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Variations in Infections of Diplostomum flexicaudum (Cort and Brooks, 1928) in Snail Intermediate Hosts of Different Sizes

1957; American Society of Parasitologists; Volume: 43; Issue: 2 Linguagem: Inglês

10.2307/3274654

1937-2345

William W. Cort, Kathleen L. Hussey, D. J. Ameel,

Aquatic Invertebrate Ecology and Behavior

Diplostomum flexicaudun (Cort and Brooks, 1928) is by far the commonest trematode species in the snails of the Douglas Lake region of northern Michigan. Its cercaria was described by Cort and Brooks (1928) and its life cycle was worked out experimentally by van Haitsma (1931). The metacercaria was described by Hughes and Berkhaut (1929) as Diplostomulum gigas from the lens of the eyes of the common sucker, Catostomus commersonnii. The adult is a parasite in the small intestine of the herring gull, Larus argentatus. The cercaria of this species is very common in the beach snails, Stagnicola emarginata angulata (Sowerby) and S. e. canadensis (Sowerby). It has also been found in the Douglas Lake region in Lymnaea stagnalis appressa Say, L. s. perampla Walker, Stagnicola exilis (Lea), Stagnicola palustris elodes (Say) and Fossaria abrussa (Say). Since its snail hosts vary so greatly in size, D. flexicaudum is ideal for the study of the adaptation of a trematode species to intermediate hosts of different sizes. The cercariae of this species are very characteristic in structure and behavior, and there is not the slightest evidence that we have been dealing in this study with more than one species or with varieties of a species. Measurements of cercariae did not show size differences related to the size of the intermediate hosts. The slight variations that we found in the different lots, which were measured, appeared to be due to differences in the killing procedures, since some lots from a large host were slightly smaller than others from much smaller ones.