Most organisms are rarely infected with just a single species of parasite and are usually simultaneously infected with a range of species. Thus, the parasite fauna of a host represents an entire community composed of multiple individuals from many different species. In nature, it is within the host that parasites can encounter conspecifics and individuals from other species. As in any ecosystem, while such interactions between parasites can be antagonistic due to competition or conflicting interests, association between different species can also be beneficial. In this thesis, I investigated patterns of associations between parasites in the New Zealand cockle Austrovenus stutchburyi through a combination of descriptive and experimental studies employing both standard ecological field techniques and molecular biology methods. It was found that the presence and infection intensity of various parasites species are not independent of each other. Among cockles, an association was found between two trematode taxa, i.e. between the infection intensity by foot-encysting echinostomes and the metacercariae of Gymnophallus sp. It was also found that the presence of the parasitic copepod Pseudomyicola spinosus was associated with greater infection intensity by the echinostomes but not Gymnophallus sp. While it was postulated that the positive association between the echinostomes and Gymnophallus sp. was due to the latter�s preference to infect cockles that are stranded on the sediment surface as a result of heavy echinostome metacercariae burden in their foot, a field experiment found that Gymnophallus cercariae did not preferentially infect cockles that have been forced to remain above the sediment surface as opposed to those that were forced to remain buried. Meanwhile, the two species of echinostomes known to encyst in the cockle�s foot, Acanthoparyphium sp. and Curtuteria australis, were found to represent cryptic species complexes. The presence of such cryptic species means that it is possible that some potential interspecific interactions are overlooked. A study of the population structure of Gymnophallus sp. found that each cockle contains multiple genetically distinct individuals and that clonal individuals rarely co-occur in the same cockle. This adds to the growing body of evidence suggesting that in addition to acting as a means of reaching the definitive host, the second intermediate host also acts to promote genetic diversity by accumulating cercariae shed by multiple first intermediate hosts in the environment. An experimental infection study conducted with Curtuteria australis cercariae deriving from singly-infected first intermediate hosts revealed that different clonal lineages varied with respect to their contribution to host manipulation. It was found that while certain lineages have a preference for host manipulation, others tend to adopt a "hitch-hiker"-type life history strategy. However, this genetic predisposition was also found to be a phenotypically plastic trait, as the presence of a higher number of manipulators seems to encourage newly-arrived cercariae to become manipulators, regardless of clonal lineage. This thesis provides evidence that patterns of interactions can affect various aspects of parasite life history. Apart from host condition, parasites can also be affected by other parasites. Studying the dynamics of mixed infections can provide informative insights for evolutionary and ecological research.

Thesis (Ph.D.)--Mississippi State University. in Veterinary Medical Sciences in the Department of Basic Sciences. / Title from title screen. Includes bibliographical references.

Site selection, and the means to access specific sites, is a keystone of parasitology. I evaluated migration and site selection behaviours of metacercariae of two congeneric species of strigeoid trematode throughout growth and encystment phases in the fathead minnow. Results showed that pre-encystment stages of Ornithodiplostomum ptychocheilus migrate along specific neural tracts to access sites in the optic lobes of the brain. Conversely, pre-encystment stages of Ornithodiplostomum sp. migrate via direct penetration, or via the vascular system to access visceral organs, especially the liver. Remarkably, both species have a bi-phasic pattern of development, with growth and encystment occurring in unique sites. Finally, I examined patterns of rodlet cell proliferation and maturation in response to growth and encystment phases of O. ptychocheilus. Cell densities were low (<11/mm2) in brain tissue adjacent to 1 and 2 week old metacercaria, but peaked to approximately 210/mm2 at 6 weeks. These results shed new light on the potential function of these enigmatic cells. / x, 125 leaves : ill. ; 29 cm.

Natural selection should favour host defenses that reduce a host’s exposure to parasites or reduce their negative effects. One strategy that resolves the substantial costs of host immunity and/or tolerance is to avoid infective stages altogether. For fish, behavioural avoidance is well-known for defense against aquatic predators, but it is poorly known for defense against parasites. I used a model system that is amenable to experimental manipulation to test the behavioural avoidance hypothesis for fathead minnows exposed to the larvae of two of their common flatworm parasites. First, I showed that minnows exposed to a liver encysting trematode, Ornithodiplostomum sp. showed an increase in lipid peroxidation, an indicator of oxidative stress, persisting through worm development. Three lines of evidence provided support for the behavioural avoidance hypothesis. First, shoal area decreased in groups of minnows exposed to O. ptychocheilus cercariae compared to those exposed to cues from other aquatic threats. Second, average worm numbers were 50 % lower in fish confined to artificial shoals compared to non-shoaling minnows, indicating that shoaling reduces risk of exposure. The third experiment showed that minnows within the centre of shoal reduced their risk of infection by 67%. Taken together, these results demonstrate a cost of trematode infection on minnows, that minnows can detect infective larvae within the water column, and that social living reduces a hosts’ risk of exposure. / xi, 84 leaves : ill. ; 29 cm

