Histological effects and localization of dissolved microcystins LR and LW in the mayfly Ecdyonurus angelieri Thomas (Insecta, Ephemeroptera)

Abstract The ability of microcystins (MCs), the main group of cyanotoxins, to affect the physiological processes and tissues of insects has received little attention. Fresh water dissolved MCs represent one of the main sources of cyanotoxins. In the experiment described herein, captured wild mayfly Ecdyonurus angelieri Thomas, 1968 larvae were exposed to 5 ppb of two distinct microcystins, MC-LR and MC-LW, in separate assays. Evidence of induced mortality, MCs bioaccumulation and severe histological damage affecting fat body and alterations in the tracheal system were evident. Our results reveal the acute sensitivity of the mayfly E. angelieri to MCS, which may serve as early indicators or cyanotoxins production and the quality of freshwater streams.