New publication on chemical sensitivity of earthworms from field populations

The environmental risk of pesticides for nontarget soil macroorganisms has mainly been assessed using the compost earthworm Eisenia fetida. However, E. fetida does not occur in agroecosystems and it is generally less sensitive than other earthworm species. Thus, the extrapolation of its response to pesticides to other earthworm species may lead to uncertainties in the environmental risk assessment. Because toxicity data for other earthworm species are scarce, chemical sensitivity of earthworms from different habitats to imidacloprid and copper was assessed in acute toxicity tests. The present study included five species (Allolobophora chlorotica, Aporrectodea caliginosa, Aporrectodea longa, Aporrectodea rosea, and Lumbricus rubellus) from different habitats (forests, wetlands, and grasslands), as well as E. fetida. The relationship between earthworm traits (ecotype and weight), habitat characteristics (ecosystem type and soil pH), and chemical sensitivity was examined. The lower limits of the hazardous concentration affecting 5% (HC5) of species were 179 and 0.32 mg active ingredient/kg dry weight for copper and imidacloprid, respectively. Some concentrations that have been measured in European agroecosystems for both pesticides were above the HC5s, indicating toxic risks for these organisms. Furthermore, soil pH from the sampling habitat played a significant role, with earthworms sampled from extremely acidic soils being less sensitive to copper than earthworms from neutral soils. In addition, endogeic earthworms were more sensitive to imidacloprid than epigeic earthworms. This may translate to changes in soil functions such as bioturbation, which is mainly carried out by endogeic earthworms. The results of the present study suggest that environmental risk assessments should include a wider range of earthworms covering different habitats and ecosystem functions to achieve a better protection of the biological functions carried out by these key soil organisms.

For further information, read the open access publication in Environmental Toxicology and Chemistry:

Duque, T., Nuriyev, R., Römbke, J., Schäfer, R.B., Entling, M.H. (2023). Variation in the chemical sensitivity of earthworms from field populations to imidacloprid and copper. Environmental Toxicology and Chemistry 42, 939-947.

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