Natural Infections of Cyclopid Copepods with Procercoids of Triaenophorus spp.

Sampling of the littoral and open water plankton from the spring of 1953 to 1959 established Cyclops bicuspidatus thomasi Forbes as the first intermediate host of Triaenophorus spp. in Heming Lake, Manitoba. Infection was apparently confined to a brood of Cyclops hatched in early May and maturing in mid July. The most heavily infected Cyclops were collected in the inshore areas. Inspection of a series of standard tows showed evidence of nonrandom distribution of infection, probably representing a clumping of the cyclopids. Implications of the uneven distribution for establishing infection rates, adequate sampling programs, and survival of the parasite are discussed.