"The focus is on the soil"

GMO Safety:  Maize that is resistant to the Western corn rootworm is awaiting approval in Europe, although only for cultivation at the moment. Which type of maize do you use for your field research?

Sabine Eber: We use MON88017 maize, which is resistant to the new pest Diabrotica. What’s special about this maize is that it produces the Bt toxin primarily in the roots, so exactly where the larvae feed and damage the plant. Maize with the Diabrotica resistance trait has been cultivated in the US since 2003 and just a few days ago an application for approval of this maize event as food and feed was submitted in Europe.

GMO Safety: What is the main focus of your research group?

Sabine Eber: Because of the ecology of the pest, the group’s focus is on the soil. Firstly the aim is to test whether and how the toxin, which is released into the soil, is broken down, or whether it accumulates there. Secondly, the aim is to see how the toxin affects soil life, i.e. ground beetles, earthworms and other organisms which break down dead plant parts. In addition, the group is investigating food-chain effects. This means that the research covers not only organisms that eat the plant directly, but also the predators of these ‘primary consumers’. There could conceivably be an accumulation effect along the food chain, which could in turn affect the breakdown rates in the soil. In this respect, we are also interested in the micro-organisms in the soil.

Another focus of the project is on research into the development of resistance. Since Diabrotica is a new pest in Europe, only a little is known about its host plant spectrum. Alternative host plants could act as a refugium for the pest if wandering larvae reach them and are able to eat them, thereby escaping the Bt toxin effect for a time. Another aim is to represent the effect mechanism of the Bt toxin on Diabrotica as a starting point for resistance management.

GMO Safety: How is the field trial research structured?

Sabine Eber: We are using a plot design with four different maize varieties, each repeated eight times: Bt maize, the isogenic line and two other conventional maize varieties. The plots are arranged in a largely random design, but with no two identical plots adjacent and with the same number of plots of each of the four varieties at the edge of the field.

GMO Safety: In the previous group project on MON810 there was always an insecticide variant as well. That’s been left out this time. Why?

Sabine Eber: In this release experiment the focus is different. In earlier experiments it was realised that insecticide treatment has a more serious effect on non‑target organisms than Bt maize. In this experiment, the main focus is on varietal differences. A problem with past research was often the differentiation between Bt and varietal effects. This is why the Bt event is being compared with three conventional maize varieties in our experiments.

But there is another reason for leaving out the insecticide variant. Insecticides which could be used against Diabrotica are not actually approved. So it would have been necessary to obtain exceptional authorisation to use them.