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Background information: Bee losses caused by insecticidal seed treatment in Germany in 2008

In late April and early May 2008 a bee mortality occurred in parts of South-West Germany, which, according to the latest data, affected approximately 11,000 colonies of bees, some of them substantially. Immediately after this became known, an intensive search for the causes of these incidences was started. For this purpose the Ministerium für Ernährung und Ländlichen Raum (Ministry for Food and Rural Areas) of the federal state of Baden-Württemberg and the local authorities collaborated with the bee-keepers, the laboratory for the investigation of bee incidents at the Julius Kühn Institute, the BVL and the plant protection products industry. Soon, maize seeds which had been treated with the insecticidal substance clothianidin were suspected as a possible cause. In the meantime, a clothianidin poisoning has been confirmed by the Julius Kühn Institute.

It is assumed that the detected clothianidin originates from treated maize seeds where the active substance did not adhere well enough to the grains. This minor dressing quality led to a strong abrasion. In the Upper Rhine Valley pneumatic seeding machines with vacuum systems were employed, which, due to their construction, release abrasion dust into the air. This way the abrasion dusts could settle on blooming plants.

The regional distribution of the bee damages and the investigation of the seeds suggest that the quality deficiencies occurred in certain lots of maize seeds, which had been treated specifically against the western corn rootworm. For this purpose a higher application rate had been authorised than for the protection against frit-flies and wire-worms.

Measures taken by the authorities

On May 15, 2008, before the complete clarification of the incidents, the BVL ordered suspension of the authorisation of eight insecticidal seed treatment products. For precautionary reasons, these measures did not only apply to products for the treatment of maize seeds, but also to products for the protection of rapeseed. On May 24, 2008, the Bundesministerium für Ernährung, Landwirtschaft und Verbraucherschutz (Federal Ministry of Food, Agriculture and Consumer Protection) banned for a period of 6 months the planting of maize by means of negative pressure pneumatic machines for single grain delivery; this ban applies to maize seeds treated with clothianidin or with one of three further insecticides.

In parallel to these immediate measures, the BVL intensively dealt with the problem of the abrasion of active substances in seed treatment products. The aim was to clarify which factors play a role in the treatment of seeds and in the sowing process, and how to minimise the damage to the environment. For this purpose the BVL asked authorisation holders for documents and held several expert meetings, during which seed producers, the industry for agricultural machinery, associations and independent experts could express their opinions.

Due to the complexity of factors like the quantity of active substances per quantity of seeds, different dressing qualities and the machinery used, the BVL holds another expert meeting on July 14, 2008, dealing with the procedures applied for the treatment of seeds and the technique of the drilling machines used in the cultivation of maize. In addition the BVL has requested further documents from authorisation holders and is in contact with European and Northern American authorisation bodies.

Presumably in autumn 2008, the BVL will decide whether the authorisations for the maize treatment products will re-enter into force under certain conditions and with certain restrictions, e. g. a limitation of the application rate, or if they will have to be revoked altogether.

Situation regarding rapeseed

The problems which occurred in connection with maize seeds are not transferable to rapeseed. The risk evaluation by the Julius Kühn Institute and the results of the German bee monitoring programme did not produce any evidence for a possible damage to bee colonies.

The Julius Kühn Institute and the Landwirtschaftliches Technologiezentrum Augustenberg (Center for Agricultural Technology in Augustenberg) tested seed samples obtained on the market for their abrasion resistance. The abrasion of the rapeseed samples proved to be very low, with values much smaller than those for maize. Furthermore, for planting rapeseed, machines are used which exclusively emit abrasion dusts into the soil and not into the air. Moreover, a lower quantity of active substances per hectare is released to the fields with treated rapeseed than with treated maize. Last but not least there is still no evidence that the pollen and nectar of the rapeseed flower present any danger to bees.

On June 25, 2008, the BVL reinstated the authorisation for rapeseed under the condition that the plant protection product is fixed to the rapeseed grains by means of an additional sticker, so that no abrasion dusts can be released into the air. This way the quality of the seeds regarding abrasion resistance and dust-freeness is ensured, independent of a commitment of the seed producers to use stickers and to perform more quality controls.

Although the BVL after thorough examination comes to the conclusion that the treatment of rapeseed with clothianidin containing plant protection products does not put bee colonies at risk it recommended, from precautionary reasons, that authorisation holders label packages containing treated rapeseeds as follows:

  • Do not let treated seeds and remnants thereof like broken grains and dusts, empty containers or packages as well as rinsing fluids enter into water. This also applies to indirect entry via the urban or agrarian drainage system and to rain-water and sewage canals.
  • Do not plant treated seeds in case of wind speeds of more than 5 m/s.
  • The treated seeds including contained dusts or dusts developing during the sowing process, have to be worked completely into the soil.
  • Treated seeds should not be planted by means of pneumatic seeding machines (vacuum system), unless the exhaust air is channelled in such a way that the dusts can be led into the soil.
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