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ARS Home » Midwest Area » Ames, Iowa » Corn Insects and Crop Genetics Research » Research » Publications at this Location » Publication #404163
Research Project: Ecologically-based Management of Arthropods in the Maize Agroecosystem

Location: Corn Insects and Crop Genetics Research

Title: Extended sentinel monitoring of Helicoverpa zea resistance to Cry and Vip3Aa toxins in Bt sweet corn: Assessing changes in phenotypic and allele frequencies of resistance

Author
item DIVELY, GALEN - University Of Maryland
item KUHAR, THOMAS - Virginia Tech
item TAYLOR, SALLY - Virginia Tech
item DOUGHTY, HELENE - Virginia Tech
item HOLMSTROM, KRISTIAN - Rutgers University
item GILREIN, DAN - Cornell University
item NAULT, BRIAN - Cornell University
item INGERSON-MAHAR, JOSEPH - Rutgers University
item HUSETH, ANDERS - North Carolina State University
item EDWARD, TIMOTHY - North Carolina State University
item Abel, Craig
item Coates, Brad

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/2023
Publication Date: 6/25/2023
Citation: Dively, G.P., Kuhar, T.P., Taylor, S., Doughty, H.B., Holmstrom, K., Gilrein, D., Nault, B.A., Ingerson-Mahar, J., Huseth, A., Edward, T., Abel, C.A., Coates, B.S., et al. 2023. Extended sentinel monitoring of Helicoverpa zea resistance to Cry and Vip3Aa toxins in Bt sweet corn: Assessing changes in phenotypic and allele frequencies of resistance. Insects. 14(7):577. https://doi.org/10.3390/insects14070577.
DOI: https://doi.org/10.3390/insects14070577

Interpretive Summary: Corn and cotton expressing different insecticidal toxins derived from the soil bacterium, Bacillus thuringiensis (Bt), are widely adopted in the United States to control corn earworm/bollworm which has resulted in major benefits to growers and the general public. However, resistance evolution in corn earworm/bollworm populations has become a major threat to the sustainability of these crops. Bt sweet corn expressing the same toxins is more attractive to corn earworm/bollworm than field corn, and thus can function as a sentinel planting to detect early stages of resistance. As part of an existing sentinel monitoring network, this study evaluated changes in corn earworm/bollworm resistance during 2020-2022 by estimating the frequencies of resistance for each of the toxins expressed in Bt corn.

Technical Abstract: Corn and cotton expressing Cry1Ab, Cry2Ab2, Cry1A.105 and VipAa derived from Bacillus thuringiensis (Bt) are widely adopted in the United States to control lepidopteran pests. Corn earworm/bollworm, Helicoverpa zea (Boddie) is evolving resistance to these toxins which is a major threat to the sustainability of the Bt crops. Using Bt sweet corn as a sentinel planting to monitor resistance development, collaborators established 146 trials in 26 states and 5 Canadian provinces during 2020-2022. The study evaluated overall changes in the phenotypic resistance in H. zea populations and estimated resistance allele frequencies for each toxin. Results revealed widespread resistance to Cry toxins, with higher number of larvae surviving per Bt ears than non-Bt ears at many trial locations, and allele frequencies ranging from 0.46 to 0.99. Although Vip3Aa still provided high control efficacy against H. zea, results showed a notable increase in ear damage and number of surviving older larvae, particularly at southern locations. Estimated resistance allele frequencies for Vip3Aa ranged from 0.1153 in the Gulf states to 0.0317 at more northern locations. These findings indicate that better resistance management practices are urgently needed to delay further Vip3Aa resistance.