PSOROSPERMIUM-HAECKELI AND ITS INTERACTION WITH THE CRAYFISH DEFENSE SYSTEM

The crayfish parasite Psorospermium haeckeli was found to degranulate the semigranular cells of the crayfish Pacifastacus leniusculus and Astacus astacus in vitro. The total haemocyte count in crayfish was also affected by injections of P. haeckeli. It was also found that P. leniusculus, carrying latent benign infections of the crayfish plague fungus Aphanomyces astaci, died as a result of crayfish plague when injected with P. haeckeli. Healthy A. astacus survived the same treatment, although the blood cells of both crayfish species were equally affected by the presence of this parasite. These data show that P. leniusculus carrying the crayfish plague fungus will be unable to cope with the additional parasitic loads and die as a result of injections with P. haeckeli.