A new approach to evaluate the functional role of earthworms as bioremediators of certain pesticides in soil

Vermiremediation is a promising technology for restoring soil functioning. Unfortunately, assays used to assess the efficacy of this process fail to evaluate the biological quality of soils. So, this study aimed to determine the functional role of earthworms (Eisenia fetida and Aporrectodea caliginosa) as bioremediators. The soil used for the experiment was collected from an agricultural field in Egypt. After collection, the soil was divided into two parts. Soil microarthropods were extracted from the first part. Sub-lethal concentrations of aldicarb, chlorpyrifos, and carbofuran were added to different sets in addition to distilled water as control, and earthworms were introduced. Thereafter, alternative units from the two parts were mixed. The obtained results revealed that while pesticides had a detrimental effect on decreasing the abundance and diversity of soil oribatid mites even when introduced at sub-lethal doses, the presence of Eisenia fetida has increased oribatid mite abundance. Furthermore, some species tended to the presence of earthworms, whereas others showed a positive correlation with the presence of Eisenia fetida. In conclusion, vermiremediation using epigeic species such as Eisenia fetida had a positive effect on the abundance of oribatid mites, which could increase soil health, therefore enhancing crop production. Consequently, we suggest that assessing oribatid mite abundance is a way to detect the efficacy of earthworms in the vermiremediation process.