RESUMO
Seals (Phocidae) undergo an annual cycle of moulting that implies hair regeneration, and in the case of southern elephant seals, it also involves the superficial strata of the epidermis. Therefore, surviving the moulting period is crucial for their obligate and permanent ectoparasites. Throughout evolutionary time, sucking lice (Echinophtiriidae) have developed morphological, behavioural and ecological adaptations to cope with the amphibious lifestyle of their hosts. Lepidophthirus macrorhini, the Southern elephant seal louse species, faces the additional challenge of surviving attached to the host during the moulting period. Since lice live on the skin, L. macrorhini has developed a unique survival strategy by piercing the skin of their host, thus keeping them protected from moulting. During fieldwork in Patagonia and Antarctica, skin samples with lice within were collected for histological analysis to assess whether these parasites caused damage to the host. Lice generate an inflammatory process in the host's dermis, and these lesions could alter the normal chemical and mechanical protective properties of the skin facilitating secondary infections. Further studies that analyse the potential pathogens in those skin lesions are necessary to properly assess the real impact of ectoparasites on their host health.
Assuntos
Anoplura , Focas Verdadeiras , Animais , Muda , Focas Verdadeiras/parasitologia , Focas Verdadeiras/fisiologia , PeleRESUMO
Lice from family Echinophthiriidae are of the few insects that have successfully colonized marine environment living as ectoparasites of pinnipeds, i.e., sea lions, seals, and the walrus. They have developed unique adaptations to cope with the amphibious lifestyle of their hosts. Because eggs do not survive underwater, lice could only reproduce when their host remains on pack ice enough time. Consequently, lice generations per year are limited by host haul-out behavior. The objective of this work is to study the effect of host sex and age class, and the annual variation on the prevalence and mean abundance of Antarctophthirus lobodontis in crabeater seals from the Antarctic Peninsula. During three consecutive field-seasons, we collected lice from 41 crabeater seals (23 females, 16 males, 2 indeterminate, being 24 adults, and 17 juveniles). We investigated this effect on the prevalence and mean abundance by a generalized linear model formulation in a Bayesian framework. According to the lowest Deviance Index Criterion model, sex host does not affect prevalence nor mean abundance. We found that juveniles present greater abundance and prevalence than adults, possibly due to foraging habits. They spent more time on the ice than adults in groups of dozens of animals. This behavior would favor both egg development and lice transmission. We do not find adult females with lice, which suggests that transmission of A. lobodontis should be horizontal. The high mean abundance of lice in 2014 could be associated with an unusual increase in Lobodon carcinophaga population, probably related to the pack-ice availability and zooplankton abundance.
Assuntos
Anoplura/patogenicidade , Infestações por Piolhos/epidemiologia , Infestações por Piolhos/transmissão , Leões-Marinhos/parasitologia , Focas Verdadeiras/parasitologia , Morsas/parasitologia , Aclimatação , Animais , Regiões Antárticas , Teorema de Bayes , Feminino , Camada de Gelo , Masculino , Estações do Ano , Fatores SexuaisRESUMO
Genetic and morphological studies were carried out on acanthocephalans belonging to Corynosoma Lühe, 1904 and referable to the species C. cetaceum Johnston & Best, 1942 and C. australe Johnston, 1937, which were recovered from both definitive and intermediate hosts in Argentinian waters. The aims were to estimate the level of genetic differentiation between the two taxa at any stage of their life-cycle, to provide genetic (allozyme) markers for their recognition and to analyse the systematic status of both taxa. Acanthocephalans were collected from the stomach and intestine of Arctocephalus australis (Zimmerman), the intestine of Mirounga leonina (Linnaeus) and the stomach of Pontoporia blainvillei Gervais & D'Orbigny (definitive hosts) in Argentinian waters. Alternative alleles at all the 13 enzymatic loci studied were observed for C. australe and C. cetaceum. The specimens from the stomach of both P. blainvillei and A. australis were identified, on the basis of the great number of diagnostic loci found, as C. cetaceum; those from intestine of both A. australis and M. leonina as C. australe. A high level of genetic differentiation (D(Nei)=infinity: I(Nei)=0.00) between the two taxa was found, suggesting a generic distinction between the two species. Cystacanths of the two species from the body-cavity of the fish Cynoscion guatucupa (Cuvier) collected from the same geographical area were identified genetically. Morphological patterns, such as the number of hooks and hook rows on the proboscis, the distribution of somatic and genital armature, and other morphometric and meristic differences, in addition to ecological data, enabled the identification of these two species at cystacanth, juvenile and adult stages. However, a number of morphological and morphometric features of the Argentinian material were different to those of C. australe and C. cetaceum described from other regions of the world.
