Laboratory and Field Performance of Cotton Containing Cry1Ac, Cry1F, and both Cry1Ac and Cry1F (Widestrike®) Against Beet Armyworm and Fall Armyworm Larvae (Lepidoptera: Noctuidae)

J. J. Adamczyk Jr, J. Gore

Abstract


The efficacy of transgenic cotton genotypes containing Cry1Ac, Cry1F, and Cry1Ac stacked with Cry1F (WideStrike®, Dow Agrosciences, Indianapolis, IN) were investigated during 2001-2003 against the beet armyworm, Spodoptera exigua (Hübner) (=BAW), and the fall armyworm, Spodoptera frugiperda (J. E. Smith) (=FAW), in laboratory bioassays and small experimental field plots. In all experiments, cotton containing Cry1F was more toxic to BAW and FAW larvae compared to cotton containing only Cry1Ac. In the majority of experiments, the addition of Cry1Ac to the Cry1F genotype had no increased effect on efficacy and certain biological parameters against BAW and FAW larvae compared to cotton containing only Cry1F. Furthermore, the presence or absence of an additive, synergistic, or antagonistic effect between Cry1Ac and Cry1F was not observed in these field and laboratory experiments.

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