Study on reproductive ability and growth traits of the Whitmania pigra Whitman

Abstract:

The Whitmania pigra Whitman has been used as a traditional Chinese medicine in cardiovascular diseases and other chronic diseases for centuries. Over the last few decades, however, overfishing and environmental pollution have caused dramatic declines in natural stocks of Whitmania pigra, and its production is low and unstable. An analysis of the reproductive ability and growth traits of the Whitmania pigra is valuable for its artificial farming. In the present study, the reproductive ability and growth traits for the wild leech were studied in the laboratory. A total of 50 wild individuals of Whitmania pigra with clitellum were kept in 50 plastic boxes full of wet soil, as a result, a set of 44 individuals (12.91±5.21 g) laid cocoons. The range of cocoons produced by every parent leech was from 1 to 4, and the mean number of cocoons was 2.45±0.88, and the lost weight of leeches was 52.38%±9.57%. However, the mean number of cocoons (2.80±0.79 per leech) produced by the parent leeches over 10.00 g was higher than the mean number of cocoons (1.71±0.62 per leech) produced by the leeches below 10.00 g. The average weight and the long diameter of the oval cocoon were (0.8735±0.3784)g and (2.2027±0.4936)cm, respectively. The hatching number of cocoons were between 1 to 59 and the mean number was 27.61±10.81. According to the number of cocoons and hatchings for each leech, the hatching numbers were 27 to 137 with 65.25±34.91 hatching per leech. The weight of juvenile leech increased from (0.0209±0.0028) g to (0.2981±0.0905) g after 21 days in laboratory conditions. The R_GR was higher in the beginning, then it increased with water temperature, and the R_GR was the highest when the water temperature was 26.00℃. Our results provide basic information for reproductive ability and growth traits of the Whitmania pigra Whitman.