Trematode Diplostomum pseudospathaceum (Diplostomidae) Larvae Penetrate the Underyearlings of Oncorhynchus mykiss (Salmonidae) and Manipulate Their Behavior

Experiments with underyearlings of Oncorhynchus mykiss and cercariae of the trematode Diplostomum pseudospathaceum show that the first parasites that infect the fish have an excitatory influence on it and triple the rate of cercaria income with water through the oral cavity and gills. This effect is considered as manipulation of fish behavior at the stage of parasite transmission from the first intermediate host (mollusk) to the second (fish) one. Experimental data on the effect of fish odor on locomotor activity and the vertical distribution of cercariae have been obtained. Analysis of the data made it possible to determine a set of conditions that ensure the successful infection of fish by diplostomum larvae.