Effect of Perkinsus qugwadi on various species and strains of scallops.
Japanese scallops (Patinopecten yessoensis), introduced into British Columbia, Canada, as a species for aquaculture, proved highly susceptible to P. qugwadi (initially called SPX). Sporadic occurrence of the parasite among cultured scallops sometimes resulted in losses exceeding 90%. Native scallops (Chlamys rubida and Chlamys hastata) were resistant to infection and the pathogenic effects of the parasite. Laboratory and field studies showed that first-generation progeny of Japanese scallops that survived an epidemic outbreak of P. qugwadi had a significant increase in resistance to infection and resulting mortalities. Hybrid scallops, resulting from a cross between Japanese scallop females (from the same group of scallops that survived an epidemic outbreak of P. qugwadi) and weathervane scallop (Patinopecten caurinus) males, had similar resistance to P. qugwadi. The identification of scallop stocks that are resistant to P. qugwadi has facilitated the development of a scallop culture industry in British Columbia.