Natural experiment to test the relevance of ribbing in Chinese Oncomelania (rissoacea: pomatiopsidae): relevance to schistosme transmission

Schistosomiasis in the People's Republic of China: Prospects and Challenges for the 21st Century

“…Molecular data (mitochondrial cytochrome oxidase I [COI] sequences and allozymes) (41,43,44,192) and detailed anatomical data are congruent; the classification (Table 1) of relevant snails transmitting schistosomes in Asia is thus supported. It is noteworthy that no members of the family Hydrobiidae, sometimes misused in China and elsewhere to classify Oncomelania and related taxa, exist in China.…”

“…All non-Chinese Oncomelania have smooth shells. In the same river system, where downstream populations are affected by flooding and upstream populations are not, the ribbed-shelled and smooth-shelled snails are not significantly different genetically (43 Two of the largest lakes in China are Poyang Lake (the largest) and Dongting Lake. Both are major areas of endemicity for S. japonicum but differ significantly with regard to schistosome transmission.…”

“…If the environment is too wet, O. hupensis will not live there. Flooding is used as a control measure in some areas of China, as flooding drowns adult snails (43,44).…”

“…Oncomelania can live over 5 years, and a female, once fertilized, can lay eggs throughout her lifetime (43,44). Finally, Oncomelania can bury deep into the soil and estivate when the temperature becomes too cold and when the environment experiences a drought.…”

“…With the subsidence of flooding, snails are deposited in aggregates that are not natural populations. We have called such genetically unstable aggregates unstable populations (43,44). Researchers in Hubei have used nets to assess the influx of snails into the canal systems when the flood gates are opened to let Yangtze River water flow in for agricultural use (210,211,213).…”