The effects of the Cry1Ab toxin from Bacillus thuringiensis (corn variety Cascade Bt MON810 and DeKalb variety 618 Bt) were studied on survival and reproduction of the soil collembolan Folsomia fimetaria, Folsomia candida, the collembolan predator mite Hypoaspis aculeifer and enchytraeids Enchytraeus crypticus. The toxicity was observed in Petri dishes with plaster of Paris substrate and in a soil-litter microcosm toxicity test system on both single species and in a predator-prey interacting test system. In petri dishes, roots and leaves of young plants (three weeks) were fed to F. candida for 16 days, dried leaves of mature plants collected after harvest and artificial food (mixture of dried leaves with yeast) were fed to F. fimetaria for 21 days. In the single species soil test system, F. fimetaria and E. crypticus were exposed for 21 days to increasing concentrations of young Bt plant material, max. 40 g kg-1 soil, and increasing concentrations of dried mature Bt plant material, max. 10g kg-1 soil. H. aculeifer and its prey F. fimetaria were used in the predatory-prey two species test system. They were exposed to increasing concentrations of dried mature Bt plant material of max. 20 g kg-1 soil for 21 days. Cry1Ab toxin was analysed by ELISA (PSB 05500 Agdia). After 16 day exposure to young plant, the reproduction of F. candida fed Bt roots was significantly reduced, while there was no statistical difference between the reproduction of F. candida fed Bt and non-Bt leaves. There was a weak significant reduction by 30% on the reproduction of F. fimetaria fed Bt corn in Petri dishes for 21 days. Likewise there was a weak significant reduction by 40% of the reproduction of H. aculeifer by Bt corn in amounts corresponding to 20 g plant material kg-1 soil in the two species soil-litter microcosm systems. There were no effects of Bt corn materials on the reproduction of F. fimetaria and E. crypticus in the single species soil-litter microcosms. No effects of Bt corn materials on mortality of all the 4 species were observed in all treatments. The tendency of effects of the Bt corn on the reproduction of F. fimetaria, F. candida and H. aculeifer is discussed.
Soil fauna Bt-toxin Collembola Gamasida
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International Symposium on The Biosafety of Genetically Modified Organisms, 2003