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ARS Home » Pacific West Area » Maricopa, Arizona » U.S. Arid Land Agricultural Research Center » Pest Management and Biocontrol Research » Research » Publications at this Location » Publication #432379
Research Project: Sustainable Pest Management for Arid-Land Agroecosystems

Location: Pest Management and Biocontrol Research

Title: Field assessment of the effects of Cry1Ac and Cry1Ac + Cry2Ab Bt cotton against pink bollworm in Pakistan

Author
item HANIF, MAHREEN - Muhammad Nawaz Shareef University Of Agriculture
item SAEED, SHAFQAT - Muhammad Nawaz Shareef University Of Agriculture
item ALI, MUDSSAR - Muhammad Nawaz Shareef University Of Agriculture
item ISHTIAQ, MUHAMMAD - Muhammad Nawaz Shareef University Of Agriculture
item KHAN, ZULQURNAIN - Muhammad Nawaz Shareef University Of Agriculture
item LI, XIANCHUN - University Of Arizona
item Fabrick, Jeffrey

Submitted to: Journal of Cotton Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/2025
Publication Date: 2/4/2026
Citation: Hanif, M., Saeed, S., Ali, M., Ishtiaq, M., Khan, Z., Li, X., Fabrick, J.A. 2026. Field assessment of the effects of Cry1Ac and Cry1Ac + Cry2Ab Bt cotton against pink bollworm in Pakistan. Journal of Cotton Research. 9(1). Article 7. https://doi.org/10.1186/s42397-025-00253-x.
DOI: https://doi.org/10.1186/s42397-025-00253-x

Interpretive Summary: Transgenic crops producing insecticidal proteins derived from the bacterium Bacillus thuringiensis (Bt) are used globally to manage some insect pests, including the pink bollworm, a major pest of cotton. Whereas Bt cotton has been successfully used with sustained susceptibility in China and the United States, pink bollworm has evolved resistance to cotton producing single Bt Cry toxin (Cry1Ac) and two Cry toxins (Cry1Ac + Cry2Ab) in India. Because of Pakistan’s proximity to India’s resistant populations and its heavy use of Bt cotton, recent studies in that country suggest that pink bollworm has similarly evolved resistance to transgenic Bt cotton. Here, an ARS scientist from Maricopa, AZ, and collaborators assessed field trials of non-Bt cotton, Cry1Ac Bt cotton, and Cry1Ac + Cry2Ab Bt cotton for pink bollworm infestation and damage in Pakistan in 2020 and 2021. High levels of infestation in flowers and bolls, as well as extensive seed damage, and cotton seed yield loss were observed in all tested varieties. Only one Bt cultivar producing Cry1Ac + Cry2Ab showed a significant reduction in pink bollworm infestation and protection from seed damage, although it was not entirely impervious to pink bollworm attack. Cotton plants were determined to produce both Cry1Ac and Cry2Ab proteins, albeit at relatively low levels, indicating that pink bollworm populations in Pakistan may not be encountering effective toxin concentrations and/or may be exhibiting field-evolved resistance to these toxins. These conditions indicate that immediate action is needed to manage this important global pest of cotton.

Technical Abstract: Background. Transgenic cotton producing toxins derived from the bacterium Bacillus thuringiensis (Bt) is used globally to manage insect pests, including the pink bollworm, Pectinophora gossypiella, one of the most damaging pests of cotton. The use of Bt cotton, which produces either a single Bt Cry toxin (Cry1Ac) or two Cry toxins (Cry1Ac'+'Cry2Ab), has sustained susceptibility and successfully managed pink bollworm in both China and the United States. In contrast, pink bollworms in India have evolved practical resistance to Bt cotton producing Cry1Ac or Cry1Ac'+'Cry2Ab. Recent studies suggest that pink bollworm may have similarly evolved resistance to transgenic Bt cotton in neighboring Pakistan. Results. Field trials of non-Bt cotton, four Cry1Ac Bt cotton varieties, and six Cry1Ac'+'Cry2Ab Bt cotton were assessed for pink bollworm infestation and damage in Pakistan in 2020 and 2021. High levels of infestation in flowers and bolls, as well as cotton seed yield loss were observed in all the tested cultivars. Only one Bt cultivar producing Cry1Ac'+'Cry2Ab (MNH-1045) showed a significant reduction in pink bollworm infestation and protection from seed damage, although it was not entirely resistant to pink bollworm attacks. Conclusion. Cotton plants were determined to produce both Cry1Ac and Cry2Ab proteins, albeit at relatively low levels, indicating that pink bollworm populations in Pakistan may not encounter effective toxin concentrations and/or may be exhibiting field-evolved resistance to these toxins. Immediate action is needed to manage this important pest of cotton.