ABSTRACT
Abstract This study evaluated the parasite fauna of farmed hybrid surubim (Pseudoplatystoma reticulatum x P. corruscans) and the host-parasite-environment relationship in two fish farms located in Mato Grosso do Sul, Central Brazil, South America. A total of 120 hybrids from two different farms, 60 in each season (30 in the hot and 30 in cold season) were examined during a year. Water quality was weekly measured to evaluate the interaction among environmental conditions and parasitism. Histopathology was used to observe the effects of the parasites and environment on the fish gills. The ciliate protozoan Ichthyophthirius multifiliis and the monogeneans (Ameloblastella sp., Amphocleithrium paraguayensis, Vancleaveus ciccinus, V. fungulus and V. janacauensis) were the most prevalent parasites detected in both seasons in both farms, with prevalence above 80%. It was stated that parasites did not cause important damage in the health status of the hybrid surubim. These results might be related to general good management practices and environmental quality implemented by the fish farmers. The presence of uncommon monogenean parasites to this hybrid compared to their parents causing an environmental and ecological concern is here discussed.
Resumo Este estudo avaliou a fauna de parasitos do surubim híbrido cultivado (Pseudoplatystoma reticulatum x P. corruscans) e a relação hospedeiro-parasito-ambiente em duas pisciculturas localizadas no Estado do Mato Grosso do Sul, região Centro-Oeste, Brasil. Um total de 120 híbridos de duas fazendas, 60 em cada estação (30 na estação quente e 30 na fria), foram examinados durante um ano. A qualidade da água foi medida semanalmente para avaliar a interação entre as condições ambientais e o parasitismo. Histopatologia foi usada para observar os efeitos dos parasitos e do ambiente nas brânquias dos peixes. O protozoário ciliado Ichthyophthirius multifiliis e Monogenea (Ameloblastella sp., Amphocleithrium paraguayensis, Vancleaveus ciccinus, V. fungulus e V. janacauensis) foram os parasitos mais prevalentes detectados em ambas estações nas duas fazendas, com prevalências acima de 80%. Observou-se que os parasitos não causaram danos ao estado de saúde do surubim híbrido. Esses resultados estão relacionados às boas práticas de manejo e qualidade ambiental implementada pelos produtores. É discutida a presença incomum de Monogenea para esse híbrido, comparado com seus progenitores, podendo causar preocupação ambiental e ecológica.
Subject(s)
Animals , Trematoda , Trematode Infections/veterinary , Catfishes/parasitology , Chimera/parasitology , Fish Diseases/parasitology , Trematode Infections/parasitology , BrazilABSTRACT
Molecular techniques can aid in the classification of Biomphalaria species because morphological differentiation between these species is difficult. Previous studies using phylogeny, morphological and molecular taxonomy showed that some populations studied were Biomphalaria cousini instead of Biomphalaria amazonica. Three different molecular profiles were observed that enabled the separation of B. amazonica from B. cousini. The third profile showed an association between the two and suggested the possibility of hybrids between them. Therefore, the aim of this work was to investigate the hybridism between B. cousini and B. amazonica and to verify if the hybrids are susceptible to Schistosoma mansoni. Crosses using the albinism factor as a genetic marker were performed, with pigmented B. cousini and albino B. amazonica snails identified by polymerase chain reaction-restriction fragment length polymorphism. This procedure was conducted using B. cousini and B. amazonica of the type locality accordingly to Paraense, 1966. In addition, susceptibility studies were performed using snails obtained from the crosses (hybrids) and three S. mansoni strains (LE, SJ, AL). The crosses between B. amazonica and B. cousini confirmed the occurrence of hybrids. Moreover, hybrids can be considered potential hosts of S. mansoni because they are susceptible to LE, SJ and AL strains (4.4 percent, 5.6 percent and 2.2 percent, respectively). These results indicate that there is a risk of introducing schistosomiasis mansoni into new areas.