Distribution of ligulid tapeworms in China.

A survey of ligulid tapeworms carried out from 1979 through 1985 covered 29 provinces and autonomous regions in China. Of the 25,800 fishes of 219 species that were dissected, fishes of 43 species were found to serve as second intermediate hosts. These tapeworms inflict heavy losses on freshwater commercial fisheries. Their distribution indicates 3 distinct major zones: the Qing Zang Gaoyuan is dominated by Ligula; the rest of China, with the exception of a crescent area in Guangdong Province bordering part of the southern coast down to Hainan Island, is dominated by Digramma; and a saddle-shaped corridor, north of 42 degrees N latitude, is characterized by a mix of both genera. Schizothoracinae are the primary hosts for Ligula, of which only Gymnocypris przewalskii przewalskii (Kessler) has economic value. Digramma is predominant in Carassius auratus auratus L. in reservoirs and lakes of 3 main water systems, Heilongjiang, Huang He (the Yellow River), and Chang Jiang (the Yangtze River), and in cultured cyprinids along the lower section of Huang He as well as in bodies of water on the Loess Plateau. Generic validity of ligulids and host specificity, their infection and periodicity, and control methods are discussed.