Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 3/2/2007
Publication Date: 7/5/2007
Citation: Greenberg, S.M., Adamczyk Jr, J.J., Armstrong, J.S., Coleman, R.J., Liu, T. 2007. Noctuid Survivorship and Damage in Widestrike, Bollgard, and Bollgard II Cottons in the Lower Rio Grande Valley of Texas. National Cotton Council Beltwide Cotton Conference, January 9-12, 2007, New Orleans, Louisiana. p. 316-320. Interpretive Summary: Beet armyworm, bollworm, cabbage looper, as a secondary cotton pest, may likely become major pests because the cotton boll weevil eradication program is currently in action, and natural enemies in cotton are under high adverse pressure from multiple applications of insecticides to control the boll weevil. Growers are aware, that in this case, the risk of secondary pest outbreaks will be increased and Bt cotton has proven to be a useful tool for controlling caterpillar pests, and augments activity of beneficial insects. Bt cotton, especially under the boll weevil eradication program, provides management options that have positive environmental, social, and economic outcomes. 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 yield and quality with acceptable costs.
Technical Abstract: In 2004-2006, Bt and non-Bt cottons were evaluated for control of bollworms, tobacco budworms, beet armyworms, and cabbage loopers in a small block trial. Results indicated less cotton damage and greater larval mortality for both dual gene products (Bollgard II® and WideStrike™) compared with Bollgard® and conventional cotton. Under densities that would exceed the threshold for these pests, Bt cottons typically showed some levels of reduced leaf and fruit damage, and the presence of live larvae, throughout the growing season, albeit some more efficacious than others. This increase in control contributed to greater cotton yield compared to conventional cotton. Under low lepidoteran populations, Bt and non-Bt cottons were similar in damage attributed to lepidopteran feeding as well as cotton yield.