Metallothionein-like metal-binding protein in the biomonitor Chaoborus: Occurrence and relationship to ambient metal concentrations in lakes

Larvae of the insect Chaoborus are used to monitor cadmium (Cd) in lakes. We set out to determine if this animal possesses a metallothionein-like protein to which its Cd could be bound and if the concentrations of such a protein are correlated with those of Cd in the insect and in lakewater. To achieve our goals, we collected water and larvae of several Chaoborus species from 10 lakes situated along an environmental Cd gradient. We found that all of the Chaoborus species possess a metallothionein-like protein and that concentrations of the protein and of Cd differed among species. Concentrations of the metallothionein-like protein were directly related to those in Chaoborus and in lakewater. These direct relationships support the use of Chaoborus larvae as a Cd biomonitor.