GM crop impact 'lasts two years'
BBC News, September 28, 2005
Richard Black

A follow-up to the UK's major trial of genetically modified crops, the Farm Scale Evaluations, finds that impacts on wildlife can persist for two years.
The original trial found that spring GM rape and sugar beet were harsher than their conventional equivalents in the short term, while GM maize was better.
The new study shows the same pattern at two years for rape and maize.
The British government has welcomed the findings, which it says "provide important information" on GM crops.
Impression confirmed
The new information relates to three of the four crops studied in the Farm Scale Evaluations (FSEs): spring oilseed rape, sugar beet and maize.
FSEs: QUESTIONS ASKED Four crops - spring and winter oilseed rape, maize, sugar beet GM varieties resistant to herbicides glyphosate or glufosinate 266 UK sites involved in trial Half of each field planted with GM crop and sprayed with appropriate herbicide; other half planted with conventional equivalent and sprayed with comparator herbicide Investigators monitored "biodiversity indicators" including weed seed numbers, insect and bird populations Initial results on these crops were published in October 2003; data on the fourth crop, winter oilseed rape, was published separately in March 2005.
"The new study confirms our impression of what would happen when we released the initial results," said Les Firbank, of the Centre for Ecology and Hydrology in Lancaster, the FSE project co-ordinator.
"We did expect the differences to persist, and I don't think it will affect any decision on approving GM crops," he told the BBC News website.
This follow-up, published in the Royal Society's journal Biology Letters, did not look at insects and birds as the initial study had done.
Instead, it confined itself to monitoring the weed seedbank - the number and diversity of weed seeds left in the soil, which will be food for insects and birds.
Delayed return
It found that the result seen at one year for maize, with the GM crop leaving a greater seedbank than conventional varieties, persisted through the second season after planting.
The converse result for spring rape - GM cultivation worse than conventional - also persisted.
Crop-spraying. Picture courtesy of FreeFoto.com Different herbicides are sprayed onto GM and conventional varieties "After the trial season ended, the land returned to normal management and farmers managed the two halves in the same way," said Dr Firbank.
"So we would expect differences to persist because weeds are controlled by the farmers anyway; if you did see a big increase in weeds, you would expect the farmer to do something about it."
However, areas which had been sown with GM beet and had initially seen a fall in the seedbank compared with conventional cultivation appeared to mount a partial recovery.
The initial trial result on maize had proved controversial because of studies indicating that the herbicide used on the conventional varieties, atrazine, is associated with a range of toxicities; its use is now banned in most EU countries, though not yet in the UK.
The scientific team points out that any results seen in the studies are direct consequences of the herbicides used rather than the plants themselves, although these GM varieties are specifically created to be used with proprietary herbicides.
Complex politics
The results are unlikely to have an impact the broader question of whether genetically modified crops are grown in the UK.
FSEs: THE RESULTS At one year, biodiversity indicators worse for spring rape and beet; better for maize Maize results compromised by concerns over comparator herbicide atrazine Results for winter rape, published later, showed GM variety decreased seeds important for birds New study shows initial impact can persist for two years Following the initial results from the FSEs, the government indicated that it would approve cultivation of the GM maize used in the trial, the Bayer product Chardon LL, and reject the others.
However, Bayer then decided not to press ahead with a UK introduction for Chardon.
The legislative situation regarding GM crops across Europe has since become more complex.
In principle, once one European Union member has approved a crop, it is automatically approved in all other member states.
However, some countries have vetoed certain crops; and the EU Council of Ministers decided in June not to remove that right, even though it may be illegal under European law.

Web Link: http://news.bbc.co.uk/1/hi/sci/tech/4287044.stm

 

Effects of genetically modified herbicide-tolerant cropping systems on weed seedbanks in two years of following crops
Biology Letters September 30, 2005
L.G. Firbank A1, P. Rothery A2, M.J. May A3, S.J. Clark A4, R.J. Scott A1 Lancaster Environment Centre Centre for Ecology and Hydrology Library Avenue, Bailrigg, Lancaster LA1 4AP, UK A2 Abbots Ripton Centre for Ecology
and Hydrology Huntingdon, Cambridgeshire PE28 2LS, UK A3 Broom¹s Barn Research Station Higham, Bury St Edmunds, Suffolk IP28 6NP, UK A4 Winfrith Technology Centre Centre for Ecology and Hydrology Dorchester, Dorset DT2 8ZD, UK A5 Rothamsted Research Harpenden, Hertfordshire AL5 2JQ, UK A6 Scottish Crop Research Institute Invergowrie, Dundee DD2 5DA, UK

Abstract:
The Farm Scale Evaluations (FSEs) showed that genetically modified herbicide-tolerant (GMHT) cropping systems could influence farmland biodiversity because of their effects on weed biomass and seed production. Recently published results for winter oilseed rape showed that a switch to GMHT crops significantly affected weed seedbanks for at least 2 years after the crops were sown, potentially causing longer-term effects on other taxa. Here, we seek evidence for similar medium-term effects on weed seedbanks following spring-sown GMHT crops, using newly available data from the FSEs. Weed seedbanks following GMHT maize were significantly higher than following conventional varieties for both the first and second years, while by contrast, seedbanks following GMHT spring oilseed rape were significantly lower over this period. Seedbanks following GMHT beet were smaller than following conventional crops in the first year after the crops had been sown, but this difference was much reduced by the second year for reasons that are not clear. These new data provide important empirical evidence for longer-term effects of GMHT cropping on farmland biodiversity.

Web Link: http://www.pubs.royalsoc.ac.uk/bio_let_content/pdf
/rsbl20050390.pdf

 

Related study:

Persistence of seeds from crops of conventional and herbicide tolerant
Biological Sciences, September 30, 2005
Peter J.W. Lutman A1, Kate Berry A1, Roger W. Payne A1, Euan Simpson A2, Jeremy B. Sweet A2, Gillian T. Champion A3, Mike J. May
A1 Rothamsted Research Harpenden Herts AL5 2JQ, UK A2 NIAB Huntingdon Road, Cambridge CB3 0LE, UK A3 Broom¹s Barn Research Station Higham, Bury St Edmunds, Suffolk, IP28 6NP, UK A4 The Scottish Agricultural College Kings Buildings, West Mains Road, Edinburgh EH9 3JG, UK A5 The Arable Group Morley St Botolph, Wymondham, Norfolk NR18 9DB, UK

Abstract: A series of rotation experiments at five sites over four years has explored the environmental and agronomic implications of growing herbicide tolerant oilseed rape and sugar beet. This paper reports on the population dynamics of volunteer rape (Brassica napus). The experiments compared four winter oilseed rape (WOSR) cultivars: a conventional cultivar (Apex) and three developmental cultivars either genetically modified (GM) to be tolerant to glyphosate or glufosinate, or conventionally bred to be tolerant to herbicides of the imidazolinone group. Seed losses at harvest averaged 3575 seedsm-2 but ranged from less than 2000 up to more than 10000 seedsm-2. There was a rapid decline in seed numbers during the first few months after harvest, resulting in a mean loss of seeds of 60%. In subsequent seasons, the seedbank declined much more slowly at four of the five sites (ca 20% per year) and the models predicted 95% seed loss after approximately 9 years. Seed decline was much faster at the fifth site. There were no clear differences between the four cultivars in either the numbers of seeds shed at harvest or in their subsequent persistence. The importance of the persistence of GM rape seeds, in the context of the coexistence of GM and non-GM crops and the role of good management practices that minimize seed persistence, are discussed.