[The population and genetic relationships in the bream-Digramma interrupta system (pl.) (Cestoda: Ligulidae)]

It was established that host individuals, characterized by a high stability of development, play the main part in the functioning of bream-D. interrupta system. Heterozygous breams turned out to be more stable to the effect of pleurocercoids than homozygous ones. Genetically determined characters of bream infection with pleurocercoids of D. interrupta have been revealed. Mechanism of population genetic relationships in this parasitic system is discussed.