Sensitivity of characteristic riverine insects, the caddisfly Cyrnus trimaculatus and the mayfly Ephoron virgo, to copper and diazinon

This study reports the effects of two model toxicants, copper and diazinon, on two characteristic riverine insect species, the caddisfly Cyrnus trimac ulatus and the mayfly Ephoron virgo. It was demonstrated that these species are very sensitive to both compounds in comparison with aquatic insects tr aditionally used in ecotoxicity tests. For diazinon, the 96-h LC50 value of Cyrnus trimaculatus (1.1 mu g/l) is lower than for any other insect specie s known from the literature and for copper it was demonstrated that Ephoron virgo is among the most sensitive aquatic insect species. The observed low LC50 values stress the importance of using these indigenous species in ass essing the risk of environmental contaminants in large European rivers and in defining conditions for ecological recovery. (C) 2000 Elsevier Science L td. All rights reserved.