Efficacy of Cry1f Insecticidal Protein in Maize and Cotton for Control of Fall Armyworm (Lepidoptera: Noctuidae)

Abstract

Efficacy of maize, Zea mays L., hybrids and cotton, Gossypium hirsutum (L.), varieties expressing Cry1F insecticidal crystal protein of Bacillus thuringiensis (Bt) var. aizawai Berliner (transformation event TC1507 in corn and event DAS-24236-5 in cotton) was evaluated for control of fall armyworm, Spodoptera frugiperda (J.E. Smith). Control of natural and artificial fall armyworm infestations of eggs and various larval stages to 3 Cry1F and non-Bt maize isoline pairs at V4-V7 corn growth stage was evaluated at 10 locations across the United States and Brazil. Varieties producing the Cry1F protein provided high levels of control. Furthermore, control provided by Cry1F-maize hybrids was frequently better than when fall armyworm were managed with 3 applications of foliar insecticides. Efficacy of transgenic Cry1Ac:Cry1F cotton against fall armyworm was evaluated for 5 varieties during anthesis in laboratory and natural infestation field studies in the southern United States. Laboratory colonies of fall armyworm originally collected from corn, bermudagrass, Cynodon dactylon (L.), cotton, and royal paulownia, Paulownia tomentosa (Thunb.) and determined to be either the rice or corn-associated host strain, all resulted in low levels of survival when fed matures leaves of Cry1Ac:Cry1F-cotton. In natural infestation studies, levels of fall armyworm in squares (flower buds), flowers, and bolls (fruit), were significantly lower in cotton containing Cry1F as compared to non-Bt cotton. These results demonstrate that maize hybrids and cotton varieties containing Cry1F can be an important component in an overall management program for fall armyworm across a broad range of geographies and crops.

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