Attitudes of European farmers towards GM crop adoption

This article analyses European Union (EU) farmers' attitudes towards adoption of genetically modified crops by identifying and classifying groups of farmers. Cluster analysis provided two groups of farmers allowing us to classify farmers into potential adopters or rejecters of genetically modified herbicide-tolerant (GMHT) crops. Results showed that economic issues such as the guarantee of a higher income and the reduction of weed control costs are the most encouraging reasons for potential adopters and rejecters of GMHT crops. This article also examines how putting in place measures to ensure coexistence between GM and non-GM crops may influence farmers' attitudes towards GMHT crop adoption. Results show that the implementation of a coexistence policy would have a negative impact on farmers' attitudes on adoption and consequently may hamper GMHT adoption in the EU.     

Effects of successive seasons of genetically modified herbicide-tolerant maize cropping on weeds and invertebrates

The use of genetically modified herbicide‐tolerant (GMHT) crops influences the abundance of weeds and some invertebrate groups because the associated herbicide regime contrasts with that of conventional systems. However, it is not clear to what extent these effects might be cumulative; should GMHT crops be grown continuously. In northern Europe, in the near future, this situation is most likely to apply to maize crops. Here, we consider the effects of continuous GMHT maize cropping on plant and invertebrate taxa using a split‐field experiment. Half of each field was managed using GMHT and the other half with a conventional variety, with the treatments retained for two seasons. The treatment effects were broadly consistent with those found in the larger sample of non‐continuous maize sites within the Farm Scale Evaluations. There was little evidence of effects being significantly more pronounced in the second year; any cumulative differences in above‐ground biodiversity between GMHT and conventional cropping were too variable to be readily detected.     

Effects of genetically modified herbicide-tolerant cropping systems on weed seedbanks in two years of following crops

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.     

A novel approach to the use of genetically modified herbicide tolerant crops for environmental benefit

The proposed introduction of genetically modified herbicide tolerant (GMHT) crops, with claims of improved weed control, has prompted fears about possible environmental impacts of their widespread adoption, particularly on arable weeds, insects and associated farmland birds. In response to this, we have developed a novel weed-management system for GMHT sugar beet, based on band spraying, which exploits the flexibility offered by the broad-spectrum partner herbicides. Here, we show the results from two series of field experiments which, taken together, demonstrate that, by using this system, crops can be managed for enhanced weed and insect biomass without compromising yield, thus potentially offering food and shelter to farmland birds and other wildlife. These results could be applicable widely to other row crops, and indicate that creative use of GMHT technology could be a powerful tool for developing more sustainable farming systems in the future.     

Effects on weed and invertebrate abundance and diversity of herbicide management in genetically modified herbicide-tolerant winter-sown oilseed rape

We evaluated the effects of the herbicide management associated with genetically modified herbicide-tolerant (GMHT) winter oilseed rape (WOSR) on weed and invertebrate abundance and diversity by testing the null hypotheses that there is no difference between the effects of herbicide management of GMHT WOSR and that of comparable conventional varieties. For total weeds, there were few treatment differences between GMHT and conventional cropping, but large and opposite treatment effects were observed for dicots and monocots. In the GMHT treatment, there were fewer dicots and monocots than in conventional crops. At harvest, dicot biomass and seed rain in the GMHT treatment were one-third of that in the conventional, while monocot biomass was threefold greater and monocot seed rain almost fivefold greater in the GMHT treatment than in the conventional. These differential effects persisted into the following two years of the rotation. Bees and Butterflies that forage and select for dicot weeds were less abundant in GMHT WORS management in July. Year totals for Collembola were greater under GMHT management. There were few other treatment effects on invertebrates, despite the marked effects of herbicide management on the weeds.     

