Der Einfluß des Eisenangebotes auf die Hämoglobinsynthese und die Entwiddung der Chironomus-Larve

Abstract

The red final instar larvae of the dipteran insect Chironomus thummi thummi, reared on powdered leaves of Urtica dioica, have a hemoglobin content of 2.2 - 4.0 g hemoglobin (Hb)/100 ml blood (i.e., 14 - 25% of the human Hb content). When the larvae are reared under deficiency of iron as realized in leaves of Alnus glutinosa, the Hb synthesis is extensively repressed; the pale larvae synthesize only 0. 5 g Hb/100 ml (i.e. 3% Hb) or less. By addition of soluble or insoluble iron salts at any time a normal Hb synthesis can be achieved. Breeding and tolerance experiments with the pale larvae show that neither in optimal O2 conditions nor in anaerobiosis is the Hb necessary. The experiments confirm the results of other authors, who demonstrated by respiration measurements of larvae with carboxyhemoglobin that the Hb is efficient only in very low O2 concentrations. As in the field the larvae of Chironomus are always exposed to very O2 concentrations and therefore are in need of Hb, a deficiency of iron in food and sediments may act as a factor limiting their ecological niches in fresh waters. With respect to the influence of O2, temperature and salinity on the Hb contents of the fresh water species of C. thummi thummi and 2 brackish water species are compared.