Post Market Monitoring of GM Herbicide-Tolerant Crops

As soon as humans adopted agriculture as the principle means of feeding themselves, they have had an effect on the environment, and by implication, also on biodiversity. It is not possible to grow crops in an intensive manner without doing so, but it is necessary to do so to feed the population. In this respect, the use of herbicides or other weed control practices (e.g. hand-hoeing) inevitably will have an effect on biodiversity, whether those methods are used in conventional, organic or genetically modified herbicide-tolerant (GMHT) crops. 

Recent literature from the UK following the Farm Scale Evaluations (FSE) of the environmental impact of GMHT oilseed rape, maize and sugar beet suggests that the recommended weed management techniques applied in the cultivation of GMHT crops caused indirect effects on non-target organisms by affecting the biodiversity of plants within a field and the creatures which depend on them. Reductions in the number of weeds in glufosinate-treated HT-oilseed rape, and glyphosate-treated HTsugar beet compared to conventionally managed crops resulted in significant reductions in weed biomass (as might be expected from a superior treatment) and subsequent weed seed production later in the season and in following crops. In contrast, weed biomass and seeds were increased in glufosinate-treated HT-maize crops, leading to higher numbers of some invertebrates that fed on or were associated with the greater mass of decaying plant matter present. These effects were entirely related to the efficacy of weed control by the different herbicide regimes, and were not a feature of the HT crops themselves. They would occur with any herbicide/crop combination that changed the spectrum and density of weeds present. A much greater effect on biodiversity was seen between crops than between herbicide regimes, with non-GM maize having the greatest adverse effect on biodiversity compared to oilseed rape and sugar beet. Thus it is the growing of crops in the first place that is likely to have the greatest impact on the environment not whether it is GM or not. 

In this context, how is it possible to devise methods of post-market monitoring of GMHT crops? What should be the baseline against which environmental impact is measured? How can this be done simply without incurring the huge costs of studies such as the FSE in the UK? This presentation will present a personal view of the FSE and other research results that could provide guidelines for future introductions of GMHT crops in Europe.
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