EFFECT OF A COMMERCIAL FUNGICIDE ON THE VIABILITY AND PHAGOCYTOSIS OF HEMOCYTES OF THE AMERICAN OYSTER, CRASSOSTREA-VIRGINICA

A commercial fungicide containing triforine as the active ingredient was tested for its effects on the viability of hemocytes of the American oyster, Crassostrea virginica. The test was conducted by measuring the cells' ability to intracellularly hydrolyze the vital stain, fluorescein diacetate. The phagocytic activity of these cells as affected by the fungicide was also measured. The results were compared with the effects of cytochalasin B, a known inhibitor of phagocytosis, and with iodoacetamide, an inhibitor of glycolysis. Both cell viability and bead phagocytosis were reduced to approximately 50% of control levels within a dose range of 0.0295 to 1.966 μg of fungicide/ml of hemolymph. Iodoacetamide showed a direct dose-related reduction in viable cell fluorescence down to zero viability confirming the validity of the fluorescein diacetate test. Cytochalasin B inhibited phagocytosis but not vital staining. The data show that the fungicide significantly reduces the number of viable hemocytes and, as a consequence, may reduce the efficacy of the animal's defense mechanism against invasion of the tissue by foreign particulates. © 1991.