Effects of larval Digenea on the free amino acid pool of Littorina littorea (L.)

Abstract

Quantitative chromatographic analysis of the free amino acids of the head–foot muscle of uninfected and infected Littorina littorea indicates that there is specific variation in the physiological effects of parasitism. The total concentration of free amino acids in the host head–foot muscle showed an increase of 10·9% with infections of Cryptocotyle lingua rediae, a decrease of 12·7% with infections of Himasthla leptosoma rediae and a decrease of 57·5% with infections of Cercaria emasculans sporocysts. These effects probably depend on three main factors namely, the nature, size and mobility of the larvae of the three species concerned and the influence of these factors in determining the extent of any damage to the hepatopancreas of the host.The larvae of C. lingua are probably less affected by the changes they induce in the free amino acid pool of the host than the larvae of H. leptosoma and Cercaria emasculans which induce changes equivalent to starvation.This work was conducted during the tenure of a Science Research Council Studentship. I would like to thank Professor B. John and Mr A. R. Hockley for their helpful advice and criticism.