Maintenance of Schistocephalus solidus in the Laboratory with Observations on Rate of Growth of, and Proglottid Formation in, the Plerocercoid

Abstract

Procedures for the maintenance of Schistocephalus solidus in the laboratory are described: recovery of eggs from low bulk faeces; incubation and hatching of eggs at 25 C; and infection of Cyclops agilis, Diaptomus gracilis, and Mesocyclops leuckarti with procercoids that at 25 C become infective in 10, 8, and 8 days, respectively. Methods for infecting Gasterosteus aculeatus with specific numbers of plerocercoids, and procedures for maintaining infected sticklebacks, are described. The rate of growth of S. solidus in G. aculeatus at 19 C has been determined up to day 83, by which time plerocercoids are infective and weigh 50 mg fresh weight. The problem of speciation in Schistocephalus is discussed with reference to the conflicting evidence concerning the number of proglottids in the plerocercoid. Statistical evidence shows the number of proglottids increases slowly during growth contrary to previous statements, and ontogenesis is discussed with reference to metamerism. Problems of growth of Schistocephalus in the fish host are enumerated.