Crop management and agronomic context of the Farm Scale Evaluations of genetically modified herbicide-tolerant crops

The Farm Scale Evaluations of genetically modified herbicide-tolerant crops (GMHT) were conducted in the UK from 2000 to 2002 on beet (sugar and fodder), spring oilseed rape and forage maize. The management of the crops studied is described and compared with current conventional commercial practice. The distribution of field sites adequately represented the areas currently growing these crops, and the sample contained sites operated at a range of management intensities, including low intensity. Herbicide inputs were audited, and the active ingredients used and the rates and the timings of applications compared well with current practice for both GMHT and conventional crops. Inputs on sugar beet were lower than, and inputs on spring oilseed rape and forage maize were consistent with, national averages. Regression analysis of herbicide-application strategies and weed emergence showed that inputs applied by farmers increased with weed densities in beet and forage maize. GMHT crops generally received only one herbicide active ingredient per crop, later and fewer herbicide sprays and less active ingredient (for beet and maize) than the conventional treatments. The audit of inputs found no evidence of bias.     

Invertebrate responses to the management of genetically modified herbicide-tolerant and conventional spring crops. I. Soil-surface-active invertebrates

The effects of herbicide management of genetically modified herbicide-tolerant (GMHT) beet, maize and spring oilseed rape on the abundance and diversity of soil-surface-active invertebrates were assessed. Most effects did not differ between years, environmental zones or initial seedbanks or between sugar and fodder beet. This suggests that the results may be treated as generally applicable to agricultural situations throughout the UK for these crops. The direction of the effects was evenly balanced between increases and decreases in counts in the GMHT compared with the conventional treatment. Most effects involving a greater capture in the GMHT treatments occurred in maize, whereas most effects involving a smaller capture were in beet and spring oilseed rape. Differences between GMHT and conventional crop herbicide management had a significant effect on the capture of most surface-active invertebrate species and higher taxa tested in at least one crop, and these differences reflected the phenology and ecology of the invertebrates. Counts of carabids that feed on weed seeds were smaller in GMHT beet and spring oilseed rape but larger in GMHT maize. In contrast, collembolan detritivore counts were significantly larger under GMHT crop management.     

Weed seed resources for birds in fields with contrasting conventional and genetically modified herbicide-tolerant crops

The UK Farm Scale Evaluations (FSEs) have shown that the use of broad spectrum herbicides on genetically modified herbicide-tolerant (GMHT) crops can have dramatic effects on weed seed production compared to management of conventional varieties. Here, we use FSE data and information on bird diets to determine how GMHT cropping might change the food resources available to farmland birds. More than 60 fields of each of four crops, spring- and winter-sown oilseed rape, beet and maize, were split, one half being sown with a conventional variety, the other with a GMHT variety. Seed rain from weeds known to be important in the diets of 17 granivorous farmland bird species was measured under the two treatments. In beet and spring oilseed rape, rain of weed seeds important in the diets of 16 bird species was significantly reduced in GMHT compared to conventional halves; for no species did it increase. In winter oilseed rape, rain of weed seeds important in the diets of 10 species was significantly reduced in GMHT halves; for only one species did it increase significantly. By contrast, in maize, rain of weed seeds important in the diets of seven species was significantly greater in GMHT halves; for no species was it reduced. Treatment effects for the total weed seed energy available to each bird species were very similar to those for seed rain alone. Measuring the effects on individual bird species was outside the scope of this study. Despite this, these results suggest that should beet, spring and winter rape crops in the UK be largely replaced by GMHT varieties and managed as in the FSEs, this would markedly reduce important food resources for farmland birds, many of which declined during the last quarter of the twentieth century. By contrast, GMHT maize would be beneficial to farmland birds.     

Invertebrates and vegetation of field margins adjacent to crops subject to contrasting herbicide regimes in the Farm Scale Evaluations of genetically modified herbicide-tolerant crops

The effects of management of genetically modified herbicide-tolerant (GMHT) crops on adjacent field margins were assessed for 59 maize, 66 beet and 67 spring oilseed rape sites. Fields were split into halves, one being sown with a GMHT crop and the other with the equivalent conventional non-GMHT crop. Margin vegetation was recorded in three components of the field margins. Most differences were in the tilled area, with fewer smaller effects mirroring them in the verge and boundary. In spring oilseed rape fields, the cover, flowering and seeding of plants were 25%, 44% and 39% lower, respectively, in the GMHT uncropped tilled margins. Similarly, for beet, flowering and seeding were 34% and 39% lower, respectively, in the GMHT margins. For maize, the effect was reversed, with plant cover and flowering 28% and 67% greater, respectively, in the GMHT half. Effects on butterflies mirrored these vegetation effects, with 24% fewer butterflies in margins of GMHT spring oilseed rape. The likely cause is the lower nectar supply in GMHT tilled margins and crop edges. Few large treatment differences were found for bees, gastropods or other invertebrates. Scorching of vegetation by herbicide-spray drift was on average 1.6% on verges beside conventional crops and 3.7% beside GMHT crops, the difference being significant for all three crops.     

