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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.
11

Avaliação da atividade do óleo da semente de andiroba (Carapa guianensis Aubl.) contra ectoparasitos de felinos domésticos

BARROS, Fabíola Nascimento de 07 February 2011 (has links)
Submitted by (edna.saturno@ufrpe.br) on 2016-10-07T11:31:32Z No. of bitstreams: 1 Fabiola Nascimento de Barros.pdf: 2299817 bytes, checksum: f8cda058792595289089b7953254755f (MD5) / Made available in DSpace on 2016-10-07T11:31:32Z (GMT). No. of bitstreams: 1 Fabiola Nascimento de Barros.pdf: 2299817 bytes, checksum: f8cda058792595289089b7953254755f (MD5) Previous issue date: 2011-02-07 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / he biological activity of oil extracted from andiroba seeds against Felicola subrostratus and Lynxacarus radovskyi was evaluated in vitro and the effect of the oil on domestic cats naturally infected with Felicola subrostratus, Lynxacarus radovskyi and Otodectes cynotis was evaluated in vivo. The in vitro tests were performed with immersion. In the experiment with Felicola subrostratus four concentrations of the andiroba seed oil were tested: 10%, 25%, 50% and 100%. In the experiment with Lynxacarus radovskyi, six concentrations were tested: 2.5%, 5%, 10%, 20%, 50% and 100%. Following the immersion test, the insects were kept in the laboratory at room temperature and examined for the occurrence of mortality for 72 hours. The in vivo tests were performed with the topical administration of a 100-ml andiroba oil solution applied with cotton swabs to the entire body of each animal for the treatment of infestation by Felicola subrostratus and Lynxacarus radovskyi. For the pediculosis, the tests were divided into two steps: 1) concentrations of 2.5%, 5% and 10% were tested in a single application; and 2) concentrations of 2.5%, 5%, 10% and 20% were used once a week for three weeks. For acariosis, a single application was tested at concentrations of 2.5%, 5%, 10% and 20%. For otodectic mange, concentrations of 2.5%, 5%, 10% and 20% were administered in the ear canal of each cat 5 drops (0.025 ml), for five consecutive days. The animals were kept in individual metal cages and periodically assessed for the determination of efficacy. The biological activity of the product achieved 100% mortality at all concentrations in the in vitro tests with Felicola subrostratus and Lynxacarus radovskyi. The high percentage of reduction in infestation by ectoparasites in all groups tested with andiroba seed oil in the in vivo experiments demonstrates the promising use of this phytotherapy, which proved effective against lice and mites and had a considerable residual effect, especially at concentrations of 20% and 30%. / Avaliou-se “in vitro” a atividade biológica do óleo da semente de andiroba contra Felicola subrostratus e Lynxacarus radovskyi, e também o efeito “in vivo” do óleo da semente de andiroba em felinos domésticos naturalmente infestados por Felicola subrostratus, Lynxacarus radovskyi e Otodectes cynotis. Os testes “in vitro” foram realizados por meio de teste de imersão em que, no experimento com Felicola subrostratus, foram testadas quatro diluições do óleo de andiroba: 10%, 25%, 50% e 100% e no teste com Lynxacarus radovskyi, foram testadas seis diluições: 2,5%, 5%, 10%, 20%, 50% e 100%. Após o teste de imersão, os ácaros e insetos foram mantidos em laboratório, em temperatura ambiente e posteriormente observados para verificação de mortalidade, até 72 horas após o início do experimento. Os testes “in vivo” foram realizados mediante aplicações tópicas de 100ml de solução de andiroba para cada animal, com auxílio de algodão, distribuídos por todo o corpo do mesmo, tanto na infestação por Felicola subrostratus quanto por Lynxacarus radovskyi. Na pediculose, os testes foram divididos em duas etapas: na primeira foram testadas concentrações de 2,5%, 5% e 10%, em aplicação única e, na segunda etapa, foram usadas concentrações de 2,5%, 5%, 10% e 20%, uma vez por semana, durante três semanas. Na linxacariose, a aplicação foi única, testando as concentrações de 2,5%, 5%, 10% e 20%. Para a sarna otodécica, testaram-se as concentrações de 2,5%, 5%, 10% e 20%, sendo instiladas dentro do conduto auditivo de cada felino, cinco gotas (0,025 ml), por cinco dias consecutivos. Os animais foram mantidos em gaiolas metálicas individuais e periodicamente avaliados para verificação da eficácia. A atividade biológica do produto demonstrou-se na mortalidade de 100% para todas as diluições testadas, tanto no teste “in vitro” com Felicola subrostratus quanto com Lynxacarus radovskyi. Os elevados percentuais de redução de infestação por ectoparasitos, para todos os grupos testados com o óleo da semente de andiroba demonstrados nos três experimentos “in vivo” revelam a utilização promissora deste fitoterápico, com ação piolhicida, acaricida e de efeito residual considerável, principalmente nas concentrações de 20% e 30%.
12

