Algemeen

Since 1995, neonicotinoid insecticides have been a critical component of arthropod management in potato, Solanum tuberosum L. Recent detections of neonicotinoids in groundwater have generated questions about the sources of these contaminants and the relative contribution from commodities in U.S. agriculture. Delivery of neonicotinoids to crops typically occurs as a seed or in-furrow treatment to manage early season insect herbivores. Applied in this way, these insecticides become systemically mobile in the plant and provide control of key pest species. An outcome of this project links these soil insecticide application strategies in crop plants with neonicotinoid contamination of water leaching from the application zone. In 2011 and 2012, our objectives were to document the temporal patterns of neonicotinoid leachate below the planting furrow following common insecticide delivery methods in potato. Leaching loss of thiamethoxam from potato was measured using pan lysimeters from three at-plant treatments and one foliar application treatment. Insecticide concentration in leachate was assessed for six consecutive months using liquid chromatography-tandem mass spectrometry. Findings from this study suggest leaching of neonicotinoids from potato may be greater following crop harvest in comparison to other times during the growing season. Furthermore, this study documented recycling of neonicotinoid insecticides from contaminated groundwater back onto the crop via high capacity irrigation wells. These results document interactions between cultivated potato, different neonicotinoid delivery methods, and the potential for subsurface water contamination via leaching.

EFSA has published new guidance that enables scientists to carry out a specialised aspect of environmental exposure assessment for pesticides. The guidance document provides a clear methodology for evaluating studies that measure the time required for the actual degradation of 50 % of a chemical pesticide and its transformation products in soil. This is known as the DegT50 value. Importantly, it allows users to exclude the effects of dissipation, another process that causes pesticide residues to disappear from soil. The guidance is aimed primarily at risk assessors and industry applicants and allows them to derive DegT50 values, critical information for the safety evaluation of pesticides. EFSA has developed the guidance document as part of its ongoing work in the field of pesticides to safeguard the environment. The methodology can be also applied to chemicals released into soil from non-pesticide uses.

Pesticides have a direct impact on the physiology and behaviour of earthworms, a Danish/French research team reports after having studied earthworms that were exposed to pesticides over generations. "We see that the worms have developed methods to detoxify themselves, so that they can live in soil sprayed with fungicide. They spend a lot of energy on detoxifying, and that comes with a cost: The worms do not reach the same size as other worms, and we see that there are fewer of them in sprayed soil. An explanation could be that they are less successful at reproducing, because they spend their energy on ridding themselves of the pesticide", the researchers, Ph. D. student Nicolas Givaudan and associate professor, Claudia Wiegand, say.

Eine Studie zeigt, dass das Ökosystem der Erde durch Insektengifte bereits schwer geschädigt ist. Die Vielfalt der Bodenorganismen hat in landwirtschaftlich genutzten Böden massiv abgenommen. Jedes Jahr geht ein Prozent der weltweiten Anbauflächen durch Erosion verloren. Hungersnöte drohen - für die Schwellenländer und den reichen Westen.

Speaking at the Vic No-Till annual conference in Ballarat last week, Dr Clapperton said: "It's bad for you, it's bad for the environment, it's bad for the soil - it's bad for everything. "But some times we need it, I get that. Our goal should be not to need it. "Insecticides are some of our most toxic substances - they kill all insects, beneficial and pests - and insects are probably more manageable than many of our other pests. "Now with our technology we can put things between rows properly and grow mixed covers, we have some opportunities to look at this more. We are starting to understand the different insects and how they interact." Dr Clapperton is a freelance scientist and farmer, proving her science in her own fields.

In a new study on ecosystems in the Midwest, scientists suggest that once-fertile landscapes dominated by tall grass prairies and supported by microbial biodiversity have been destroyed due to decades of agricultural production. The study, Reconstructing the Microbial Diversity and Function of Pre-Agricultural Tall Grass Prairie Soils in the United States, published in the journal Science, demonstrates the crucial role soil microbial diversity plays in ecosystem stability and health. Although soil microbes are inherently important for the breakdown of organic matter, the cycling of nutrients, as well as plant productivity, previous research has narrowly focused on the role of nitrogen fixing root fungi, rather than broader aspects of soil microbial diversity. Thus, this new study represents one of the first to delve into the importance of soil microorganisms in ecosystem restoration projects.