Most organisms are rarely infected with just a single species of parasite and are usually simultaneously infected with a range of species. Thus, the parasite fauna of a host represents an entire community composed of multiple individuals from many different species. In nature, it is within the host that parasites can encounter conspecifics and individuals from other species. As in any ecosystem, while such interactions between parasites can be antagonistic due to competition or conflicting interests, association between different species can also be beneficial. In this thesis, I investigated patterns of associations between parasites in the New Zealand cockle Austrovenus stutchburyi through a combination of descriptive and experimental studies employing both standard ecological field techniques and molecular biology methods. It was found that the presence and infection intensity of various parasites species are not independent of each other. Among cockles, an association was found between two trematode taxa, i.e. between the infection intensity by foot-encysting echinostomes and the metacercariae of Gymnophallus sp. It was also found that the presence of the parasitic copepod Pseudomyicola spinosus was associated with greater infection intensity by the echinostomes but not Gymnophallus sp. While it was postulated that the positive association between the echinostomes and Gymnophallus sp. was due to the latter�s preference to infect cockles that are stranded on the sediment surface as a result of heavy echinostome metacercariae burden in their foot, a field experiment found that Gymnophallus cercariae did not preferentially infect cockles that have been forced to remain above the sediment surface as opposed to those that were forced to remain buried. Meanwhile, the two species of echinostomes known to encyst in the cockle�s foot, Acanthoparyphium sp. and Curtuteria australis, were found to represent cryptic species complexes. The presence of such cryptic species means that it is possible that some potential interspecific interactions are overlooked. A study of the population structure of Gymnophallus sp. found that each cockle contains multiple genetically distinct individuals and that clonal individuals rarely co-occur in the same cockle. This adds to the growing body of evidence suggesting that in addition to acting as a means of reaching the definitive host, the second intermediate host also acts to promote genetic diversity by accumulating cercariae shed by multiple first intermediate hosts in the environment. An experimental infection study conducted with Curtuteria australis cercariae deriving from singly-infected first intermediate hosts revealed that different clonal lineages varied with respect to their contribution to host manipulation. It was found that while certain lineages have a preference for host manipulation, others tend to adopt a "hitch-hiker"-type life history strategy. However, this genetic predisposition was also found to be a phenotypically plastic trait, as the presence of a higher number of manipulators seems to encourage newly-arrived cercariae to become manipulators, regardless of clonal lineage. This thesis provides evidence that patterns of interactions can affect various aspects of parasite life history. Apart from host condition, parasites can also be affected by other parasites. Studying the dynamics of mixed infections can provide informative insights for evolutionary and ecological research.

Orientador: Reinaldo José da Silva / Banca: Tânia de Freitas Raso / Banca: Alessandro Francisco Talamini do Amarante / Resumo: O presente estudo relata o resultado da análise parasitológica de 62 exemplares juvenis da espécie Chelonia mydas (L.) necropsiadas no Centro de Reabilitação de Tartarugas Marinhas do Projeto TAMAR-IBAMA na região de Ubatuba, Litoral Norte do Estado de São Paulo, Brasil. Trinta e três animais apresentaram parasitas da classe Trematoda das seguintes espécies: Cricocephalus albus, Cricocephalus megastomum, Pleurogonius longiusculus, Pronocephalus obliquus (Pronocephalidae), Deuterobaris proteus, Neoctangium travassosi, Polyangium linguatula, Microscaphidium reticulare (Angiodictyidae) e Metacetabulum invaginatum (Metacetabulidae). A prevalência variou de 3 a 66,7%, sendo as espécies N. travassosi, D. proteus e M. invaginatum, aquelas de maior prevalência nos animais estudados. A intensidade média de infecção foi maior na espécie da família Metacetabulidade (80,2) em relação às famílias Angiodictyidae (35,7) e Pronocephalidae (7,3). Em 13 (39,4%) animais o parasitismo foi monoespecífico, com predomínio das espécies N. travassosi e D. proteus. Por outro lado, em 20 (60,6%) tartarugas foi observada associação entre parasitas, sendo encontrado 2, 3, 4 ou 5 parasitas, sendo as freqüências desta associação de 33,3%, 0,06%, 0,18% e 0,03%, respectivamente. Observamos associação entre sinais de debilidade e carga parasitária (p = 0,03). / Abstract: A parasitological survey of 62 juvenile specimens of the Chelonia mydas (L.) necropsied in the Centro de Reabilitação de Tartarugas Marinhas of the Projeto TAMAR-IBAMA, Ubatuba city, North Coast of the São Paulo State, Brazil, is presented. Thirty three animals were parasitized by flukes of the following species: Cricocephalus albus, Cricocephalus megastomum, Pleurogonius longiusculus, Pronocephalus obliquus (Pronocephalidae), Deuterobaris proteus, Neoctangium travassosi, Polyangium linguatula, Microscaphidium reticulare (Angiodictyidae) and Metacetabulum invaginatum (Metacetabulidae). The prevalence varied from 3 to 66.7%, and the species N. travassosi, D. proteus and M. invaginatum, presented the higher prevalence among the studied animals. The mean intensity of infection was higher in the species of the family Metacetabulidade (80.2) in comparison to the families Angiodictyidae (35.7) and Pronocephalidae (7.3). In 13 (39.4%) animals the parasitism was monospecific, and the species N. travassosi and D. proteus were predominates. On the other hand, in 20 (60.6%) sea turtles an association among parasites was observed. It was found 2, 3, 4 or 5 parasites and the frequencies of this association were 33.3%, 0.06%, 0.18% and 0.03%, respectively. The relation between signs of weakness and mean intensity of infection was also observed (p = 0.03). / Mestre

