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VIII SIMPOSIO INTERNAZIONALE ICPBR HAZARDS
OF PESTICIDES TO BEES Effetti dell’imidacloprid sulle api Honey bee safety of Gaucho® corn seed treatment. Further technical innovation Heinz Friedrich Schnier, Guido Wenig, Frank Laubert, Volker Simon and Richard Schmuck Bayer AG,
Bayer CropScience, Alfred-Nobel-Str. 50, 40789 Monheim, Germany. In 2000, beekeepers form the Italian region of Friuli reported about losses of a higher number of bee hives during the spring season. At the time of this bee incident farmers in Friuli had started to drill their corn fields and some of the seeds had been treated with the seed dressing product Gaucho® (active ingredient is imidacloprid). Reports by some French beekeepers on suspected impacts of seed dressed sunflowers on honey bees made some Italian beekeepers to believe that there might be a link between their bee losses and the use of Gaucho® seed dressing on corn seeds. In response to this concern, investigations were conducted to examine whether or not such a link exists. Besides the Gaucho® FS 350 seed dressing formulation which is marketed in Italy, two new formulations have been examined which contained adjuvants for further optimising seed loading and abrasions from dressed seed during transport and drilling. It could be shown that the addition of an adhesive have had a positive influence on the loss of active ingredient-containing dust deposits. Honey bees may be exposed to the Gaucho® seed dressing when during drilling particles are abraded from dressed corn seeds which may subsequently deposit in the field and along the field margins. A replicated cage test was conducted to examine potential effects on honey bees of such imidacloprid-containing dust deposits on flowering plants. From the findings of this replicated cage study it can be concluded that deposition rates which were much higher than those potentially emitted from pneumatic corn drilling machines used in praxis have no detrimental effect on honey bees. Nevertheless, the Gaucho® seed dressing formulation was technically improved resulting in a further minimised abrasion of formulation particles from dressed corn seed during drilling. In 2001, no hive losses were recorded in the region
of Friuli. The real causative factors (e.g. climatic conditions, bee
diseases) of the bee hive losses in 2000 remains to be elucidated in
order to develop reliable appropriate preventive measures against hive
losses in future. The present evaluation shows that the reported hive
losses in the Italian region of Friuli can not be linked to the drilling
of Gaucho® treated corn seeds.
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