Environmental Entomology, XX(X), 2018, 1–8 doi: 10.1093/ee/nvy142 Forum Forum Bt Resistance Implications for Helicoverpa zea (Lepidoptera: Noctuidae) Insecticide Resistance Downloaded from https://academic.oup.com/ee/advance-article-abstract/doi/10.1093/ee/nvy142/5096937 by guest on 26 October 2018 Management in the United States Dominic D. Reisig1,3 and Ryan Kurtz2 1Department of Entomology and Plant Pathology, North Carolina State University, Vernon G. James Research and Extension Center, 207 Research Station Road, Plymouth, NC 27962, 2Agricultural & Environmental Research, Cotton Incorporated, 6399 Weston Parkway, Cary, NC 27513, and 3Corresponding author, e-mail:
[email protected] Subject Editor: Steven Naranjo Received 19 June 2018; Editorial decision 27 August 2018 Abstract Both maize and cotton genetically engineered to express Bt toxins are widely planted and important pest management tools in the United States. Recently, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) has developed resistance to two toxin Bt maize and cotton (Cry1A and Cry2A). Hence, growers are transitioning to three toxin Bt cotton and maize that express both Cry toxins and the Vip3Aa toxin. H. zea susceptibility to Vip3Aa is threatened by 1) a lack of availability of non-Bt refuge crop hosts, including a 1–5% annual decline in the number of non-Bt maize hybrids being marketed; 2) the ineffectiveness of three toxin cultivars to function as pyramids in some regions, with resistance to two out of three toxins in the pyramid; and 3) the lack of a high dose Vip3Aa event in cotton and maize. We propose that data should be collected on current Cry-resistant H.