ABSTRACT

Diesel contamination is a serious environmental issue with detrimental effects on biodiversity, ecological integrity, and soil health. This study assesses the histological changes and oxidative stress responses in the clitellum of Eisenia fetida exposed to different diesel-contaminated soil concentrations. For 28 days, E. fetida, a species commonly considered a bioindicator, was exposed to diesel concentrations of 10%, 25%, and 50% in addition to a control in a lab setting. Avoidance behaviour, mortality, antioxidant enzyme activity (catalase [CAT], glutathione peroxidase [GPX], and superoxide dismutase [SOD]), lipid peroxidation (MDA levels), and clitellum structural integrity were among the important characteristics evaluated. Oxidative stress increased in a dose-dependent manner, according to the study, with SOD, CAT, and GPX activities peaking at 50% diesel concentration on Day 7 and then sharply declining by Day 21. Significant lipid peroxidation and membrane damage were suggested by elevated MDA levels, which were seen at higher diesel concentrations. Histopathological examination showed a progressive breakdown of clitellum components, such as granular and mucous glands that are necessary for reproduction. As shown by the lack of cocoons in every treatment group, this resulted in reproductive failure. In addition to highlighting the use of oxidative stress biomarkers and histopathological evaluations in ecotoxicology, this work underlines the usefulness of E. fetida as a bioindicator for soil health. This study advances knowledge of the ecological dangers posed by diesel pollution and aids in the creation of remediation techniques such as using earthworms' innate capacity to break down hydrocarbons. Future research should examine the effectiveness of bioremediation techniques in diesel-polluted areas, long-term effects, and interactions with soil microbial communities.