Risks to bees from dusts emitted at sowing of coated seeds: concerns, risk assessment and risk management

Field: Environmental Science (Physical Sciences)

The use of Plant Protection Products (PPP) through seed coating may lead to honey bee exposure mainly in the case of systemic properties, through residues that thus may reach green and flowering parts of growing plants. Incidents occurred in France, Germany and Slovenia. These revealed mortality events in honey bee colonies occurring immediately after sowing of coated seeds which could not be explained by systemic properties. These incidents were related to a loss of active substance from the outflow air fan of pneumatic sowing machines and possible pollution of vegetation in nearby fields. Investigations were undertaken in France in order to identify the factors responsible of these incidents. A low coating quality was demonstrated, which lead to the emission of higher level of dusts compared to usual coating. Higher levels of residues could also be observed in the dusts generated by the low quality coating compared to a normal one. Further research was performed in Italy, on outflow air from pneumatic seed drills, which demonstrated a pollution of plants in the vicinity of sowed areas, at levels directly dependant on the length of sowing duration. This observation leads to recommend a quality control of the dust level at the seed treatment plant. Specific equipments exists, which may reduce the risks by limiting dust emission during sowing operations. Outflow fans may for example be oriented towards the soil so that dust drift is limited. In addition, deflecting devices may redirect dust to the soil and avoid turbulence and further drift. An efficacy assessment of these devices compared to ‘conventional’ equipment may be a preliminary requirement to their generalized implementation on seed drills. Hazards of pesticides to bees – 10 International Symposium of the ICP-Bee Protection Group 132 Julius-Kuhn-Archiv 423, 2009 Prior to an adaptation of sowing material, the question of the risks posed by sowing dusts to honey bees remains. In France, a dedicated risk assessment has recently been performed for two PPPs to be used as seed coating. Exposure of bees was assessed from dedicated experimental data on dust emission from the coated seeds according to high quality standard. The amount of active substance emitted was determined and used as an application rate estimate in a hazard quatient calculation, further compared to Directive 91/414/EEC trigger and by comparing the drift dose rate on dusts to acceptable exposure levels in tunnel testing. Due to the nature of the risks related to a sowing event, contact toxicity value was preferred. This risk assessment lead to conclude to acceptable acute risks for the products evaluated. Nevertheless, such an assessment may probably be improved and remains a precondition to routinely implemented controls of coating quality, through e.g. dust emission/abrasion tests. _______________________ 1 Commission d’etude de la toxicite, des produits antiparasitaires et supports de culture, proces verbal de fevrier 2004 (http://agriculture.gouv.fr/IMG/pdf/avisctweb200401.pdf) 2 Greatti M., Barbattini R., Stravisi A., Sabatini A. G. and Rossi S., 2006. Presence of the a.i. imidacloprid on vegetation near corn fields sown with Gaucho dressed seeds. Bulletin of insectology 59 (2): 99-103. 3 AVIS du CES relatif a une demande d'autorisation de mise sur le marche de la preparation Cruiser a base de thiamethoxam, de la societe Syngenta Agro SAS, dans le cadre d'une procedure de reconnaissance mutuelle. Avis du CES relatif a une demande d'autorisation de mise sur le marche de la preparation Poncho Mais a base de clothianidine, de la societe Bayer Cropscience France, dans le cadre d'une procedure de reconnaissance mutuelle (http\\www.afssa.fr). An effective risk management approach to prevent bee damage due to the emission of abraded seed treatment particles during sowing of seeds treated with bee toxic insecticides Alexander Nikolakis, Andrew Chapple, Reinhard Friessleben, Paul Neumann, Thorsten Schad, Richard Schmuck, Heinz-Friedrich Schnier, Hans-Jurgen Schnorbach, Ralf Schoning, Christian Maus* Bayer CropScience AG, Alfred-Nobel-Str. 50, 40789 Monheim, Germany *Tel.: +49 2173 38 3750; Fax: +49 2173 38 4981. E-mail: christian.maus@bayercropscience.com