Weeds in fields with contrasting conventional and genetically modified herbicide-tolerant crops. II. Effects on individual species

We compared the effects of the management of genetically modified herbicide-tolerant (GMHT) and conventional beet, maize and spring oilseed rape on 12 weed species. We sampled the seedbank before and after cropping. During the season we counted plants and measured seed rain and biomass. Ratios of densities were used to calculate emergence, survival, reproduction and seedbank change. Treatments significantly affected the biomass of six species in beet, eight in maize and five in spring oilseed rape. The effects were generally consistent, with biomass lower in GMHT beet and spring oilseed rape and higher in GMHT maize. With few exceptions, emergence was higher in GMHT crops. Subsequent survival was significantly lowered for eight species in beet and six in spring oilseed rape in the GMHT treatments. It was increased for five species in maize and one in spring oilseed rape. Significant effects on seedbank change were found for four species. However, for many species in beet and spring oilseed rape (19 out of 24 cases), seed densities were lower in the seedbank after GMHT cropping. These differences compounded over time would result in large decreases in population densities of arable weeds. In maize, populations may increase.     

Responses of plants and invertebrate trophic groups to contrasting herbicide regimes in the Farm Scale Evaluations of genetically modified herbicide-tolerant crops

Effects of genetically modified herbicide-tolerant (GMHT) and conventional crop management on invertebrate trophic groups (herbivores, detritivores, pollinators, predators and parasitoids) were compared in beet, maize and spring oilseed rape sites throughout the UK. These trophic groups were influenced by season, crop species and GMHT management. Many groups increased twofold to fivefold in abundance between early and late summer, and differed up to 10-fold between crop species. GMHT management superimposed relatively small (less than twofold), but consistent, shifts in plant and insect abundance, the extent and direction of these effects being dependent on the relative efficacies of comparable conventional herbicide regimes. In general, the biomass of weeds was reduced under GMHT management in beet and spring oilseed rape and increased in maize compared with conventional treatments. This change in resource availability had knock-on effects on higher trophic levels except in spring oilseed rape where herbivore resource was greatest. Herbivores, pollinators and natural enemies changed in abundance in the same directions as their resources, and detritivores increased in abundance under GMHT management across all crops. The result of the later herbicide application in GMHT treatments was a shift in resource from the herbivore food web to the detritivore food web. The Farm Scale Evaluations have demonstrated over 3 years and throughout the UK that herbivores, detritivores and many of their predators and parasitoids in arable systems are sensitive to the changes in weed communities that result from the introduction of new herbicide regimes.     

Invertebrate responses to the management of genetically modified herbicide-tolerant and conventional spring crops. II. Within-field epigeal and aerial arthropods

The effects of the management of genetically modified herbicide-tolerant (GMHT) crops on the abundances of aerial and epigeal arthropods were assessed in 66 beet, 68 maize and 67 spring oilseed rape sites as part of the Farm Scale Evaluations of GMHT crops. Most higher taxa were insensitive to differences between GMHT and conventional weed management, but significant effects were found on the abundance of at least one group within each taxon studied. Numbers of butterflies in beet and spring oilseed rape and of Heteroptera and bees in beet were smaller under the relevant GMHT crop management, whereas the abundance of Collembola was consistently greater in all GMHT crops. Generally, these effects were specific to each crop type, reflected the phenology and ecology of the arthropod taxa, were indirect and related to herbicide management. These results apply generally to agriculture across Britain, and could be used in mathematical models to predict the possible long-term effects of the widespread adoption of GMHT technology. The results for bees and butterflies relate to foraging preferences and might or might not translate into effects on population densities, depending on whether adoption leads to forage reductions over large areas. These species, and the detritivore Collembola, may be useful indicator species for future studies of GMHT management.     

