Life History of Lymnaea columella (Say) and its Experimental Infection with Fasciola hepatica (L.)

Abstract

The life history of Lymnaea columella was studied under laboratory conditions at Río Piedras, Puerto Rico. The snail matured in 21 to 23 days after hatching, when shell length was 5 to 6 mm. A culture box 27 X 21 X 11 cm. provided adequate space for a colony of 20 adult specimens. A mature snail raised individually produced an average of 20 eggs daily. The incubation period of the eggs at 26° to 28° C. varied from 10 to 13 days with 98 to 100 percent hatchability. Both eggs and adult snails were highly sensitive to desiccation; not so young snails. To test the behavior of L. columella under stress of infection with Fasciola hepatica, adult specimens were exposed to a variable number of miracidia. These were obtained by cultivation of eggs from the gall-bladder of infected cattle. The miracidia hatched in 10 to 13 days at 26° to 28° C. and did not live more than 3 1/2 hours. Snails receiving 2 to 4 miracidia tolerated the infection well with low mortality but died within 2 to 6 days after cercariae started emerging. Specimens receiving four to six miracidia were able to survive but the mortality rate was high. Inocula of 10 to 16 miracidia caused early death of the snail. The cercariae, released from the snail in 57 to 60 days after infection encysted within 15 to 20 minutes to become metacercariae. Mice tolerated infection with one metacercaria; rats, with five metacercariae. Eggs first were observed in feces at 31 and 51 days post-exposure in mice and rats respectively.