Comparative Production of Helicoverpa zea (Lepidoptera: Noctuidae) from Transgenic Cotton Expressing Either One or Two Bacillus thuringiensis Proteins with and without Insecticide Oversprays

• Published in: Journal of economic entomology 2004-10, Vol.97 (5), p.1719-1725
• Main Authors: Jackson, R. E., Bradley, J. R., Van Duyn, J. W., Gould, F.
• Format: Article
• Language: English
• Subjects: Animals; Bacillus thuringiensis; Bacillus thuringiensis subsp. kurstaki; Bacterial Proteins - biosynthesis; Bacterial Toxins - biosynthesis; Biological and medical sciences; bolls; bollworm; Control; cotton; crop damage; crystal proteins; Endotoxins - biosynthesis; Fundamental and applied biological sciences. Psychology; Generalities; Gossypium - genetics; Gossypium - parasitology; Gossypium hirsutum; Helicoverpa zea; Hemolysin Proteins; Insecticide Resistance; INSECTICIDE RESISTANCE AND RESISTANCE MANAGEMENT; Insecticides; Lepidoptera; Pest Control, Biological - methods; pesticide application; Phytopathology. Animal pests. Plant and forest protection; Plants, Genetically Modified; population density; Population Dynamics; Protozoa. Invertebrates; pyrethroid insecticides; resistance management; spraying; transgenic plants
• ISSN: 0022-0493; 1938-291X; 0022-0493
• DOI: 10.1603/0022-0493-97.5.1719

Transgenic cotton, Gossypium hirsutum (L.), expressing either one or two Bacillus thuringiensis ssp. kurstaki Berliner (Bt) proteins was compared with the conventional sister line in field experiments with regard to production of bollworm, Helicoverpa zea (Boddie), and bolls damaged by bollworm. The relative numbers of bollworms that developed on Bollgard (Monsanto Co., St. Louis, MO), Bollgard II (Monsanto Co.), and conventional cotton were estimated under nontreated conditions in 2000 and both insecticide-treated and nontreated conditions in 2001–2002 in North Carolina tests. Averaged across seven field studies under nontreated conditions, Bollgard cotton generated statistically similar numbers of large (L4–L5) bollworm larvae compared with the conventional variety; however, Bollgard cotton produced significantly fewer damaged bolls and bollworm adults than the conventional variety. Production of large larvae, damaged bolls, and adults was decreased dramatically by Bollgard II cotton as compared with Bollgard and conventional varieties. When comparing insecticide-treated and nontreated cotton genotypes, both Bt cotton sustained less boll damage than the conventional variety averaged across insecticide regimes; furthermore, Bollgard II cotton had fewer damaged bolls than the Bollgard variety. When averaged across cotton genotypes, pyrethroid oversprays reduced the numbers of damaged bolls compared with the nontreated cotton. Insecticide-treated Bollgard cotton, along with insecticide-treated and nontreated Bollgard II cotton reduced production of bollworm larvae, pupae, and adults. However, the addition of pyrethroid oversprays to Bollgard II cotton seemed to be the best resistance management strategy available for bollworm because no bollworms were capable of completing development under these conditions.