Nutritional Factors affecting the Rate of Development of Fasciola hepatica in Limnaea truncatula

Abstract

This paper describes some hitherto unrecorded aspects of trematode development in a molluscan host.It is shown that the rate of development of Fasciola hepatica in its host Limnaea truncatula is influenced not only by temperature but by the amount of food assimilated by the snail and by the number of rediae which are in competition within a single host.The most rapid development of the parasite will occur in hosts which have access to ample supplies of food and in which moderate numbers of rediae become established. At laboratory temperatures, infection with a single miracidium rarely leads to the establishment of more than 40 rediae, a number which is apparently adjusted to the economy of the host, since it allows development at a maximum rate.

Aspects of the Maintenance of the Life Cycle of Fasciola hepatica in Lymnaea columella in Minas Gerais, Brazil

“…This high mortality therefore was not due to the presence of the parasite but rather to other factors, or predatory organisms such as oligochaetes in the aquaria. The mean numbers of metacercariae obtained from L. columella in the individual (353) and mass (214) infections were similar to the results obtained by Abrous et al (1998) of 56.5-107 in the infection of L. truncatula but inferior to the numbers recorded by Kendall (1949), who obtained 800-2,300 larvae when snails of this species were fed on algae. The maximum number of cercariae eliminated per snail in this experiment was 1,530.…”

“…The maximum number of cercariae eliminated per snail in this experiment was 1,530. The greatest number of metacercariae obtained was through the dissection of the snails, large numbers of cercariae being seen around the digestive gland, as described by Kendall (1949) in his study of developmental effects produced by nutritional factors. After 60 days of infection some metacercariae were found encysted on the internal surface of the shell.…”

The influence of different food sources on cercarial production in Lymnaea truncatula experimentally infected with Digenea

“…The greater production of F. hepatica cercariae in snails which fed on algae or the Boray diet had already been reported by Boray [2], Kendall [5], or Lee et al [6] when these authors used the same sources of food for the rearing of L. truncatula or L. viridis under laboratory conditions. Higher numbers of F. gigantica or P. daubneyi cercariae were also found in the case of Boray diet-reared snails and this finding indicated that this source of food had a significant influence on cercarial production in snails, whatever the digenean species used for infection.…”

The effect of nutrition on the growth of Fasciola hepatica in its snail host

“…I n a series of experiments under laboratory conditions it was shown (Kendall, 1949) that the rate of development of the parasite, as indicated by the number of cercariae which attained full maturity in a given time, was influenced partly by the number of rediae which were present in each snail but more markedly by the amount of food which the snail received. Table I shows that those snails that had had access to unlimited supplies of food contained many more mature cercariae than those kept under starvation conditions.…”