A comparative study on the food-locating ability of Helisoma duryi, Biomphalaria camerunensis and Bulinus truncatus (Pulmonata: Planorbidae).

Published online
06 Mar 1993
Content type
Journal article
Journal title
Journal of Applied Ecology

Madsen, H.

Publication language


Helisoma duryi has been suggested as a biological control agent against the snail intermediate hosts of schistosomes, Biomphalaria and Bulinus species. It has been demonstrated that competition for food resources is involved. The accumulation of groups of Helisoma duryi, Biomphalaria camerunensis and Bulinus truncatus on varying amounts of 2 different artificial food preparations and the movement of individual snails of these 3 species when approaching a food source (by analysing their tracks) were compared. There were slight differences in the ability of H. duryi and Biomphalaria camerunensis to locate food preparations, but both were superior to Bulinus truncatus. The 2 types of food preparations differed markedly in their attraction of B. truncatus. H. duryi was less attracted to the food preparations with the 2 lowest amounts of food of both types than to preparations with larger amounts of food, while this was not observed for Biomphalaria camerunensis and Bulinus truncatus. Medium-sized H. duryi were superior to small and large snails in their ability to locate food, while no significant differences were found among 3 size groups of B. truncatus. Analysis of snail tracks did not reveal an increased frequency of turning in any of the 3 species as the food source was approached. The reason for the higher accumulation of H. duryi and B. camerunensis on the food could in part be explained by their higher activity level. Other explanations are also discussed.

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