The Effects of Suburbanization on Nest Ectoparasites and Nest Defense Behavior in the Wood Thrush

Dalton, Evan N 07 November 2014 (has links)
The Wood Thrush (Hylocichla mustelina) is declining throughout its range, yet is capable of persisting in both contiguous forests and small forest patches surrounded by human suburban development. Thus, it is an ideal species for gaining insight into the effects of suburbanization on migrant songbirds. I investigated two aspects of Wood Thrush nesting ecology: nest ectoparasites and nest defense behavior in order to determine if suburbanization influences either aspect. Nests from suburban forests had fewer haematophagous mites, though the abundance of haematophagous blowfly larvae did not differ between suburban and contiguous forests. There was no relationship between the abundance of mites and nest site characteristics, though blowfly abundance may be related to nesting substrate species. Parasites had little effect on nestling condition. In regard to nest defense, suburban Wood Thrushes had shorter flight initiation distances and mounted more active defenses during initial nest visits than birds nesting in contiguous forests, suggesting a previously-established sensitization response to human disturbances in suburban birds. I found no consistent shifts in aggression over subsequent nest visits in either habitat type, suggesting that throughout the breeding season, Wood Thrushes neither habituate nor sensitize further to repeated human disturbances. My results suggest that Wood Thrushes nesting in suburban forest patches are subject to fewer nest ectoparasites and defend their nests more aggressively than conspecifics nesting in contiguous forests. These results draw attention to the fact that although Wood Thrushes persist in both rural and suburban habitats, their nesting ecology may be different between these habitat types.
13

Comparative responses of salmon to sea lice Lepeophtheirus salmonis infections, and lice responses to chemical and environmental stressors

Sutherland, Ben James Gerard 29 May 2014 (has links)
Systems biology methods can provide novel insight into the responses of an organism to a suboptimal environment, an infection or exposure to a xenobiotic. In the interaction of salmon and salmon lice, there are several areas requiring further research. These include the impacts of lice infection on wild salmon, response mechanisms of different salmon species or life stages to lice infections, effects of environmental conditions on lice stress, and mechanisms underlying the emergence of resistance to important parasiticidal chemicals. Here, I combine global gene expression analyses with phenotypic and physiological responses of salmon or salmon lice to further our understanding of these topics. In the first chapter, I introduce the work by discussing relevant background material on the current knowledge of salmon and salmon lice interactions, salmon immunity, the state of salmon and louse genomics and the emerging field of ecological genomics. I also discuss how these approaches are applied to the study of non-model organisms and sustainable aquaculture development and fisheries conservation. In the second chapter, I present the first large-scale transcriptome profiling of a Pacific salmon to a salmon lice infection, identifying transcript signatures associated with an infection in a sensitive life stage of pink salmon Oncorhynchus gorbuscha. In the third chapter, I present the results of multiple co-habitation infections of three species of Pacific and Atlantic salmon to compare physiological and transcriptomic responses at the local (skin) and systemic levels (anterior kidney). In the fourth chapter, I explore louse transcriptome functioning during temperature and salinity perturbations to characterize the molecular stress response and coping strategies of lice, as well as provide stressor context to response genes. In the fifth chapter, I evaluate sensitive Pacific and resistant and sensitive Atlantic lice responses to emamectin benzoate, an important compound for louse control which has recently been evaded by the louse through resistance development in multiple regions worldwide. In the sixth and final chapter, I conclude with a synthesis of what was learned about knowledge gaps discussed above and how to best apply this information by providing some approaches for future research to address remaining challenges. / Graduate / 0369 / 0792 / 0718 / bensutherland7@gmail.com
14

