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Effects of diazinon on survival and growth of two amphibian larvae

Authors:

DM Sumanadasa,

Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, P.O. Box 6, Thalagolla Road, Ragama, LK
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Mayuri R Wijesinghe ,

Department of Zoology, Faculty of Science, University of Colombo, Colombo 03, LK
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WD Ratnasooriya

Department of Zoology, Faculty of Science, University of Colombo, Colombo 03, LK
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Abstract

Amphibian populations are declining globally at an alarming rate and evidence suggests that pesticides may be a principal cause. The present study investigated the effects of diazinon on the survival and growth of larvae of two amphibians, Bufo melanostictus (Asian common toad) and the Sri Lankan endemic Polypedates cruciger (Common hourglass frog).

Larvae were laboratory bred from egg clutches collected from ponds and wells in home gardens in the Gampaha and Colombo districts. Two separate trials were conducted using gill stage hatchlings (Gosner stages 20-22) of each species. The larvae were repeatedly exposed to 4 μg/L, 400 μg/L and 10 mg/L of diazinon for seven days. Results showed that exposure to 10 mg/L of diazinon caused significant elevations (p < 0.05) in larval mortality in both B. melanostictus and P. cruciger as compared to the controls. No significant increases in mortality were noted at 4 μg/L and 400 μg/L. The trends in mortality were significant and positive for both species. Growth retardation was also noted at the highest dose of 10 mg/L, these larvae being significantly smaller than those in the controls (p < 0.05). Larval activity was also seriously impaired at the highest dose.

Keywords: Amphibian, Bufo melanostictus, diazinon, mortality, organophosphate pesticide, Polypedates cruciger, tadpoles  

doi:10.4038/jnsfsr.v36i2.149

Journal of the National Science Foundation of Sri Lanka 36 (2) 165-169

How to Cite: Sumanadasa, D., Wijesinghe, M.R. and Ratnasooriya, W., 2008. Effects of diazinon on survival and growth of two amphibian larvae. Journal of the National Science Foundation of Sri Lanka, 36(2), pp.165–169. DOI: http://doi.org/10.4038/jnsfsr.v36i2.149
Published on 25 Jun 2008.
Peer Reviewed

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