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United States Department of Agriculture

Agricultural Research Service

Title: Development of Bollworm, Helicoverpa Zea (Boddie), on Two Commercial Bollgard Cultivars That Differ in Overall Cry1ac Levels

Authors
item Adamczyk, John
item Gore, Jeffrey

Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 18, 2004
Publication Date: October 8, 2004
Citation: Adamczyk, Jr., J.J., Gore, J. 2004. Development of bollworm, Helicoverpa zea (Boddie), on two commercial Bollgard cultivars that differ in overall Cry1Ac level. Journal of Insect Science. Available online: insectscience.org/4.32.

Interpretive Summary: Research was conducted to determine the development of a common caterpillar pest, the bollworm, on two different genetically modified cotton cultivars that contained different levels of Bacillus thuringiensis (Bt.), a common soil bacterium. Using a field cage, an inverse relationship between the level of Cry1Ac among cultivars versus the weight of bollworm larvae was observed. Larvae that were recovered from the lower level cultivar weighted significantly more than larvae collected from the higher level cultivar. Cotton plants from the higher level cultivar were measured as expressing 300% more Bt than the lower expressing cultivar.

Technical Abstract: Research was conducted to quantify the development of the corn earworm (= bollworm), Helicoverpa zea (Boddie), on two different transgenic cotton cultivars that contained different levels of the Cry1Ac delta-endotoxin from the soil bacterium, Bacillus thuringiensis Berliner, (Bt). Using a field cage, an inverse relationship between the amount of Cry1Ac among cultivars versus the weight of bollworm larvae was observed. Larvae that were recovered from the lower expressing DP 50B cultivar weighed significantly less than larvae collected from the higher expressing NuCOTN 33B cultivar. Cotton plants from NuCOTN 33B were measured as expressing 300% more Cry1Ac than DP 50B plants. The distribution of larval weights indicates that more late-instars (> 200 mg) were collected from the lower expressing DP 50B cultivar than the higher expressing NuCOTN 33B cultivar. Within a single population, bollworm larvae were highly variable in their development when feeding on Bollgard cotton. Possible reasons and consequences for this variation are discussed.

Last Modified: 4/20/2014
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