The Influence of Transgenic Cottons Expressing One or Two Bacillus Thuringiensis Proteins Against Helicoverpa zea (Lepidoptera: Noctuidae) and Factors Affecting B. t. Resistance in H. zea

Show simple item record

dc.contributor.advisor J. R. Bradley, Jr., Committee Co-Chair en_US Jackson, Ryan Everett en_US 2010-04-02T19:18:50Z 2010-04-02T19:18:50Z 2002-11-06 en_US
dc.identifier.other etd-11052002-144451 en_US
dc.description.abstract Because control of bollworm with transgenic Bacillus thuringiensis var. kurstaki cottons that express the Cry1Ac protein has not been absolute compared to that of tobacco budworm, transgenic cottons expressing two B. t. proteins (Cry1Ac + Cry2Ab) have been developed to provide greater control of bollworm. To substantiate this, various field, greenhouse, and laboratory studies were designed to investigate the influence of single-gene and dual-gene B. t. cottons, Bollgard® and Bollgard II, respectively, against bollworm and to determine the elements affecting resistance evolution to the Cry1Ac and Cry2Ab endotoxins. Bollgard II cottons exhibited an increased field efficacy against bollworm by reducing larval survival and associated damage compared to Bollgard cottons. Seed cotton yields of Bollgard II cottons were comparable to those of Bollgard cottons under pyrethroid-treated and non-treated conditions. In greenhouse studies, Bollgard II cottons exhibited an increased efficacy against both a feral and Cry1Ac-selected strain of bollworm compared to that of Bollgard cottons. The Cry1Ac-selected strain exhibited increased survival and damage potential compared to the feral strain on both Bollgard and Bollgard II cottons, which suggests that Bollgard II cottons should be commercialized before field level resistance occurs to Bollgard cottons. In field studies, Bollgard II cottons offered the best B. t. resistance management strategy available for bollworm since bollworm adult production was much lower in Bollgard II cottons than in Bollgard cottons. Pyrethroid oversprays may also serve as an effective resistance management tool by reducing bollworm larval production and consequently, adult production. Laboratory studies indicated that no measurable shift has occurred in the frequency of major resistance genes for Cry1Ac or Cry2A proteins. Reciprocal cross data suggested that inheritance of resistance to Cry1Ac and Cry2Ab proteins is dominant or semi-dominant. Results demonstrated that there is heritable variation for minor resistance genes that could decrease the efficacy of Bollgard cottons. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject Helicoverpa zea en_US
dc.subject Bacillus thuringiensis en_US
dc.subject insect resistance management en_US
dc.title The Influence of Transgenic Cottons Expressing One or Two Bacillus Thuringiensis Proteins Against Helicoverpa zea (Lepidoptera: Noctuidae) and Factors Affecting B. t. Resistance in H. zea en_US PhD en_US dissertation en_US Entomology en_US

Files in this item

Files Size Format View
etd.pdf 761.7Kb PDF View/Open

This item appears in the following Collection(s)

Show simple item record