Reproduction, growth and circadian activity of the snail Bradybaena fruticum (O. F. Muller, 1774) (Gastropoda: Pulmonata: Bradybaenidae) in the laboratory

摘要

Selected life cycle parameters of the snail Bradybaena fruticum were studied in the laboratory. The initial material for the laboratory culture was taken from a population in South Western Poland; the snails were kept in Petri dishes and plastic containers. The temperature, humidity and lighting conditions were maintained at a constant level (day 18A degrees C, night 12A degrees C, rh 80%, light:dark 12:12). Circadian activity observations were conducted outside the climatic chamber. Eggs - calcified, slightly oval, of mean dimensions 2.67x2.56 mm - were laid singly or in batches of 6-62, as a result of both biparental and uniparental reproduction. Incubation took 27-76 days and hatching was asynchronous. Hatching success was lower among eggs produced by single parents compared to eggs produced by two parents (c.a. 56 and c.a. 88%, respectively). Growth included fast (2.25 to 5 whorls) and slow (1.9-2.25 and > 5 whorls) phases as well as lip formation, and took 261 to 420 days. The first eggs/batches were laid c.a. one year later, and for uniparentally reproducing snails the period was even longer. The growth of snails kept singly was faster than in those kept in groups. Juvenile snails were much more active than adults in the spring, summer and autumn but the adults were more mobile in the winter. In all seasons, juveniles were more active at night than adults.