Plant background, not Bt proteins, drives Daphnia magna life table responses: a multi-tissue chronic study with
Yi Chen1, Hang Tang1,2, Shulin Ma1,2
1Sanya Research Institute & Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Sanya, Hainan, China.
Introduction:
The environmental safety of genetically engineered (GE) crops expressing insecticidal proteins remains debated, partly because observed biological effects are often difficult to distinguish from natural variation in plant genetic background.
Methods:
Here, we conducted a 21-day chronic feeding experiment to assess the effects of two Bt maize lines expressing three insecticidal proteins on the aquatic model organism Daphnia magna. Individuals were exposed to four ecologically relevant maize materials (pollen, leaves, flour, and straw leachate), alongside near-isogenic non-engineered controls and eight conventional maize varieties used to establish a natural variation baseline.
Results:
Protein concentrations varied substantially among tissues and between maize lines. However, life-table responses of D. magna, including survival, reproduction, and growth, were more strongly influenced by plant genetic background than by the presence of insecticidal proteins. Importantly, nearly all response values observed under exposure to Bt maize fell within the natural variation range defined by conventional varieties.
Discussion:
These results indicate that the tested maize lines do not cause biologically meaningful effects beyond the variability inherent to conventional crops. More broadly, this study demonstrates that incorporating natural variation baselines provides a robust and generalizable framework for distinguishing trait-related effects from background variability, thereby improving the scientific basis of environmental risk assessment for GE crops.
