Assimilation of Zinc, Cadmium, Lead and Copper By the Centipede Lithobius variegatus (Chilopoda)

Abstract

Specimens of L. variegatus Leach collected from a contaminated deciduous woodland 3 km downwind of a primary smelting works, and a similar but uncontaminated site, were fed hepatopancreas tissue from the woodlouse Oniscus asellus L. (Crustacea, Isopoda) containing known amounts of Zn, Cd, Pb and Cu. The extent to which Zn, Cd and Cu are assimilated or lost from the tissue of centipedes depends on the concentrations of these elements in the food and the degree of contamination of the site from which the centipedes are collected. Lead is not assimilated by L. variegatus. Centipedes from the contaminated site survive longer than centipedes from the uncontaminated site when both populations are fed on the hepatopancreas of woodlice in which the concentrations of metals are very high. This information, together with a consideration of the levels of metals in the animals at the end of the experiment, suggests that the midgut cells of centipedes from the contaminated site are able to tolerate higher concentrations of Cd than those of centipedes from the uncontaminated site. The concentrations of Cd and Cu in the midgut increase considerably when centipedes are fed on the hepatopancreas of woodlice from their ''own'' site. This suggests that adult O. asellus do not form a major proportion of the diet of L. variegatus in deciduous woodlands, although they probably consume large numbers of juvenile woodlice in which the concentrations of heavy metals are lower.