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ARS Home » Southeast Area » Stoneville, Mississippi » Southern Insect Management Research » Research » Publications at this Location » Publication #415092
Research Project: Ecologically Sustainable Approaches to Insect Resistance Management in Bt Cotton

Location: Southern Insect Management Research

Title: Resistance allele frequency to Cry1Ab and Vip3Aa20 in Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) in Louisiana and three other Southeastern U.S. States

Author
item LIN, S. - Louisiana State University
item OYEDIRAN, I. - Syngenta Crop Protection
item NIU, Y. - Louisiana State University
item BROWN, S. - University Of Tennessee
item COOK, D. - Mississippi State University
item NI, X. - US Department Of Agriculture (USDA)
item ZHANG, Y. - Syngenta Crop Protection
item REAY-JONES, P.F. - Clemson University
item CHEN, J.S. - Syngenta Crop Protection
item WEN, Z - Syngenta Crop Protection
item DIAMASE, M. - Louisiana State University
item HUANG, F. - Louisiana State University

Submitted to: Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2022
Publication Date: 4/2/2022
Citation: Lin, S., Oyediran, I., Niu, Y., Brown, S., Cook, D., Ni, X., Zhang, Y., Reay-Jones, P., Chen, J., Wen, Z., Diamase, M., Huang, F. 2022. Resistance allele frequency to Cry1Ab and Vip3Aa20 in Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) in Louisiana and three other Southeastern U.S. States. Toxins. 04/02/2022. https://doi.org/10.3390/toxins14040270.
DOI: https://doi.org/10.3390/toxins14040270

Interpretive Summary: Insects often develop resistance to toxicants used to control them in agronomic crops. This paper measured the frequency of resistance alleles in corn earworm from wild populations. Resistance allele frequencies increased were very low for Vip3A.

Technical Abstract: The corn earworm/bollworm, Helicoverpa zea (Boddie), is a pest species that is targeted by both Bacillus thuringiensis (Bt) maize and cotton in the United States. Cry1Ab and Vip3Aa20 are two common Bt toxins that are expressed in transgenic maize. The objective of this study was to determine the resistance allele frequency (RAF) to Cry1Ab and Vip3Aa20 in H. zea populations that were collected during 2018 and 2019 from four southeastern U.S. states: Louisiana, Mississippi, Georgia, and South Carolina. By using a group-mating approach, 104 F2 iso-lines of H. zea were established from field collections with most iso-lines (85) from Louisiana. These F2 iso-lines were screened for resistance alleles to Cry1Ab and Vip3Aa20, respectively. There was no correlation in larval survivorship between Cry1Ab and Vip3Aa20 when the iso-lines were exposed to these two toxins. RAF to Cry1Ab maize was high (0.256) and the RAFs were similar between Louisiana and the other three states and between the two sampling years. In contrast, no functional major resistance allele (RA) that allowed resistant insects to survive on Vip3Aa20 maize was detected and the expected RAF of major RAs with 95% probability was estimated to 0 to 0.0073. However, functional minor RAs to Vip3Aa20 maize were not uncommon; the estimated RAF for minor alleles was 0.028. The results provide further evidence that field resistance to Cry1Ab maize in H. zea has widely occurred, while major RAs to Vip3Aa20 maize are uncommon in the southeastern U.S. region. Information that was generated from this study should be useful in resistance monitoring and refinement of resistance management strategies to preserve Vip3A susceptibility in H. zea.