Document: DEB-3-61-6

Potential ecological effects of Bt transgenes in wild plants.

LETOURNEAU, D.K.*

University of California, Santa Cruz, CA 95064 USA ¹

Abstract:
Predicting the potential invasiveness of plant species in different habitats is extremely important given the fact that plant introduction can lead to a reduction in biological diversity and threaten ecosystem integrity. Clearly, many factors interact to determine the success of a novel plant at a given introduction site and time of introduction, including abiotic factors, the abundance and identities of mutualists, competitors, herbivores, etc. The context of this paper is current and future deployment of transgenic crops with resistance traits against herbivores, the possible movement of these traits to relatives of crop plants, and the potential to shift the balance of plant traits in a particular environment towards invasiveness. I report the results of field and laboratory experiments to assess the potential impacts of a gene transfer from Bt crops (specifically, Brassica oleracea) to weedy relatives by using Bacillus thuringiensis sprays to mimic the constitutive expression of the Bt anti-herbivore trait in wild plants. First, the likelihood of gene transfer was assessed from the literature on Brassica crops and related weeds. Second, local herbivore levels were monitored in the field. Third, laboratory experiments showed no significant effects of Bt alone on seed output of plants but a significant decrease in herbivory and a significant increase in seed production in Brassica nigra sprayed with Bt compared to control plants. The results suggest significant changes are required in the context of better-informed practical decisions for the deployment of new transgenic crops.

Keywords: herbivory, plant fitness, invasiveness, biotechnology, transgenic crops

This abstract is being presented at: 10:45 AM in session:
Oral Session #4: Herbivore Responses to Plants.