Movement of Bt toxin (Cry3Bb1) in the soil

(2005 – 2008) University of Göttingen, Institute of Applied Biotechnology in the Tropics (IBT e.V.)

Cry3Bb1 Bt protein binds more strongly than Cry1Ab to the clay fractions of the plots under investigation. The Cry3Bb1 protein was found to bind more strongly to the clay fraction in the topsoil than in the subsoil.
Cry3Bb1 could move to lower soil layers in soils with a low binding capacity. However, the type and extent of movement depend on the stability of the Cry proteins, the properties of the soil and the microbial activity in the soil in question.

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Persistence of the Bt toxin Cry1Ab in areas where Bt maize is grown

(2004 – 2007) Federal Agricultural Research Centre (FAL)(since 2008 Johann Heinrich von Thünen-Institut (vTI)), Institute of Agroecology; Braunschweig

Cry1Ab levels in the roots were on average 30,000 times higher than in the rhizosphere soil. Fifteen months after harvesting, no more Cry 1Ab was found on any of the sites. There was also no movement of the toxin to deeper soil layers.

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Breakdown of Bt toxin and effects on micro-organisms in the soil

(2005 – 2008) Federal Agricultural Research Centre (FAL) (since 2008 Johann Heinrich von Thünen Institute (vTI)), Institute of Agroecology; Braunschweig

No differences were found in the bacterial community of the soil in the root area which could be attributed to the genetic modification.
Cry3Bb1 levels in the soil are very low compared with those in intact roots, which are around 600,000 times higher.
Harvest residues: Cry3Bb1 concentrations in root residues four weeks after harvesting correspond to only around one percent of the levels in intact roots.

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Bt maize: Effects on soil organisms – a Swiss field study

(2005 – 2006) The Zoological Institute, University of Bern, Switzerland

Overall, no significant differences were found either in the number of soil-dwelling decomposers or in the breakdown of the leaf material between the different maize varieties. There were no preferences for individual maize varieties, i.e. the varieties are comparable in terms of their nutritional quality.

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Safety research project: Environmental effects of Bt gene

(2000 – 2004) Bavarian State Research Center for Agriculture, Freising

The cultivation of Bt maize has been shown to have no negative effects on beneficial insects (earthworms, springtails, aphids, cicadas, parasitic wasps, lacewings, hover fly larvae, ladybirds, predatory bugs and spiders). It was noticed that there were shifts in occurrence of some groups in Bt maize fields. However, these shifts did not always occur consistently during the trial period. Application of an insecticide had a clear negative effect on various species.
Butterflies: In the laboratory, maize pollen from Bt176 varieties was found to have an adverse effect on caterpillars, but this has not been replicated in field trials, where no adverse effects have yet been found.

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Is Bt toxin from genetically modified maize bound in the soil?

(2001 – 2004) University of Göttingen, Institute of Applied Biotechnology University of Trier, Department of Soil Science/Soil Chemistry

The higher the level of organic matter, particularly in the upper soil layers, the less Bt toxin is bound.
The lower the negative charge of the soil particles, the more Bt toxin is bound.
The larger the surface area of the soil particles, the more Bt toxin is bound to the soil particles.

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Breakdown of Bt maize in soils and impacts on micro-organisms

(2001 – 2004) Federal Agricultural Research Centre (FAL), Institute of Agroecology; Braunschweig

Bt toxin (MON810) in plant roots leads to slight shifts in micro-organism communities. These are less significant than changes caused by different soils, the age of the plant or variations in field conditions.
Small quantities of Bt toxin persist beyond the vegetation period. The quantities of Bt toxin released remain below the threshold for triggering effects in the target organisms. For this reason the toxin is unlikely to have an effect on non-target organisms.

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