Impact of a rhabditid nematode on survival and fecundity of Cernuella virgata (Mollusca : Helicidae)

Pairs and single adults of the terrestrial snail Cernuella virgata were exp osed to various densities of the rhabditid isolate R954 during breeding exp eriments in the laboratory. Fecundity and viability of C, virgata breeding in nematode-free and in nematode-infested soil was compared Exposure to R95 4 significantly reduced the number of eggs produced by C. virgata and the s urvival of adult snails. Differences in nematode densities (50, 100 and 150 nematodes cm(-2)) had no effect on egg production or mail survival. Snail eggs laid during the breeding experiments were fertile and young hatched af ter 2-3 weeks. R954 was not able to penetrate eggs of C. virgata but nemato des,were observed inside the hatchings and caused high mortality.