils than in susceptible adult-infested skin (P<0.05). Eosinophils were absent in skin from naïve animals, but were present in normal and infested skin. They were present in infested skin of both breeds and more significantly so in nymph and adult-infested skin of resistant breed (P<0.05). However, mast cell numbers were equally diminished in nymph and adult-infested skin of both breeds when compared with non-infested skin (P<0.05). The neutrophils were equally present in infested skin of both breeds, but they are more numerous in skin infested with adults than with nymphs (P<0.05). Conversely, mononuclear cells were more abundant in skin infested with nymphs than with adults (P=0.001). Bites by nymphs and adults recruit more CD3+ T cells in skin of resistant breeds than in that of susceptible ones (P<0.05). The CD4+ populations of cells 11 were more numerous in adult-infested skin of resistant than in that of susceptible (P<0.05); CD8+ cells were increased in nymph-infested skin of resistants relative to that of susceptibles (P<0.05). The population of gd/WC1+ T cells were more abundant (P<0.05) in adult-infested skin of resistant when compared with those found in control skin of the same animals. The numbers of B lymphocytes were diminished in nymph and adult-infested skin of susceptibles when compared with those found in control skin (P<0.05); in adult-infested skin of resistants, B lymphocytes were more numerous (P < 0,05) than in skin of susceptibles. Bites by nymph and adult tends to recruited more Natural Killers cells to skin in resistant breed than in susceptible one (P > 0,05). The results suggest that mast cells are source of cytokines and inflammatory mediators that play effectors and modulator roles in immune responses, their reduction possibly due to degranulation by tick saliva. Amount of neutrophils in infested skin may reflect the fact that only nymphs express RGD-containing disintegrins, which are possibly neutrophils-specific. Eosinophils, as well as basophils, are important to ticks resistance, their skin kinetic suggesting a systemic effect of tick infestations. Basophils resistant host increasing suggesting that they are the pivotal cells that impair haematophagy. The observed increase of CD3+ T cells in nymph and adult-infested skin of resistants suggests their importance to regulate anti-tick immune responses. The diminished numbers of B cells in susceptible breed indicate that antibodies are important in acquired resistance to ticks. On the other hand, the reduction of gd/WC1+ T cells seen in the infested skin of susceptible bovines indicates that these cells may play a role in resistance to ticks. Natural Killers cells could help the development of efficacious immune responses to ticks-borne diseases. In conclusion, these results reflect the fact that local responses involve resident and infiltrating leukocytes and lymphocytes that are sources of immunoregulatory, effectors and memory responses elicited against ticks.
76

Reavalia??o dos caracteres da placa peritrem?tica e fest?es para a diagnose de Anocentor nitens (Neumann, 1897), na regi?o Sudeste / Reevaluation of peritremal plate characters and festoons for the diagnosis of Anocentor nitens (Neumann, 1897), in the Southeast region

GAZ?TA, Gilberto Salles 19 July 1993 (has links)
Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-04-10T18:37:45Z No. of bitstreams: 1 1993 - Gilberto Salles Gaz?ta.pdf: 930210 bytes, checksum: 0c425531817e903d01966c5e960cb65b (MD5) / Made available in DSpace on 2018-04-10T18:37:45Z (GMT). No. of bitstreams: 1 1993 - Gilberto Salles Gaz?ta.pdf: 930210 bytes, checksum: 0c425531817e903d01966c5e960cb65b (MD5) Previous issue date: 1993-07-19 / CNPq / Two hundred and four females and one hundred and twenty males of Anocentor nitens (Neumann, 1897), obtained of equines from 12 districts in the Southern part of Brazil were analyzed morphologically concerning its peritremal plate and festoons, that are taxonomics parameters utilized for diagnosis of this species. The number of peritremal plate should variation with predominant asymmetry. Variations observed in the peritremal plate of males and females of A. nitens suggest the formation of cline in Minas Gerais State going to Rio de Janeiro State and S?o Paulo State. The number of festoons in males and females of the species analyzed was equal to the one characterized in the diagnosis of A. nitens / Duzentos e quatro f?meas e cento e vinte machos de Anocentor nitens (Neumann, 1897), oriundos de equ?deos localizados em 12 munic?pios da regi?o Sudeste, foram analisados morfologicamente quanto aos caracteres placa peritrem?ticas e fest?es, par?metros taxon?micos utilizados na diagnose desta esp?cie. As varia??es ocorridas nas Placas Peritrem?tica de macho e f?meas de A. nitens, sugerem a forma??o de ?cline? a partir do Estado de Minas Gerais, em dire??o ao Estado do Rio de Janeiro e ao Estado de S?o Paulo. O n?mero de fest?es dos esp?cimes analisados foi igual, em machos e f?meas, ?quele caracterizados na diagnose de A. nitens.
77

