Neonicotinoid seed treatment products – Occurrence and relevance of guttation for honeybee colonies

Background: Guttation is a natural botanical phenomenon and describes the active excretion of liquid water (guttation fluid) by some vascular plants in form of droplets on the tips of leaves or on leaf edges. Guttation fluid may contain neonicotinoid residues after plant uptake from seed treatments. To clarify the relevance of the guttation fluid as a water source for honey bee colonies and to assess potential associated risks under conditions of agronomic practice, various studies were performed in key broad acre crops such as maize, sugar beet, potato (in-furrow application), winter barley and oilseed rape by placing honeybee colonies adjacent to freshly emerged fields for several weeks and by following up potential lethal and sub-lethal effects, as well as potential effects on colony performance.Results: Guttation droplets contained peak residue levels theoretically capable of harming individual honeybees (i.e. several hundred ppm). Residue levels, however, generally decreased with time, as expected based on the physiological process involved. The temporal coincidence of honeybee flight activity and the presence of guttation droplets were generally limited to early morning hours and to a much lesser extent to evening hours. Spatially, honeybees were found to predominately collect water, if any, in the direct vicinity of the hives. Water collection generally ceased within a couple of metres distance to the hives, which renders distance to the crop to be a significant exposure factor, and in turn renders dew and guttation from off-crop vegetation to be more relevant to water collecting honeybees than guttation from the crop. Mortality events, if any, were scarce and generally matched in treatments and in controls. The absolute numbers of dead bees involved in these rare cases were so low that they did not translate into any colony level effects or impacts on bee health or overwintering success, nor on adverse effects on honey production of the involved colonies.Conclusions: Given the overall body of data, the associated intensity of the assessments in each study as well as the worst-case exposure conditions employed, it can be concluded that exposure of honeybee colonies to guttation fluid, excreted from neonicotinoid seed-treated crop plants, did not pose an unacceptable acute or chronic risk to honeybee colony development or survival, and does not adversely interfere with bee keeping practices. Overall, guttation water from seedtreated crop plants was found not to be a significant exposure route for honeybees.Keywords: pesticide, honey bee, guttatio

ICPBR-Working Group Risks posed by dusts: overview of the area and recommendations

Background: In 2008 the poisoning of about 12000 bee colonies was reported from Germany. These poisonings were caused by the drift of dust particles containing the insecticidal substance clothianidin following the seeding of maize seeds, inadequately treated with the insecticide Poncho Pro. Results: Investigations were done on the dust load contained in seed packages of different crops, on the experimental abrasion of dust from treated seeds using the Heubach-Dustmeter as well as on the actual dust drift during the sowing operation of treated seeds with different machinery under field conditions. Resistance to abrasion of treated seeds and subsequent dust drift during sowing operations differ significantly between crops, coating recipes and facilities. Furthermore dust drift depends on particle size, sowing technology as well as on environmental conditions (e.g. wind speed, soil humidity). Conclusions: The drift of dust from treated seeds may pose a risk to honeybees, which needs to be appropriately considered within the authorization process of pesticides. The total quantity of abraded dust as well as the actual emission of dust during the sowing operation can be significantly reduced by technical means (e.g. coating recipe and facility equipment, deflector technology) and by additional mitigation measures (e.g. maximum wind speed). Keywords: honeybee, poisoning, risk, seed treatment, dust, drif

The advantage of a toxicokinetic model of the honey bee colony in the context of the risk assessment of plant protection products

Within the current discussions about risk assessment of plant protection products regarding honey bees, one of the most important aspects is how to link pesticide exposure on field and landscape scale to potential effects within the colony. A dynamic toxicokinetic model may help to improve the evaluation of dose rates individuals are exposed to through various compartments of the colony, which may result from the application of plant protection products in the field. In addition, it may help to interpret the significance of ecotoxicological test results, especially from lower-tier studies, in the risk assessment and help to refine the exposure assessment and risk evaluation. Linking it to a realistic population model and a landscape-based foraging model would give an improved insight into the dynamics in a honey bee colony under exposure of plant protection productsKeywords: modelling, toxicokinetics, risk assessment, exposur

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

contribution to session V Honey bee poisoning incidents and monitoring schemes In spring of 2008, a bee incident occurred in the Upper Rhine Valley (Germany) during drilling of corn: bees were exposed to dust from abraded particles of the seed-coating containing the insecticide clothianidin. An inspection of drilled seed batches for resistance to abrasion and a geographical correlation analysis between specified seed batches and reported bee damages revealed that the incident was caused by improperly dressed batches of corn seeds with excessive abrasion of seed treatment particles which were subsequently emitted via the outlet air stream of the pneumatic drilling machines. Concerns raised by local beekeepers regarding effects on bees from foraging in seed-treated corn fields during bloom could be dispelled by a large-scale survey of clothianidin residues in pollen from the treated crop and an accompanying monitoring of bee hives exposed to flowering corn fields. In order to ensure the bee safety of seed-dressing products, technical improvements of seed treatment quality and drilling technology were developed resulting in a minimization of formation and emission of dust from abraded seed treatment particles. The efficacy of these improvements was proven in field trials. Keywords: seed treatment, drilling machines, corn, clothianidin, dust, honey bee