Toxicity of vegetable tannins on Crustacea associated with alpine mosquitobreeding sites

The impact of tannins from the environmental vegetation naturally polluting Alpine mosquito breeding sites was experimentally investigated by studying the toxicity of tannic acid, a natural hydrolyzable tannin, on the nontarg et crustacean fauna associated with culicine populations. Bioassays indicat e that exposure to tannic acid at concentrations from 0.06 to 2.0 mM is mor e deleterious to Chydorus sphaericus, Diaptomus castor, and Eucypris fuscat a, than to Daphnia pulex, Acanthocyclops robustus, and Eucypris virens. His topathological investigations after treatment with tannic acid at concentra tions from 0.125 to 0.500 mM reveal sequential degenerative patterns of the midgut epithelium depending on the taxon, duration of the treatment, and c oncentrations assayed, These differential toxic effects on Crustacea are co mpared with those previously observed in larval Dipteral in order to evalua te the plant tannins as potentially useful products in integrated mosquito management programs. (C) 2000 Academic Press.