The Usefulness of physiological and biochemical stress response of soil collembola (Xenylla welchi Folsom, 1916) as a biomarker in a lead-amended garden soil

This study investigates the physiological and biochemical stress responses of the microarthropod Xenylla welchi to different sublethal doses of lead-contaminated garden soil in microcosms, aiming to assess the impact of metallic contamination in tropical ecosystems. 24-hour LC50 for lead acetate was determined to be 2653.23 mg/kg. Chronic exposure to various sublethal concentrations (1/2, 1/4, 1/6, and 1/8 of LC50) revealed significant reductions in exuvia production, fecundity, and lifespan, particularly at higher lead concentrations. Several biochemical parameters were assessed to further understand lead-induced stress responses. A marked decrease in glutathione (GSH) levels indicated oxidative stress, while glutathione-S-transferase (GST) activity displayed temporal variations, initially increasing and then declining with prolonged exposure. Acetylcholinesterase (AChE) activity was consistently inhibited across the treatment groups, reflecting neurotoxicity. Additionally, metallothionein (MT) levels were significantly elevated after extended lead exposure, suggesting an adaptive response to metal detoxification. The cumulative responses of Xenylla welchi suggest that they could be reliable biomarkers for assessing the ecological impact of lead pollution in soil ecosystems, highlighting their potential usefulness in monitoring heavy metal contamination.