Ants as bioaccumulators of metals from soils: Body content and tissue-specific distribution of metals in the ant Crematogaster scutellaris

• Crematogaster scutellaris ants were collected from polluted and unpolluted sites.
• Whole body burdens and tissue-specific distribution of six metals were examined.
• Five metals accumulated in ants or had concentrations correlated with soil amounts.
• Metals concentrated in the midgut, the Malpighian tubules and fat body.

Ants possess several features that make them good candidates as indicators of environmental contamination. Concentrations of six metals (Cu, Cd, Ni, Mn, Pb and Zn) were investigated in Crematogaster scutellaris, a myrmicine ant common throughout the Mediterranean basin. Concentrations of metals in ant bodies and soil samples from polluted and unpolluted sites were compared. Tissue-specific distribution of metals in a non-soluble form was examined using a novel technique that coupled histological imagery and micro-PIXE analysis. Zinc and cadmium accumulated in ants with respect to the soil. Copper body burdens were independent of soil concentration, while lower concentrations of nickel, manganese and lead were found in ants than in the soil, although ant body content was correlated with soil concentrations. Most of the metals were concentrated in the midgut, the Malpighian tubules and fat body, supporting the role of these organs as primary sites of metal storage and contaminant immobilization.