516 resultados para Parasitism.
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Oligoplites palometa (Cuvier) and Oligoplites saurus (Bloch & Schneider) (Osteichthyes: Carangidae) are coastal pelagic fish species. The objective of this study was to investigate the effect of parasitism by isopods and the reproductive biology of the leather jack, Oligoplites spp. A total of 113 individuals of Oligoplites spp (35 of O. saurus and 78 of O. palometa) were captured during the period between January, 2005 and July, 2007 from the coastal waters of Natal, RN. The morphometric and meristic characters were registered; macroscopic analyses were done to collect the isopod parasites and the gonads were observed to verify the reproductive aspects. The crustacean isopod parasite, Cymothoa spinipalpa (Isopoda: Cymothidae) was encountered on the tongue in the oral cavity in both fish hosts. The parasitic indices of C. spinipalpa showed high values of prevalance of 51,4% for O. saurus and 64,1% for O. palometa. The host presented significant correlations between body mass and body length of O. palometa and the number of parasites. Body lengths of female C. spinipalpa were small due to the limited space available in the oral cavity of the host. There was a significant difference in the sex ratio of O. palometa, males outnumbered the females. The isopod parasites showed specificity to the oral cavity of hosts. Macroscopic analyses of gonads showed four stages of gonadal development for both sex of O. palometa: immature, maturing, mature and spent
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Historically, ever since the pre-Darwinian naturalists interspecific competition was considered the main force responsible for structuring ecological communities. This interpretation lost strength in the late 70s and throughout the 80s giving room for other views, which consider other factors such as predation, parasitism and the phylogenetic inertia more important. Studies on changes in the trophic niche of a species are still uncommon in general and especially in amphibians. Species considered generalist might actually be a group of individual specialists, or individuals that specialize in a particular category of prey during a period of scarcity of resources, thus reducing intraspecific competition. This work studied the community structure of litter amphibians and trophic variation along the dry and rainy seasons in a population of Leptodactylus macrosternum. Sixteen-litter frog species were studied for their diet. Two central assumptions were tested: 1a) if the community is structured in the niche trophic level, and 1b) if there is a significant difference in the use of food resources by different species (i.e. if the community is structured), the observed structure is the result of ecological interactions or just the current phylogenetic inertia of species. Finally, 2) if there is variation in food resource use between seasons for L. macrosternum. The community showed a structure with respect to the use of food resources, and this structure persisted after taking into account the phylogenetic relationships among species. The diet of Leptodactylus macrosternum varied with the seasons, with a significant degree of individual specialization for the dry season. Patterns of a local community are important to understand its dynamics, and this may play a role in larger- scale processes. Therefore, the studies in community ecology are fundamental to understand and eventually restoring degraded areas
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Few studies have been performed with parasites of marine and estuarine fish in southern Brazil. In the present study, unpublished results show the ways of parasitism of juvenile mullet by parasites. The toxicity of formaldehyde and the effectiveness of this chemotherapy in controlling parasites in reared juvenile mullet Mugil liza were also studied. Juvenile mullets (1 +/- 0.26 g; 4.1 +/- 0.4 cm) were exposed to different concentrations of 37% formaldehyde: control group and five formaldehyde concentrations which were tested: T1 (13.5), T2 (21.6), T3 (40.5), T4 (81) and T5 (135) mg L-1 with 8 fish per repetition in triplicate. To verify the drug effectiveness in parasitic control, juvenile mullets were exposed to 1 h prophylactic bath of 37% formaldehyde with a control group and five formaldehyde concentrations: T1 (67.5), T2 (135), T3 (270), T4 (405) and T5 (540) mg L-1, 8 fish per repetition in triplicate. Ligophorus cf. uruguayensis (Monogenoidea: Ancyrocephalidae) and Solostamenides cf. platyorchis (Monogenoidea: Microcotylidae) were identified in the gills. Digenea and Nematoda were observed in the intestines. This is the first occurrence of S. cf. platyorchis in Brazil. During the toxicity test, the LC50-96 h was estimated at 20.77 mg L-1 of formaldehyde. During the 1 h formaldehyde prophylactic bath, all parasites were eliminated in formaldehyde concentrations between 135 and 540 mg L-1. High survival rate was observed in all treatments. Values of prevalence and intensity of infestation observed in this study showed the potential damage caused by Monogenoidea to mullet. Formaldehyde baths with 135 mg L-1 are recommended to control Monogenoidea in mullet and the safe limits for formaldehyde use were presented. Besides, the endoparasites were tolerant to formaldehyde exposure. (C) 2012 Elsevier B.V. All rights reserved.
