Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/12/2010
Publication Date: 4/28/2010
Citation: Haugenbucher, S. Olson, D.M. Ruberson, J. Wackers, F. Romeis, J. 2010. Reduced foliage herbivory in Bt cotton benefits phloem-feeding insects. Inter-University Doctoral Program in Ogranismal Biology Annual Ph.D. Students Meeting. Neuchatel University, Switzerland. March 10, 2010. Abstract only. Interpretive Summary:
Technical Abstract: Genetically modified cotton plants that express Lepidoptera-active toxins from Bacillus thuringiensis are grown on 15.5 millions hectares worldwide. Numerous studies have established that these plants pose a negligible risk to non-target arthropods due to the narrow spectrum of activity of the expressed toxins. However, potential indirect effects of Bt cotton have received little attention. We have thus studied the natural inducible defence mechanisms of cotton, specifically the induction of terpenoid toxins, and whether they are affected by the introduced insecticidal trait. The reduced damage level in Bt cotton could lead to a decreased state of the plant’s inducible defence system. This could leave the plant vulnerable to attack by other herbivores such as aphids, which do not induce a defence response by the plant. We tested this hypothesis by monitoring the success of cotton aphids (Aphis gossypii Glover) on Lepidoptera-damaged and undamaged Bt- and non-Bt cotton plants in the greenhouse and in a field experiment. As hypothesized, aphids benefitted by increased plant density from the reduced lepidopteran damage on Bt cotton, presumably through the indirect affect of a reduction of induced terpenoids in response to herbivory. We will investigate the latter through HPLC analyses of plant tissue.