Parasite-host interactions in an arctic goose colony

Harriman, Vanessa Brooke 02 January 2007
The arctic is currently experiencing some of the greatest rates of warming. Newly emerging diseases in the arctic are of particular interest due to the implications these may have at southern latitudes if temperatures continue to rise around the globe. It is important to document changes in pathogen populations, such as alterations in range, virulence, prevalence, and abundance, and the effect these may have on their host populations. Parasites influence the reproductive success of their hosts in some cases. Studies on impacts of ectoparasites on avian reproductive success have generally been focused on species with altricial young. I studied the abundance of an apparently newly emerging nest-parasite and the effects of this parasite on Rosss (<i>Chen rossii</i>) and lesser snow goose (<i>Chen caerulescens caerulescens</i>) reproductive success in the Karrak Lake goose colony, Nunavut, Canada from 2001 to 2004. <p>The nest parasite, identified as the flea <i>Ceratophyllus vagabundus vagabundus</i>, was associated with goose eggs covered with spots of blood. The proportion of goose egg-shells covered by blood was positively correlated with flea abundance in the nest. This relationship allowed the use egg blood-coverage as an index of flea abundance for remaining analyses. Flea abundance in goose nests was associated with variables associated with the host and the hosts habitat. I used general linear models in conjunction with Akaikes information criterion (AIC) to determine which factors were most important in influencing flea abundance in goose nests. The most parsimonious model to explain the relationship between egg blood coverage and flea abundance in goose nests included goose clutch size, age of nest bowl (new vs. old), history of nesting by geese on a specific plot within the colony, habitat within 0.5m of nest, and year. The best predictor of flea abundance was the age of the nest bowl, with nest bowls re-used by geese containing more fleas than new bowls. This relationship was expected as fleas over-wintered in goose nests at the Karrak Lake colony.<p> Logistic regression and AIC were used to determine whether egg blood-coverage was an important variable influencing nest success. All top five models included blood-coverage. Goose nest success was negatively influenced by fleas in most years. There was a threshold of egg blood-coverage at which nest success was affected, and this threshold varied, with >20% blood indicating a significant decline in nest success in two years, and >5% blood-coverage indicating a decrease in nest success in one year. To my knowledge, this is the first study that has examined the parasites of avian nests in an arctic ecosystem and was also the first to investigate the effect of nest parasites on birds with precocial young. More research is needed to determine what factors limit this flea population and whether fleas may become a regulating factor for geese in the Karrak Lake colony.
15

Parasite-host interactions in an arctic goose colony

Harriman, Vanessa Brooke 02 January 2007 (has links)
The arctic is currently experiencing some of the greatest rates of warming. Newly emerging diseases in the arctic are of particular interest due to the implications these may have at southern latitudes if temperatures continue to rise around the globe. It is important to document changes in pathogen populations, such as alterations in range, virulence, prevalence, and abundance, and the effect these may have on their host populations. Parasites influence the reproductive success of their hosts in some cases. Studies on impacts of ectoparasites on avian reproductive success have generally been focused on species with altricial young. I studied the abundance of an apparently newly emerging nest-parasite and the effects of this parasite on Rosss (<i>Chen rossii</i>) and lesser snow goose (<i>Chen caerulescens caerulescens</i>) reproductive success in the Karrak Lake goose colony, Nunavut, Canada from 2001 to 2004. <p>The nest parasite, identified as the flea <i>Ceratophyllus vagabundus vagabundus</i>, was associated with goose eggs covered with spots of blood. The proportion of goose egg-shells covered by blood was positively correlated with flea abundance in the nest. This relationship allowed the use egg blood-coverage as an index of flea abundance for remaining analyses. Flea abundance in goose nests was associated with variables associated with the host and the hosts habitat. I used general linear models in conjunction with Akaikes information criterion (AIC) to determine which factors were most important in influencing flea abundance in goose nests. The most parsimonious model to explain the relationship between egg blood coverage and flea abundance in goose nests included goose clutch size, age of nest bowl (new vs. old), history of nesting by geese on a specific plot within the colony, habitat within 0.5m of nest, and year. The best predictor of flea abundance was the age of the nest bowl, with nest bowls re-used by geese containing more fleas than new bowls. This relationship was expected as fleas over-wintered in goose nests at the Karrak Lake colony.<p> Logistic regression and AIC were used to determine whether egg blood-coverage was an important variable influencing nest success. All top five models included blood-coverage. Goose nest success was negatively influenced by fleas in most years. There was a threshold of egg blood-coverage at which nest success was affected, and this threshold varied, with >20% blood indicating a significant decline in nest success in two years, and >5% blood-coverage indicating a decrease in nest success in one year. To my knowledge, this is the first study that has examined the parasites of avian nests in an arctic ecosystem and was also the first to investigate the effect of nest parasites on birds with precocial young. More research is needed to determine what factors limit this flea population and whether fleas may become a regulating factor for geese in the Karrak Lake colony.
16

Varroa destructor Anderson & Truemann, 2000: Perfil genético, taxas de infestação e reprodução em abelhas Apis mellifera L. (africanizadas) no Brasil / Varroa destructor Anderson & Truemann, 2000 in africanized honey bees (Apis mellifera L.): Genetic profile, infestation rates and reproduction in Brazil

