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Bollworm Survival on Reproductive Structures of Non-Transgenic (cv. Deltapine 5415) and Transgenic Bt (cv. NuCOTN 33B) Cottons

J. Gore, B. R. Leonard, T. S. Hall and J. H. Fife


 
ABSTRACT

A fresh cotton tissue bioassay was used to evaluate bollworm, Helicoverpa zea (Boddie), larval survival on selected components of non-transgenic (cv. Deltapine 5415) and transgenic Bacillus thuringiensis Berliner var. kurstaki (Bt) (cv. NuCOTN 33B) cotton flower buds (squares) and flowers. Squares and flowers were removed from field plots of Deltapine 5415 and NuCOTN 33B during three plant development stages. Plant development was based on the number of main-stem nodes between the uppermost white flower at the first position on a fruiting branch and the last unfolded leaf in the plant terminal. Growth stages included nodes above white flower (NAWF) 8 to 9, NAWF 6 to 7, and NAWF 4 to 5. Individual components were dissected from squares and flowers and placed into 9.9 cm Petri dishes with moistened filter paper. Treatments included whole intact squares (bracts removed); immature anthers, stigmas, and styles (square anthers); flower bracts; flower petals; and mature anthers, stigmas, and styles (flower anthers). Five neonate larvae were transferred into each Petri dish and 5 dishes were infested for each treatment at each growth stage. Treatments were arranged in a randomized complete block design with 4 replications. Bollworm survival was measured at 24, 48, and 72 hours after infestation (HAI). Data within each cultivar were subjected to analysis of variance and means were separated according to Fisher's protected LSD. Bollworm survivability was compared between NuCOTN 33B and Deltapine 5415 using paired t-tests.



Reprinted from Proceedings of the 2000 Beltwide Cotton Conferences pp. 975 - 976
©National Cotton Council, Memphis TN

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Document last modified Saturday, Jun 17 2000