Crayfish plague; Aphanomyces astaci; oomycete; mass mortalit; Czech Republic; molecular diagnosis; PCR; Orconectes limosus; Astacus astacus

In recent years, mass mortalities of Astacus spp. with symptoms of possible crayfish plague were noticed in three streams in the country, two in Central Bohemia (1998-9) and one in Silesia (2004). The pathogen, Aphanomyces astaci, was confirmed by a PCR-based diagnostic method. The indirect evidence of mass mortalities from two other localities supports the same conclusion. The main potential vector of A. astaci in Czechia is the American spiny-cheeck crayfish Orconectes limosus. We investigated the presence of A. astaci in living O. limosus individuals from six localities (three running and three standing waters). The analysis indicated the presence of the pathogen in animals from 5 out of 6 populations. Our results suggest that the crayfish plague is still present in Czechia, and that populations of O. limosus represent a reservoir for the crayfish plague pathogen, which directly endangers populations of the native crayfish

In recent years, mass mortalities of Astacus spp. with symptoms of possible crayfish plague were noticed in three streams in the country ? two in Central Bohemia (1998-9) and one in Silesia (2004). The pathogen, Aphanomyces astaci, was confirmed by a PCR-based diagnostic method. The indirect evidence of mass mortalities from two other localities supports the same conclusion. The main potential vector of A. astaci in Czechia is the American spiny-cheeck crayfish Orconectes limosus. We investigated the presence of A. astaci in living O. limosus individuals from six localities (three running and three standing waters). The analysis indicated the presence of the pathogen in animals from 5 out of 6 populations. Our results suggest that the crayfish plague is still present in Czechia, and that populations of O. limosus represent a reservoir for the crayfish plague pathogen, which directly endangers populations of the native crayfish