Journal of Economic Entomology (2015) 108, 2761-2769

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Eric C. Burkness, T.M. Cira, S.E. Moser and W.D. Hutchison (2015)
Bt maize seed mixtures for Helicoverpa zea (Lepidoptera: Noctuidae): Larval movement, development, and survival on non-transgenic maize
Journal of Economic Entomology 108 (6), 2761-2769
Abstract: In 2012 and 2013, field trials were conducted near Rosemount, MN, to assess the movement and development of Helicoverpa zea (Boddie) larvae on non-Bt refuge corn plants within a seed mixture of non-Bt and Bt corn. The Bt corn hybrid expressed three Bt toxins—Cry1Ab, Cry1F, and Vip3A. As the use of seed mixtures for insect resistance management (IRM) continues to be implemented, it is necessary to further characterize how this IRM approach impacts resistance development in ear-feeding Lepidopteran pests. The potential for Bt pollen movement and cross pollination of the non-Bt ears in a seed mixture may lead to Bt toxin exposure to larvae developing on those refuge ears. Larval movement and development by H. zea, feeding on non-Bt refuge plants adjacent to either transgenic Bt or non-Bt plants, were measured to investigate the potential for unintended Bt exposure. Non-Bt plants were infested with H. zea eggs and subplots were destructively sampled twice per week within each treatment to assess larval development, location, and kernel injury. Results indicate that H. zea larval movement between plants is relatively low, ranging from 2–16% of larvae, and occurs mainly after reaching the second instar. Refuge plants in seed mixtures did not produce equivalent numbers of H. zea larvae, kernel injury, and larval development differed as compared with a pure stand of non-Bt plants. This suggests that there may be costs to larvae developing on refuge plants within seed mixtures and additional studies are warranted to define potential impacts.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Eric C. Burkness, William (Bill) D. Hutchison

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
resistance/tolerance/defence of host

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Helicoverpa zea Maize/corn (Zea mays) U.S.A. (mid N)
Bacillus thuringiensis Cry1A-toxin (entomopathogen) Helicoverpa zea Maize/corn (Zea mays) U.S.A. (mid N)
Bacillus thuringiensis Cry1F-toxin (entomopathogen) Helicoverpa zea Maize/corn (Zea mays) U.S.A. (mid N)
Bacillus thuringiensis Vip-toxins (entomopathogen) Helicoverpa zea Maize/corn (Zea mays) U.S.A. (mid N)