Studies on parasitic castration: Aminopeptidase activity levels and protein concentrations in Ilyanassa obsoleta (mollusca) parasitized by larval trematodes

Specimens of the estuarine prosobranch Ilyanassa obsoleta collected in the vicinity of Charleston, South Carolina, during June, July, and August 1981, were found to be parasitized by larvae of the digeneans Cercaria dipterocerca, Himasthla quissetensis, Lepocreadium setiferoides, Microbilharzia variglandis, Microphalloides nassicola, Stephanostomum tenue, and Zoogonus lasius. The aminopeptidase activity levels and the total protein concentrations of the hemocytes and sera of these infected snails were determined. It was ascertained that snails parasitized by larvae of L. setiferoides had significantly higher levels of hemocytic aminopeptidase activity and hemocytic total protein concentrations than noninfected snails. Furthermore, snails parasitized by L. setiferoides larvae had significantly higher hemocytic levels of aminopeptidase activity than snails parasitized by larvae of S. tenue, Z. lasius, M. nassicola, and H. quissetensis.