Heavy metals as stressing factors in the red wood ants (Formica polyctena) from industrially polluted forests

Abstract

Relations between metal contaminations in social groups of ants from colonies of Formica polyctena, from 5 localities variously contaminated by industrial pollution, and their metabolic and detoxifying strategies have been investigated. Cd, Pb, Zn, Mn, Cu levels have been measured in social groups of workers and pupae throughout the season. Patterns of metabolic, transport and detoxifying enzymes have been assayed and phosphoadenine nucleotides and the energy charge (AEC) have been determined. The metal content is a measure of the level of contamination and has been the highest in foragers returning to the nest. Body burdens of Cd, Pb and Zn diminished progressively from the surface workers to those from the inner part of the hill. The concentration of total adenylates was slightly lower than stated in Finnish ants poisoned with Cd, but the AEC index was always above 0.8, with high variations between the social groups. Carboxylesterases showed a positive correlation of activity pattern with the metal load in foraging workers, with the highest value for cadmium load in ants from a locality in the middle of a pollution gradient. The pattern of superoxide dismutase activity has been site-dependent, but it did not correlate well with the metal load in workers.