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The effects of parasitic infections in condition factor, hematocrit, hemoglobin, mean corpuscular hemoglobin concentration (MCHC), and leucocytes and thrombocytes distribution in Piaractus mesopotamicus, Leporinus macrocephalus, hybrid tambacu (P. mesopotamicus x Colossoma macropomum and Brycon amazonicus collected in feefishing from Franca, São Paulo, Brazil were evaluated. Parasitized tambacu and L. macrocephalus had higher (p<0.05) condition factor than unparasitized fish. However, the contrary occurred in P. mesopotamicus and B. amazonicus. Changes in the hematocrit, hemoglobin and MCHC were not related to parasitism. Parasitic infections did not cause effect on leucocytes and thrombocytes percentage (p>0.05) of tambacu. In P. mesopotamicus parasitized by Monogenea Anacanthorus penilabiatus and dinoflagellate Piscinoodinium pillulare, increase in monocytes and decrease in thrombocytes percentage (p<0.05) were found. However, the same parasitic association in L. macrocephalus caused a decrease in lymphocytes percentage accompanied by increase in neutrophils percentage (p<0.05). In B. amazonicus, infection by Ichthyophthirius multifiliis, P. pillulare and monogeneans caused increase in neutrophils percentage.
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The influence of temperatures on the life parameters of the solitary oothecal parasitoid Evania appendigaster, was investigated in the laboratory. Parasitized oothecae of Periplaneta americana were left to develop under seven constant temperatures: 15, 17, 20, 25, 30, 35, and 40 degrees C. At the end, we found that: (i) E. appendigaster was able to complete development within the temperature range of 17-34 degrees C; (ii) mean adult longevity decreased as temperature increased, with the temperature of 40 degrees C being fatal in a matter of hours; (iii) males lived longer than females between 15 and 30 degrees C; (iv) adult emergence rate was the highest at 25 degrees C, and (v) no wasps emerged at 15 or 40 degrees C. Non-emerged oothecae contained either unhatched eggs or dead larvae. We determined the theoretical lower developmental threshold and thermal constant for the complete development as 12.9 degrees C and 584.8 day-degrees for males, and 13.1 degrees C and 588.2 day-degrees for females, respectively. A good balance between faster development, maximum adult longevity and good egg viability was obtained between 25-30 degrees C, and that would be the best temperature range for rearing E. appendigaster. (C) 2009 Elsevier B.V. All rights reserved.
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The preferential sites of infection of Cysticercus bovis were evaluated in the skeletal muscle and entrails of 25 cattle that were experimentally infected with Taenia saginata (2 x 10(4) eggs). Two other animals were not inoculated (control). Ninety days after inoculation, all the cattle were euthanized. The carcasses were deboned and dissected into 26 anatomical sections (masseter muscles, brain, tongue, esophagus, heart, diaphragm, lungs, liver, kidneys, spleen, top sirloin butt, bottom sirloin butt, outside round, top (inside) round, transversus abdominus, top sirloin cap, strip loin, full tenderloin, eye of round, knuckle, shoulder clod, foreshank, shank, chuck, back ribs, and tail muscles). The dissected tissues were sliced into 5 mm sections. From the 25 cattle, 9258 C. bovis (cysticerci) were recovered; 75.02% (6946) of these were recovered from skeletal muscles and 24.98% (2312) from the entrails. A high parasitism level was found in the shoulder clod (12.55%), heart (11.02%), liver (9.48%), masseter muscles (8.51%), chuck (8.25%), strip loin and full tenderloin (7.26%), knuckle (6.63%), and back ribs (5.53%), totaling 69.23% (5738) of all of the detected cysticerci. on the other hand, there was a low C. bovis parasitism level in the brain, spleen, tail muscles, kidneys, esophagus, and diaphragm, representing just 3.9% of the total number of cysticerci. Given these results, we conclude that specific skeletal musculature regions, such as the shoulder blade, chuck, strip loin and full tenderloin, knuckle, back ribs and top round, which are not officially examined in many countries, are effective sites to efficiently screen C. bovis infection. To date, these regions have not been considered as preferential sites of C. bovis infection. Based on our work, however, these regions deserve greater attention from health inspectors because they contained a greater number of Cysticercus than the other regions of carcasses that are parasitized by T. saginata larvae. (c) 2010 Elsevier Ltd. All rights reserved.
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Descrevem-se os achados clínico, cirúrgico e anatomopatológico de intussuscepção em quatro bovinos fêmeas. Observaram-se intussuscepção do jejuno, com obstrução total, em três animais, e intussuscepção do cólon, com obstrução parcial, em um animal. A presença de parasitismo intenso por Oesophagostomum sp. em dois animais sugere a participação desse parasita na gênese da intussuscepção.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fertility life tables were developed for both Trichogramma pretiosum and Trichogramma acacioi reared on Sitotroga cerealella eggs as an alternative host at five different temperatures. The egg parasitoids were first collected from Nipteria panacea eggs, a lepidopterous pest of avocado. Egg parasitoid females were individualized in small glass vials along with 40 eggs of the host during 24 h for parasitization. For evaluation of the parasitism capacity, a similar procedure was adopted, but cardboards with eggs were replaced every day. The net reproductive rate (Ro), intrinsic rate of increase (rm), finite rate of increase (lambda), and mean generation time (T) were estimated. Temperature affected all parameters for both Trichogramma species. The highest fecundity for both species was observed at 25degreesC. Extreme temperatures such as 15degreesC or 35degreesC negatively affect the development rate of both species.
