Diel rhythmicity of an echinostome cercaria (Cercaria beaveri Pandey & Agrawal, 1977)

Abstract

We have observed the rhythmic pattern of echinostome cercariae, infecting Lymnea stagnalis Linnaeus, 1758 in a freshwater body located near Barabanki. There is high cercarial shedding (74%) during dark phase (18.30–06.30 h), which is statistically significant (F = 861.04, p < 0.001). Sesonal pattern of rhythmicity shows maximum yield in summer months (April, May and June) and low yeild in February and July. Periodicity of 2 h shows their high shedding in dark phase (12.30–14.30 h). We also observed the effect of temperature at four different temperatures (10°, 15°, 20° and 25°) and their shedding was found to be high at 20 °C and low at 10 °C. Probably, in an effort to approach their intermediate hosts, they acquire this pattern of rhythmicity.

Keywords:

• rhythmicity
• echinostome cercariae
• nocturnal emergence
• intraredial
• encystment

Acknowledgements

Financial assistance to S. Ray under Rajeev Gandhi National Fellowship of UGC: F-1-17.1/2011-12/ RGNF-SC-UTT-2050/ (SA-III), is acknowledged. Facilities developed under UGC-SAP (DRS-I & II), DST-PURSE Department of Zoology, University of Lucknow, Lucknow were utilized for the present work.

Disclosure statement

No potential conflict of interest was reported by the authors.