Farmland biodiversity is an important characteristic when assessing sustainability of agricultural practices and is of major international concern. Scientific data indicate that agricultural intensification and pesticide use are among the main drivers of biodiversity loss. The analysed data and experiences do not support statements that herbicide-resistant crops provide consistently better yields than conventional crops or reduce herbicide amounts. They rather show that the adoption of herbicide-resistant crops impacts agronomy, agricultural practice, and weed management and contributes to biodiversity loss in several ways: (i) many studies show that glyphosate-based herbicides, which were commonly regarded as less harmful, are toxic to a range of aquatic organisms and adversely affect the soil and intestinal microflora and plant disease resistance; the increased use of 2,4-D or dicamba, linked to new herbicide-resistant crops, causes special concerns. (ii) The adoption of herbicide-resistant crops has reduced crop rotation and favoured weed management that is solely based on the use of herbicides. (iii) Continuous herbicide resistance cropping and the intensive use of glyphosate over the last 20 years have led to the appearance of at least 34 glyphosate-resistant weed species worldwide. Although recommended for many years, farmers did not counter resistance development in weeds by integrated weed management, but continued to rely on herbicides as sole measure. Despite occurrence of widespread resistance in weeds to other herbicides, industry rather develops transgenic crops with additional herbicide resistance genes. (iv) Agricultural management based on broad-spectrum herbicides as in herbicide-resistant crops further decreases diversity and abundance of wild plants and impacts arthropod fauna and other farmland animals. Taken together, adverse impacts of herbicide-resistant crops on biodiversity, when widely adopted, should be expected and are indeed very hard to avoid. For that reason, and in order to comply with international agreements to protect and enhance biodiversity, agriculture needs to focus on practices that are more environmentally friendly, including an overall reduction in pesticide use. (Pesticides are used for agricultural as well non-agricultural purposes. Most commonly they are used as plant protection products and regarded as a synonym for it and so also in this text.)Electronic supplementary materialThe online version of this article (doi:10.1186/s12302-016-0100-y) contains supplementary material, which is available to authorized users.

Glyphosate-based herbicides (GBHs), consisting of glyphosate and formulants, are the most frequently applied herbicides worldwide. The declared active ingredient glyphosate does not only inhibit the EPSPS but is also a chelating agent that binds macro- and micronutrients, essential for many plant processes and pathogen resistance. GBH treatment may thus impede uptake and availability of macro- and micronutrients in plants. The present study investigated whether this characteristic of glyphosate could contribute to adverse effects of GBH application in the environment and to human health. According to the results, it has not been fully elucidated whether the chelating activity of glyphosate contributes to the toxic effects on plants and potentially on plant–microorganism interactions, e.g., nitrogen fixation of leguminous plants. It is also still open whether the chelating property of glyphosate is involved in the toxic effects on organisms other than plants, described in many papers. By changing the availability of essential as well as toxic metals that are bound to soil particles, the herbicide might also impact soil life, although the occurrence of natural chelators with considerably higher chelating potentials makes an additional impact of glyphosate for most metals less likely. Further research should elucidate the role of glyphosate (and GBH) as a chelator, in particular, as this is a non-specific property potentially affecting many organisms and processes. In the process of reevaluation of glyphosate its chelating activity has hardly been discussed.

Genetically modified herbicide-resistant (GMHR) sugar beet (Beta vulgaris L.) has been cultivated in the US for several years and an application has been submitted for cultivation in Europe. Concerns have been raised about how GMHR sugar beet cultivation might impair the agro-environment.European legislation for GM plants requires, prior to their commercial import and/or cultivation, a stepwise reduction of the containment and a gradual increase in the scale of release. Experimental results gained during this procedure enter an environmental risk assessment; after the GM plant approval, a systematic monitoring of potential adverse environmental effects is required.We collected information on sugar beet biology and cultivation and the HR technology. We categorised the literature findings, evaluated the evidence of agro-environmental effects and indicated adverse effects. The impacts are directly and indirectly linked to sugar beet biology and/or to the HR technology. Most likely are a) adverse herbicide effects on field organisms, aquatic communities and soil microbial communities, b) persistence of the GM plant triggered by a potential selective advantage and/or genetic drift after hybridisation of GMHR cultivated, feral and weed beet with neighbouring beets and wild relatives, c) the increase of HR in weeds and subsequent increase and/or change in the herbicide application regime after several years of glyphosate application, and d) decline in agrobiodiversity (weed communities, herbivores, pollinators and beneficial species).Our study reveals a lack of experimental data on potential agro-environmental effects. This suggests that the principle of a stepwise scale increase of release is inadequately applied to the GMHR sugar beet approval process. The adverse effects identified should prompt further research experiments to gain information for the ERA and/or specific monitoring activities at the respective identified spatial scale levels.

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