Biomarker response in the earthworm Lumbricus terrestris exposed to chemical pollutants

Earthworms are important organisms for the soil ecosystem. They are sensitive to toxic chemicals and represent useful bioindicator organisms for soil biomonitoring. Recently the use of biomarkers in earthworms has been increasingly investigated for soil monitoring and assessment purpose. The aim of the preset paper was to analyze the pollutant-induced response of a suite of cellular and biochemical biomarkers in the earthworm Lumbricus terrestris exposed to copper sulphate or methiocarb in OECD soil at the maximal concentrations recommended in agriculture. These responses were compared to lifecycle parameters such as survival, growth and reproduction. Granulocyte morphometric alteration, lysosomal membrane stability, metallothionein concentration, and acetylcholinesterase activity were considered. In either copper sulphate or methiocarb exposure conditions the mean percentage variation of the pollutant-induced molecular and cellular biomarkers was consistent with the whole organism end-point responses. In particular pollutant-induced granulocyte enlargement, detected in either copper sulphate or methiocarb exposed organisms, showed to be a potential general biomarker that may be directly linked to organism health. Compared to the other biological responses to pollutants, it showed high sensitivity to pollutant exposure suggesting its possible applications as a sensitive, simple, and quick general biomarker for monitoring and assessment applications. ► A suite of biomarkers was standardized in the earthworm L. terrestris for detecting the pollutant induced stress syndrome. ► Exposure to either copper sulphate or methiocarb induced dramatic granulocyte enlargement. ► Pollutant induced granulocyte enlargement showed high sensitivity to pollutant exposure compared to other biomarkers. ► Granulocyte enlargement showed to be a potential general biomarker suitable to be included in a multi-biomarker strategy.