Sorption-desorption processes govern the movement of all chemicals including pesticides in soils. The present investigation was undertaken to study the sorption-desorption of imidacloprid, using a batch method, on soils of five different location of India. Sorption data were fitted to Freundlich isotherm. The log K value was the highest for loam type soil (1.830) and the lowest for clay type soil (1.661). The value of 1/n was the maximum for silt loam soil (0.909) but minimum for loam soil (0.723). Simple correlation analysis indicated that among soil properties only electrical conductivity showed a higher but marginally non-significant negative correlation with log K (r = -0.826) indicating that higher concentration of solutes solutes are conducive to low sorption capacity of soil. The desorption data conformed to two surfaces Freundlich desorption isotherm. The values of 1/n1' corresponding to easily desorbed fraction of imidacloprid showed significant negative correlation with soil pH (r = -0.886, significant at p ≤0.05) but significant positive correlation with clay content (r = 0.980, significant at p ≤0.01). The desorption index for easily desorbed fraction of imidacloprid (n1’/n) also had significant negative correlation with soil pH (r = 0.953, significant at p ≤0.05). From cumulative desorption data, it appeared that bioavailability of imidacloprid would be lower in neutral soil than acidic or alkaline soils.

Neonicotinoids are now the most widely used insecticides in the world. They act systemically, travelling through plant tissues and protecting all parts of the crop, and are widely applied as seed dressings. As neurotoxins with high toxicity to most arthropods, they provide effective pest control and have numerous uses in arable farming and horticulture. However, the prophylactic use of broad-spectrum pesticides goes against the long-established principles of integrated pest management (IPM), leading to environmental concerns. It has recently emerged that neonicotinoids can persist and accumulate in soils. They are water soluble and prone to leaching into waterways. Being systemic, they are found in nectar and pollen of treated crops. Reported levels in soils, waterways, field margin plants and floral resources overlap substantially with concentrations that are sufficient to control pests in crops, and commonly exceed the LC50 (the concentration which kills 50% of individuals) for beneficial organisms. Concentrations in nectar and pollen in crops are sufficient to impact substantially on colony reproduction in bumblebees..Although vertebrates are less susceptible than arthropods, consumption of small numbers of dressed seeds offers a route to direct mortality in birds and mammals. Major knowledge gaps remain, but current use of neonicotinoids is likely to be impacting on a broad range of non-target taxa including pollinators and soil and aquatic invertebrates and hence threatens a range of ecosystem services.

Steeds meer boeren en consumenten sluiten zich aan bij de opvatting dat het Europees landbouwbeleid anders moet. De bodem- en waterkwaliteit worden door grootschalige landbouw en pesticiden aangetast. Europarlementariër Bas Eickhout: “Dat willen wij anders: Landbouwbeleid mag niet ten koste gaan van gezondheid en milieu. We moeten met belastinggeld niet méér problemen veroorzaken, maar juist strenge eisen stellen ter bescherming van milieu en gezondheid.”

Deutschland ist grün. Von oben jedenfalls. Doch wer an der Oberfläche kratzt und tiefer gräbt, stößt auf eine dramatische Verschlechterung der Bodenqualität. Schwere Landmaschinen, Monokulturen, Pestizide und Kunstdünger vernichten Humus und nehmen der dünnen, fruchttragenden Schicht ihre Funktion als natürlicher Wasser- und Kohlenstoffspeicher. Im norddeutschen Maisgürtel spricht man bereits von "toter Erde" - und nicht nur hier. Die Folgen sind Staubstürme, Schlammlawinen sowie eine stetig sinkende Artenvielfalt. Etliche Landwirte versuchen den Raubbau zu stoppen und dem Boden seine Fruchtbarkeit zurückzugeben. Doch noch fehlt es an der nötigen Unterstützung. Nur zögernd stellen sich Behörden und Politiker dem Problem.