Toxicological and Biochemical Analyses Demonstrate the Absence of Lethal or Sublethal Effects of cry1C- or cry2A-Expressing Bt Rice on the Collembolan Folsomia candida

Yan Yang, Bing Zhang, Xiang Zhou, Jörg Romeis, Yufa Peng, Yunhe Li

Assessing the potential effects of insect-resistant genetically engineered (GE) plants on collembolans is important because these common soil arthropods may be exposed to insecticidal proteins produced in GE plants by ingestion of plant residues, crop pollen, or root exudates. Laboratory studies were conducted to evaluate the potential effects of twoBacillus thuringiensis(Bt)-rice lines expressing Cry1C and Cry2A in pollen and leaves and of their non-Btconventional isolines on the fitness of the collembolanFolsomia candidaand on the activities of its antioxidant-related enzymes, superoxide dismutase and peroxidase, and of its detoxification-related enzymes, glutathione reductase and glutathioneS-transferase. Survival, development, reproduction, and the intrinsic rate of increase (rm) were not significantly reduced whenF. candidafed on theBtrice pollen or leaf powder than on the non-Btrice materials; these parameters, however, were significantly reduced whenF. candidafed on non-Btrice pollen or non-Btleaf-based diets containing the protease inhibitor E-64 at 75 μg/g. The activities of the antioxidant-related and detoxification-related enzymesin F. candidawere not significantly affected whenF. candidafed on theBtrice materials, but were significantly increased whenF. candidafed on the non-Btrice materials containing E-64. The results demonstrate that Cry1C and Cry2A are not toxic toF. candida, and also indicate the absence of unintended effects on the collembolan caused by any change in plant tissue nutritional composition due to foreign gene transformation.