A Bt Transgene Reduces Herbivory and Enhances Fecundity in Wild Sunflowers

Authors

A. A. Snow, Ohio State UniversityFollow
Diana Pilson, University of Nebraska–LincolnFollow
L. H. Rieseberg, Indiana University - BloomingtonFollow
M. J. Paulsen, University of Nebraska State MuseumFollow
N. Pleskac, University of Nebraska-Lincoln
M. R. Reagon, Ohio State University
D. E. Wolf, Indiana University - BloomingtonFollow
S. M. Selbo, Ohio State UniversityFollow

Date of this Version

4-2003

Document Type

Article

Citation

Ecological Applications 13(2), 2003, pp. 279–286

Comments

Copyright 2003 by the Ecological Society of America. Used by permission.

Abstract

Gene flow from transgenic crops can introduce novel traits into related species, but the ecological importance of this process is unknown. Here, we report the first empirical evidence that wild plants can benefit from a bacterial transgene under uncaged, natural conditions. Cultivated sunflower (Helianthus annuus) is known to hybridize frequently with wild sunflower (H. annuus) in the western and midwestern United States. We studied a crop-developed Bacillus thuringiensis (Bt) transgene, cry1Ac, in backcrossed wild sunflower populations. Lepidopteran damage on transgenic plants was strongly reduced relative to control plants at our two study sites, while damage by several weevil and fly species was unaffected. Our results suggest that reduced herbivory caused transgenic plants to produce an average of 55% more seeds per plant relative to nontransgenic controls at the field site in Nebraska. A similar but nonsignificant trend was seen at the site in Colorado (14% more seeds per plant). In a greenhouse experiment the transgene had no effect on fecundity, suggesting that it was not associated with a fitness cost. If Bt sunflowers are released commercially, we expect that Bt genes will spread to wild and weedy populations, limit damage from susceptible herbivores on these plants, and increase seed production when these herbivores are common.