Effects of various larval digeneans on the calcium carbonate content of the shells of Helisoma trivolvis, Biomphalaria glabrata, and Physa sp.

Abstract

The calcium carbonate concentrations in the shells of Helisoma trivolvis and Physa sp. naturally infected with larval trematodes and Biomphalaria glabrata experimentally infected with larval trematodes were analyzed quantitatively. The larval trematode-snail relationships studied were H. trivolvis infected with larval Echinostoma trivolvis and Physa sp. infected with various larval digeneans, and B. glabrata infected with Echinostoma caproni or Schistosoma mansoni. The calcium carbonate concentrations of the shells of infected snails and uninfected cohorts and of the water in which the snails were maintained were determined by ion exchange chromatography. No significant differences in the calcium carbonate concentrations of shells of infected versus uninfected snails were found. The shells of B. glabrata infected with E. caproni contained significantly less calcium carbonate than the shells of uninfected B. glabrata. The hypercalcification hypothesis, i.e., larval trematodes induce an increase in the calcium concentrations in the shells of their snail hosts, was not upheld in any of the snail-larval digenean systems studied herein.

Effects of Schistosoma mansoni and Schistosoma haematobium infections on calcium content in their intermediate hosts

“…This observation was correlated with that of White et al (2005) who mentioned that, under conditions of variable Ca concentrations in the water and trematode parasitism, pulmonate snails are able to maintain a high concentration of CaCo 3 in their shells.…”

“…In contrast, hypercalcification in the shells of snails infected with trematodes was 1969). The present findings are like the results of Zbikowska (2003) and White et al (2005), although they have not validated the hypothesis of hypercalcification of snail shells induced by parasites. The cercariae sequester large amounts of calcium in their pre-acetabular glands, and such sequestration probably occurs at the expense of calcium in the shell and hemolymph of the snail (Davies and Erasmus 1984).…”

“…Hypocalcification observed in the shells of cercariae shedding B. alexandrina and B. truncatus snails in the present study was correlated with the observation of White et al (2005) on their study on the effect of Echinostoma trivolvis, E. capproni, and S. mansoni on Heliosoma trivolvis, B. glabrata, and Physa sp. They reported that the hypercalcification hypothesis was not upheld in any of the snail-larval digenean system studied.…”

“…Moreover, the effects of larval trematodes on the metallic ion concentrations in freshwater snails were observed in several snail-larval trematode models (Layman et al 1996;Kirichuk et al 2002;Zbikowska 2003;Ong et al 2004;White et al 2005). The changes in metallic ion concentrations as a result of larval parasitism in the snails reflect alterations in ionic balance and an influx of certain ions as well as outflux of other ions from the larval trematodes to the snail hosts (Layman et al 1996).…”

Studies of echinostomes using chromatography and atomic spectrometry.

“…White et al (2005) used ion exchange HPLC to determine that the calcium carbonate content of the shells of B. glabrata infected with E. caproni was significantly lower than in the shells of uninfected B. glabrata . This result, and others with H. trivolvis , Physa sp., and Schistosoma mansoni , disproved the popular hypercalcification thesis, i.e., that larval trematodes induce an increase in the calcium concentrations in shells of their snail hosts.…”