Weeds in fields with contrasting conventional and genetically modified herbicide-tolerant crops. I. Effects on abundance and diversity

We compared the seedbanks, seed rains, plant densities and biomasses of weeds under two contrasting systems of management in beet, maize and spring oilseed rape. Weed seedbank and plant density were measured at the same locations in two subsequent seasons. About 60 fields were sown with each crop. Each field was split, one half being sown with a conventional variety managed according to the farmer's normal practice, the other half being sown with a genetically modified herbicide-tolerant (GMHT) variety, with weeds controlled by a broad-spectrum herbicide. In beet and rape, plant densities shortly after sowing were higher in the GMHT treatment. Following weed control in conventional beet, plant densities were approximately one-fifth of those in GMHT beet. In both beet and rape, this effect was reversed after the first application of broad-spectrum herbicide, so that late-season plant densities were lower in the GMHT treatments. Biomass and seed rain in GMHT crops were between one-third and one-sixth of those in conventional treatments. The effects of differing weed-seed returns in these two crops persisted in the seedbank: densities following the GMHT treatment were about 20% lower than those following the conventional treatment. The effect of growing maize was quite different. Weed density was higher throughout the season in the GMHT treatment. Late-season biomass was 82% higher and seed rain was 87% higher than in the conventional treatment. The difference was not subsequently detectable in the seedbank because the total seed return was low after both treatments. In all three crops, weed diversity was little affected by the treatment, except for transient effects immediately following herbicide application.     

Sensitive dependencies and separation distances for genetically modified herbicide-tolerant crops

The amount of land available for the coexistent growing of both organic and genetically modified herbicide-tolerant (GMHT) crops depends on the separation distance between the two types of crop. The form of the decline in the proportion of land available for growing one of these crop types due to increasing separation distance is linear on a suitable scale, but with a slope and intercept that are sensitively dependent on the proportion of the other crop already present. Spatially explicit simulations from realistic scenarios indicate that a major increase in separation distances, currently under review by the UK government, may have serious implications for the future coexistence of organic and GMHT crops in the UK.     

抗除草剂转基因水稻对二种刺吸性害虫和二种天敌的影响

为探明转基因抗除草剂水稻对非目标生物的影响,于2007年和2008年对转Bar基因抗除草剂籼稻Bar68-1和非转基因对照D68稻田的2种常见刺吸性害虫和2种天敌在水稻分蘖中期、分蘖末期、齐穗期和乳熟期4个时期的种群密度进行了调查和比较。结果显示,抗除草剂水稻与对照稻田的飞虱、叶蝉、盲蝽、蜘蛛的发生密度,除不喷药处理区的2007年水稻乳熟期和2008年分蘖中期的盲蝽科的发生密度差异显著外,其余均无显著差异。试验结果表明,转基因抗除草剂水稻Bar68-1对包括飞虱、叶蝉、盲蝽、蜘蛛等类群在内的稻田非目标生物的田间自然种群的影响与非转基因水稻基本相同。     

Functional approaches for assessing plant and invertebrate abundance patterns in arable systems

A functional group approach was developed for plant and invertebrate assemblages from UK arable fields to assess the variation in functional composition of these highly disturbed, managed systems. Data were taken from the Farm-Scale Evaluations (FSE) of genetically modified herbicide-tolerant (GMHT) crops where the impact of management of the GMHT crop has been assessed for winter and spring sown oilseed rape, beet and maize. Twenty plant and 36 invertebrate functional groups were defined according to trophic behaviour and traits that affect resource capture, quality and availability. The functional composition of the plant community was significantly affected by season of sowing, the type of crop sown and, to a lesser extent, herbicide management. The invertebrate community composition was also affected by crop type and sowing season, but not by management. Resource and consumer groups were positively related, and data provide strong evidence for top-down control of herbivore populations. Two main interaction groups were identified within the arable food web: one between omnivores, generalist predators and detritivores, which are positively associated with monocots, and one between omnivores, parasitoids, sap feeders and leaf chewers, which have a stronger association with dicots. Although management has an impact on within-field arable biodiversity, crop type and sowing season have an overriding effect on the functional composition of plant and invertebrate assemblages in arable systems.     

