Long-Term Effects of an Inorganic Fertilizer on the Grey Worm, Aporrectodea caliginosa

Earthworms play a significant role in soil fauna communities across various ecosystems, constituting a substantial portion of macrofauna biomass. Their contributions to soil health are diverse, making them crucial biological indicators in terrestrial environments. Unfortunately, these essential organisms face exposure to agrochemicals applied to increase crop yield. Our study aims to test the effects of a complete fertilizer (NPK) on adults of Aporrectodea caliginosa Savigny, 1826, an earthworm species that is common in the Tebessa region (Northeast Algeria). Under laboratory conditions, adult earthworms were treated by two doses of the fertilizer (LD₂₅ and LD₅₀, as determined for juvenile earthworms). During a four-week exposure period, growth rate, biochemical profile, and biomarkers of oxidative stress were assessed. The growth of A. caliginosa adults was negatively impacted by both Dose 1 and Dose 2. Furthermore, the fertilizer caused a considerable decrease in the nutrient reserves indicated by a decline in protein, lipid, and carbohydrate contents in earthworm tissues. Biomarkers assay showed a stimulation of detoxification system via the increase in activity of Glutathione S-transferase and reduction in Glutathione content. Glutathione peroxidase and lactate dehydrogenase activities showed no treatment effect. Finally, tissues of treated earthworms showed histological changes that were significantly correlated with NPK concentration. Overall, results indicate that application of the NPK fertilizer could cause harmful effects on earthworms.