Are soil-dwelling nematodes sensitive to GM Bt maize?

Sebastian Höss of the Institute for Biodiversity in Regensburg has been studying nematodes in agricultural soils for years. Nematodes are very important for soil fertility. In one research project, Sebastian Höss and his team are therefore investigating whether nematodes are sensitive to a particular type of GM maize. No indications of sensitivity have been found so far. The research acitivties are documented in a report and a video clip.

Nematodes, or roundworms, are the most species-rich and abundant group of soil-dwelling organisms, and are found in almost all habitats, including the soil, rivers and lakes and the sea. By specialising in a range of different feeding habits, they occupy key positions in food webs and play a vital role in the soil nutrient cycle.

In a research project funded by the German Ministry of Education and Research, Sebastian Höss is investigating the effects on nematodes of the genetically modified Bt maize cultivar MON89034xMON88017, which contains three different Bt proteins. In the soil, nematodes can be exposed to the Bt proteins from Bt maize and are therefore potentially at risk. In laboratory experiments the scientists initially observed a negative effect of the Bt proteins on the nematodes. The nematodes responded to all three proteins with a significantly reduced breeding rate. However, the worms had been exposed to much higher concentrations of the Bt proteins than one would expect to find in the soil of a Bt maize field.

The Bt maize was then grown in field trials for three years and the team investigated whether the nematode communities were any different to those found in the fields of conventional maize, both in terms of numbers and in terms of species composition. According to the preliminary results of the 2008 and 2009 field trials, the Bt maize under investigation has no impact on the nematode communities in the soil. By contrast, significant changes in the nematode community were observed over the course of the growing season, and as a function of the sand content in the soil, irrespective of whether the plot contained genetically modified or conventional maize.

Source: farming monthly