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Title: Artificial infestations of transgenic cotton with beet armyworm (Lepidoptera: Noctuidae) and evaluation of insect mortality and damage under field conditions

Author
item Greenberg, Shoil
item Adamczyk, John
item Yang, Chenghai

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 2/5/2010
Publication Date: 4/15/2010
Citation: Greenberg, S.M., Adamczyk Jr, J.J., Yang, C. 2010. Artificial infestations of transgenic cotton with beet armyworm (Lepidoptera: Noctuidae) and evaluation of insect mortality and damage under field conditions. National Cotton Council Beltwide Cotton Conference. CDROM.

Interpretive Summary: Transgenic cottons expressing insecticidal crystal proteins are important tools for management of key lepidopteran pests in the United States. Companies and breeders annually produce numerous numbers of transgenic cottons. Assessing the efficacy of Bt cotton under new environment and management regimes is of prime importance to the companies which produce new or improved existing transgenic products, breeders, which create different varieties stacked with Bt endotoxins, and growers, which use them for production cotton. Field performance of cotton containing endotoxins should be standardized. In this presentation, we demonstrated our results of bioassays of beet armyworm (BAW), Spodoptera exigua (Hübner) on different transgenic cottons, and discussion about criterion needed for standardizations of field methods evaluation efficacy of Bt cottons. Only these findings can provide accurate and stabilized data for insect control with different transgenic technology.

Technical Abstract: Transgenic cottons containing Bollgard(R), Bollgard II(R), and Widestrike(TM) traits along with nonBt cotton were grown during 2005-2009, to examine efficacy against beet armyworm, Spodoptera exigua (Hubner), and (BAW) in field performance using natural and artificial infestations. Damage and mortality of BAW assessed by visual observation and ground reflectance spectra indicated that both dual-gene traits were significantly more efficacious than the single gene trait. The best method for field evaluations of effectivness of different Bt and non-Bt cottons on BAW survival and leaf damage was artificial infestation with adults. We demonstrated that field bioassays with BAW on different transgenic cottons using natural and artificial infestations that can serve as a standard. The criteria needed for standardization of field methods for evaluations of efficacy of Bt cottons under artificial infestation are discussed.