Pinto, Fábio de Assis 23 July 2012 (has links)
Made available in DSpace on 2015-03-26T13:30:42Z (GMT). No. of bitstreams: 1 texto completo.pdf: 2184805 bytes, checksum: 609b308cb0f9082feb3004b7c0f7356f (MD5) Previous issue date: 2012-07-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The mite Varroa destructor (Mesostigmata Varroidae) (Anderson & Truemann, 2000) is a major problem in the apiculture. Besides being the vector of viruses related to Colony Collapse Disorder (CCD), causes mortality of colonies at high levels of infestation. Its damage depends upon a number of biotic and abiotic factors, in which the variation in the pattern of haplotypes is believed to be a key. In Brazil, the mite does not appear to cause major damage to the colonies, remained at low levels of infestation, however with the entry of haplotype K in the country, in example of other countries, we speculate a possible increase in reproductive rate of the mite. In this context, we analyzed the genetic profile in 58 municipalities, divided into 14 states along with evaluations of infestation rates and reproductive potential of the parasite in Africanized honeybee (Hymenoptera Apidae). The Haplotype J, considered less problematic mitochondrial genotype was found only in four localities, yet the K haplotype was also identified in these counties, except the island of Fernando de Noronha, Pernambuco. Infestation levels ranged from 0.33 ± 0.55% to 15.3 ± 9.2%, while the reproductive potential ranged from 0 to 1.5 ± 0.2. There were significant differences (P < 0,001) in the dynamics of mite infestation in the different municipalities assessed, although the levels found are considerably low compared to most other countries that use chemical treatment, and such variations could not be attributed to the pattern of haplotypes. Apparently factors not involving differences in mitochondrial genotype as climatic variations between regions, management and selection for hygienic behavior are related to variations in the dynamics of mite infestation in Brazil. / O ácaro Varroa destructor (Mesostigmata Varroidae) (Anderson & Truemann, 2000) é um dos maiores problemas na apicultura mundial. Além de ser o vetor de vírus que têm sido frequentemente relacionados à síndrome do desaparecimento das abelhas (CCD), causa mortalidade de colônias em níveis elevados de infestação. Seus danos dependem de uma série de fatores bióticos e abióticos e, acredita-se que, variações genotípicas (haplótipo) são uma das principais causas. No Brasil, o ácaro aparentemente não causa grandes danos às colônias, mantendo-se em níveis baixos de infestação, contudo, com a entrada do haplótipo K no país, especula-se um possível aumento na taxa reprodutiva do ácaro, a exemplo do que vem sendo relatado em outros países. Nesse contexto, realizamos identificações do perfil genético de Varroa destructor em 58 municípios brasileiros, distribuídos em 14 estados juntamente com avaliações nas taxas de infestação e potencial reprodutivo do parasita em Apis mellifera L. africanizada (Hymenoptera Apidae). O haplótipo J, genótipo considerado menos problemático, foi encontrado somente em quatro localidades, muito embora o H. K também tenha sido identificado nestes municípios, exceto na Ilha de Fernando de Noronha-PE, onde apenas o H. J foi identificado. Os níveis de infestação do total de amostras analisadas variaram de 0,33±0,55% a 15,3±9,2%, enquanto que o potencial reprodutivo variou de 0 a 1,5±0,2. Observamos diferenças significativas (P < 0,001) na dinâmica de infestação do ácaro nos diferentes municípios avaliados, embora os níveis encontrados tenham sido consideravelmente baixos quando comparados aos encontrados em outros países. Tais variações não puderam ser atribuídas ao padrão de haplótipos (K ou J), uma vez que não foi constatada diferença entre os mesmos para o parâmetro avaliado. Aparentemente, fatores não envolvendo diferenças no genótipo mitocondrial, como variações climáticas entre regiões, manejo e seleção para comportamento higiênico possuem maior relação às variações na dinâmica de infestação do ácaro no Brasil.
17

Avaliação clínica e laboratorial do óleo essencial da lippia sidoides cham em dermatites parasitarias de cães (Canis familiares)

