Effect of Crowding, Food quality and Body Size on Food Utilization of the Exotic Snail, Pomacea canaliculata (Lamarck), a Potential Pest of Rice in Sri Lanka
P.A.D. AJITH KUMARA, W.U. CHANDRASEKARA and H.H. COSTA
Pomacea canaliculata (Family; Ampullaridae) is an exotic freshwater snail introduced to Sri Lanka as an ornamental commodity. Although P. canaliculata is a potential rice pest, its food preference and energy budget under Sri Lankan conditions are not known. In order to assess the above, the snails were fed with three commonly found fresh water weed species, i.e Salvinia molesta, Azolla sp. and Hydrilla verticellata, and their energy budget (i e feeding rate, absorption rate, food conversion rate, metabolic rate, absorption efficiency and conversion efficiency) was investigated in relation to the body size and crowding.
The snails preferred to consume H. verticellata, the rooted aquatic weed, than the other two species which were floating. Young snails showed the highest energy budget while the old snails showed the lowest. Simillarly, the energy budget of the snails in less crowded aquaria was higher than in the highly crowded aquaria.
Considering the morphology of H. verticellata which is the highly preferred food by Pomacea, the present preliminary study urges the importance of conducting further investigations to assess the potential of this snail to infest rice cultivation in Sri Lanka as it has become a major pest of rice in many countries in the south-east Asian region.