Zinc tolerance in the ant species Myrmica rubra originating from a metal pollution gradient

This study was designed to test whether the ant species Myrmica rubra had developed a tolerance to metal pollution. Larvae and workers, collected from seven sites located along a metal pollution gradient in the vicinity of Olkusz, Poland were exposed to a range of Zn concentrations in food, artificially contaminated in a laboratory experiment. The mortality of adults and larvae, as well as maximum larvae body mass, was recorded. The results of this study indicate that larvae mortality was independent of the site pollution, but decreased significantly with the Zn concentration in food. Opposite results were found for workers: irrespectively of Zn concentration in the food, the mortality decreased with site pollution, indicating enhanced metal tolerance in workers. Contrary to the expectations, the maximum larvae mass estimated with the von Bertalanffy curve, increased by the pollution gradient. Larvae were more sensitive to Zn than the adults, but their higher mass at the most polluted sites, may have enhanced tolerance to metal pollution.