Dust drift from treated seeds during seed drilling: comparison of residue deposition in soil and plants

Drilling of seeds treated with plant protection products leads to dust drift carrying active substances (a.s.) into adjacent areas. Since these residues potentially pose a risk for bees, standardised field experiments have been conducted between 2009 and 2017 to investigate the deposition pattern of a.s. and the potential bee exposure to a.s. The large resulting data set contains a lot of information that can be used to improve our understanding of how different parameters influence the deposition pattern of dust and a.s. of seed treatments. For the present analysis, residues sampled in different matrices were used, including Petri dishes placed on bare soil and within neighbouring cultures (oil seed rape and mustard) as well as plant material (divided into flowering and nonflowering plant parts). In a nested design, multiple samples were taken at each distance of 0, 1, 3 and 5 m from the field edge within a total of 6 blocks per trial. The a.s. content per sample was determined analytically, using high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). By means of generalized linear mixed effect models (GLMM; R package ‘lme4’) and automated model selection (R package ‘MuMIn’), the effects of environmental and drilling parameters, seed treatment quality and sampling matrix were analysed taking into account the information from multiple trials and thus allowing for analysing the effects independently from another. A high amount of variation cannot be explained by the resulting models, probably due to environmental factors not incorporated into the models, such as varying wind speed and direction as well was heterogeneous field characteristics (terrain, crop density). However, the incorporated fixed effects resulted to be relevant in the majority of the selected models. Overall, the dust-borne a.s. emission per hectar (Heubach value expressed as g a.s./ha) has a strong impact on the amount of residues, which decrease markedly within the observed distance of 5 m to the field edge. Comparing different sampling matrices, i.e., flowering plant parts and ground-based Petri dishes, a similar distance-related residue pattern was observed within the neighbouring crops. Based on field realistic data, the presented results will contribute to enabling a more precise risk assessment of seed treatment applications with regard to bees. 1.10 Coumaphos residues in beeswax after a single application of CheckMite® affect larval development in vitro Christina Kast, Verena Kilchenmann, Benoît Droz Agroscope, Swiss Bee Research Centre, Schwarzenburgstrasse 161, 3003 Bern, Switzerland E-Mail: christina.kast@agroscope.admin.ch, verena.kilchenmann@agroscope.admin.ch, benoit.droz@agroscope.admin.ch DOI 10.5073/jka.2020.465.010 Abstract Coumaphos is an organophosphate insecticide used on bees for the control of the parasitic mite Varroa destructor. We studied the distribution of coumaphos in beeswax after a single application of CheckMite® andCoumaphos is an organophosphate insecticide used on bees for the control of the parasitic mite Varroa destructor. We studied the distribution of coumaphos in beeswax after a single application of CheckMite® and Hazards of pesticides to bees 14th international symposium of the ICP-PR Bee protection group, October 23 – 25 2019, Bern (Switzerland) Abstracts: Oral Presentation 32 Julius-Kühn-Archiv, 465, 2020 studied the effect of coumaphos in beeswax on larval development. Fifteen Apis mellifera colonies were treated with CheckMite® containing 2.72 g of coumaphos per application. During the following spring season, average coumaphos levels of 65 mg/kg were measured in combs that came into contact with the strips and average concentrations of 6.7 mg/kg were measured in combs that did not come into contact with the strips. Coumaphos was also detected in wax that was not present during the treatment, such as newly constructed wax, wax of honeycombs and capping wax, respectively. In vitro larval rearing in cups coated with beeswax containing coumaphos at a concentration of 70 mg/kg or 10 mg/kg demonstrated that coumaphos levels of 70 mg/kg in beeswax negatively affected larval development, while no differences to the controls (0 mg/kg) were observed for larvae exposed to beeswax containing coumaphos at 10 mg/kg. Therefore, beeswax exposed to CheckMite® should not be recycled in order to prevent elevated coumaphos residues in new foundations and hence to prevent honeybee larvae from being exposed to high residue levels. For further information please see Kast, C., Kilchenmann, V. and Droz, B. (2019) Distribution of coumaphos in beeswax after treatment of honeybee colonies with CheckMite® against the parasitical mite Varroa destructor. Apidologie 1.11 Exposure following pre-flowering insecticide applications to pollinators Edward Pilling1, Jeremey Barnekow1, Vincent Kramer1, Anne Alix1, Olaf Klein2, Lea Franke2, Julian Fricke2, 1, 2Eurofins Agroscience Services GmbH E-Mail: edward.pilling@corteva.com DOI 10.5073/jka.2020.465.011