THE ORIGIN OF 2 CRAYFISH PLAGUE (APHANOMYCES-ASTACI) EPIZOOTICS IN FINLAND ON NOBLE CRAYFISH, ASTACUS-ASTACUS

A fungus identified as Aphanomyces astaci was isolated from two crayfi sh plague epizootics among noble crayfish, Astacus astacus, in Central Finland. The isolated fungal strains from Vaikkojoki, Kaavi and Iso-S uojarvi, Saarijarvi were able to kill healthy A. astacus crayfish in a quarium experiments and the fungus could be reisolated from the diseas ed animals. The genomic DNA of the isolated strains were characterized by applying a polymerase chain amplification technique with arbitrari ly primed DNA. One strain was identical, i.e, showed an identical DNA band pattern, with an A. astaci strain earlier isolated from signal cr ayfish, Pacifastacus leniusculus. The latter strain has been the cause of several crayfish plague outbreaks in Sweden. These data suggest th at the introduction of North American crayfish into Finland has result ed in the transmission of the disease to populations of the native cra yfish, A. astacus.