|
KMID : 0359319930330020277
|
|
Korean Journal of Veterinary Research
1993 Volume.33 No. 2 p.277 ~ p.283
|
|
|
The life - history of Lymnaea viridis , the intermediate host of Fasciola hepatica , under laboratory conditions
|
|
|
|
|
Abstract
|
|
|
In the present study, observations were made on the life-history of Lymnaea viridis under laboratory conditions, involving incubation period of the eggs and their hatching rate, shell length of the newly hatched snails, sexual maturity, size of the snails when the snail produced the first egg-mass, the number of eggs in each egg-mass, egg-laying, ovipostion, ,growth rate of the snails, and longevity of the snail.
At temperatures between 19.8℃ to 22.5℃, incubation period of the eggs occupied 10∼12 days, and after beginning of hatching, all young snails emerged completely from the egg-mass within 5 days. The hatching rate was 88%. The average shell length of the newly hatched snails was about 0.064㎝.
The rate of growth was extraordinarily rapid under good laboratory conditions. When two snails were reared in one culture vessel(20×15×5㎝) with blue-green algae at about 22℃, snail growth was optimal, taking 37 days to reach 1.2㎝ in shell length.
Sexual maturity reached in about 19 days. The size of the snails at sexual maturity was 0.78±0.05㎝ in length and 0.47±0.04㎝ in width. The first egg-masses produced were 0.59±0.22㎝ in length and 0.34±0.08㎝ in width, and contained 7∼38 eggs.
The eggs are usually laid in water. The egg-laying was affected by food and temperature. Snails fed with blue-green algae at about 22℃ produced larger egg-masses than the snails fed with fish food at about 26℃.
Under conditions of continuous activity and growth, the maximum expectation of life appears to be 109∼350(mean 230) days. And the shell length of snails at death were 1.39∼1.64㎝.
|
|
|
KEYWORD
|
|
|
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|