Laevicaulis stuhlmanni slugs as accumulation bio-indicators of lead metal pollution: immunotoxic, physiological, and histopathological alterations.

Abstract

Trace metal pollution of soils is a widespread consequence of anthropogenic activity. Land slugs can be used as bio-indicators of the metals' pollution in the soil, so the present study aimed to determine the metal in the soil and Laevicaulis stuhlmanni land slug tissues by studying its effects on different physiological parameters. Slugs and soil samples were collected from fields in Abu-Rawash, Giza, Egypt. Slugs were identified, and the metals were determined in slug tissues and soil samples. On the other hand, slugs were reared in the laboratory and the new generation was fed on lettuce dipped in 0.027 µg/ml lead (Pb) for 10 days. The results revealed that the soil and slug tissues contained copper, manganese, lead, and zinc; the lead metal bioaccumulation factor was the highest. Also, the results showed that the hemocytes' count, testosterone, and estradiol hormones were significantly decreased. At the same time, the phagocytic index was increased considerably, and some morphological alterations in the granulocytes and hyalinocytes were observed after treatment with 0.027µg/ml lead compared to untreated slugs. On the other hand, all the oxidative stress parameters were significantly increased in the treated slugs compared with the control. Concerning the histopathological studies, lead caused a rupture, vacuolation, or degeneration in the digestive cells of treated slugs. Finally, it can be concluded that the land slugs were sensitive to lead which was reflected by endocrine disruption, immunotoxicity, and increased oxidative stress parameters with histopathological damages. Hence, Laevicaulis stuhlmanni can be used as a metal accumulation bio-indicator to reflect the metal pollution in the soil.