Competitive interactions and the effect of herbivory on Bt‐Brassica napus, Brassica rapa and Lolium perenne

Abstract

Summary1. The probability of a transgenic crop establishing a feral population outside cultivated areas and possibly outcompeting naturally occurring species needs to be assessed to make an ecological risk assessment of the transgenic crop. 2. The interaction between herbivory and competition is thought to determine the ecological success of insect-resistant plants, and this interaction was investigated in a competition experiment with transgenic insect-resistant Bt-Brassica napus, Brassica rapa, Lolium perenne, and herbivory from the large white butterfly Pieris brassicae. 3. As expected, herbivory had a negative effect on the biomass of B. rapa at high plant densities. The competitive ability of L. perenne, when growing with B. rapa, increased significantly with the level of herbivory on B. rapa. 4. To predict the effect of herbivory in a natural ecosystem, plant competition between the two annual Brassica species was analysed in a population ecological model. It was concluded that it is probable that transgenic Bt-B. napus plants may invade a natural habitat if herbivory is sufficiently high and the habitat is suitable for B. napus. 5. Synthesis and applications. The results indicate that it is important to study the interaction between herbivory and competition when assessing the ecological risk of insect-resistant genetically modified crops. Furthermore, combining ecological data from manipulated experiments with population ecological modelling is a fruitful approach when conducting environmental risk assessments.

Scientific Opinion on application (EFSA-GMO-BE-2010-81) for the placing on the market of genetically modified herbicide-tolerant oilseed rape Ms8, Rf3 and Ms8 × Rf3 for food containing or consisting of, and food produced from or containing ingredients pro

“…The ability of oilseed rape to successfully invade natural habitats is limited principally by the availability of seed germination sites and interspecific plant competition (Crawley et al, 1993(Crawley et al, , 2001Crawley and Brown, 1995;Hails et al, 2006;Damgaard and Kjaer, 2009). Moreover, in controlled sowings into road verges, field margins and wasteland, very few seedlings survived to maturity due to grazing (e.g.…”

Assessment of effects of Bt‐oilseed rape on large white butterfly (Pieris brassicae) in natural habitats

“…The transgenic crop used in this study was an insect‐resistant Bt‐oilseed rape, Brassica napus L. Oilseed rape is known to form feral populations in natural and semi‐natural habitats, given a certain amount of disturbance (Crawley & Brown, 1995; Pessel et al., 2001). Furthermore, competition experiments have shown that Bt‐oilseed rape may out‐compete insect‐susceptible plants at high herbivore densities (Damgaard & Kjær, 2009).…”

Scientific Opinion on application (EFSA‐GMO‐NL‐2010‐87) for the placing on the market of genetically modified herbicide tolerant oilseed rape GT73 for food containing or consisting of, and food produced from or containing ingredients produced from, oilseed rape GT73 (with the exception of refined oil and food additives) under Regulation (EC) No 1829/2003 from Monsanto

“…The ability of oilseed rape to successfully invade natural habitats is limited principally by the availability of seed germination sites and interspecific plant competition (Crawley et al, 1993(Crawley et al, , 2001Crawley and Brown, 1995;Hails et al, 2006;Damgaard and Kjaer, 2009). Moreover, in controlled sowings into road verges, field margins and wasteland, very few seedlings survived to maturity due to grazing (e.g., by molluscs) and abiotic stress (Charters et al, 1999).…”