VARIABILIDAD DEL ENSAYO ECOTOXICOLÓGICO CON Chironomus calligraphus Goeldi (DIPTERA: CHIRONOMIDAE) PARA EVALUAR CADMIO, MERCURIO Y PLOMO.

Environmental Risk Assessment (ERA) of freshwater environment in Peru needs the employment of standardized biological organisms such as the larval midge Ohironomus calligraphus Goeldi. The biological organisms to be employed as ecotoxicological tools should be easy, practical, sensitive and reproductible. The aim of this research was to evaluate Cd+2, Hg+2 and Pb+2 as cadmium chlorure (CdCl2), mercury chlorure (HgCl2) and lead nitrate (Pb3(NO)2) forms, on the mortality of first instar larva of diptera C. calligraphus at 48 h exposure and in this way determinate its variability. The species was acclimated and reared under standardized laboratory conditions. Six bioassays of acute static toxicity for each metal were done, in each one a randomized block experimental design (RBED) was used with four repetitions of five concentrations and employing 240 larvae for each bioassay. The median lethal concentration (LC50) in µg metal L-1 at 48 h exposure and the coefficient of variation (CV %) were: 132 µg L-1 and 45,45 % for Cd+2; 127 µg L-1 and 22,83 % for Hg2+; and finally 18.730 µg L-1 and 33 % for Pb2+. The variability of the essay of C. calligraphus is compared with other freshwater biological organisms all over the world. [ABSTRACT FROM AUTHOR]