RAPD EVIDENCE FOR THE ORIGIN OF CRAYFISH PLAGUE OUTBREAKS IN BRITAIN

Two isolates of Aphanomyces astaci obtained from diseased white-clawed crayfish (Austropotamobius pallipes) in Herefordshire, England were c ompared against representative isolates of three groups of the fungus found in Sweden and one from Spain by means of random amplification of polymorphic DNA (RAPD). The English isolates proved to be very simila r to a Swedish strain which is considered to have been introduced from North America with shipments of the signal crayfish (Pacifastacus len iusculus) from 1970 onwards, and has since spread to indigenous popula tions of noble crayfish (Astacus astacus). This strain has not been fo und to be involved in recent incidences of crayfish plague in Turkey a nd Spain. It is therefore most likely that at least some of the outbre aks of crayfish prague in England resulted from imports of P. leniuscu lus from northern Europe after 1970, or directly from North America. ( C) 1997 Elsevier Science B.V.