Made available in DSpace on 2014-06-11T19:23:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-02-12Bitstream added on 2014-06-13T19:08:45Z : No. of bitstreams: 1 werneck_mr_me_botib.pdf: 1984153 bytes, checksum: 8fe7df123d7db009ca20e57b7b9f8439 (MD5) / Universidade Estadual Paulista (UNESP) / O presente estudo relata o resultado da análise parasitológica de 62 exemplares juvenis da espécie Chelonia mydas (L.) necropsiadas no Centro de Reabilitação de Tartarugas Marinhas do Projeto TAMAR-IBAMA na região de Ubatuba, Litoral Norte do Estado de São Paulo, Brasil. Trinta e três animais apresentaram parasitas da classe Trematoda das seguintes espécies: Cricocephalus albus, Cricocephalus megastomum, Pleurogonius longiusculus, Pronocephalus obliquus (Pronocephalidae), Deuterobaris proteus, Neoctangium travassosi, Polyangium linguatula, Microscaphidium reticulare (Angiodictyidae) e Metacetabulum invaginatum (Metacetabulidae). A prevalência variou de 3 a 66,7%, sendo as espécies N. travassosi, D. proteus e M. invaginatum, aquelas de maior prevalência nos animais estudados. A intensidade média de infecção foi maior na espécie da família Metacetabulidade (80,2) em relação às famílias Angiodictyidae (35,7) e Pronocephalidae (7,3). Em 13 (39,4%) animais o parasitismo foi monoespecífico, com predomínio das espécies N. travassosi e D. proteus. Por outro lado, em 20 (60,6%) tartarugas foi observada associação entre parasitas, sendo encontrado 2, 3, 4 ou 5 parasitas, sendo as freqüências desta associação de 33,3%, 0,06%, 0,18% e 0,03%, respectivamente. Observamos associação entre sinais de debilidade e carga parasitária (p = 0,03). / A parasitological survey of 62 juvenile specimens of the Chelonia mydas (L.) necropsied in the Centro de Reabilitação de Tartarugas Marinhas of the Projeto TAMAR-IBAMA, Ubatuba city, North Coast of the São Paulo State, Brazil, is presented. Thirty three animals were parasitized by flukes of the following species: Cricocephalus albus, Cricocephalus megastomum, Pleurogonius longiusculus, Pronocephalus obliquus (Pronocephalidae), Deuterobaris proteus, Neoctangium travassosi, Polyangium linguatula, Microscaphidium reticulare (Angiodictyidae) and Metacetabulum invaginatum (Metacetabulidae). The prevalence varied from 3 to 66.7%, and the species N. travassosi, D. proteus and M. invaginatum, presented the higher prevalence among the studied animals. The mean intensity of infection was higher in the species of the family Metacetabulidade (80.2) in comparison to the families Angiodictyidae (35.7) and Pronocephalidae (7.3). In 13 (39.4%) animals the parasitism was monospecific, and the species N. travassosi and D. proteus were predominates. On the other hand, in 20 (60.6%) sea turtles an association among parasites was observed. It was found 2, 3, 4 or 5 parasites and the frequencies of this association were 33.3%, 0.06%, 0.18% and 0.03%, respectively. The relation between signs of weakness and mean intensity of infection was also observed (p = 0.03).