Assuntos
Acantocéfalos/anatomia & histologia , Acantocéfalos/classificação , Cetáceos/parasitologia , Peixes/parasitologia , Otárias/parasitologia , Focas Verdadeiras/parasitologia , Acantocéfalos/genética , Animais , Argentina , Especificidade da EspécieRESUMO
The ultrastructure of Proechinophthirus zumpti Werneck, 1955, mainly the external chorionic features of the egg, is described through electronic microscopy techniques. This species was first cited in Argentina, infesting Arctocephalus australis (Zimmermann, 1873). The morphological adaptations of adults and nymphs are described in both species of Proechinophthirus parasitic on Otariidae: P. fluctus (Ferris, 1916) and P. zumpti.
Assuntos
Anoplura/ultraestrutura , Focas Verdadeiras/parasitologia , Animais , Anoplura/classificação , Feminino , Masculino , Microscopia Eletrônica de Varredura/métodosRESUMO
We found significant morphometric and electrophoretic differences between sealworm larvae collected from four sympatric fish host species off the central coast of Chile. The South American sea lion, Otaria byronia, is a suitable host and most likely the only definitive host species in the study area. Morphological patterns of caudal papillae in adult males collected from sea lions and electrophoretic evidence from larvae and adults substantiate our conclusion that they belong to just one, new species yet to be described. The genetic and morphometric differences found between sealworm larvae from sympatric fish hosts may be due to selective pressures arising from the internal environment of the intermediate hosts, although they may serve only for passing sequential filters along the life cycle. The discussion deals with the roles that definitive and intermediate hosts may play in the micro-evolutionary processes of sealworms.
Assuntos
Anisakis/classificação , Evolução Biológica , Proteínas de Helminto/genética , Isoenzimas/genética , Focas Verdadeiras/parasitologia , Animais , Anisaquíase/parasitologia , Anisaquíase/veterinária , Anisakis/anatomia & histologia , Anisakis/enzimologia , Doenças dos Peixes/parasitologia , Variação Genética , Masculino , Oceano PacíficoRESUMO
Con el propósito de estudiar la fauna helmintológica de los lobos finos de Juan Fernández (Arctocephalus philippii) habitantes de la Isla de Alejandro Selkirk, Archipiélago de Juan Fernández, se analizaron 300 muestras de excrementos y se realizaron 37 necropsias (17 adultos y 20 crías) a animales encontrados muertos por causas naturales. Los resultados de los exámenes coprológicos por flotación y/o sedimentación, indicaron la presencia de huevos de Uncinaria hamiltoni, Ogmogster heptalineatus y Diphyllobothrium sp., con prevalencias de un 2 por ciento , 22 por ciento y 23,3 por ciento respectivamente. Los resultados de las necropsias a animales adultos, permitieron evidenciar la presencia de los parásitos Phocanema decipiens, Corynosoma sp., Ogmogster heptalineatus y Diphyllobotrium sp. por porcentajes de infección de un 5,8, 52,9, 58,8 y 82,3 por ciento respectivamente. De las crías necropsiadas sólo se recuperó el nemátodo Uncinaria hamiltoni con u 30 por ciento de infección. No se encontró este parásito en los intestinos de los lobos finos adultos. No se encontraron parásitos en el tejido subcutáneo, órganos ni cavidades.