Efficacy of Single and Dual Gene Cotton Gossypium hirsutum (L.) Events on Yellowstriped Armyworm (Lepidoptera: Noctuidae) in South Texas and the Mississippi Delta

J. Scott Armstrong, Jeff Gore, John J. Adamczyk, Jr.

Abstract


The yellowstriped armyworm (YSAW), Spodoptera ornithogalli (Guenée), has a broad host range and can be an economic threat to cotton in southern growing regions of the United States by consuming leaves and damaging fruiting forms. Field grown cotton varieties containing the endotoxins from Bacillus thuringiensis, (Cry1Ac = Bollgard®; Cry1Ac + Cry2Ab = Bollgard II®; Cry1F + Cry1Ac = Widestrike) and a Non-Bt cotton were evaluated for YSAW susceptibility to cotton leaf tissue. Bioassays conducted at Stoneville, MS, from leaves collected from the lower, middle, and top canopy showed that YSAW were highly susceptible to Bollgard II® and WideStrike traits. No live larvae were collected from the WideStrike replicated plots and only 2 larvae that weighed 171.5 ± 53.5 mg were collected from Bollgard II® cotton. Larvae collected from Bollgard® and Non-Bt cotton were plentiful and averaged 886 ± 63.5 and 824.25 ± 51.53 mg, respectively. Additional bioassays from late-season cotton plots at both Stoneville and Weslaco, TX, indicated that WideStrike and Bollgard II® are very active against YSAW larvae. Results from these assays indicate that cotton producers have very effective options for controlling YSAW even late in the growing season.

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