Journal of Environmental Biology

Use of tropical artificial soil as a new substrate for avoidance behavioral test of earthworm, Eisenia foetida exposed to urea

K.S. Abbiramy^1*, P. Ronald Ross¹, J. Paramanandham¹ and P. Thenmozhi²

¹Department of Zoology, Annamalai University, Annamalai Nagar ? 608 002, India

²Department of Zoology, St. Joseph's Arts and Science College, Cuddalore ? 607 001, India

*Corresponding Author E-mail: umak.senthil@gmail.com

Publication Data

Paper received:

21 July 2012

Revised received:

13 April 2013

Accepted:

03 June 2013

Abstract

The original avoidance behavioral test was developed by temperate countries like North American and Europe which uses the sphagnum peat as organic component of artificial soil for ecotoxicological studies. Since sphagnum peat is difficult to procure in tropical countries like India, the suitability of commonly available coir pith was undertaken. A modified Tropical Artificial soil (TAS) was prepared by mixing 70% sand and 20% kaolin clay with 10% coir pith (fermented) and used for avoidance behavioural test with the earthworm, Eisenia foetida. Urea was used as a test chemical and the eligibility of coir pith as organic component was tested. The dual control avoidance tests, EC₅₀, LOEC and NOEC estimation, avoidance tests with different concentrations of urea (500mg, 1000mg, 1500mg and 2000mg) were performed with two soils (OECD recommended Sphagnum peat artificial soil (SPAS) and TAS) for 48hr according to ISO guideline 17512-1 but were adapted to tropical conditions (i.e. 28⁰C temperature). After 48hr, the preliminary results of the avoidance behavioural test indicated a varied distribution (NR = 10%) of the organisms in the soil sections (SPAS without urea spiked). Also E. foetida showed a significant congregating behaviour when exposed to low concentration of urea spiked SPASs (500mg, NR = 67%, n = 4), which indicated that the substrate is not suitable for earthworms under tropical condition. Though there was no mortality observed, the avoidance criterions of dual control test (net response 50 ? 0.50%) and avoidance test against urea (net response 50 ? 10%) was valid only in TAS and not in SPAS. Thus this study concludes that the sphagnum peat which was used as an organic component of SPAS is not suitable for ecotoxicological tests in tropical regions. Though fermented coir pith is suitable, furthermore investigations are required for its suitability as an alternate organic component of artificial soil in tropical regions.

 Key words

Avoidance behavioral test, Eisenia foetida, Fermented coir pith, Sphagnum peat, Urea 

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