SOUZA, Wagner Mcklayton Alves de 08 February 2012 (has links)
Submitted by (edna.saturno@ufrpe.br) on 2016-11-08T16:41:32Z No. of bitstreams: 1 Wagner Mcklayton Alves de Souza.pdf: 1430165 bytes, checksum: 6865be14673aa551296e87905cdd469c (MD5) / Made available in DSpace on 2016-11-08T16:41:32Z (GMT). No. of bitstreams: 1 Wagner Mcklayton Alves de Souza.pdf: 1430165 bytes, checksum: 6865be14673aa551296e87905cdd469c (MD5) Previous issue date: 2012-02-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The Lippia sidoides Cham (rosemary pepper) is a plant present in part of the semi-arid on Brazil northeastern. Their leaves have shown a high potential in the treatment of dermatitis in humans. This study aimed to evaluate the biological activity of the L. sidoides Cham oil on ectoparasites of domestic dogs (Canis familiares) and antimicrobial activities on Staphylococcus sp. isolated in these animals. To this end, were selected 20 dogs suffering from ectoparasites. In 40 samples of skin culture for bacterial growth it was found positive result in 09 samples analyzed, being Staphylococcus sp isolated, for in vitro evaluation of antimicrobial activity of oil L. sidoides they were subjected to MIC. The results also revealed the presence of flea C. felis felis, tick R. sanguineus. For in vitro evaluation of insecticidal activity against Ctenocephalides felis felis through the filter paper test, were used 150 adult fleas divided into three groups each with ten subjects. G 01 being distilled water + Tween 20, G 02 oil L. sidoides 5% with Tween 20 as a dispersant and G3 three spray fipronil, evaluating motility in time of 10 minutes 1, 3, 6, 12, 24 hours. In the in vivo test 20 pet dogs of both sexes parasitized by C. felis felis were divided into two groups G1 with shampoo of essential oil of L. sidoides 5% and G2 shampoo neutral, bathed twice a week for nine weeks. To in vitro acaricide evaluation against R. sanguineus were used 90 female ticks divided into three treatment groups, being G1 based on essential oil of L. siodoides Cham using Tween 20 as a dispersant at distilled water, G2 cypermethrin + Dichlorvos ® DDVP and in the negative control G3 distilled water and Tween 20. The results showed significant inhibition of bacterial growth at a concentration of 5% against S. sp. 100% mortality against R. sanguineus in the same concentrations. On in vivo tests against C. felis was a reduction of 100% in the number of fleas treated with L. sidoides and efficacy of 100% in the mortality in vitro of C. felis felis after 24 hours exposure to oil L. sidoides. It was concluded that the essential oil of Lippia sidoides Cham 5% presented insecticide effectiveness on the adult form of Ctenocephalides felis felis in both tests. Well as antimicrobial activity against Staphylococcus spp and acaricide against ticks of R. sanguineus. / A Lippia sidoides Cham (alecrim pimenta) é uma planta presente em parte do semi-árido do Nordeste Brasileiro. Suas folhas tem apresentado elevado potencial no tratamento de diversas dermatites em humanos. O presente trabalho objetivou avaliar a atividade biológica do óleo de L. sidoides Cham sobre ectoparasitos de cães domésticos (Canis familiares) e antimicrobiana sobre Staphylococcus sp isoladas destes mesmos animais. Para tal, foram selecionados 20 cães acometidos de ectoparasitoses. Em 40 amostras de cultura de pele para crescimento bacteriano foi verificado resultado positivo em 09 amostras analisadas, sendo isolada a bactéria Staphylococcus sp , para avaliação in vitro da atividade antimicrobiana do óleo de L. sidoides as mesmas foram submetidas ao MIC. Os resultados revelaram ainda a presença da pulga C. felis felis, e carrapato R. sanguineus. Para avaliação in vitro da atividade inseticida contra Ctenocephalides felis felis através do teste de papel filtro, foram utilizadas 150 pulgas adultas divididas em três grupos com dez indivíduos cada. Sendo G 01 água destilada + Tween 20, G 02 óleo de L. sidoides a 5% tendo como dispersante o Tween 20 e G3 fipronil spray, avaliando-se a motilidade em tempos de 10 minutos 1, 3, 6, 12, 24 horas. No teste in vivo 20 cães domiciliados de ambos os sexos parasitados por C. felis felis foram divididos em dois grupos G1 com shampoo de óleo essencial de L. sidoides a 5% e G2 shampoo neutro, banhados duas vezes por semana por nove semanas. Para avaliação acaricida in vitro contra R. sanguineus utilizou-se 90 fêmeas teleóginas divididas em três grupos de tratamento, sendo o G1 à base de óleo essencial de L. siodoides Cham a 5% utilizando-se tween 20 como dispersante em água destilada, G2 cipermetrina + Diclorvós® DDVP e no controle negativo G3 água destilada e tween 20. Os resultados revelaram inibição do crescimento bacteriano significativo na concentração de 5% frente a S. sp. mortalidade de 100% frente R. sanguineus nas mesmas concentrações. Nos testes in vivo contra C. felis houve uma redução de 100% no número de pulgas tratadas com L. sidoides bem como eficácia de 100% na mortalidade in vitro de C. felis felis após 24h de exposição ao óleo de L. sidoides. Conclui-se que o óleo essencial de Lippia sidoides Cham a 5% apresentou eficácia inseticida sobre a forma adulta de Ctenocephalides felis felis em ambos os testes. Bem como ação antimicrobiana frente a isolados de Staphylococcus spp e acaricida frente a teleóginas de R. sanguineus.
18

