Evaluation de la toxicité des métaux lourds par l’utilisation d’un biotest dans la plaine de R’mila

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Université Abbes Laghrour -Khenchela-
Abstract The present study suggests evaluating soil quality by using earthworms as bioindicators. A study was set up to highlight the influence of pesticides on earthworms. In this sense, a survey has been established in the field with farmers. This investigation showed that Zinebe, the most used pesticide in their agricultural practice. Field sampling is carried out in the region of Khenchela, at the station, R’mila. The diversity of earthworms inventoried in the sampled sites, reveals the presence of 9 species: Allolobophora minuscula, Amynthas californica, Octodrilus maghrebinus maghrebinus, Microscolex phosphoreus, Octodrilus complanatus, Alollobophora chlorotica, Eisenia andrei, Nicodrilus caliginosa caliginosa and Alollobophora rosea rosea distributed in 3 families including Lumbricidae, Megascolecidae and Acanthodrilidae. From our investigation we announce for the first time in Algeria the species Eisenia andrei. In our work, two toxicity tests are performed, the acute toxicity test and the avoidance test. The acute toxicity test is carried out essentially on the species Alollobophora rosea rosea, and the avoidance toxicity test is performed on the species Nicodrilus caliginosus caliginosus. The use of these two species in the toxicity tests was because of their abundance in the field. Four concentrations of Zinebe insecticide were used to perform the acute toxicity test, which are in the order of 0.165, 0.312, 0.625 and 1.250 ml / l. for the avoidance test, we used the sublethal concentration (0.625 ml / l) of the same pesticide. Zinebe showed a moderately toxic effect to adults and all earthworms during the acute toxicity test. On the other hand, it is very toxic for juveniles, recording a lethal dose of 0.247 ml / l after seven days of the test. Regarding the avoidance test, earthworms exposed to sublethal concentration (0.625ml / L) showed a leak behavior with respect to the insecticide Zinebe, expressed by a rate of avoidance of the order 65%