Le Haut Conseil des biotechnologies (HCB) a ete sollicite le 4 avril 2018 par la direction generale de l’alimentation du ministere de l’Agriculture et de l’Alimentation et par la direction generale de la prevention des risques du ministere de la Transition ecologique et solidaire pour examiner et commenter le projet de document consensus de l’OCDE (version du 3 avril 2018) sur les considerations environnementales relatives a l’evaluation des risques associes a la dissemination de plantes genetiquement modifiees en vue de la reunion du groupe de travail de l’OCDE sur l’harmonisation de la surveillance reglementaire en biotechnologie les 21 et 22 juin 2018. Le Comite scientifique (CS)1 du HCB a examine ce document en seance du 26 avril 2018 sous la presidence de Jean-Christophe Pages. Les commentaires du CS du HCB a destination de l’OCDE, en version francaise et anglaise2, ont ete valides par voie electronique et transmis aux autorites competentes francaises le 23 mai 2018, et publies apres envoi a l’OCDE le 30 mai 2018.
The sunflower crop provides an important honey flow for beekeepers. In France, beekeepers observed a decrease in honey yield from this crop these past years compared to the 1980s–1990s. They suspect the new cultivars to be less productive in nectar compared to the older ones, but no data is available to support this, and it is known that climate conditions have a strong impact on nectar secretion. This study aimed to explore the effect of abiotic environmental conditions on nectar secretion in sunflower, as well the range of variation of this secretion in a sample of current cultivars. Thirty-four current sunflower hybrid cultivars were sampled in test plots for their nectar secretion under varying conditions of temperature, air humidity and soil moisture. Air humidity controlled the sugar concentration of nectar, and thus its volume. To study nectar secretion independently from this effect, analyses subsequently focused on nectar sugar mass per floret. The nectar sugar mass increased with temperature up to an optimum of 32 °C, while the variation range of soil water tension was not sufficient to detect an effect on nectar sugar mass. This varied by up to 100% among the 34 cultivars (from 101 to 216 μg sugar per staminate floret in average), with a similar range to those reported in the literature for older cultivars. Likewise, oleic cultivars, a new type introduced since the early 2000s, were found to secrete the same amounts of nectar as linoleic cultivars, an older conventional type. The more self-fertile cultivars also showed no reduction in nectar secretion. Finally, we tested the method that measures the nectar gross secretion rate in one hybrid, and we observed that this hybrid secreted in average 28 μg sugar per hour per staminate floret. The potential benefits of this method were discussed.
Contribution of insect pollinators to crop yield and quality varies with agricultural intensificationBackground.Up to 75 % of crop species benefit at least to some degree from animal pollination for fruit or seed set and yield.However, basic information on the level of pollinator dependence and pollinator contribution to yield is lacking for many crops.Even less is known about how insect pollination affects crop quality.Given that habitat loss and agricultural intensification are known to decrease pollinator richness and abundance, there is a need to assess the consequences for different components of crop production.Methods.We used pollination exclusion on flowers or inflorescences on a whole plant basis to assess the contribution of insect pollination to crop yield and quality in four flowering crops (spring oilseed rape, field bean, strawberry, and buckwheat) located in four regions of Europe.For each crop, we recorded abundance and species richness of flower visiting insects in ten fields located along a gradient from simple to heterogeneous landscapes.Results.Insect pollination enhanced average crop yield between 18 and 71% depending on the crop.Yield quality was also enhanced in most crops.For instance, oilseed rape had higher oil and lower chlorophyll contents when adequately pollinated, the proportion of empty seeds decreased in buckwheat, and strawberries' commercial grade improved; however, we did not find higher nitrogen content in open pollinated field beans.Complex landscapes had a higher overall species richness of wild pollinators across crops, but visitation rates were only higher in complex landscapes for some crops.On the contrary, the overall yield was consistently enhanced by higher visitation rates, but not by higher pollinator richness.Discussion.For the four crops in this study, there is clear benefit delivered by pollinators on yield quantity and/or quality, but it is not maximized under current agricultural intensification.Honeybees, the most abundant pollinator, might partially compensate the loss of wild pollinators in some areas, but our results suggest the need of landscape-scale actions to enhance wild pollinator populations.
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