Modalités fonctionnelles et évolutives des parasitoses développées par les crabes Pinnotheridae aux dépens des échinides fouisseurs

De Bruyn, Colin 14 December 2010 (has links) (PDF)
Ce travail s'est intéressé aux liens existant entre la stratégie d'exploitation développée par un crustacé ectoparasite et son comportement reproductif. Le crabe Pinnotheridae Dissodactylus primitivus exploite deux espèces Spatangidae vivant dans la Mer des Caraïbes, Meoma ventricosa et Plagiobrissus grandis. Des approches comportementales, démographiques et génétiques ont été adoptées afin de mettre en lumière le fonctionnement et la biologie de cette symbiose. Par son comportement alimentaire, le crabe occasionne des lésions tégumentaires sur ses hôtes. Celles-ci affectent la fitness de M. ventricosa, au travers de son développement gonadique. Dissodactylus primitivus exploite ses deux espèces hôtes de façon asymétrique. La reproduction des parasites se déroule sur les deux hôtes, alors que le recrutement ne s'effectue que sur M. ventricosa. Ce cycle vital asymétrique du crabe serait stabilisé par la qualité et la rareté de P. grandis. En outre, Le comportement sexuel du crabe sur M. ventricosa répondrait aux critères de la polygynandrie à femelles mobiles. Selon ce modèle, les mâles et les femelles se déplacent entre les hôtes à la recherche de partenaires multiples. Lors de ces déplacements, le crabe s'aiderait de son aptitude à localiser chimiquement ses hôtes. Néanmoins, ce mécanisme s'avère plastique et pourrait refléter l'asymétrie du cycle vital. En effet, cette différence n'a pas d'origine génétique, car les crabes vivant au sein du site d'étude constituent la même population quelle que soit l'espèce hôte considérée. Les marqueurs moléculaires microsatellites mis au point dans ce travail permettront lors de futurs travaux d'affiner les observations sur les modalités d'accouplement du crabe et d'estimer sa capacité de dispersion.
19

Seasonal variation in the life histories of a viviparous ectoparasite, the deer ked

