Accumulation of Cu and Ni in successive stages of Lymantria dispar L. (lymantriidae, lepidoptera) near ore smelters at Sudbury, Ontario, Canada

Abstract

The accumulation of Cu and Ni in successive life stages of the gypsy moth ( Lymantria dispar), feces, and foliage near an ore smelter at Sudbury, Ontario and a control site was investigated. Higher concentrations of Cu and Ni were found in all larval stages collected at Sudbury than in those from the control site indicating that elevated levels of these metals in the Sudbury environment is an important factor influencing body burdens. These differences were associated with higher metal concentrations in the foliage of host trees from this site. However, differences between sites became less significant for pupae and adult stages. At the Sudbury site, concentrations of Cu (μg g −1 dry wt) decreased in successive instars and then increased in tissues of pupae and adults. In contrast, Cu content (μg/individual) increased during larval development and then decreased in pupae and adults. The pattern of Ni concentration and content in larvae from the Sudbury site was similar to that of Cu. Patterns of Cu and Ni concentration and content throughout the life stages are explained by changes in weight resulting in a dilution effect in early stages, and a concentrating effect in later stages. Differences in Cu and Ni concentration and content between Sudbury and control populations became less significant following the pupal stage suggesting metal elimination with the exuviae and meconium. This study also illustrates the importance of sampling all stages in an insect's development when measuring accumulation of metals. Fecal and foliar concentrations of Cu and Ni from Sudbury were not significantly different suggesting that metal assimilation is low. Even though gypsy moths from Sudbury contain elevated levels of Cu and Ni, metal burdens in their tissues do not represent a significant route through the food chain. However, the conversion of foliage with high metal content to feces implies that other ecosystem consequences should be investigated.