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Helicoverpa zea and Bt Cotton in the United States

Permanent URL:
http://handle.nal.usda.gov/10113/55427
File:
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Abstract:
Helicoverpa zea (Boddie), the bollworm or corn earworm, is the most important lepidopteran pest of Bt cotton in the United States. Corn is the preferred host, but the insect feeds on most flowering crops and wild host plants. As a cotton pest, bollworm has been closely linked to the insecticide-resistance prone Heliothis virescens, tobacco budworm. Immature stages of the two species are difficult to separate in field environments. Tobacco budworm is very susceptible to most Bt toxins, and Bt cotton is considered to be “high dose”. Bollworm is less susceptible to Bt toxins, and Bt cotton is not “high dose” for this pest. Bt cotton is routinely sprayed with traditional insecticides for bollworm control. Assays of bollworm field populations for susceptibility to Bt toxins expressed in Bt cotton have produced variable results since pre-deployment of Bt cottons in 1988 and 1992. Analyses of assay response trends have been used by others to suggest that field resistance has evolved to Bt toxins in bollworm, but disagreement exists on definitions of field resistance and confidence of variable assay results to project changes in susceptibility of field populations. Given historical variability in bollworm response to Bt toxins, erratic field control requiring supplemental insecticides since early field testing of Bt cottons, and dramatic increases in corn acreage in cotton growing areas of the southern U.S., continued vigilance and concern for resistance evolution are warranted.
Author(s):
Randall G. Luttrell , Ryan E. Jackson
Subject(s):
Bacillus thuringiensis , Gossypium , Helicoverpa zea , Heliothis virescens , Zea mays , bacterial toxins , corn , cotton , evolution , field experimentation , hosts , insect control , insect pests , insecticide resistance , insecticides , plant pests , plant-insect relations , transgenic plants , United States
Source:
GM crops and food 2012 July-September v.3 no.3
Language:
English
Year:
2012
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
Rights:
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.