Ecologists plead for scientific research to aid risk assessment
August 28, 2003, no. 051
A survey among nine prominent Dutch ecologists has identified gaps in knowledge on the potential effects of Bt-crops on food chains and ecosystems. Bt-crops have been modified to express a bacterial gene that codes for a toxin that kills certain groups of insects. The toxin is continuously produced in all plant tissues and target as well as non-target organisms are exposed to it. Moreover, the toxin may be exuded by the roots and accumulate in the soil or it may be transferred to surrounding natural habitats through pollen of the Bt-crop. This may result in unforeseen hazards either in the short run or in the long run.Researchers of Wageningen University report on this in the September issue of Nature Biotechnology.
The recent stand-off in front of the World Trade Organization (WTO) between the USA and the EU on the acceptance of genetically-modified (GM) crops clearly illustrates the differential approach towards the criteria for approval of such crops. EU policy is based on the precautionary principle, which means that the mere conception of a possible ecological hazard, even in the absence of scientific evidence, requires precautionary interim measures until research enables full risk management. As a member state of the EU, the Dutch government applies the precautionary principle. To make progress in understanding whether (certain) GM crops pose a risk to EU agriculture and/or the environment, scientific research is essential.
In their publication the authors Bart Knols and Marcel Dicke of the Laboratory of Entomology of Wageningen University report the knowledge gaps recognized by nine leading ecologists that took part in a survey on behalf of the Dutch Commission on Genetic Modification (COGEM)*, which advises the Ministry of Housing, Spatial Planning and the Environment (VROM).
The ecologists are concerned about the potential effects of the application of toxic Bt-crops on natural and agricultural ecosystems. For example, agriculture in Europe occurs on a smaller scale than in the USA with much more interaction between natural and agricultural ecosystems. As a result pollen from Bt-crops that contains the toxin may contaminate plants in natural habitats around the agricultural field. Caterpillars of endangered butterflies may then be exposed and killed. Many butterfly species have suffered already from fragmented habitats and an extra mortality from toxin exposure may be fatal. The Bt-toxins are specific for groups of insects, but not all insects in the group are pests. For instance, a Bt-toxin that affects beetle pests will also affect beneficial beetles such as ladybird beetles that function as biological control agents.
The survey has resulted in the proposal of a four-pronged approach to make a scientific contribution to understanding whether, where and how Bt-crops pose risks to agricultural and natural ecosystems. The four steps range from short-term studies on interactions between the Bt-crop and organisms in the agro-ecosystem to long-term modelling studies relating to a larger spatial scale. Especially studies of long-term effects are badly needed. This is the only way to assess whether pest control through Bt-crops is an improvement or a deterioration of current pest control.
NOTE FOR THE EDITOR
* The report (in Dutch) can be downloaded from www.cogem.net/pdfdb/2003-1.pdf
For more information please contact prof. Marcel Dicke, Wageningen University, Laboratory of Entomology, tel. +31 317 484311, fax +31 317 484821, e-mail marcel.dicke@wur.nl.
Handled by: Communications Office, Wageningen UR, Jac Niessen, tel. +31 317 485003You can also send a mail to the Communications Office: pers.communicatie@wur.