Search results for "Diplostomum"

QUALITATIVE AND QUANTITATIVE BEHAVIORAL TRAITS IN A COMMUNITY OF FURCOCERCARIAE TREMATODES: TOOLS FOR SPECIES SEPARATION?

2008

Many trematode cercariae show distinct behavioral features, which have commonly been used in species identification in combination with morphological characteristics. However, information regarding cercariae behavior has often not been quantified in detail, or it is scattered in the literature, which is why the appropriate level of precision in behavioral identity, particularly in groups of cercariae species showing considerable morphological overlap, has not been properly established. In this study, we investigated one such group, the furcocercariae trematodes, by studying their behavior in a community consisting of 8 species (Diplostomum pseudospathaceum, Ichthyocotylurus variegatus, Coty…

Reciprocal interaction matrix reveals complex genetic and dose-dependent specificity among coinfecting parasites

2012

Understanding genetic specificity in factors determining the outcome of host-parasite interactions is especially important as it contributes to parasite epidemiology, virulence, and maintenance of genetic variation. Such specificity, however, is still generally poorly understood. We examined genetic specificity in interactions among coinfecting parasites. In natural populations, individual hosts are often simultaneously infected by multiple parasite species and genotypes that interact. Such interactions could maintain genetic variation in parasite populations if they are genetically specific so that the relative fitness of parasite genotypes varies across host individuals depending on (1) t…

Interactions among bacterial strains and fluke genotypes shape virulence of co-infection.

2015

Most studies of virulence of infection focus on pairwise host–parasite interactions. However, hosts are almost universally co-infected by several parasite strains and/or genotypes of the same or different species. While theory predicts that co-infection favours more virulent parasite genotypes through intensified competition for host resources, knowledge of the effects of genotype by genotype (G × G) interactions between unrelated parasite species on virulence of co-infection is limited. Here, we tested such a relationship by challenging rainbow trout with replicated bacterial strains and fluke genotypes both singly and in all possible pairwise combinations. We found that virulence (host mo…

Increased ventilation by fish leads to a higher risk of parasitism

2014

Background: Fish are common intermediate hosts of trematode cercariae and their gills can potentially serve as important sites of penetration by these larval stages. We experimentally tested the hypothesis that volume of ventilation flow across the gills contributes to acquisition of these parasites by fish. We manipulated the intensity of ventilation by using different oxygen concentrations. Methods: Juvenile Oncorhynchus mykiss were individually exposed for 10 minutes to a standard dose of Diplostomum pseudospathaceum cercariae at three levels of oxygen concentration, 30, 60 and 90%. Ventilation amplitude (measured as a distance between left and right operculum), operculum beat rate, and …

Kuhan (Sander lucioperca) soveltuvuus kolmen imumatoloislajin väli-isännäksi: alttius infektiolle ja loisten vaikutus kalan käyttäytymiseen

2008

Grouping facilitates avoidance of parasites by fish

2013

Background. Parasite distribution is often highly heterogeneous, and intensity of infection depends, among other things, on how well hosts can avoid areas with a high concentration of parasites. We studied the role of fish behaviour in avoiding microhabitats with a high infection risk using Oncorhynchus mykiss and cercariae of Diplostomum pseudospathaceum as a model. Spatial distribution of parasites in experimental tanks was highly heterogeneous. We hypothesized that fish in groups are better at recognizing a parasitized area and avoiding it than solitary fish. Methods. Number of fish, either solitary or in groups of 5, was recorded in different compartments of a shuttle tank where fish co…

Interactions among co-infecting parasite species: a mechanism maintaining genetic variation in parasites?

2008

Individuals of free-living organisms are often infected simultaneously by a community of parasites. If the co-infecting parasites interact, then this can add significantly to the diversity of host genotype×parasite genotype interactions. However, interactions between parasite species are usually not examined considering potential variation in interactions between different strain combinations of co-infecting parasites. Here, we examined the importance of interactions between strains of fish eye flukes Diplostomum spathaceum and Diplostomum gasterostei on their infectivity in naive fish hosts. We assessed the infection success of strains of both species in single-strain exposures and in co-…

Molecular and morphological evidence for three species of Diplostomum (Digenea: Diplostomidae), parasites of fishes and fish-eating birds in Spain

2014

Background Recent molecular studies have revealed high species diversity of Diplostomum in central and northern Europe. However, our knowledge of the distribution of Diplostomum spp. in the southern distributional range in Europe of the snail intermediate hosts (Lymnaea stagnalis and Radix spp.) is rather limited. This study aims to fill this gap in our knowledge using molecular and morphological evidence. Methods Nineteen fish species and six fish-eating bird species were sampled opportunistically in three regions (Catalonia, Extremadura and Aragon) in Spain. All isolates of Diplostomum spp. were characterised morphologically and molecularly. Partial sequences of the barcode region of the …

Maternal effects in vulnerability to eye-parasites and correlations between behavior and parasitism in juvenile Arctic charr

2017

Hatchery-reared fish show high mortalities after release to the wild environment. Explanations for this include potentially predetermined genetics, behavioral, and physiological acclimation to fish farm environments, and increased vulnerability to predation and parasitism in the wild. We studied vulnerability to Diplostomum spp. parasites (load of eye flukes in the lenses), immune defense (relative spleen size) and antipredator behaviors (approaches toward predator odor, freezing, and swimming activity) in hatchery-reared juvenile Arctic charr (Salvelinus alpinus) using a nested mating design. Fish were exposed to eye-fluke larvae via the incoming water at the hatchery. Fish size was positi…

Evidence of enhanced bacterial invasion during Diplostomum spathaceum infection in European grayling, Thymallus thymallus (L.)

2006

Farmed grayling, Thymallus thymallus (L.), are susceptible to atypical Aeromonas salmonicida (aAS) infections. Interactions between bacteria and parasites were studied using grayling subjected to concomitant exposure to aAS bacteria and the digenean parasite Diplostomum spathaceum. Atypical AS was detected from fish by a combination of bacterial cultivation and polymerase chain reaction techniques. A detection level of 17 aAS cells per 100 mg intestine tissue sample was obtained. Concomitant bacterial exposure did not enhance the severity of grayling eye rupture and nuclear extrusion induced by D. spathaceum, but D. spathaceum invasion into grayling increased the proportion of fish carrying…