Cadmium, zinc, lead and copper inChironomus riparius (Meigen) larvae (Diptera, Chironomidae): uptake and effects

Abstract

Cadmium, Zn, Pb and Cu uptake and effects in larvae of Chironomus riparius (Meigen) were studied in an integrated laboratory investigation, in which metal analyses in different instar stages, uptake kinetics and effects on development and growth were considered in three separate experiments.In short-term experiments with fourth instar larvae, it was demonstrated that only a minor portion of metals was adsorbed on the larval exoskeletons. No conclusive evidence on the uptake mechanism was found, but active uptake of trace metals seemed highly unlikely.In partial life cycle experiments, all four metals studied were readily accumulated in chironomid larvae. Uptake could be described satisfactorily utilizing a first-order one-compartment uptake model which incorporated growth. In all cases steady state conditions were approached and high uptake and elimination rate constants were estimated. Distinct differences between essential (Zn and Cu) and nonessential (Cd and Pb) metals were noted. Larval growth was significantly impaired upon exposure.Finally, long-term exposure experiments with low Cd concentrations (0.010 and 0.025 mg I -) resulted initially in growth impairment and high mortality in first instar stages, but surviving larvae restored growth and adults emerged even before control adults. In similar experiments with Zn (0.1 and 1.0 mg I ), development of larvae was significantly retarded. High Zn concentrations in larvae were noted and almost no adult midges emerged.

Chronic toxicity of cadmium to Chironomus riparius (Diptera: Chironomidae) at different food levels

“…At higher cadmium concentrations (both 5.6 and 16.2 Ixg Cd/L), however, negative effects were observed. This is in accordance with data from Pascoe et al (1989) and Timmermans et al (1992), who observed a reduction of the growth rate and an increased mortality at 15 and 10 Ixg Cd/L, respectively. Hatakeyama (1987Hatakeyama ( , 1988 reported that the number of eggropes deposited per female Polypedilulm nubifer (Diptera, Chironomidae) is insensitive to both copper and cadmium, as we found in our cadmium experiments with well-fed C. riparius.…”

Hormesis and stage specific toxicity induced by cadmium in an insect model, the queen blowfly, Phormia regina Meig.

“…Stage specific toxicity observed in these experiments are consistent with reports in the mosquito (Aedes aegypti) (Rayms-Keller et al, 1998) (Aedes albopictus) (Bellini et al, 1988), fruit fly (Drosophila melonogaster) (Lynch et al, 1991), housefly (Musca domestica) (Raina et al, 2001), and chironomids ( Timmermans et al, 1992 andWentsel et al, 1978). The stage-specific effects in these blowfly experiments are in general agreement with the previously reported studies.…”

Alterations in life-history traits of Chironomus riparius (diptera) obtained from metal contaminated rivers

“…The present observations on both the chronic toxicity of cadmium and the life-history characteristics of unexposed field populations of C. riparius are in good agreement with those based on laboratory populations (Pascoe et al 1989;Postma and Davids 1995;Timmermans et al 1992). The hatchability of egg masses was, however, exceptional as it was low for unexposed populations (about 50-60%, compared to 80-100% for laboratory populations) and decreased significantly under cadmium exposure.…”