Multigenerational effects of cultivating transgenic maize straw on earthworms: A combined laboratory and field experiment

The cultivation of genetically modified (GM) maize has aroused notable public concern related to the potential risks to soil fauna caused by the release of foreign proteins. In this study, the potential effects of cultivating the GM maize variety DBN9936, which exhibits the expression of the Cry1Ab and EPSPS proteins, on earthworms (Eisenia fetida) were evaluated under laboratory and field conditions. No significant differences in the survival, body weight, cocoon production, or hatching of earthworms fed GM or non-GM DBN318 maize were detected after three consecutive generations in a laboratory test. The enzymatic activity assay results revealed no significant differences in superoxide dismutase (SOD) or catalase (CAT) enzyme activity between the GM and non-GM maize varieties. Furthermore, exogenous Cry1Ab and EPSPS proteins were undetectable in the gut tissues of earthworms raised with GM maize straw. GM maize cultivation imposed no adverse effects on the species composition or density of soil earthworms in the two consecutive years during the field test, and the soil earthworm species, total number of earthworms and density of each earthworm species did not significantly differ between the GM maize and non-GM maize lines. On the basis of our findings, we concluded that the cultivation of the GM maize variety DBN9936 does not pose a risk to earthworms.