Earthworm-based test system applied for environmental risk assessment

Background and Objective

Compared to direct analyses of toxicities, recent findings on possible effects of GM plants on earthworms indicate that the investigation of life-history traits incl. fitness parameters are more relevant to conclude on potential long-term effects and changes in ecological functions. Furthermore, risk analyses on earthworms should not rely on common laboratory species, which are mostly irrelevant in field soils. The present study aims at developing laboratory test systems that could be used for standard testing of the impact of GM crops (here: maize and potatoes) of selected European biogeographic regions (atlantic, mediterranean and boreal) on respective focal earthworm species, defined here according to the EFSA ERA guidance document as focal species.

Approach

In a first step, earthworm species of significant functional relevance in different European bio-geographic regions will be identified. For this reason a literature survey has to be done in order to identify respective focal earthworm species as important non-target decomposers in the soil system. In a second step, the risk assessment will be conducted under constant laboratory conditions using microcosms with selected focal earthworm species, soil and residues of genetically modified crops. The risk assessment will focus on life-history traits of fitness and fertility, including longevity, biomass, developmental time (from hatch to sexual maturity), percentage of cocoon hatching, and biomass, fertility and survival of offspring.

Results

Based on condensed literature data, earthworm species, typically occurring in Irish, Spanish or Swedish arable soils, were selected as appropriate focal species for the respective biogeographical region (atlantic, mediterranean and boreal). According to the 4-step selection matrix of the EFSA Guidance Document on ERA (Environmental Risk Assessment) of GM plants, Aporrectodea caliginosa (endogeic) and Lumbricus terrestris (anecic) were selected as focal earthworm species. A laboratory ERA test system on their life-history traits has been developed and successfully applied to GM maize and GM potato.