EFFECT OF WATER PLANTS AND NON-TARGET SNAILS ON THE INFECTIVITY OF BULINUS TRUNCATUS WITH SCHISTOSOMA HAEMATOBIUM

摘要

The application of the water plant (Ceratophyllum demersum, Eichhornia crassipes and Lemna gibba) and/or non-target snails (Planorbis planorbis, Physa acuta and Melanoides tubercidatd) gave a significant degree of reduction in the infection rate of B.tmncatus subjected to S. haematobium miracidia. The data also indicated a reduction in mean total number of cer-carial production/snail. However, no significant difference was detected in the prepatent period and duration of cercarial shedding of the parasite when compared with the control group. So, the results revealed that the snails exhibited a competitive ability against B. tmncatus. Both survival rate and egg production of B. tnmcatus were greatly reduced when existed in mixed cultures with non-target snails and the magnitude of this reduction increased by increasing the number of the non-target snails.