Influence of substrate on reproduction of Subulina octona (Bruguiere)(Mollusca, Subulinidae), under laboratorial conditions

The influence of substrate on reproduction of Subulina octona (Bruguiere,1789), reared in sand, clay and humus, was investigated under laboratorial conditions. There were significant differences in onset of sexual maturity, egg production, shell length and aging in each reproductive event, total number of eggs produced and total number of reproductive events. The individuals reared in humus spent more time to reach sexual maturity, as well as to accomplish the subsequent reproductive events. Moreover, produced fewer eggs in the second, third and fourth ovipositions and exhibited a longer interval between the first and second reproductive events. After 120 days of experiment such individuals had produced fewer eggs, and performed fewer reproductive events, when compared with those kept in sand and clay. There was a progressive decline in egg number increase with time. In this study was also observed that S. octona of different developmental stages fed on substrate and the molluscs reared in humus consumed less food. This is probably due to the fact that humus is more likely tobe take as food resource. So that, the snails reared in humus tend to consumemore substrate and less ration, obtaining less proteins, carbohydrates and calcium than those snails reared in sand and clay. This low intake of ration might have negative effects over reproduction of the snails.