Size-dependent growth and fecundity variations of three land snails: implications for population management

ABSTRACT Size class dependent variations of growth and fecundity of three small land snails, Allopeas gracile (Hutton 1834) (Gastropoda: Subulinidae), Succinea daucina (Pfeiffer, 1855) (Gastropoda: Succineidae) and Glessula gemma (Reeve 1850) (Gastropoda: Subulinidae) were assessed in the laboratory condition. The field collected snails were segregated according to the size (shell length, in mm), and the frequency distribution of each size class was estimated. Subsequently, each size class was reared in the laboratory with continuous monitoring for the deposition of the eggs in the rearing terrarium for a period of six weeks using three replicates per size class. The growth rate of each species was highest in the smallest size class and declined gradually with the increment of shell length. The shell lengths of A. gracile and S. daucina at sexual maturity were 4–5 mm and 6–7 mm, respectively, and fecundity was positively linked with the size (shell length). G. gemma did not oviposit, except that the large size-class had given few small offspring. The results showed that growth and reproduction of three species varied significantly with size classes, which reflects the ability for these snails to colonize and establish in favourable habitats in short time period.