Apr 2, 2008

Research Maize

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Bt maize and nature conservation

“Bt maize pollen outside of maize fields does not pose a threat to butterflies.”

In future a separation distance of 800 metres between Bt maize fields and nature reserves will have to be observed in the German state of Brandenburg. A corresponding ruling by the Brandenburg State Office for the Environment is based on pollen measurements carried out at the Ruhlsdorfer Bruch nature reserve. GMO Safety spoke to Prof. Ingolf Schuphan from the Institute of Environmental Research at RWTH Aachen University.

Prof. Ingolf Schuphan, RWTH Aachen University, has been studying the possible ecological effects of Bt maize fur 10 years. He is the coordinator of three large research associations funded by the Federal Ministry of Education and Research (BMBF), as well as several European research projects.

Photo: presentation of results from the current research association at the BMBF conference on biosafety research on 10 March 2008 in Berlin.

GMO Safety: You have been involved in several research projects which have looked at the effects of Bt toxin on non-target organisms. Do you think special measures are needed to protect nature reserves from the possible harmful effects of Bt maize?

Ingolf Schuphan : The Bt protein produced in Bt maize acts specifically against butterfly and moth larvae. However, it only eliminates the larvae of the European corn borer, since they are the only ones which eat the maize. Other butterfly and moth larvae don’t eat maize. This high degree of specificity of the Bt protein protects the ecological community in the maize field, whilst effectively controlling the European corn borer. From an ecological perspective, this makes it the perfect selective crop protection agent, because beneficial organisms are protected. This is why organic farmers like using conventional Bt sprays.

GMO Safety: Better protection for rare species of butterfly is cited as the reason for the 800 metre separation distance.

Ingolf Schuphan: We know from many studies that maize pollen concentrations are very low outside maize fields. Pollen landing on the leaves of caterpillar fodder plants is significantly reduced by the effects of wind and rain. Furthermore, pollen is only released over a few days and this only rarely coincides with the larval stage of the butterflies. All the national and international literature clearly supports the fact that Mon810 pollen concentrations outside fields of MON810 Bt maize with field margins of at least 10 metres are insufficient to harm butterfly populations. Results from our own BMBF-funded research projects also confirm this. Any reports on the toxic effects of Bt maize on butterflies in the literature refer to the Bt176 strain of Bt maize. This contains 10 to 20 times more Bt protein than MON810 maize. Bt176 maize is now no longer licensed in the EU.

GMO Safety: But isn’t the ruling on separation distances in Brandenburg based on pollen measurements from the Ruhlsdorfer Bruch nature reserve?

Ingolf Schuphan: The results of these pollen measurements actually support the current understanding that there is no danger to butterflies outside of Bt maize fields, even Habitats Directive sites and nature reserves. In areas adjacent to the maize fields, 175 pollen grains per square centimetre were recorded. The amount of Bt maize pollen in these samples was between ten and thirty percent. At a distance of 120 metres, ten pollen grains per square centimetre were recorded, in other words one to three grains of Bt maize pollen per square centimetre. This was the total amount recorded throughout the pollen season. In studies of the highly sensitive monarch butterflies in the USA, MON810 Bt maize was found to have an effect only in concentrations of 1000 pollen grains per square centimetre or more. The large copper butterfly has also been given the all clear.

GMO Safety: It has also been mentioned that storks and cranes visit maize fields and may also be at risk from Bt maize. You are also an ornithologist - do you share these concerns?

Ingolf Schuphan: The lifestyle of storks and cranes alone is enough to prevent this: they prefer damp habitats. Maize fields are not attractive to either species. Even if individual storks or cranes were to stray onto maize fields, they feed mainly on small creatures such as earthworms and beetles; storks even eat mice. We know from studies that Bt protein levels in animals decrease along the food chain. Consequently only ineffective traces of Bt protein (if indeed any) would be absorbed. In autumn when cranes gather for migration, individual cranes could conceivably eat maize kernels on harvested fields, but this would be of no significance because of the tiny concentrations involved. In addition, we know from feed trials that Bt protein has no effect on birds. According to current scientific knowledge, we can rule out any harmful effects of Bt maize on storks, cranes and other birds.

GMO Safety: Once again: Can you see any scientific justification for the 800-metre separation distance now agreed in Brandenburg?

Ingolf Schuphan: No. It is a political decision. Even the study carried out at the Ruhlsdorfer Bruch nature reserve at the request of the Brandenburg State Office for the Environment, which was cited as justification, confirms that MON810 pollen concentrations outside of maize fields are much too low. Our research findings clearly show that the cultivation of MON810 Bt maize has no harmful effects on the ecosystem. Separation distances from nature reserves are not necessary. The minimum separation distances of 150 and 300 metres stipulated in the Genetic Engineering Act serve only to reduce outcrossings to adjacent conventional maize fields.