Rapid quality control of a live attenuated Peste des petits ruminants (PPR) vaccine by monoclonal antibody based sandwich ELISA.

Peste des petits ruminants (PPR) is a highly contagious and economically important viral disease of goats and sheep. A homologous Vero cell-based attenuated PPR vaccine developed in our laboratory and used extensively throughout the country, is available for control of PPR. The presently used quality control test, titration in Vero cells for PPR virus titre in vaccine batches, takes at least 6-8days to determine the quality and dose of vaccine. In this study, 74 freeze-dried PPR vaccine batches were tested simultaneously by both virus titration and PPR sandwich ELISA (S-ELISA) to correlate the titre of the vaccine virus with reactivity in S-ELISA. It was found that the vaccine batches with titre more than 10(3)TCID(50)/ml gave positive results in S-ELISA and correlated well with the virus titre of the freeze-dried vaccines. The correlation coefficient between the virus titration and S-ELISA reactivity was estimated as 0.96, indicating a high correlation between the two parameters based on 74 batches of freeze-dried PPR vaccine. The vaccine batches with titres of 3.0, 4.3, 4.5, 5.0, 6.5 and 7.0 had shown a positive reaction when tested in two-fold dilutions in S-ELISA at 1, 5, 6, 7, 8 and 9log2 titres, respectively. The test vaccine batches were found to be negative in S-ELISA when the titre of the vaccine was less than 10(3)TCID50/ml, suggesting that the vaccine could not be passed for field use. It is concluded that S-ELISA could be a preliminary tool useful for the quality control of PPR vaccine as it is rapid and easy to perform when compared to virus titration.     

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.     

On the rationale and interpretation of the Farm Scale Evaluations of genetically modified herbicide-tolerant crops

Farmland biodiversity and food webs were compared in conventional and genetically modified herbicide-tolerant (GMHT) crops of beet (Beta vulgaris L.), maize (Zea mays L.) and both spring and winter oilseed rape (Brassica napus L.). GMHT and conventional varieties were sown in a split-field experimental design, at 60-70 sites for each crop, spread over three starting years beginning in 2000. This paper provides a background to the study and the rationale for its design and interpretation. It shows how data on environment, field management and the biota are used to assess the current state of the ecosystem, to define the typical arable field and to devise criteria for selecting, sampling and auditing experimental sites in the Farm Scale Evaluations. The main functional and taxonomic groups in the habitat are ranked according to their likely sensitivity to GMHT cropping, and the most responsive target organisms are defined. The value of the seedbank as a baseline and as an indicator of historical trends is proposed. Evidence from experiments during the twentieth century is analysed to show that large changes in field management have affected sensitive groups in the biota by ca. 50% during a year or short run of years--a figure against which to assess any positive or negative effects of GMHT cropping. The analysis leads to a summary of factors that were, and were not, examined in the first 3 years of the study and points to where modelling can be used to extrapolate the effects to the landscape and the agricultural region.     

Invertebrate biodiversity in maize following withdrawal of triazine herbicides

Responses of key invertebrates within Farm Scale Evaluations (FSEs) of maize reflected advantageous effects for weeds under genetically modified herbicide-tolerant (GMHT) management. Triazine herbicides constitute the main weed control in current conventional systems, but will be withdrawn under future EU guidelines. Here, we reappraise FSE data to predict effects of this withdrawal on invertebrate biodiversity under alternative management scenarios. Invertebrate indicators showed remarkably consistent and sensitive responses to weed abundance. Their numbers were consistently reduced by atrazine used prior to seedling emergence, but at reduced levels compared to similar observations for weeds. Large treatment effects were, therefore, maintained for invertebrates when comparing other conventional herbicide treatments with GMHT, despite reduced differences in weed abundance. In particular, benefits of GMHT remained under comparisons with best estimates of future conventional management without triazines. Pitfall trapped Collembola, seed-feeding carabids and a linyphiid spider followed closely trends for weeds and may, therefore, prove useful for modelling wider biodiversity effects of herbicides. Weaker responses to triazines applied later in the season, at times closer to the activity and capture of invertebrates, suggest an absence of substantial direct effects. Contrary responses for some suction-sampled Collembola and the carabid Loricera pilicornis were probably caused by a direct deleterious effect of triazines.