Occurrence and distribution of earthworms in agricultural landscapes across Europe with regard to testing for responses to plant protection products

Purpose

Within the regulatory framework for authorisation of plant protection products (PPPs) (EU Directive 91/414/1991/EEC replaced by Regulation (EC) 1107/2009), higher tier risk assessments and earthworm field tests are conducted in different countries across Europe. This paper describes dominant earthworm species for regulatory and biogeographical regions in agricultural landscapes across Europe and examines regional differences in earthworm communities and densities and their respective response to a toxic reference.

Materials and methods

For the assessment of earthworm abundance and species distribution, data of untreated control plots from 30 earthworm field studies were analysed; each conducted according to the ISO 11268–3 (1999) guideline by European Crop Protection Association member companies in the context of registration of PPPs. For the evaluation of the response to PPPs under different regional and climatic conditions, the effect on earthworm abundance was assessed by comparing plots treated with toxic references with untreated control plots. Additionally, a comparative literature review was included providing an overview of earthworm species composition and densities in agricultural crops from 14 European countries.

Results and discussion

The assessment of earthworm field studies from six different European countries revealed that common earthworm species of anecic and endogeic ecological groups are present at most field sites. Dominant species groups of endogeic and anecic earthworms can be defined that are abundant in all assessed countries. These are the endogeic species Aporrectodea caliginosa, Aporrectodea rosea and Allolobophora chlorotica, and the anecic species Lumbricus terrestris (Northern and Central Europe) and Lumbricus friendi (Southern Europe). Taking into account the high variability in total earthworm abundances, it can be concluded that the variability within regions was larger than the variability between regions.

Conclusions

Analysis of the earthworm community and data of toxic references lead to the conclusion that testing in different zones is not considered necessary.