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Open AccessArticle

Demographic Performance of Helicoverpa zea Populations on Dual and Triple-Gene Bt Cotton

1
Department of Entomology, Universidade Federal de Viçosa, Viçosa 36570-900, MG, Brazil
2
Department of Entomology and Nematology, West Florida Research and Education Center, University of Florida, Jay, FL 32565, USA
3
National Institute of Science and Technology in Plant-Pest Interactions, Universidade Federal de Viçosa, Viçosa 36570-900, MG, Brazil
4
Department of Entomology and Nematology, University of Florida, Gainesville, FL 32608, USA
*
Author to whom correspondence should be addressed.
Toxins 2020, 12(9), 551; https://doi.org/10.3390/toxins12090551
Received: 2 July 2020 / Revised: 10 August 2020 / Accepted: 26 August 2020 / Published: 28 August 2020
(This article belongs to the Section Bacterial Toxins)
Insecticidal toxins from Bacillus thuringiensis (Bt) are valuable tools for pest management worldwide, contributing to the management of human disease insect vectors and phytophagous insect pests of agriculture and forestry. Here, we report the effects of dual and triple Bt toxins expressed in transgenic cotton cultivars on the fitness and demographic performance of Helicoverpa zea (Boddie)—a noctuid pest, known as cotton bollworm and corn earworm. Life-history traits were determined for individuals of three field populations from a region where H. zea overwintering is likely. Triple-gene Bt cotton cultivars that express Cry and Vip3Aa toxins killed 100% of the larvae in all populations tested. In contrast, dual-gene Bt cotton that express Cry1Ac+Cry1F and Cry1Ac+Cry2Ab allowed population growth with the intrinsic rate of population growth (rm) 38% lower than on non-Bt cotton. The insects feeding on Bt cotton plants that express Cry1Ac+Cry2Ab, Cry1Ac+Cry1F, or Cry1Ab+Cry2Ae exhibited reduced larval weight, survival rate, and increased development time. Additionally, fitness parameters varied significantly among the insect populations, even on non-Bt cotton plants, likely because of their different genetic background and/or previous Bt toxin exposure. This is the first report of the comparative fitness of H. zea field populations on dual-gene Bt cotton after the recent reports of field resistance to certain Bt toxins. These results document the population growth rates of H. zea from an agricultural landscape with 100% Bt cotton cultivars. Our results will contribute to the development and validation of resistance management recommendations. View Full-Text
Keywords: fitness; life table; cotton bollworm; corn earworm; toxin; resistance management fitness; life table; cotton bollworm; corn earworm; toxin; resistance management
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MDPI and ACS Style

Rabelo, M.M.; Paula-Moraes, S.V.; Pereira, E.J.G.; Siegfried, B.D. Demographic Performance of Helicoverpa zea Populations on Dual and Triple-Gene Bt Cotton. Toxins 2020, 12, 551.

AMA Style

Rabelo MM, Paula-Moraes SV, Pereira EJG, Siegfried BD. Demographic Performance of Helicoverpa zea Populations on Dual and Triple-Gene Bt Cotton. Toxins. 2020; 12(9):551.

Chicago/Turabian Style

Rabelo, Marcelo M.; Paula-Moraes, Silvana V.; Pereira, Eliseu J.G.; Siegfried, Blair D. 2020. "Demographic Performance of Helicoverpa zea Populations on Dual and Triple-Gene Bt Cotton" Toxins 12, no. 9: 551.

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