Acute toxicity: novel mode of pesticides on earthworm.

Accepted : August, 2009 Earthworms are the representative of soil fauna being largest invertebrate biomass of soil ecosystem and they are common in many soils and thus are vulnerable to various impacts on soil. The soil not only acts as a substrate for organisms but also as a recipient medium for chemicals. Agrochemicals irrespective of their place or mode of application exert certain unwanted influence on this non-target organism, which in turn becomes undesirable victim. It is used as an efficient biomonitor for eco-toxicological studies, both as an indicator and test species. It is an excellent tool to detect soil pollutants (Bouche, 1988). The earthworm, Eisenia foetida (Savigny) is reported to be a suitable test species (Heimbach, 1988). The laboratory tests used for ecotoxicological assessment of pollutants to earthworms mainly constitute the acute and chronic exposure studies; majority are designed to measure acute toxicity i.e. mortality of earthworm, as the main end point (Reinecke and Reinecke, 1998). In general, nine distinct tests have been described. The European Economic Community (EEC) and the Organization for Economic Co-operation and Development (OECD) have standardized and advocated three tests for estimation of field hazards viz., contact filter paper test, artificial soil test and silica paste glass-ball test. Besides, United States Environmental Protection Agency (EPA) has also recommended ecological effects test guidelines. Amongst the nine tests, contact filter paper test is simpler, cheaper and