# A Systematic Review on Earthworms in Soil Bioremediation
## 3 Results
### Alloobe Organic Vermieremediation
The increment of TPHs degradation was evident and significant in substrates with earthworms compared to the negative control. More in detail, the treatment which implied the highest reduction is the one with _E. fetida_ (60.81%), followed by _A. morrisi_ (46.74%) and, finally, the treatment with the incorporation of the two species (45.2%). _E. fetida_ seems to be the most effective species in the vermiremediation process; furthermore, it is also more resistant, with higher survival rates than _A. morrisi_. Another study [109] explored the ability of two earthworm species used together, _D. modesta_ (epigeic) and _L. mauritii_ (anecic), to restore a soil polluted by PAHs and TPHs. The species selected by the authors are commonly isolated from fields and are widely known for their ability to detoxify heavy metals in industrially contaminated substrates; however, they are underutilised in studies with crude oil contaminations. Authors found that co-inoculating these worms can alter the contamination level till the intermediate dose (7.5 mL), with a PAHs and TPHs reduction of 68.6% and 34.3%, respectively. This capacity undergoes a substantial breakdown at higher doses of oil contamination (10 mL), indicating suffering in both earthworms associated with low activity and histopathological damage observed on cross sections under a compound microscope such as degradation of cells, irregular surface epidermis or detected cellular debris. Vermiremediation is also suitable for matrices contaminated by pesticides: a pilot study [110] was conducted to vermiremediate soil contaminated by organophosphateinsecticide dichlorvos, using _L. terrestris_ and _E. eugeniae_ alone and in combination. As shown in Figure 3, the best results were obtained by _E. eugeniae_, with an average reduction percentage of 72.29%, followed by the co-inoculated treatment (66.27%) and _L. terrestris_ (54.23%). [PERSON] et al. [110] concluded that _E. eugeniae_ is the better remediator agent in this research case. [PERSON] et al. [103] evaluated in their study three different species of earthworms, including _E. eugeniae_, _Alma millsoni_ and _Libydrilus violaceus_, against the glyphosate-based herbicides (GBHs). At the end of the experiment, all organisms significantly reduced the GBHs concentration in soil; however, the bioaccumulation factor (ratio between xenobiotic concentration in earthworm tissue and substrate) demonstrated that _E. eugeniae_ (1.11) and _L. violaceus_ (1.15) are better accumulators than _A. millsoni_ (0.40). Moreover, the enzymatic analyses showed that _E. eugeniae_ and _L. violaceus_ responded to the exposure with physiological and biochemical adjustments, activating antioxidant defence mechanisms as a compensatory response. Other authors who worked with glyphosate were [PERSON] et al. [99], who tested the capacity of _E. fetida_ in a biobed system. They studied different biomixtures in the presence or absence of earthworms, concluding that _E. fetida_ leads to a 90% reduction of the pesticide compared to the test without worms (80%). This earthworm species can tolerate elevated glyphosate levels without altering its life characteristics. Also, [PERSON] et al. [111] set up a vermiremediation test in a biobed system contaminated with four different pesticides: Diuron, Imidacloprid, Tebuconazole and Oxylfluorfern. As can be seen in Figure 3, _E. fetida_ successfully reduced the amount of Diuron (100%) and Oxylfluorfern (70.25%). At the same time, the other two pesticides were not significantly reduced compared to uninoculated controls, maybe due to the high levels of pesticides and the composition of the biomixtures, which could limit the vermiremediation. The same epigeic earthworm versus the endogeic _A. robustus_ was evaluated against atrazine, a triazine herbicide used worldwide at low cost for agricultural production. [PERSON] et al. [112] found that both species coupled with soil microbes can decrease atrazine contamination, performing trials with sterilised and non-sterilised soil.