Feeding Behavior of Wild and Captive Oxpeckers (Buphagus spp.): A Case of Conditional Mutualism

Plantan, Tiffany Brooke 15 May 2009 (has links)
Mutualisms are delicately balanced partnerships and are increasingly recognized as being fundamental to patterns and processes within ecological systems. Changes to the ecological setting in which such interactions operate can disrupt this balance. By understanding the context-dependent nature of such associations, researchers can begin to understand how changes in the environment can have cascading effects on the entire community within which they occur. Oxpeckers (Buphagus spp.) feed on the ectoparasites of ungulates in sub-Saharan Africa and from the blood of ungulate wounds. Because of this dichotomy in feeding behavior, the role of oxpeckers as consistently beneficial partners of their hosts has been questioned, and it has been suggested that the concept of conditional mutualism be applied to this interaction. I combined observational studies of oxpeckers in Kruger National Park, South Africa, with experiments on oxpeckers in captivity at the Mokopane Biodiversity Conservation Centre, South Africa, to test the hypothesis that the ectoparasite cleaning service provided by oxpeckers to their hosts is context-dependent. The results of my dissertation research demonstrate that the oxpecker-ungulate association has conditional outcomes. Under certain conditions, the oxpecker-ungulate relationship is a nutritional mutualism where ungulates provide food (ticks) for oxpeckers in exchange for a cleaning service. Under other conditions, oxpeckers exploit their hosts to feed from their blood. My findings suggest that a high abundance of the tick species and tick stages oxpeckers prefer is necessary to maintaining an alignment of interests between oxpeckers and ungulates. When ungulates host few ticks of the species oxpeckers prefer, these birds will wound-feed to meet their nutritional demands. Such wound-feeding threatens the balance of the oxpecker-ungulate mutualism. Although oxpeckers frequently wound-fed in captivity, the frequency of wound-feeding events on wild host species was only 3.1% of feeding events. Whether the relationship between oxpeckers and domesticated hosts differs from that between oxpeckers and wild hosts, or if this observed difference is actually a result of researcher constraints in the wild, needs further exploration.
78

Plant-Derived Chemicals as Tick Repellents

Sadek Garboui, Samira January 2008 (has links)
Ixodes ricinus is the main vector of Lyme borreliosis and Tick-borne encephalitis in Europe. Repellents provide a practical means of protection against tick bites and can therefore reduce transmission of tick-borne diseases. In laboratory tests, pieces of cloth treated with MyggA Natural® (a commercial insect repellent) or with the essential oils of Corymbia citriodora (30%), Lavandula angustifolia (1 and 30%), Pelargonium graveolens (1 and 30%), Hyptis suaveolens (10%), Salvadora persica, Pistacia atlantica, Juniperus phoenicea (20%) and methyl jasmonate (MJ) (0.5%, 1.0%, 2.0% and 5.0%) showed strong repellent activity against I. ricinus nymphs. In a tick-infested woodland in east-central Sweden, we tested by randomized, standardised methodology the potential anti-tick repellent activity of MyggA Natural® (roll-on), two concentrations of MyggA Natural® spray, RB86 (a commercially available insect repellent for horses), the essential oil of C. citriodora and three concentrations of MJ. Each substance was dissolved in acetone and applied separately to 1 m2 cloths which were then pulled over vegetation. Nymphal tick numbers on the cloths were recorded at 10-m intervals and differed significantly between treated cloths and the untreated control and also between collectors. Volatile compounds from fresh and dried leaves of H. suaveolens and the essential oils of H. suaveolens (from Laos and Guinea Bissau) and S. persica, P. atlantica and J. phoenicea (from Libya) were collected by solid phase micro-extraction (SPME) and the constituents were identified by gas chromatography - mass spectrometry (GC-MS). Two main sesquiterpene hydrocarbons in the H. suaveolens oil were β-caryophyllene and humulene. These were modified by oxidation and sulphidation to obtain effective tick repellent compounds with lower volatility. In all three oils from Libyan plants the main monoterpene hydrocarbons were α-pinene, sabinene, β-pinene, myrcene, α-phellandrene, 4-carene, β-phellandrene and γ-terpinene. The selected plant species contained numerous volatiles known to have insecticidal, acaricidal, and/or insect repellent properties.
79

