[SEASONAL CHANGES IN THE BIOLOGY OF LEUCOCHLORIDIUM PARADOXUM (TREMATODA, LEUCOCHLORIDIOMORPHIDAE)].

Infection of molluscs Succinea putris by trematodes Leucochloridium paradoxum was studied in the region of Vyritsa (Leningrad Province) during the period of 2008-2014. On the basis of the obtained data, seasonal dynamics of infection of molluscs can be presented as follows. Infection of S. putris occurs during the whole warm period from May to August. Young sporocysts of L. paradoxum overwinter and the metacercariae that develop in their extensions mature during spring becoming infective for birds. In the second half of summer, sporocysts start degenerating and die in late August-September. Each sporocyst can form 2-3 mature broodsacs (maximum 5) simultaneously. In cases of multiple infections, their number can reach 19. Several cases of independent release of sporocysts from molluscs were observed. They survive in environment for about an hour, retaining the ability to infect definitive hosts. Additionally, birds can be infected by pecking of horns of infected snails.