Large-scale monitoring of effects of clothianidin-dressed oilseed rape seeds on pollinating insects in northern Germany: residues of clothianidin in pollen, nectar and honey
Large-scale monitoring of effects of clothianidin-dressed oilseed rape seeds on pollinating insects in northern Germany: residues of clothianidin in pollen, nectar and honey
Daniel Rolke 0 1 2
● Markus Persigehl 0 1 2
● Britta Peters 0 1 2
● Guido Sterk 0 1 2
● Wolfgang Blenau 0 1 2
0 IPM Impact , Kuringen , Belgium
1 tier3 solutions GmbH , Leverkusen , Germany
2 Institut für Bienenkunde (Polytechnische Gesellschaft), Goethe University Frankfurt , Oberursel , Germany
This study was part of a large-scale monitoring project to assess the possible effects of Elado® (10 g clothianidin & 2 g β-cyfluthrin/kg seed)-dressed oilseed rape seeds on different pollinators in Northern Germany. Firstly, residues of clothianidin and its active metabolites thiazolylnitroguanidine and thiazolylmethylurea were measured in nectar and pollen from Elado®-dressed (test site, T) and undressed (reference site, R) oilseed rape collected by honey bees confined within tunnel tents. Clothianidin and its metabolites could not be detected or quantified in samples from R fields. Clothianidin concentrations in samples from T fields were 1.3 ± 0.9 μg/kg and 1.7 ± 0.9 μg/kg in nectar and pollen, respectively. Secondly, pollen and nectar for residue analyses were sampled from free flying honey bees, bumble bees and mason bees, placed at six study locations each in the R and T sites at the start of oilseed rape flowering. Honey samples were analysed from all honey bee colonies at the end of oilseed rape flowering. Neither clothianidin nor its metabolites were detectable or quantifiable in R site samples. Clothianidin concentrations in samples from the T site were below the limit of quantification (LOQ, 1.0 µg/kg) in most pollen and nectar samples collected by bees and 1.4 ± 0.5 µg/kg in honey taken from honey bee colonies. In summary, the study provides reliable semi-field and field data of clothianidin residues in nectar and pollen collected by different bee species in oilseed rape fields under common agricultural conditions.
Honey bees ● Bumble bees ● Mason bees ●; Neonicotinoids ● Residues ● Seed treatment
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All bee species rely on pollen and nectar as food sources. In
collecting these plant substrates, they serve as economically
valuable pollinators of cultivated crop plants and contribute
to ecosystem services (Klein et al. 2007). Not only honey
bees (Apis spp.) but also bumble bees (Bombus spp.) and
mason bees (Osmia spp.) are commercially reared for
pollination services and can be more or less ifically targeted to
crop monocultures. In addition, various species of bumble
bees and mason bees (among many other bee species) are
common and widespread in the wild and, to some extent,
can also be attracted by crop monocultures. Since
agricultural crop plants are commonly treated with plant
protection products (PPPs) against insect pests, pollinating
insects such as bees may potentially be affected by this
treatment. Thus, PPPs contribute to the multiple and varying
stressors bees are exposed to and which also include habitat
loss, agricultural intensification, parasites and pathogens
(Potts et al. 2010). In particular, systemically acting PPPs of
the neonicotinoid class of compounds are often held
responsible for losses of honey bee colonies and declines
in the abundance of wild bees (Sánchez-Bayo, 2014;
Goulson et al. 2015; Pisa et al. 2015, Rundlöf et al. 2015).
As synthetic nicotine analogues, neonicotinoids affect the
nicotinic acetylcholine receptor in the insect brain (for
reviews, see: Tomizawa and Casida 2005; Jeschke et al.
2013). Neuroactive neonicotinoids are commonly used as
seed dressings in a variety of crops including oilseed rape
(OSR). The growing plant absorbs the insecticide, which is
distributed to all plant tissues and substrates, including
pollen and nectar (Elbert et al. 2008). Because of this
systemic activity, neonicotinoids can be applied as a seed
dressing or to soil at low rates, which reduces the need for
foliar insecticide applications that are applied at much
greater rates.
The European Union has temporarily suspended the use
of three neonicotinoids (clothianidin, imidacloprid and
thiamethoxam) for seed treatment, soil application and
foliar treatment in bee attractive crops (European
Commission 2013) to allow for in depth studies of their
environmental effects. Many laboratory and semi-field studies
have provided data about lethal and sublethal effects of
neonicotinoids to bees under certain application regimes
and at specific concentrations (Godfray et al. 2014, Godfray
et al. 2015). However, from an environmental perspective
they have been criticised (Cresswell and Thompson 2012;
Guez 2013; Carreck and Ratnieks 2014; Godfray et al.
2014, Godfray et al. 2015), e.g., for not using field realistic
doses or for subjecting bees exclusively to food spiked with
neonicotinoids under laboratory conditions. Because of the
basic toxicological principle of the relationship between
dose and response, a central ques (...truncated)