Individual and combined effects of a fungicide (Valette) and an herbicide (Oscar) on the growth and mortality of earthworm <i>Lumbricus terresteris</i> (linnaeus, 1758)

Abstract

Earthworms are valuable soil invertebrate mainly used to monitor environmental quality. Thus, the present study was undertaken to provide insights on the individual and combined toxicological effects of two commonly used pesticides in Souk Ahras city (Northeast Algeria), namely Valette (fungicide) and Oscar (herbicide) on a soil invertebrate – earthworm (Lumbricus terresteris) as a bio-indicator of soil pollution. The invertebrates were subjected to increasing concentrations of each chemical (0, 2, 4, 6, 8, 12.5, 25 and 50 mg/500 mg soil) for four treatment periods (24, 48, 72 and 96 hours). Physicochemical analysis revealed that the soil pH is alkaline, and water and KCl pH are respectively 8.05 and 7.72, in addition to a sandy-loamy soil texture with a saturation rate of 49.43%, and high level of organic matter (11%). Additionally, both chemicals caused a significant weight decrease (p˂0.05) from the concentration of 12.5 mg/mg soil, and noteworthy, no mortality was recorded during the entire experimental period, either for the individual or combined exposure. Furthermore, the histopathological observations showed no signs of alteration or damage to epidermal cells and muscle fibers during the treatment periods with either chemical.