Made available in DSpace on 2014-08-20T14:31:28Z (GMT). No. of bitstreams: 1 dissertacao_mariana_moura_mendes.pdf: 1113562 bytes, checksum: 48d46dd9dafe94b682264135d3d172ef (MD5) Previous issue date: 2011-11-18 / The Great Kiskadee, Pitangus sulphuratus (Linnaeus, 1766) (Tyrannidae), occurs only in the Americas, is distributed from the United States (Texas) to Argentina. It is the most popular bird species of Brazil and Rio Grande do Sul, being easily recognized by its onomatopoeic song, vivid colorations and aggressive behavior in a dispute over territory and when guarding the nest. These birds can be found in a wide variety of habitats such as crop fields, towns, orchards, woods and edge of aquatic environments, such as margins of ponds, streams, rivers and dams. They have skills to identify foods in natural environments and exploring food resources of anthropic origin, which contributes to its efficiency in colonizing urban environments and their abundance in various environments. The Great Kiskadee can be considered an omnivorous species, and its flexibility in their food can influence their helminthofauna, since the majority of gastrointestinal parasites are acquired through ingestion of food. Due to lack of information on parasite biodiversity of P. sulphuratus, this work was developed aimed to characterize and disseminate the helminthofauna and nasal mites that parasites the Great Kiskadee, and to calculate the parameters of prevalence, average intensity and average abundance of parasitism. Were examined 78 specimens of P. sulphuratus belonging to the municipality of Pelotas and adjacent municipalities, among those who came to death at the Center for Wildlife Rehabilitation Center and Triage of Wild Animals (NURFS / CETAS / UFPel) and were run over, collected on the highways. At the Laboratory of Parasitology of Wild Animals, Department of Microbiology and Parasitology, birds were necropsied to collect helminths and nasal mites. Helminths found and their parameters of prevalence (P), average abundance (AM) and average intensity (IM) were Dispharynx nasuta (P = 3.85%, AM = 0.10, IM = 2.66), Acuaria Mayor (P = 7 , 69%, AM = 0.18, IM = 2.33), representatives of the subfamily Capillariinae (P = 10.26%, AM = 0.22, IM = 2.12), Eucoleus sp. (P = 10.26%, AM = 0.38, IM = 3.75), Aproctella sp. (P = 6.41%, AM = 0.08, MI = 1.2), Syngamus sp. (P = 7.69%, AM = 0.26, IM = 3.33), Lophosicyadiplostomum nephrocystis (P = 14.10%, AM = 3.18, MI = 22.54), Lutztrema sp. (P = 3.85%, AM = 0.08, IM = 2), Echinostoma sp. (P = 2.56%, AM = 0.15, IM = 6), Centrorhyncus spp. (P = 48.72%, AM = 3.87, IM = 7.95), and representatives of the order Ciclophyllidae (Cestoda) (P = 2.56%). The nasal mites Ptilonyssus spinosus were found with 12.82% prevalence, AM = 1.13, IM = 8.8, sex ratio 4:2, ♀ / ♂ and Sternostoma longisetosae, 5.13%, 0.13 and 2.5, respectively, all specimens were females. A parasitic association between the two species was observed in only one P. sulphuratus. Pitangus sulphuratus features a new host for helminths Dispharynx nasuta, Acuaria mayor, Capillariinae, Eucoleus sp. Aproctella sp. Syngamus sp. (Nematoda), Lutztrema sp. and Echinostoma sp. (Trematoda). That expands the area of occurrence of A. Mayor and L. nephrocystis for the state of Rio Grande do Sul. / O bem-te-vi, Pitangus sulphuratus (Linnaeus, 1766) (Tyrannidae), ocorre apenas nas Américas, distribui-se dos Estados Unidos (Texas) até a Argentina. É a espécie de pássaro mais popular do Brasil e do Rio Grande do Sul (RS), sendo facilmente reconhecido pelo seu canto onomatopéico, sua coloração viva e comportamento agressivo na disputa de território e guarda do ninho. Estas aves podem ser encontrados em uma ampla variedade de habitats, como campos de culturas, cidades, pomares, orla de matas e em ambientes aquáticos, tais como margens de lagoas, córregos, rios e represas. Apresentam habilidades para identificar alimentos em ambientes naturais e em explorar recursos alimentares de origem antrópica, o que contribui para sua eficiência em colonizar ambientes urbanos e sua abundância em vários ambientes. O bem-te-vi é consideradauma espécie onívora, e sua flexibilidade alimentar pode influenciar na sua helmintofauna, uma vez que a maioria dos parasitos gastrointestinais é adquirida através da ingestão de alimentos. Devido a escassez de informações sobre a biodiversidade parasitária de P. sulphuratus, desenvolveu-se este trabalho com o objetivo de conhecer a helmintofauna e ácaros nasais parasitos do bem-te-vi, bem como determinar os parâmetros de prevalência, abundância média e intensidade média de parasitismo. Foram examinados 78 espécimes de P. sulphuratus provenientes de municípios do RS, dos quais alguns vieram ao óbito no Núcleo de Reabilitação da Fauna Silvestre e Centro de Triagem de Animais Silvestres (NURFS/CETAS/UFPel) e outros recolhidos mortos por atropelamento nas rodovias. No Laboratório de Parasitologia de Animais Silvestres, Departamento de Microbiologia e Parasitologia, Instituto de Biologia, Universidade Federal de Pelotas, as aves foram necropsiadas para coleta de helmintos e ácaros nasais. Os helmintos encontrados e respectivos parâmetros de prevalência (P), abundância média (AM) e intensidade média (IM) foram: Dispharynx nasuta (P= 3,85%, AM=0,10, IM=2,66), Acuaria mayori (P= 7,69%, AM=0,18, IM=2,33),representantes da subfamília Capillariinae (P= 10,26%, AM=0,22, IM=2,12), Eucoleus sp. (P= 10,26%, AM=0,38, IM=3,75), Aproctella sp. (P= 6,41%, AM=0,08, IM=1,2), Syngamus sp. (P= 7,69%, AM=0,26, IM= 3,33), Lophosicyadiplostomum nephrocystis (P= 14,10%, AM=3,18, IM=22,54), Lutztrema sp. (P= 3,85%, AM=0,08, IM=2), Echinostoma sp. (P= 2,56%, AM=0,15, IM=6), Centrorhyncus spp. (P= 48,72%, AM=3,87, IM=7,95) e representantes da ordem Cyclophyllidea (P= 2,56%). Os ácaros nasais encontrados foram Ptilonyssus spinosus com 12,82% de prevalência, AM=1,13, IM=8,8, razão sexual 4:2, ♀/♂ e Sternostoma longisetosae, 5,13%, 0,13 e 2,5, respectivamente, todos os exemplares eram fêmeas. A associação parasitária entre essas duas espécies de ácaros foi observada em apenas uma ave. Este achado caracteriza o primeiro relato de P. spinosus e S. longisetosae em P. sulphuratus e amplia a distribuição geográfica destas espécies, sendo a primeira ocorrência de S. longisetosae na região neotropical e primeira citação de P. spinosus no Rio Grande do Sul, Brasil. Pitangus sulphuratus caracteriza um novo hospedeiro para os helmintos Dispharynx nasuta, Acuaria mayori, Capillariinae, Eucoleus sp., Aproctella sp., Syngamus sp. (Nematoda), Lutztrema sp. e Echinostoma sp. (Trematoda). Amplia-se a área de conhecimento de ocorrência de A. mayori, e L. nephrocystis para o estado do Rio Grande do Sul.

