Deposition of dust with active substances in pesticides from treated seeds in adjacent fields during drilling: disentangling the effects of various factors using an 8-year field experiment

Abstract

The side effects from the use of plant protection products and their potential effects on non-target arthropods (NTAs) such as honey bees, other insects within the vegetation layer and epigeic arthropods nowadays receive more attention. However, uncertainties about the factors driving the deposition of active substances (a.s.) into off-crop areas persist, in particular during sowing of treated seeds. Analysing a highly standardised 8-year field experiment, we assessed the importance of various factors potentially affecting dust drift and deposition of a.s., emitted during the sowing process of treated seeds and deposited on fields adjacent to the drilling field, i.e. on the ground, on flowers, and on nonflowering plant parts. Regarding a.s. deposition, the Heubach a.s. value has a predictive capability, which is independent from all other factors taken into account in this study, and can thus be considered as a scenario-independent measure of potential dust deposition. Petri dish samplers, an established standard method for measuring a.s. deposition, were representative of the results from the plant samplers for a given combination of drilling technique and adjacent crop type. Adjacent crop type is likely to impact on a.s. deposition. The present work will enable a more field-realistic exposure assessment for bees and other NTAs.

Potential Risk of Residues From Neonicotinoid‐Treated Sugar Beet in Flowering Weeds to Honey Bees (Apis mellifera L.)

“…In addition, weeds and other plants must not be allowed to flower on the relevant field before and after sowing until the end of 2022. To avoid exposure to seed treatment dust (Krahner et al, 2021), only drift‐reduced pneumatic seed drilling machines may be used for sowing.…”

Dust abraded from thiamethoxam‐treated seed during sowing: Refining the risk assessment for native bees in Brazil

“…The dust deposition factors were derived from field trials measuring residue deposition on Petri dishes containing glycerol placed on the soil surface and residues deposited on plants and flower surfaces wetted with glycerol so as to be a worst‐case scenario (Heimbach et al, 2014; Krahner et al, 2021). This is exemplified by results from a range of treated crop seeds, where doubling of the Heubach AI g/ha resulted in a 21.6% increase in residues on Petri dishes (µg/m 2 ), whereas a 10‐fold increase in Heubach AI g/ha resulted in a doubling of residues (Krahner et al, 2021). Therefore the one‐to‐one relationship assumed between Heubach AI measured under laboratory conditions and predicted residues on plants under field conditions, as assumed using the Heubach AI (application rate) and dust deposition factor, is likely to be conservative.…”

“…Brazil currently adopts the dust deposition factors used in the EU by EFSA (2013a) based on SANCO/10553/ 2012 (Cham et al, 2017). These dust deposition factors were based on measured residues on Petri dishes after sowing treated seed and extrapolation to plants at the field edge (Krahner et al, 2021). In the absence of crop-specific dust deposition factors for soybean, cotton, drybean, and sunflowers, the highest EU deposition factor (maize) was also used for these crops.…”

Dust drift during mechanical and pneumatic wheat sowing and insights into the physicochemical characteristics of the abraded dust

“…The major honey bee poisoning incidents were attributed to sowing seeds treated with neonicotinoids without any mitigation measures 1 and since then most applications of these insecticides have been banned in Europe, 8 various dust drift mitigation devices have been developed 9 and seed coating quality has drastically improved 10 . However, dust drift still remains highly relevant, going beyond neonicotinoids and bees 8 . Other a.i.…”