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 As tacus astacus in vitro. The total haemocyte count in crayfish was also affected by injections of P. haeckeli. It was also found that P. leni usculus, carrying latent benign infections of the crayfish plague fung us Aphanomyces astaci, died as a result of crayfish plague when inject ed with P. haeckeli. Healthy A. astacus survived the same treatment, a lthough 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 a dditional parasitic loads and die as a result of injections with P. ha eckeli.