The aim of this project was to study the population genetics of Echinostoma trivolvis, a parasitic trematode that uses multiple hosts in its lifecycle and has a significant impact on amphibian populations. Microsatellite markers were to be identified and isolated because of their highly variable nature and reported ease of use with PCR. Parasite DNA was extracted from planorbid snails from several locations within California including: Point Reyes National Seashore, Lake Tahoe, and the San Francisco Bay Area. In addition, parasite samples were obtained from Manitoba, Canada. Several microsatellites were identified and 29 PCR primers sets were designed, six of which were capable of amplifying consistently. Sequencing other published molecular markers, COl, NDl, and ITS, unveiled intriguing phylogenetic relationships and potential cryptic species. The echinostome population in central California, as a result of this project, may be much more diverse than has long been reported in the literature.

Studies on trematodes of marine organisms of the Pacific Coast have been of a scattered and fragmentary nature. J. Stafford (1904) collected and described a number of trematodes from fishes of the north Pacific, but, in his historical survey, Manter (1926) fails to mention specifically any studies covering the waters south of Canada. More recently, in the United States, several contributions to the field have been made by Dr. John E. Guberlet at the University of Washington and at the College of the Pacific by Dr. Alden Noble, under whose guidance this study was made. James Park (1937) revised the genus Podocotyle and added eight new species .from Dillon Beach, California. Descriptions of individual trematodes have been made by various other investigators. The investigation covered by this paper was begun during the summer or 1946 at the Pacific Marine Station.