To illustrate the impact of genetically modified (GM) Bt maize on the natural enemy communities in the Huang-Huai-Hai summer maize-growing region in China, the abundance of seven common predator groups (Geocoris pallidipennis, Harmonia axyridis, lacewings, Orius sauteri, Propylea japonica, spiders, Staphylinidae) was quantitatively evaluated by planting Bt-Cry1Ab DBN9936 and Bt-Cry1Ab/Cry2Aj Ruifeng 125 events during the growing season from 2016 to 2019. A total of 11,172- 13,739 predators were observed in each varieties during four years, and the abundance of each groups on Bt maize varied between sample dates and among those enemy taxons. The shannon-Wiener diversity index from seven groups showed very similar temporal dynamics and there were not significant differences in Bt and non-Bt maize, showing that Bt maize did not disrupt the stability of predator enemy aggregation in the field. Spiders, H. axyridis, P. japonica, Lacewing, O. sauteri with positive taxon weights after using principal response curve (PRC) method, indicated that Bt maize had a positive effect on the abundances of individual taxa. All this indicating that the two Bt maize hybrids did not adversely affect predator community in the Huang-Huai-Hai summer maize-growing region of China.

Whole-plant visual inspections were carried out every 7 days from the 20th day after planting to harvest in each Bt and non-Bt maize plot during 2016-2019. We used a five-point sampling method along the two corner-to-corner diagonals in each plot, and twenty plants were selected from each point (totaling 100 plants sampled per plot, per time and each replication). The numbers of visible natural enemies on leaves, ears, husks, stalks, sheaths, and tassels were noted, and the total numbers per plot (100 plants) were counted.