Impact of herbivory and pollination on performance and competitive ability of oilseed rape transformed for pollen beetle resistance

Competitive ability of transgenic oilseed rape transformed with a pea lectin gene was estimated by comparisons of its performance when grown in a mixture with its non-transgenic counterpart and when grown singly, with and without pollen beetles present. The experiments were carried out in cages, once with bumblebees as pollinators and once without. In the absence of herbivory but with the presence of bumblebees, singly grown plant lines without lectin generally performed better than lines with lectin. Pollen beetles affected plant growth and reproduction, but there were no consistent differences between the lectin and non-lectin plant lines indicating that the transgenic trait did not protect plants from pest attack. Herbivory reduced the number of seeds when bumblebees were present. In the absence of bumblebees, however, plants produced more seeds with pollen beetles than without, indicating that some pollination was carried out by the beetles. Efficient pollination affected the competitive abilities of the lines; lectin lines were more competitive with bumblebees present and the reverse was true when bumblebees were absent. In the presence of bumblebees, lectin lines gained from being grown mixed with its non-transgenic counterpart. Because the transgenic plants expressed pea lectin in developing pollen it is possible that pollen quality in those plants was reduced, which may explain why the lectin lines had an advantage over non-lectin lines when exchange of pollen between the two plant types was facilitated by bumblebees

Feral genetically modified herbicide tolerant oilseed rape from seed import spills: are concerns scientifically justified?

One of the concerns surrounding the import (for food and feed uses or processing) of genetically modified herbicide tolerant (GMHT) oilseed rape is that, through seed spillage, the herbicide tolerance (HT) trait will escape into agricultural or semi-natural habitats, causing environmental or economic problems. Based on these concerns, three EU countries have invoked national safeguard clauses to ban the marketing of specific GMHT oilseed rape events on their territory. However, the scientific basis for the environmental and economic concerns posed by feral GMHT oilseed rape resulting from seed import spills is debatable. While oilseed rape has characteristics such as secondary dormancy and small seed size that enable it to persist and be redistributed in the landscape, the presence of ferals is not in itself an environmental or economic problem. Crucially, feral oilseed rape has not become invasive outside cultivated and ruderal habitats, and HT traits are not likely to result in increased invasiveness. Feral GMHT oilseed rape has the potential to introduce HT traits to volunteer weeds in agricultural fields, but would only be amplified if the herbicides to which HT volunteers are tolerant were used routinely in the field. However, this worst-case scenario is most unlikely, as seed import spills are mostly confined to port areas. Economic concerns revolve around the potential for feral GMHT oilseed rape to contribute to GM admixtures in non-GM crops. Since feral plants derived from cultivation (as distinct from import) occur at too low a frequency to affect the coexistence threshold of 0.9% in the EU, it can be concluded that feral GMHT plants resulting from seed import spills will have little relevance as a potential source of pollen or seed for GM admixture. This paper concludes that feral oilseed rape in Europe should not be routinely managed, and certainly not in semi-natural habitats, as the benefits of such action would not outweigh the negative effects of management

Native birds and alien insects: spatial density dependence in songbird predation of invading oak gallwasps

Revealing the interactions between alien species and native communities is central to understanding the ecological consequences of range expansion. Much has been learned through study of the communities developing around invading herbivorous insects. Much less, however, is known about the significance of such aliens for native vertebrate predators for which invaders may represent a novel food source. We quantified spatial patterns in native bird predation of invading gall-inducing Andricus wasps associated with introduced Turkey oak (Quercus cerris) at eight sites across the UK. These gallwasps are available at high density before the emergence of caterpillars that are the principle spring food of native insectivorous birds. Native birds showed positive spatial density dependence in gall attack rates at two sites in southern England, foraging most extensively on trees with highest gall densities. In a subsequent study at one of these sites, positive spatial density dependence persisted through four of five sequential week-long periods of data collection. Both patterns imply that invading galls are a significant resource for at least some native bird populations. Density dependence was strongest in southern UK bird populations that have had longest exposure to the invading gallwasps. We hypothesise that this pattern results from the time taken for native bird populations to learn how to exploit this novel resource

Genetically modified organisms in agriculture : can regulations work?

Genetically modified (GM) crops have been recognised to be economically beneficial to subsistence farmers and have been projected as essential tools for addressing challenges in hunger, environmental sustainability and international development. Yet the uncertainty of their effects on human health and the undesirable ecological consequences of these organisms have raised concerns on the rapid pace of their production. Regulating the release of these organisms is a critical environmental issue. The Cartagena protocol on bio-safety, the principle legal arrangement for the regulation of these organisms, has ratifications from only 157 countries and has proven to be a weak regulator. Countries like India and Brazil have seen the proliferation of unapproved stealth GM varieties which make regulation even more difficult. In this paper, we explore the debate surrounding the introduction of GM organisms and analyse the effectiveness of existing legal regimes to regulate their use

Free radicals – an evolutionary perspective

This chapter provides an evolutionary perspective on free radical biology. We first explain the concept of life history trade-offs and discuss how the need to manage oxidative stress in an optimal way may be an important mechanism driving the outcome of many of these trade-offs. We examine the different solutions that organisms have evolved to combat the damaging consequences of oxidative stress. We then examine the ways in which balancing investment in such defenses against the consequences of sustaining damage has influenced life history traits such in the context of growth, foraging, diet and activity patterns, sexual signaling, reproduction, and defense against infection