In Vitro Biomarker Responses of Earthworm Lumbricus terrestris Exposed to Herbicide Sekator and Phosphate Fertilizer

Earthworms are important soil macroinvertebrates and are often used in assessing soil pollution. The present study was conducted in order to investigate the effect of two compounds, triple superphosphate (TSP; fertilizer), sekator (herbicide), and their mixture at two agricultural doses on a Lumbricus terrestris population. Neurotoxicity (acetylcholinesterase (AChE)), metabolization (glutathione-S-transferase (GST)), glutathione (GSH), and protein content were evaluated as biomarkers. Treated earthworms with sekator showed a non-significant increase of protein content (p > 0.05). In contrast, protein content increased significantly (p < 0.0001) up to (104.75 ± 4.75 and 109.09 ± 5.4 μg/worm) after 72 h of exposure with TSP and the mixture, respectively. As compared with TSP exposure, sekator in mixture substantially decreased AChE activity. In control series, the GST activities and GSH concentrations remain stable after 72 h while sekator and TSP induced the biomarker responses, which was proportional to exposure time and administered dose. Non-significant correlations were recorded between AChE and GSH, GST and the protein contents in most interactions. The obtained results indicate that application of sekator in mixture with triple superphosphate could have harmful effects on earthworms since it caused significant changes in measured biomarkers.