Toxic effects of the fungicide carbendazim on the midge Chironomus riparius in two consecutive generations and the detection of body burden after metamorphosis

Environmental pollution is an ongoing threat to biodiversity worldwide, and pesticides largely account for that. Micropollutants may enter sensitive and threatened aquatic ecosystems via run-off or as wastewater effluents. The fungicide carbendazim (CBZ) is used as a biocide in paints for outdoor use and as a systemic broad-spectrum plant protection product. To assess the toxic effects of CBZ to aquatic organisms, a spiked sediment life-cycle test with the midge Chironomus riparius was conducted according to the OECD guideline 233. Six concentrations were used, from 0.25 μg/g up to 8 μg/g sediment. Midges were allowed to reproduce and larvae were exposed to the same CBZ concentration as the parental generation. Toxic effects were significantly stronger in the second generation (EC 50 = 2.39 ± 0.24 μg/g) than in the first (EC 50 = 3.13 ± 0.29 μg/g). In the second generation, emergence was delayed and the population growth rate decreased. Accumulation of CBZ in midges was analyzed in pools of 3 to 6 individuals using a newly established extraction method. CBZ was detected in all tested adult midges from all treatments, except the controls. A concentration-dependent increase of CBZ accumulation was observed only in the first generation, but tissue concentration correlated with mortality in both generations. We described the toxic effects of CBZ to chironomids in environmentally relevant concentrations, combined with CBZ tissue concentrations. Our findings further demonstrate that CBZ can be spread in different environmental compartments due to tissue accumulation, potentially causing biomagnification in the consuming species. • CBZ exposure led to delayed emergence and reduced reproduction of Chironomus riparius • Toxic effects of CBZ to larvae increased in the second generation • Imago body burden was determined with the SWIEET extraction method • Body burden correlated positively with mortality in both generations • Male midge body burden correlated negatively with fecundity in the second generation