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UNLABELLED BACKGROUND Success of trophically transmitted parasites depends to a great extent on their ability to manipulate their intermediate hosts in a way that makes them easier prey for target hosts. Parasite-induced behavioural changes are the most spectacular and diverse examples of manipulation. Most of the studies have been focused on individual(More)
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(More)
In the production of the infective cercariae of trematodes, the terminal investment hypothesis of life-history theory predicts that the rate of host exploitation and cercarial production should increase during the period of cercarial shedding since the reproductive value of the parasite decreases during this period. In contrast, a bet hedging hypothesis(More)
By sampling individual rainbow trout, Oncorhynchus mykiss, at a fish farm we showed that Argulus coregoni were aggregated within their host population. The relative significance of susceptibility and exposure generating the observed pattern was tested using experimental infections. We examined, whether rainbow trout developed protective resistance(More)
The transmission dynamics of the cercariae of Diplostomum spathaceum were investigated under laboratory conditions using cercariae collected from naturally infected Lymnaea stagnalis. Cercariae were kept in a constant temperature of 20 degrees C and the survival and infectivity to naïve young rainbow trout recorded at 3-h intervals until few cercariae were(More)
In laboratory experiments the swimming behaviour of the ectoparasite Argulus foliaceus and its infection rates on juvenile perch (Perca fluviatilis) and roach (Rutilus rutilus) were examined. The highest infection rate and a preference for perch juveniles were obtained in darkness, the lowest infection rate and a lack of preference in the light, when(More)
Argulus foliaceus, an obligate fish ectoparasite, can search for its hosts in both light and dark conditions and uses vision in the light. We have examined what searching mode is used at night, when the infection rate was at its highest, and which stimuli produced by the fish are most important. A change of illumination produced a clear difference in the(More)
A precision measurement by AMS of the positron fraction in primary cosmic rays in the energy range from 0.5 to 500 GeV based on 10.9 million positron and electron events is presented. This measurement extends the energy range of our previous observation and increases its precision. The new results show, for the first time, that above ∼200  GeV the positron(More)
When FRTL-5 cell cytosol was incubated with increasing amounts of [3H]1,25-dihydroxy-vitamin D3 [( 3H]1,25-(OH)2D3), saturation of specific hormone binding occurred. Scatchard analysis of specific binding of [3H]1,25-(OH)2D3 to the macromolecule yielded an apparent Kd value of 0.41 +/- 0.08 X 10(-10) M and a single maximum binding capacity of 42.8 +/- 8.8(More)
In benthic habitats, predators can generally not be detected visually, so olfaction may be particularly important for inducing anti-predation behaviors in prey organisms. Manipulative parasites infecting benthic hosts could suppress these responses so as to increase the probability of predation and thus trophic transmission. We studied how infection with(More)