Redial productivity of Clinostomum complanatum (Trematoda: Clinostomatidae) within the snail host.

Studies have been conducted on the rediae of Clinostomum complanatum Rud., including the problem of intramolluscan productivity, their population structure and the nature of rediae of different generations. It has been found that the reproduction of rediae is marked by their mass multiplication in the first two generations: this ensures the establishment of a population of considerable size. The mother redia is the sole parent redia which produces daughter rediae. The longevity of the mother redia is about 12 days, with a production period of 5 days. Rediae of the second generation which appear on the 7th-8th day start to propagate 3 days later. The peak of production of the second generation lasts for 3 days and then shifts to an entirely different phase, to that of cercarial production. The majority of the third generation are cercarial producers, with only a few "mixed" rediae which are important in maintaining the redial population. The size of redial population maintains a level of over 1,000-2,500 individuals during a period from 39-59 days. The polyembryony and the changes in nature in the production of rediae are considered to be attributable to their adaptation to the parasitic life of the digenetic trematodes.