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Effects of Large Scale Bt Cotton Production on Tobacco Budworm Populations

Wade Worley, Frank Mitchener, Tucker Miller, III, R.G. Luttrell, J.C. Schneider


Pheromone trap captures and egg densities of tobacco budworm were monitored in large blocks of Bt and non-Bt cotton in Tallahatachie County, MS, to examine the effects of large scale Bt cotton production on tobacco budworm populations. Data from the unreplicated observations indicated that tobacco budworm populations were reduced 40 to 60% during July and August in the center of a management unit approximately 0.6 miles in radius. Bt cotton provided effective control of tobacco budworm season long, even when populations reached densities 10 fold those typically triggering insecticide applications. Laboratory colonies established from males collected in the Bt cotton did not exhibit measurable levels of resistance to Bt endotoxin. The amount of population reduction observed in the Bt cotton was much more than that expected for the size of the area planted to Bt cotton using previously obtained estimates of tobacco budworm movement for May and June. This suggests that tobacco budworm movement during later periods of the growing season may be less than that previously estimated for May and June when cotton is actively flowering. Given the importance of population level effects on resistance management and area-wide manage-ment strategies, more detailed studies of within season movement of tobacco budworm are needed.

Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 917 - 920
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998