Bt maize can provide non‐chemical pest control and enhance food safety in China

Abstract

Summary China is the world's second‐largest maize producer and consumer. In recent years, the invasive fall armyworm Spodoptera frugiperda (J.E. Smith) has adversely affected maize productivity and compromised food security. To mitigate pest‐inflicted food shortages, China's Government issued biosafety certificates for two genetically modified (GM) Bt maize hybrids, Bt‐Cry1Ab DBN9936 and Bt‐Cry1Ab/Cry2Aj Ruifeng 125, in 2019. Here, we quantitatively assess the impact of both Bt maize hybrids on pest feeding damage, crop yield and food safety throughout China's maize belt. Without a need to resort to synthetic insecticides, Bt maize could mitigate lepidopteran pest pressure by 61.9–97.3%, avoid yield loss by 16.4–21.3% (range −11.9–99.2%) and lower mycotoxin contamination by 85.5–95.5% as compared to the prevailing non‐Bt hybrids. Yield loss avoidance varied considerably between experimental sites and years, as mediated by on‐site infestation pressure and pest identity. For either seed mixtures or block refuge arrangements, pest pressure was kept below established thresholds at 90% Bt maize coverage in Yunnan (where S. frugiperda was the dominant species) and 70% Bt maize coverage in other sites dominated by Helicoverpa armigera (Hübner) and Ostrinia furnacalis (Guenée). Drawing on experiences from other crop/pest systems, Bt maize in se can provide area‐wide pest management and thus, contribute to a progressive phase‐down of chemical pesticide use. Hence, when consciously paired with agroecological and biodiversity‐based measures, GM insecticidal crops can ensure food and nutrition security, contribute to the sustainable intensification of China's agriculture and reduce food systems' environmental footprint.

Long-term expansion of cereal crops promotes regional population increase of polyphagous Helicoverpa armigera

“…We suspect that area-wide adaptation of such Bt maize would reduce H. armigera infestation across the growing season, both in maize and in various spring and summer crops the following year. To delay the evolution of Bt resistance in H. armigera, refuges of non-Bt maize should be planned and required, given that the other crops that are hosts for H. armigera produce only a few overwintering individuals (Li et al, 2020b;Yang et al, 2022).…”

The invasive Spodoptera frugiperda (J.E. Smith) has displaced Ostrinia furnacalis (Guenée) as the dominant maize pest in the border area of southwestern China

“…69 The commercial cultivation of genetically modified (GM) Bacillus thuringiensis (Bt) crop varieties is a core constituent of IPM, e.g., suppressing the population of herbivorous pests, reducing pesticide use, and improving the ecology of crop fields. [71][72][73] Since 2002, the Bt corn events MON810 and Bt11 (expressing Cry1Ab protein) have been approved for commercial cultivation in Philippines and Vietnam, which proved to be effective against ACB, and drastically reduced leave injury and borer tunnels by 84-99%. 74,75 Moreover, the ACB populations in this area still remain susceptible to Bt corn hybrids containing Cry1Ab toxin.…”

Managing Practical Resistance of Lepidopteran Pests to Bt Cotton in China

“…However, the deeper commercialization of Bt corn and Bt soybean in China will pose a challenge to the natural refuge strategy of the cotton bollworm [ 86 ]. Small-scale experiments have shown that the control effect of transgenic insect-resistant corn on the fall armyworm ( Spodoptera frugiperda) could reach 95%, and the yield could increase by 6.7–10.7%, thus greatly reducing the cost of pest control [ 87 ]. The increase in yield and reduction in control costs may attract a large number of Chinese farmers to widely plant related varieties.…”