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Korean J Parasitol > Volume 24(2):1986 > Article

Original Article
Korean J Parasitol. 1986 Dec;24(2):115-120. English.
Published online Mar 20, 1994.  http://dx.doi.org/10.3347/kjp.1986.24.2.115
Copyright © 1986 by The Korean Society for Parasitology
The effect of temperature and salinity on maturation and hatching of Fibricola seoulensis eggs
Soon Hyung Lee,Ho Jin Lee,Sung Tae Hong,Sun Huh and Byong Seol Seo*
Department of Parasitology, Institute of Endemic Diseases, College of Medicine, Seoul National University, Seoul 110, Korea.
*Department of Parasitology, College of Medicine, Inha University, Inchon 160-01, Korea.

This study was carried out to reveal the effect of temperature, salinity and aeration on maturation and hatching of Fibricola seoulensis eggs. The eggs were incubated and were observed daily for the appearance of eyespots and hatching. The results were summerized as follows: From 4-5 days after incubation in distilled water at 28℃ or at 11~26℃, the eyespots began to appear and the rate of eggs with eyespots were over 90% in 28℃ on the 7th or 8th day. However, eyespots did not appear in 5~15℃ or 4℃ by the 18th day. The mature eggs began to hatch at the 8th day, and hatching rate 2 weeks after incubation was over 90% at 28℃, but it was below 5% at 11~26℃, and 0% at 5~15℃ and 4℃. Aeration did not influence the appearance of eyespots nor hatching. In saline under 0.6%, the rates of eyespots were over 90% on the 7th day. The rate was 55.0% in 0.9% at 20 days, and 0% in 1.2%. The hatching rates in salines below 0.3% concentration were over 90% by 14 days of incubation. However, the rate decreased to 44% in 0.6% saline and to 0% over 0.9% salinity. The eggs incubated in the dark hatched in 12.5% on the 10th day, but hatching rate of maturation eggs increased to 85.7% within 2 hours after exposure to light. Above results demonstrated that the best temperature for maturation and hatching of F. seoulensis eggs was 28℃, and the miracidia began to hatch at 8-9 days after incubation. In the field hatching and invasion into snails of the miracidia may occur from May to September in Korea. In salines under 0.3 percent concentration maturation and hatching were not influenced, but as salinity increased hatching was inhibited more than maturation was.


Figs. 1~4
Fig. 1 An immature egg of F. seoulensis, bar=50µm.

Fig. 2 A mature egg of F. seoulensis with a miracidium, bar=50µm.

Fig. 3 An empty egg shell of F. seoulensis, bar=50µm.

Fig. 4 A hatched miracidium of F. seoulensis, bar=50µm.


Table 1
The rates of eyespots appearance in F. seoulensis eggs* by incubation day

Table 2
The hatching rates of F. seoulensis eggs* by incubation day in each group of temperature

Table 3
The rates of eyespots appearance in F. seoulensis eggs* by incubation day in various salines

Table 4
The hatching rates of F. seoulensis eggs* by incubation day in various salines

Table 5
Hatching rate of F. seoulensis eggs* after illumination

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