Härkönen, L. (Laura) 15 August 2012 (has links)
Abstract The life histories of ectoparasites are shaped by both host and off-host environment. A suitable host is primarily needed during reproduction, whereas juvenile stages outside the host are directly exposed to environmental variability. Viviparity, i.e. the development of an embryo inside the body of the mother resulting in large offspring size, increases offspring survival. The production of large offspring has its consequences in terms of high variation in offspring age and in the environment that each young individual will face. I used a viviparous ectoparasite, the deer ked (Lipoptena cervi), to investigate the consequences of long reproductive lifespan and varying offspring environment on offspring life-histories and seasonal adaptations. Offspring life-histories varied seasonally. I showed that the resources provided by the deer ked females determine offspring performance throughout its off-host period. Offspring size increased towards the spring and the end of the reproductive period, and simultaneously offspring survival and cold tolerance increased. Seasonal variation in offspring size did not reflect the resources that would guarantee offspring survival during the longest diapause or the highest cold tolerance during the harshest winter period. Diapause intensity varies with birth time according to the expected length of the winter ahead. However, the deer ked pupae, regardless of their age, overwinter at an opportunistic diapause, which may be terminated rapidly only by an exposure to high temperature. Contrary to general observations, photoperiod has no role in regulating the seasonal shifts of the deer ked. Neither is high cold tolerance associated only with diapause, but it remains high through four seasons, also in the active developmental and adult stages. I also evaluated the effects of life-history variation on the invasion potential of the deer ked. I conducted a large-scale transplant experiment to test the survival and pupal development at and beyond the current range. I found that the lower spring and summer temperatures and the shorter growth season in the north cause a deterioration in pupal performance and shorten the flight period. However, the colder climate may not totally prevent further spread. A more important factor that will affect deer ked invasion is host availability, and especially in Finland, the density of the moose population. Seasonal variation in offspring life histories in viviparous ectoparasites differs from the variation patterns reported in most invertebrates. This may be due to the extremely large offspring size and to the fact that maternally derived resources determine offspring performance through the entire off-host period. Variation in offspring performance is thus determined by maternal resources and seasonal variation in the condition of the moose. / Tiivistelmä Useimpien ulkoloisten elinkierto on riippuvainen isännästä ja isännän ulkopuolella kasvavien jälkeläisten kohtaamista ympäristöoloista. Viviparia eli jälkeläisen kehitys naaraan sisällä ja siitä usein seuraava suuri jälkeläiskoko parantavat jälkeläisten selviytymistä. Suurten jälkeläisten tuottaminen pitkällä aikavälillä johtaa siihen, että eri-ikäiset jälkeläiset kohtaavat vuodenajasta riippuen hyvin erilaiset olosuhteet. Väitöstyössäni tarkastelin Suomessa nopeasti yleistyneen hirvieläinten ulkoloisen, hirvikärpäsen (Lipoptena cervi), avulla, mitä seurauksia viviparialla, pitkällä lisääntymiskaudella ja ympäristön vuodenaikaisvaihtelulla on jälkeläisten elinkierto-ominaisuuksiin. Väitöskirjatyössäni havaitsin, että hirvikärpäsjälkeläisten elinkiertopiirteet vaihtelevat jälkeläisen syntymäajan mukaan. Osoitin myös, että hirvikärpäsnaaraan jälkeläisilleen tarjoamat ravintovarat määrittelevät jälkeläisten isännästä riippumattoman elinkierron aikaisen menestyksen. Jälkeläisten keskimääräinen koko kasvoi lisääntymiskauden edetessä talvesta kohti kevättä, jolloin myös selviytyminen ja kylmänsietokyky paranivat. Jälkeläiskoon vuodenaikaisvaihtelu ei näin ollen vastaa jälkeläisten tarvitsemia resursseja suhteessa talvehtimisen pituuteen eikä korreloi koville talvipakkasille altistumisen todennäköisyyden kanssa. Lepotilan keston määrittelevä diapaussin syvyys vaihteli syntymävuodenaikaa vastaavasti. Diapaussin havaitsin kuitenkin olevan ensisijaisesti opportunistinen, jolloin pelkästään korkea lämpötila voi nopeasti päättää lepotilan kaikenikäisillä yksilöillä. Vastoin yleisiä käsityksiä valorytmi ei vaikuta diapaussin säätelyyn. Vastoin ennakko-odotuksia kylmänsietokyky säilyy korkeana vuoden ympäri ja kaikissa tutkituissa elinkierron vaiheissa. Sovelsin tutkimieni elinkiertopiirteiden vaikutusta myös lajin invaasiokykyyn, ja tutkin istutuskokeen avulla koteloiden selviytymistä ja kehitystä nykyisellä esiintymisalueella ja sen pohjoispuolella. Alhaisemmat kevät- ja kesälämpötilat sekä lyhyempi kasvukausi vähentävät aikuiseksi selviytymistä ja lyhentävät lentoaikaa syksyllä. Ilmastotekijöiden suhteen hirvikärpänen voisi esiintyä nykyistä pohjoisempana. Tärkein tekijä hirvikärpäsen leviämistä tarkasteltaessa on kuitenkin sopivien isäntäeläimien saatavuus ja Suomen oloissa erityisesti hirven eli hirvikärpäsen pääisännän kannan tiheys. Tutkimukseni perusteella ulkoloisten vivipariasta seuraava jälkeläisten elinkiertopiirteiden ajallinen vaihtelu eroaa muiden selkärangattomien vastaavasta vaihtelusta. Yhtenä syynä eroihin lienee se, että hirvikärpäsnaaras tuottaa erityisen suuria jälkeläisiä ja että jälkeläiset puolestaan ovat täysin riippuvaisia emon antamista resursseista. Emon lisääntymisresurssit ja hirven kunnon vuodenaikaisvaihtelu vaikuttavat mahdollisesti siihen, minkälaisia jälkeläisiä hirvikärpänen milloinkin kykenee tuottamaan.
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The potential role of ABC transporters as factors influencing drug susceptibility in the salmon louse, Lepeophtheirus salmonis (Kroyer, 1837)

