Carlos Vieites

Discrete observations of the spatial distributions of the Helix aspersa snail in an outdoor system

O. Gonzalez, G. Perez Camargo, M. Membiela, D. Frezza, N. Bartoloni, and C. Vieites. 2009. Discrete observations of the Helix aspersa land snails’ spatial distribution in an outdoor system. Cien. Inv. Agr. 36(1):123-130. In this study, adult Helix apersa land snails with previously established periodicity were observed at three densities in their fi nishing stage in order to contribute to the body of knowledge about spatial distribution and certain behavior patterns in an outdoor system. From November 8 to December 18, 2006, snails that were in their fi nal fattening phase were grouped at three densities (50 snailm ², 100 snailm ², 200 snailm ²) and randomly placed in nine cubicles, with three replicates of each density. Twelve observations of the snail behavior were made between 12 am and 1 pm. The categories selected as “discrete acts” include: observing the snails in the shelters, on Swiss chard leaves (Beta vulgaris), adhered to the netting, on the balanced feed, on the water supply tray, and on the ground. A statistical analysis employing marginal and partial frequency tests was completed on the density x category x time interactions. It was concluded that around midday, the majority of the snails remained in the artifi cial shelters and on the Swiss chard monoculture leaves. In addition, differences were not detected for the rest of the categories in regard to the spatial distribution of the individuals in the three densities analyzed. If lower densities than the ones most commonly employed in studies (200 snailm ²) are used in an open outdoor system in the fattening stage, the individuals will use the available space in a similar way, thereby exhibiting similar behavior patterns.