Acute toxicity of an insecticide (Acetamiprid) on Lumbricus terrestris (linnaeus, 1758)

Abstract

Earthworms are effective bio-indicators of biodiversity, soil quality and the environmental impact on cropping systems. Therefore, this study was conducted to assess the toxicological effect of Acetamiprid, a widely used insecticide by farmers in the region of Souk-Ahras (Algeria), on a biological model named Lumbricus terrestris using seven increasing concentrations 0, 5, 7, 9, 12.5, 25 and 50 mg/500 mg soil for four control periods; 24, 48, 72 and 96 hours. The physicochemical soil analysis indicated that the soil pH was strongly alkaline, and the pH water and pH KCl were respectively 8.52 and 7.72. The soil texture was sandy loam with a high level of organic matter (OM = 12.9%). In addition, the LC₅₀ and LC90 values were remarkably decreased (LC₅₀ = 12.4, 10, 7.30 and 6.69/500 mg soil; LC₉₀ = 18.52, 14.21, 9.50, 9.15 mg/500 mg soil, corresponding respectively for each LC values to the four exposure periods 24, 48, 72 and 96 hours). Furthermore, no significant change was noticed in body weight and growth of
earthworms treated with Acetamiprid at various concentrations. The mortality rate was concentration-dependent; increased with increasing concentration, and this was supported by the histopathological observations showing cellular alterations in the epidermis and muscle fibers. Additionally, treatment with Acetamiprid at high concentrations caused marked morphological abnormalities in the earthworms as evidenced by the winding of the body, loss of pigmentation, cut of the posterior part, lesions, or bloody wounds.