Research Bt Maize 2005-2008
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11 Projects
Research Projects
Research into the impact of Bt maize (Cry 3Bb1) on non-target organisms living in the soil
(2005 – 2008) Biological Research Centre for Agriculture and Forestry (BBA) (since 2008 Julius Kühn Institute (JKI)), Institute for Plant Protection in Field Crops and Grassland; Braunschweig
Labratory Cry3Bb1 Bt protein in maize plant litter did not affect the development of sciarid fly larvae in tested amounts of up to 16.45 micrograms per gram.
A significant reduction in offspring production was observed in the rove beetle Atheta coriaria after it had consumed sciarid fly larvae that had been reared on MON88017 Bt maize litter.
Field trial MON88017 Bt maize litter did not take longer to decompose in the field than maize litter from non-Bt varieties. Neither was the diversity of two-winged flies (dipterans) affected.
Research Projects
Research into side-effects of Bt maize (Cry3Bb1) on non-target organisms
(2005 – 2008) Biological Research Centre for Agriculture and Forestry (BBA) (since 2008 Julius Kühn Institute (JKI)), Institute for Biological Control, Darmstadt
Leaf beetles are related to the Western corn rootworm, which is targeted by the Bt maize variety being studied in this project (MON 88017).
Young larval stages in particular of three of the leaf beetle species studied were found to be sensitive to pure Cry3Bb1 protein on their food plants. The mortality rate was higher; weight gain and pupation rates were lower.
By contrast, when maize pollen was fed to two species of leaf beetle larvae, no negative effects on larval mortality, weight gain or pupation rate were observed.
Acute damage to the species investigated is unlikely under field conditions, since the amount of toxin ingested via the pollen is probably a lot less than the calculated LD50 dose.
Neither were any indications of possible chronic toxicity or sublethal damage found as a result of ingesting pollen from MON88017 maize.
Research Projects
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.
Research Projects
Development of resistance to Bt maize among Western corn rootworm
(2005 – 2008) University of Göttingen, Institute of Plant Pathology and Plant Protection, Göttingen
Bt maize with resistance to the Western corn rootworm (Diabrotica v. virgifera) primarily attacks the pest in its first larval stage. Unlike the European corn borer, the Western corn rootworm can also feed on other plants found in maize fields. If the newly hatched larvae initially eat these alternative host plants and then switch to maize, partially resistant pests could emerge over time, leading to the development of resistance over several generations.
Alternative host plants increase the probability of survival of the Western corn rootworm larvae. Important factors are the plant species and the positions of the plants within the crop.
A comparison of various different arrangements of refuges showed that the ‘refuge in a bag’ strategy, in which 20 per cent conventional seed is mixed in with the GM seed, encourages the development of partial resistance rather than preventing it. If Bt and conventional maize are grown in adjacent plots, a separation distance of at least two rows needs to be left between them to prevent the larvae, which are very mobile in the soil, from moving between them.
The presence of the larvae led to more serious colonisation by a fungus that produces a mycotoxin (F. verticillioides).
Research Projects
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.
Research Projects
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.
Research Projects
(2005 – 2008) Institute for Biodiversity - Experts Network, Regensburg
A large number of nematodes were found in the soil samples – two to four million per square metre. No significant differences were seen in the composition of the communities in terms of feeding types or diversity between the different maize varieties. Nematode biotest: No Bt effect was measured in the soil samples. This is attributed to the fact that the concentration in the soil never exceeded 1 ng/g dry weight of soil. In the laboratory, an effect was first measured concentrations above 36 mg/L; i.e., the concentration in the soil was far below the concentration that can produce an observable effect on the nematodes. In addition, no differences in nematode growth were found in tests with different leaf samples.
Research Projects
Monitoring the effects of Bt maize (Cry1Ab) on non-target organisms
(2005 – 2007) Federal Biological Research Centre for Agriculture and Forestry (BBA) (since 2008 Julius Kühn Institute (JKI)), Institute for Integrated Plant Protection, Kleinmachnow
Varietal differences were found among the insects in the herbaceous layer and among the pollen feeders and flower visitors, but no Bt effect was found. Fluctuations were attributed to differences in soil and weather conditions. There were also fluctuations from year to year.
Research Projects
Research into the activation of Bt proteins in the Western corn rootworm
(2005 – 2008) Federal Biological Research Centre for Agriculture and Forestry (BBA) (since 2008 Julius Kühn Institute (JKI)), Institute for Biological Control, Darmstadt
Bt Protein (in this project Cry3Bb1, which targets the Western corn rootworm) is broken down by certain enzymes (proteases) in the intestinal juice of insects.
The intestinal juice of the Western corn rootworm was found to contain a whole range of different proteases.
In individual tests on the types of proteases found in the intestinal juice, some commercially available proteases broke down the Cry3Bb1 protein. In tests with intestinal juice from the Western corn rootworm, however, Cry3Bb1 and two other Bt toxins (Cry34Ab1 and Cry35Ab1) were not broken down. The probability of protease-related resistance to the Bt proteins studied is therefore judged to be slight.
During these experiments the team characterised the specific binding sites for the Bt toxins in the intestinal wall.
Research Projects
Impacts of the cultivation of Diabrotica-resistant Bt maize on the maize ecosystem
(2005 – 2008) RWTH Aachen University, Institute of Environmental Research (Biology V) Chair of Ecology, Ecotoxicology and Ecochemistry
In the field trial a comparison of the feeding activity of the soil fauna in the various maize variants - MON88017 Bt maize, the isogenic variety and two other conventional varieties – found no differences. A comparison of the feeding activity on different types of bait in one maize variant (isogenic) found variety-specific differences in some years.
In mesocosms (model field system, soil cores, diameter 30 cm, height 40 cm) no difference in feeding activity was found between the different maize varieties.
Ground beetles: No differences in ground beetle numbers or species spectrum were found between the various maize variants.
The level of Bt protein decreased by at least a factor of 20 along the food chain (maize – European corn borer – ground beetle).
Biotests did not find any acute Bt effect on ground beetles.
Research Projects
Effects of the cultivation of Diabrotica-resistant Bt maize on the maize ecosystem II
(2005 – 2008) RWTH Aachen University, Institute of Environmental Research (Biology V), Chair of Environmental Biology and Chemodynamics
Varietal differences were found among the insects in the herbaceous layer and among the pollen feeders and flower visitors, but no Bt effect was found. Fluctuations were attributed to differences in soil and weather conditions. There were also fluctuations from year to year.
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