Infection of terrestial snails with larvae of Elaphostrongylus cervi (Nematoda, Protostrongylidae) in Białowieża National Park

Species composition of intermediate hosts of Elaphostrongylus cervi — terrestrial snails, prevalence and intensity of their infection in natural invasions have been determined. The intermediate hosts of E. cervi are Succinea putris, Bradybena fruticum, Perforatella bidentata and Zonitoides nitidus. From June to August the percentage of snails S. putris infected with E. cervi larvae has been on constant level and in September and October decreased. Snails B. fruticum the highest prevalence of invasion showed on July and later it successively lowered. In the case of P. bidentata prevalence of E. cervi infection was the lowest in August, and than raised up to the highest value in October. For the first time the highest extensiveness of spontaneous infection has been found in P. bidentata. Till now as the most infected species of snail always has been noted S. putris. The highest intensity of infection — 242 larvae was found in B. fruticum, and little lower 73- 202 in S. putris. In two other species intensiveness ranged from 1 to 23 larvae. The most important role in spreading of E. cervi in Białowieża Forest fulfil S. putris and B. fruticum because of their high number in environment and P. bidens because of the highest intensiveness of infection.