Assessing the effect of soil properties on the toxicity of pesticides to soil invertebrates

Background

Before being allowed on the market, pesticides have to be tested for their possible risk to soil invertebrates. This is among others done by performing toxicity tests with earthworms, springtails and predatory mites as representatives of the soil invertebrate communities. These tests usually are performed according to internationally accepted test guidelines, and using an artificial test soil. Since this soil by definition has an organic matter content of 10%, which is higher than found in most agricultural soils (typically 5%), regulatory authorities divide the outcome of such tests by a factor of 2 to correct for differences in soil organic matter content, and to arrive at a more realistic assessment of the possible risk of the pesticide.

However, the factor of 2 has only a weak scientific basis. It is based on acute toxicity tests with earthworms for a few selected chemicals. Additionally, little data is available on the influence of other soil properties (i.e. pH, clay content, etc.) on the toxicity of pesticides to soil invertebrates. As a consequence, there is an urgent need for a better underpinning of the correction of soil toxicity data for differences in soil properties.

Approaches

Toxicity tests will be performed with earthworms and other soil invertebrates to assess the effect of soil properties on the toxicity of selected pesticides. The tests will focus on sublethal endpoints like growth and reproduction, and use both the standard artificial soil as well as a range of different field soils with different organic matter contents.

What you can learn?

Culturing and toxicity testing with different species of soil invertebrates, determining basic soil properties, analysis of dose-response relationships and statistical methods to compare differences between dose-response relationships for different soils. You will write a scientific report at the end of this internship, with the possibility of contributing to a publication in a peer-reviewed scientific journal.

Supervision and information

Prof.dr. C.A.M. (Kees) van Gestel
Room H150, W&N building, VU Amsterdam
E-mail: kees.van.gestel@vu.nl
Phone: +31 (0)20 – 59 87079

B.G. (Bart) van Hall MSc
Room M152, W&N building, VU Amsterdam
E-mail: b.g.vanhall@vu.nl