Predation and prey preference of the land snail Gulella bicolor - implication for land snail regulation

Abstract

The predation and the prey preference of the land snail Gulella bicolor (Hutton, 1834) (Gastropda: Streptaxidae) against coexisting land snails, Allopeas gracile (Hutton, 1834 (Gastropoda: Achatinidae), Succinea daucina (L. Pfeiffer, 1854) (Gastropoda: Succineidae) and Glessula gemma (Reeve, 1850) (Gastropoda: Achatinidae) were evaluated. The prey size class, prey density and predator density were considered as the explanatory variable to evaluate the predation pattern and the prey selectivity of G. bicolor. For snail species A. gracile and S. daucina, the predation pattern varied significantly as a function of prey size classes, prey density and predator density but not for G. gemma. The prey selectivity suggested that for selected size classes, the preference was inclined towards A. gracile, when G. gemma or S. daucina were present as alternative prey. However, when S. daucina and G. gemma were present together, the significant preference was observed. As a consequence, the potential apparent competition web (PAC) of the interactions of the predatory snail G. bicolour and the prey snails, A. gracile, G. gemma and S. daucina was calculated. Although, the predatory snail G. bicolour can be promoted as a biocontrol agent, the successful regulation may vary with the size and density of the prey snails and the extent of the PAC.