Influence of metal concentrations in food on metal uptake and accumulation in sawfly larvae

Uptake and accumulation of Cd, Cu, Fe, and Zn by sawfly larvae, Dolerus sp, were studied. Larvae were reared under controlled conditions, allowing their uptake of ingested metals to be calculated after exposure to two different doses of metals. After 10 days of exposure, the concentration of Cd was higher than at the start of exposure, whereas concentration of Cu was higher only in the high dose group. In contrast, the Fe concentration decreased during exposure. Concentrations of Zn in the larvae were the same irrespective of the Zn concentrations in the food. Uptake of the metals, quantified in percent of ingested amounts, was 11% for Cd in both low and high dose groups. The uptake of Zn was 26% at the low dose and 12% at the high dose, while that of Cu was 12% and 19%, respectively. There was a loss in both low and high doses of Fe. The amount of a metal taken up by the larvae was correlated with their growth increment. In conclusion, the concentrations of Cd and Cu in plants influence the concentrations of these metals in plant-eating insects more than the Fe and Zn concentrations.