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2C - Biomarkers (TUP/88) Using biomarkers and microcosms to explore the presence and effects of agricultural pesticides in soil organisms. Reinecke, Adriaan1, Reinecke, Sophia1, 1 Department of Zoology, Stellenbosch University, Stellenbosch, Western Cape, South Africa ABSTRACT- The aim of the study was to evaluate biomarker endpoints under field-relevant conditions. Soil microcosms containing soil from areas where regular spraying with azinphos-methyl, chlorpyrifos and copper oxychloride had taken place as well as from control areas, were used to expose earthworms. In the laboratory experiments earthworms were also exposed to soils spiked at field concentrations as well as to a range of sublethal concentrations. Survival and growth were monitored as well as reproduction parameters. Biomarkers were also used to determine effects on all experimental groups, monitoring lysosomal integrity (neutral red retention test), cholinesterase inhibition (Ellman method), DNA strand breaks (Comet assay). The results obtained with the biomarker tests indicated that the earthworms were affected negatively by sublethal concentrations of the pesticides and that the dose-related responses correlated strongly with life-cycle parameters such as growth and reproduction. These responses can therefore serve as early warnings of changes which manifests in life-cycle characteristics which could, in turn, affect survival and consequently population densities. The fact that these biomarker endpoints can be measured accurately and reliably may make them very useful in environmental monitoring, the only caveat being that unless causality is clearly established, specificity cannot be assumed. Key words: biomarkers, pesticides, earthworms, microcosms |
