Cellular inflammatory response of Penaeus aztecus and P. setiferus to the pathogenic fungus, Fusarium sp., isolated from the California brown shrimp, P. californiensis

Host response of two penaeid species, Penaeus aztecus and P. setiferus, from the Gulf of Mexico to the pathogenic fungus Fusarium sp. isolated from the California brown shrimp, P. californiensis, was studied in vivo. The hemocytic response to this fungus was traced histologically in the gills. Both species showed complete resistance to infection by the fungal spores when normal or wounded shrimp were held in seawater containing the spores or when spores were injected directly into the shrimp in low concentrations. Complete melanization and encapsulation of the micro- and macroconidia were observed. Spore dosages of 3.2 × 10⁶ or more were lethal, apparently due to mechanical blockage of the blood sinuses of the gills.