Production of juveniles of the freshwater, egg-laying lymnaeid snail Radix plicatula as prey for the juveniles of Whitman leech (Whitmania pigra)

The leech Whitmania pigra is well known in traditional Chinese medicine for promoting human blood circulation and alleviating blood stasis. To evaluate the suitability as bait for this neonate leech, we investigate the reproductive efficiency of the snail Radix plicatula under laboratory conditions. Furthermore, the effects of the size of R. plicatula on the growth of newborn W. pigra were evaluated. Wild snails laid eggs in mid-March with body weight >0.223 g and peaked at the beginning of April to early May. The accumulated number of eggs was 1489.70 +/- 895.98 and 2145.67 +/- 694.47 separately for individual and paired snails (P = 0.083). The time elapsed up to the hatching of the first egg in the four collected egg masses ranged from 12 to 18 days, and the hatching percentage ranged from 97.14% to 100.00% . The predation rate of the newborn W. pigra was significantly higher when feeding on small snails than on medium and large snails (P < 0.01). Furthermore, increased snail size resulted in decreased leech growth and survival rates. The investigations demonstrated that R. plicatula snail could serve as a suitable living bait in the rearing of W. pigra to help alleviate the leech scarcity in the market.