Heumann, Jan H. January 2014 (has links)
Efficient control of sea lice is a major challenge for the sustainable production of farmed Atlantic salmon (Salmo salar (Linnaeus, 1758)). These marine ectoparasites feed on mucus, skin and blood of their hosts, thereby reducing the salmon’s growth rate and overall health. In the northern hemisphere, the most prevalent species is Lepeophtheirus salmonis (Krøyer, 1837). In 2006, global costs of sea lice infections are estimated to have exceeded €300 million, with the majority spent on a limited number of chemical delousing agents. Emamectin benzoate (EMB; SLICE®), an avermectin, has been widely used since its introduction in 2000, due to its convenient administration as an in-feed medication and its high efficacy against all parasitic stages of L. salmonis. However, over-reliance on a single or limited range of medicines favours the emergence of drug resistance and, as a result, the efficacy of this compound in treating L. salmonis has decreased in recent years, as reported from e.g. Chile, Norway, Scotland and Canada. Declining efficacy underlines the need for an improved understanding of the molecular mechanisms underlying EMB drug resistance in L. salmonis. Elucidation of these mechanisms would allow for improved monitoring tools, earlier detection of developing resistance, extended usability of current delousing agents and development of new parasiticides. The work described in this thesis sets out to examine the molecular mechanisms underlying EMB resistance in L. salmonis. In earlier studies, research in nematodes and arthropods has linked drug efflux transporters belonging to the family of ATP-binding cassette (ABC) transporters to ivermectin (IVM) resistance, a parasiticide with high chemical similarity to EMB. ABC transporters such as permeability glycoprotein (P-gp), transport a wide range of substrates, including drugs, and have been suggested to provide a potential molecular mechanism through which EMB resistance might be mediated in sea lice. As an example of such mechanisms, increased expression of P-gp is one of the causative factors for drug resistance in human cancer cells and avermectin resistance in nematode parasites such as Caenorhabditis elegans or Haemonchus contortus. Initial research involved screening for novel salmon lice P-gps that might contribute to EMB resistance. A novel P-gp, SL-PGY1, was discovered using a combined bioinformatic and molecular biological approach. The expression was compared in two well-characterised L. salmonis strains differing in their susceptibility to EMB (S = susceptible, R = resistant). Prior to EMB exposure, mRNA levels did not differ from each other, while, after 24 h exposure, a 2.9-fold increase in SL-PGY1 mRNA expression was observed in the R strain. SL-PGY1 appears not to be a major factor contributing to reduced EMB susceptibility, although it could play a role, as expression levels increased upon exposure to EMB. A further four additional drug transporters (ABC C subfamily) were also discovered showing high homology to multidrug-resistance proteins (MRP). The relative expression levels of each MRP was compared in the strains S and R, before and after exposure to EMB. No significant changes were found in their expression patterns. If ABC drug transporters mediate the efflux of EMB and thereby reduce the intracellular concentrations of the drug in exposed animals, the inhibition of those ABC drug transporters was expected to lead to higher intracellular levels of EMB. This could result in an enhanced toxic effect when EMB is co-administered with an inhibitor. Two known inhibitors of human P-gps and MRPs, cyclosporin A (CSA) and verapamil (VER), were co-administered with EMB. CSA increased the toxic effect of EMB in both tested strains, implying that the targets of CSA are expressed at comparable levels and that they may be part of the mechanism conferring EMB resistance. VER increased the toxic effect of EMB in the R strain, but had no significant effects on the S strain. This implies that the expression of factors inhibited by VER differs between the two L. salmonis strains. It is hypothesised that a number of ABC transporters with distinct, yet overlapping patterns of inhibitor specificity are affected by those inhibitors. The search for drug-resistance conferring genes was complemented with a systematic, genome-wide survey of ABC transporters in L. salmonis to find additional members of this important gene family. Next-generation high-throughput RNA sequencing (RNA-seq) was employed to assemble a reference transcriptome from pooled total RNA of salmon lice at different development stages. The transcriptome was assembled against the L. salmonis genome and annotated. Thirty-nine putative ABC transporters were found. Of further interest were transcripts of the subfamily B, C and G, as they contain drug-transporting ABC proteins. For the ABC B subfamily, one full (SL-PGY1) and three half transporter transcripts were found. Only full transporters are known to transport drugs and SL-PGY1 is apparently not a major factor contributing to EMB resistance. Fourteen ABCC sequences were found – 11 MRPs and 3 homologues to sulfonylurea receptors. Of interest are MRPs, as they contribute to drug detoxification in humans and invertebrates. Four MRPs had been identified previously and their expression ratios did not differ between S and R strain parasites. Seven sequences belonging to ABCG subfamily were found. However, none of the L. salmonis ABCG transcripts identified showed sufficient homology to known drug transporters in other species. With the currently limited understanding of the mechanisms conferring EMB resistance, monitoring the susceptibility of L. salmonis subpopulations is essential. Dose-response bioassays are currently widely used. Tests with pre-adult II or adult parasites requires relatively large numbers of parasites (~150) to conduct this type of bioassay, which may not always be available. Addressing this issue, we tested the feasibility of a single-dose bioassay (requiring fewer test animals than dose-response bioassays) to discriminate between L. salmonis strains with differing EMB susceptibility. This alternative approach uses time-course toxicity analysis, where the toxic effect of EMB is monitored over time. After clearly defining the effect criteria, we found that it is possible to discriminate between those L. salmonis strains. However, while requiring fewer test animals, time course toxicity analysis is more labour-intensive, but the alternative design can be suitable under certain circumstances. The work reported here has provided new knowledge concerning the mechanisms of EMB resistance in sea lice. Several novel putative drug transporters have been identified, an important first step toward unravelling the complex interactions of genes involved in EMB resistance in this commercially important parasite.

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