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Este trabalho teve como objetivo estudar a biologia de Telenomus remus Nixon criado em ovos de Spodoptera frugiperda (J.E. Smith) em diferentes temperaturas. Com base no desenvolvimento do ciclo (ovo-adulto), foram determinados as exigências térmicas e o número de gerações dos parasitóides em temperaturas constantes. Inicialmente, ovos de S. frugiperda, com 24 horas de idade, foram submetidos ao parasitismo por T. remus, durante cinco horas, sendo então transferidos para câmaras climatizadas reguladas para as temperaturas de 15, 20, 25, 28, 31 e 35°C. A duração do ciclo (ovo-adulto) foi influenciada pela temperatura variando de 8,3±0,01 a 47,2±0,01 dias para fêmeas e 8,1±0,01 a 46,8±0,01 dias para machos de T. remus nas temperaturas de 31 e 15°C, respectivamente. A porcentagem de emergência (viabilidade) de T. remus em ovos de S. frugiperda também foi influenciada pela variação da temperatura, apresentando redução significativa apenas nas temperaturas extremas. Foi observada redução na viabilidade a 15°C e não houve desenvolvimento biológico do parasitóide a 35°C. A razão sexual de T. remus não sofreu influência da temperatura. em relação às exigências térmicas, a constante térmica (K) e temperatura base (Tb) foram maiores para as fêmeas de T. remus (158,88 graus dias e 12,52°C) quando comparadas aos machos (154,12 graus dias e 12,59°C). A estimativa do número de gerações anuais para T. remus para machos e fêmeas em condições de laboratório foi respectivamente 5,6 e 5,6; 16,9 e 17,3; 28,3 e 29,0; 35,1 e 36,0; 39,6 e 40,7 nas temperaturas de 15, 20, 25, 28 e 31°C.
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Avaliou-se a resistência de genótipos de batata aos afídeos Myzus persicae (Sulz.), Macrosiphum euphorbiae (Thomas) e Aphis gossypii (Glover), e a influência desses genótipos sobre parasitóides, em dois ensaios em plantios de inverno (1996 e 1997), em condições de campo, em Jaboticabal, SP. Os genótipos plantados no primeiro ano foram: Achat, Baronesa, Bintje, BR-2, Contenda, Monalisa, N 140-201 e NYL 235-4, distribuídos em quatro blocos ao acaso. Dois levantamentos foram efetuados, aos 70 e 85 dias após o plantio, avaliando-se o número de pulgões/folha e pulgões parasitados, nos terços superior, médio e inferior da planta. em 1997 plantaram-se os mesmos genótipos, excetuando-se o N 140-201, com levantamentos aos 72 e 80 dias. O genótipo NYL 235-4 mostrou-se suscetível a M. euphorbiae, sob infestações médias de 2,90 (1996) e 1,19 pulgões/folha (1997); dentre as cultivares comerciais, Baronesa foi a menos atacada por M. persicae (0,12 e 0,10 pulgões/folha em 1996 e 1997), enquanto BR-2 foi bem suscetível (1,10 e 0,66 pulgões/folha). Os afídeos ocorreram em maior população nas partes média e inferior das plantas; maior número de pulgões mumificados por Aphidius ervi Hal. e Diaretiella rapae (McIntosh), com parasitismo variando de 15 a 36%, foi observado em NYL 235-4, que foi o genótipo mais infestado pelos afídeos.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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A competição intraespecífica e a ausência de hospedeiros podem comprometer o sucesso de programas de controle biológico. Assim, este trabalho objetivou avaliar o efeito de diferentes densidades de fêmeas (1, 3, 6 e 9 fêmeas/ 100 ovos) e da ausência de hospedeiro no parasitismo de Telenomus remus Nixon (Hymenoptera, Scelionidae) em ovos de Spodoptera frugiperda (J. E. Smith) (Lepidoptera, Noctuidae). Observou-se aumento no parasitismo de ovos de S. frugiperda por T. remus a partir da densidade 3 fêmeas/ 100 ovos tanto em condições de laboratório (18%) quanto em campo (32%), embora o parasitismo causado por densidades maiores que 1 fêmea/100 ovos não foi significativamente diferente. Todavia, isso não causou superparasitismo. Por outro lado, o número de fêmeas produzidas na progênie diminuiu (39%) com a maior densidade de fêmeas sob condições de laboratório. Contudo, não verificou-se diferença significativa sob condições de campo. Mesmo após 9 dias de ausência de hospedeiro não houve redução nos índices de parasitismo, permanecendo em torno de 95 ovos parasitados/fêmea/dia. Todavia, no décimo dia pode-se observar redução (40%) no número médio de ovos parasitados. Desse modo, a liberação de três fêmeas por 100 ovos é adequada para se obter elevados níveis de parasitismo.