| Popis: |
1. Acute toxicity tests with the Bt-spray product MVP®II (active substance Cry11Ac) exhibited in Folsomia candida a LC50 of 12,48 mg/g Lufa 2.1 soil and 1,08 mg/g quartzous sand. Presumably this was an effect of seed treatment products. 2. Trypsin-resistant Cry1Ab (Monsanto, SLFA Neustadt) caused no effects on F. candida in acute toxicity tests (maximum concentration: 80 respectively 125 µg/g soil). 3. Trypsin-resistant Cry1Ab (Monsanto) caused no effect on F. candida in reproduction tests (maximum concentration: 80 µg/g soil). 4. Vital leave material from both, transgenic and non-transgenic corn (Nobilis and Novelis, Mon810) caused total inhibition of reproduction of F. candida. It was supposed that inhibitory substances of the leaves caused total inhibition of reproduction. 5. A greenhouse model system with the components soil-corn (Novelis/Nobilis)-F. candida was developed. It was demonstrated that seed treatment products could cover possible effects of Bt-corn. 6. Tests with washed seeds exhibited significant higher reproduction rates. The almost identical reproduction rates indicate the standardisation of the model test system. 7. Summing up the results obvious negative effect of Cry1Ab expressing corn on F. candida could be detected. 8. Investigations on abundances of collembola and mites in the soil of field experiment plots never indicated significant differences between isogenic untreated, isogenic insecticide treatment and transgenic plots. 9. The reduction of DMSO can be used to determine the microbial activity. For this purpose investigations of the soil from field experiment plots were carried out. There was no indication for a negative impact of Bt-corn on the microbial activity in the soil. 10. The ECB-population adapted to sagebrush was susceptible to all used Cry1Ab toxins. 11. The LC50 was 0,19 µg/ml culture medium for trypsin-resistant Cry1Ab (Monsanto) and 1,63 µg/ml culture medium for Syngenta-protoxin. The results did not differ significantly from the results with ECB-population adapted to corn.12. The effectiveness of the SLFA trypsin-resistant core protein was clearly reduced. This result highlights that Cry1Ab protein from different producers can differ in their effectiveness. 13. Mating experiments demonstrated that internal mating was significantly more successful than mating between ECB adapted to sagebrush and ECB adapted to corn (“hybrid mating”). 14. The living period of the adults did not differ significanty but hybrid mating exhibited a delayed first oviposition. 15. The low probability for a female to lure a male belonging to the other pheromone strain combined with the obtained results indicate that ECB-populations adapted to sagebrush will not be suitable to act as a reservoir for susceptibility alleles for delaying resistance. |
