Faunistische Umweltrisikobewertung von Bt-Mais mit multiplen Resistenzgenen und Evaluierung von Trigonotylus caelestialium (Kirkaldy) und Lumbricus terrestris Linnaeus als Modellorganismen (2011)

Modern agricultural plants not only shall warrant a high yield, but also shall have resistance against several pests. Genetically modified Bt plants expressing Cry proteins from Bacillus thuringiensis (BERLINER) defend themselves specifically against pests. The maize line DKC 5143-Bt MON 89034 x MON 88017 expresses the Cry1A.105 and Cry2Ab2 against the Ostrinia nubilalis and the Cry3Bb1 against the Diabrotica virgifera virgifera. As all GM plants the risk for the consumer and the environment of these plants has to be assessed. One aspect of those studies is to consider the effects of the new plants on non-target organisms occurring in or next to the field. Therefore the exposition to new plant ingredients and their hazard for the organisms have to be studied in a risk assessment. To get robust and comparable results, working with surrogate species seems to be the best way. In this project arthropods of the herb layer and earthworms were chosen due to their important role in the field to show advantages and disadvantages of different approaches. Part A of the project dealt with the effects of growing the stacked maize line in a field release experiment on the biocoenosis of the soil, the herb layer and the male flowers. To study those, the Bt line was compared during three consecutive growing seasons to its near isogenic line, two conventional lines and a soil insecticidal treatment against Diabrotica virgifera virgifera. All sampled organisms were determined to family or species level and the data statistically analyzed. The measured communities showed no effect of the GM maize line. An influence of the conventional varieties could be observed. The GM maize line matched with the near isogenic line. Trigonotylus caelestialium (KIRKALDY) could be identified as the most abundant plant bug in the field. Therefore it was chosen as a surrogate species in part B of the project. Additionally the earthworm Lumbricus terrestris LINNAEUS as an established model was chosen and both studied in the laboratory. A concept to breed and keep T. caelestialium under controlled conditions was established and the fate of the ingested Cry proteins studied. A full life cycle test with all used maize varieties was performed. Adult L. terrestris were treated with pure Cry proteins or GM leaves in an earthworm avoidance test. A long term study with dried leaves or plants of all used maize lines was performed over 200 days. All data were statistically analyzed. T. caelestialium could be used as a model. A hazard of the ingested Cry proteins could not be observed. Hints for an accumulation could not be shown. After six hours an internal content of the proteins was no longer measurable. In the full life cycle test effects of conventional varieties could be observed. The bioactivity of the ingested Cry proteins could be shown in a first experiment. L. terrestris showed no avoidance of the pure Cry proteins in 100fold concentrations higher than those measured in the field. Due to methodical problems the long term approach had to be cancelled.