ABSTRACT: The protozoan parasite Bonamia ostreae (Pichot et al., 1980) is a serious pathogen of the native European flat oyster Ostrea edulis. Field and laboratory based experiments were carried out in Ireland and Spain to investigate the susceptibility to this protozoan of the Pacific oyster Crassostrea gigas, the mussels Mytilus edulis and Mytilus galloprovincialis, the European native clam Ruditapes decussatus and the Manila clam Ruditapes philippinarum. Their ability to act as vectors or intermediate hosts was also investigated. The study corroborated previous findings that demonstrated that flat oysters can be successfully infected both naturally in the field and experimentally in the laboratory, and the pathogen can be transmitted directly between flat oysters in the laboratory. However, the other bivalves tested could not be infected with the parasite either naturally or experimentally, and these bivalves did not appear to act as vectors or intermediate hosts for the parasite. These results have implications for movements of bivalves between areas within the European Union.

KEY WORDS: Bonamia ostreae · Bonamiasis · Ostrea edulis · Crassostrea gigas · Mytilus edulis · Mytilus galloprovincialis · Ruditapes decussatus · Ruditapes philippinarum · Transmission experiments · European Union directives

Published in DAO Vol. 37, No. 1 (1999) on June 23
ISSN: 0177-5103. Copyright © Inter-Research, Oldendorf/Luhe, 1999