Control efficacy of Bt-Cry1Ab maize (event DBN9936) against Ostrinia furnacalis (Guenée) in Sichuan Province, China.

Background: The Asian corn borer (ACB), Ostrinia furnacalis (Guenée), is a major pest restricting maize production in Asia. The Chinese government has approved the commercial planting of Bt-Cry1Ab maize (event DBN9936), but its control potential against the ACB in southern regions remains unclear. This study evaluated the sensitivity of ACB to Cry1Ab protein expressed in Bt-Cry1Ab maize and determined the control efficacy of Bt-Cry1Ab maize against the ACB in Sichuan Province, a major maize-producing region in southern China, based on pilot planting in the field, and larval feeding bioassays in the field and laboratory.

Result: The Cry1Ab protein contents in different tissues of Bt-Cry1Ab maize ranged from 31.20-88.27 μg g^-1. The range of median lethal concentrations (LC₅₀) and median growth inhibitory concentration (GIC₅₀) values of Cry1Ab protein expressed in Bt-Cry1Ab maize against ACB larvae were 0.036-0.109 μg mL^-1 and 0.002-0.018 μg mL^-1, respectively. The first and fourth instar ACB larvae were unable survive feeding on different tissues of Bt-Cry1Ab maize plants. Field experiments conducted from 2023 to 2024 indicated that the number of ACB larvae per 100 plants, plant damage rate, leaf damage rate, male ear damage rate, female ear damage rate, and stalk damage rate in the Bt-Cry1Ab maize fields were reduced by 95.36% ± 2.17%, 83.98% ± 1.73%, 89.45% ± 1.50%, 100.00% ± 0.00%, 69.79% ± 4.88% and 100.00% ± 0.00%, respectively, compared to conventional maize fields.

Conclusion: The ACB population in Sichuan Province, China is sensitive to Cry1Ab expressed in Bt-Cry1Ab maize (event DBN993). Planting Bt-Cry1Ab maize efficiently reduces the population of ACB larvae and the percentage of damaged maize plants, and has great application potential in the integrated pest management of the ACB in Sichuan Province, China. © 2024 Society of Chemical Industry.