Ecotoxicity of Folsomia candida induced by 1,2,4-TCB: Insights from multi-level experiments and molecular simulations

The large-scale production and application of industrial chemicals and pesticides have intensified soil contamination by chlorobenzenes particularly 1,2,4-trichlorobenzene (1,2,4-TCB), thereby posing a serious threat to the safety of soil-dwelling organisms. However, the toxicological impacts of 1,2,4-TCB on soil biota remain poorly characterized. In the present study, the effects of 1,2,4-TCB on soil invertebrates specifically the springtail Folsomia candida were investigated by integrating multiple biomarkers, transcriptomic profiling, and molecular docking analyses. The results of the study indicated that after 7 days of exposure, the dynamic changes in the activities of acetylcholinesterase (AChE) and antioxidant enzymes showed that different concentrations of 1,2,4-TCB might induce oxidative damage and neurofunctional abnormalities in springtails, and then these results were subsequently confirmed by molecular docking simulations. Transcriptomic analysis revealed that chitin-binding, (endo)peptidase activity and serine (endo)peptidase activity were suppressed functions shared by treatment groups. Moreover, high-dose treatment (97.16 mg/kg) significantly induced pathways associated with neurotoxicity and multiple disease comorbidities. These molecular-level alterations were accompanied by a marked increase in springtail mortality and a decline in breeding. Collectively, these findings expand our mechanistic understanding of 1,2,4-TCB toxicity toward soil invertebrates and provide essential information for environmental risk assessment of chlorobenzene contaminants.