Effects of Single and Combined Exposure to Environmentally Relevant Concentrations of Cyfluthrin and Copper on Digestive Gland Histology of Lymnaea stagnalis

Abstract

Pyrethroid insecticides and heavy metals frequently co-exist in aquatic systems, due to intensive anthropogenic activities, and their effects on aquatic organisms are needed to be investigated. In the present work, single and combined effects of environmentally realistic concentrations of cyfluthrin and copper on the digestive gland histology of the freshwater pond snail (Lymnaea stagnalis) were evaluated. Snails were exposed to 1 µg/L cyfluthrin, 10 µg/L copper, and 1 µg/L cyfluthrin + 10 µg/L copper mixture for 96 h. Cyfluthrin-exposed samples showed apparent vacuolization, basal lamina separations, and disrupted digestive cells. Exposure to copper alone gave rise to enlargements of the tubule lumens and the intertubular area, degenerated tubules, atrophied basophilic cells, prominently disrupted and ruptured digestive cells, and nuclear enlargements in some basophilic cells. Cyfluthrin and copper mixture caused more severe histopathological changes in the digestive gland. General tissue appearance was altered by prominently degenerated, and fused tubules lacking cellular structure; tubule lumens filled with cellular content were noted. Increased intertubular regions were filled with connective tissue formations. Progressive disruption of digestive cells; and basophilic cell atrophy were also observed. The findings of the current study highlighted that cyfluthrin and copper at environmentally relevant concentrations caused a biological response in L. stagnalis; however, this response was more intense following their co-exposure.