Meteorological Factors Regulating the Population Expansion and Contraction of Amblyomma maculatum (Acari: Ixodidae) in Texas

Coburn, Jordan McQuade 2009 August 1900 (has links)
The interaction of tick species and the microclimate that they inhabit is a subject that is frequently studied. The known biology of the Gulf Coast tick, Amblyomma maculatum Koch (Acari: Ixodidae), was used to conduct analyses to determine which meteorological factors regulate Gulf Coast tick survivorship in an area of Texas that is known for reduced occurrence of this tick species. Gulf Coast tick collection records, that indicated the collection of a single tick or multiple ticks from one animal or multiple animals at livestock markets, were obtained from the Texas Animal Health Commission. These records were used as an indicator of adult Gulf Coast tick abundance during each year in the 90 county study area and were used as the dependent variable in linear, quadratic, and cubic regression analyses. Independent variables used in these analyses were precipitation and differing drought thresholds during the peak activity time of the four life stages of the Gulf Coast tick and during combined life stage peak activity times. Linear, quadratic, and cubic regression analyses to measure the effect of precipitation during differing peak activity times of the Gulf Coast tick on adult Gulf Coast tick collection records were not statistically significant. These three regression analyses were also used to measure the effect of increasing drought thresholds, measured using a Keetch-Byram Drought Index, on adult Gulf Coast tick collection records. A determination was made that increasing drought thresholds during the peak activity time of differing Gulf Coast tick life stages reduce the number of Gulf Coast tick collection records the following year.
80

Ticks and Tick-Borne Pathogens Associated with Feral Swine in Edwards Plateau and Gulf Prairies and Marshes Ecoregions of Texas

Sanders, David M. 2011 May 1900 (has links)
Feral swine (Sus scrofa domesticus) are spreading across North America at an alarming rate. Four Canadian provinces and 39 states within the continental United States now report standing populations of feral pigs. Estimates place the number of feral hogs in Texas >2M, accounting for more than half of the United States population. It is known that feral swine impact local ecology following establishment, with regard to shifts in local flora and fauna. The overall objective of this research was to investigate the role of feral swine in tick-borne pathogen transmission in Texas. The underpinning objectives were to establish host records for tick species parasitizing feral swine, determine the species assemblages associated with feral swine among different ecoregions of Texas, determine by immunoassay to which tick-borne bacteria feral pigs were being exposed, and detect the DNA of tick-borne bacteria by polymerase chain reaction assay in the event of poor or early immune response by the host. Feral pigs (N=432) were harvested from June 2008 to June 2010 using box and corral traps and by aerial gunning. Seven species of ticks, Amblyomma americanum, A. cajennense, A. maculatum, Dermacentor albipictus, D. halli, and D. variabilis; and Ixodes scapularis, were collected. Immature stages of A. cajennense and A. americanum were collected as well. All classes of feral pigs, gender by age, were infested with ticks. Serum was collected through a multi-organizational effort from 2006 to 2010 and tested by ELISA for previous exposure to tick-borne pathogens in the genera Rickettsia and Ehrlichia (N=888) and Borrelia (N=849). Prevalence percentages by immunoassay were 27.59 percent, 13.18 percent and 2.12 percent for Rickettsia, Ehrlichia, and Borrelia, respectively. Samples positive by ELISA for exposure to Borrelia were further screened by Western Blot for exposure to Borrelia turicatae. The results were equivocal in most cases. Blood samples (N=233) were collected from 2008 to 2010 and analyzed by polymerase chain reaction for the detection of the DNA of these same three genera of bacteria. Two of the samples were positive by PCR for the presence of Borrelia DNA. Texas feral swine are serving as hosts for at least seven species of ticks and are interacting with tick-borne pathogen transmissions cycles in Texas.

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