Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 24, 2010
Publication Date: August 31, 2010
Citation: Greenberg, S.M., Adamczyk Jr, J.J. 2010. Effectiveness of transgenic Bt cottons against noctuids in the Lower Rio Grande Valley of Texas. Southwestern Entomologist. 35(4):539-549. Interpretive Summary: In the USA, transgenic cottons are important tools in minimizing the risk of outbreaks of lepidopterans and augment the activity of beneficial insects. Our data suggest that varieties of dual Bt traits can be a vital tool in the LRGV, especially under the Boll Weevil Eradication Program. Bt cotton large field performance can be assessed from both an environmental standpoint in terms of the reduction in chemical pesticides usage and from a commercial standpoint in terms of the benefit to the growers in producing high yields and quality at acceptable cost.
Technical Abstract: Evaluations of the comparative efficacy of Bacillus thuringiensis Bollgard, Bollgard II and non-Bt traits expressing cottons for control of the noctuid complex composed of bollworms, Helicoverpa zea (Boddie), fall armyworms, Spodoptera frugiperda (J.E. Smith), beet armyworms, Spodoptera exigua (Hübner) and cabbage loopers, Trichoplusia ni (Hübner) were conducted in the Lower Rio Grande Valley of Texas during 2004-2008. Under high populations of this noctuid complex, Bollgard II cotton had significantly reduced leaf, fruit damage and numbers of live larvae throughout the growing season compared with non-Bt trait. Under low to moderate lepidopteran populations, these two technologies were similar in damage. One insecticide application on Bollgard, Bollgard II, Widestrike and non-Bt traits significantly reduced the number of bollworm and beet armyworm larvae and damage on fruiting structures per hectare compared to untreated cotton. Beet armyworm leaf damage and larval survival rates on non-Bt cotton was 3.6-fold higher than Bollgard II and WideStrike, and 1.5-fold higher than on Bollgard trait varieties.