Large-scale monitoring of effects of clothianidin dressed oilseed rape seeds on pollinating insects in Northern Germany: implementation of the monitoring project and its representativeness
Ecotoxicology
Large-scale monitoring of effects of clothianidin dressed oilseed rape seeds on pollinating insects in Northern Germany: implementation of the monitoring project and its representativeness
Fred Heimbach 0 1
● Anja Russ 0
● Maren Schimmer 0 1
● Katrin Born 0
0 Spatial Business Integration GmbH , Darmstadt , Germany
1 tier3 solutions GmbH , Leverkusen, Germany 2
Monitoring studies at the landscape level are complex, expensive and difficult to conduct. Many aspects have to be considered to avoid confounding effects which is probably the reason why they are not regularly performed in the context of risk assessments of plant protection products to pollinating insects. However, if conducted appropriately their contribution is most valuable. In this paper we identify the requirements of a large-scale monitoring study for the assessment of side-effects of clothianidin seed-treated winter oilseed rape on three species of pollinating insects (Apis mellifera, Bombus terrestris and Osmia bicornis) and present how these requirements were implemented. Two circular study sites were delineated next to each other in northeast Germany and comprised almost 65 km2 each. At the reference site, study fields were drilled with clothianidin-free OSR seeds while at the test site the oilseed rape seeds contained a coating with 10 g clothianidin and 2 g beta-cyfluthrin per kg seeds (Elado®). The comparison of environmental conditions at the study sites indicated that they are as similar as possible in terms of climate, soil, land use, history and current practice of agriculture as well as in availability of oilseed rape and non-crop bee forage. Accordingly, local environmental conditions were considered not to have had any confounding effect on the results of the monitoring of the bee species. Furthermore, the study area was found to be representative for other oilseed rape cultivation regions in Europe.
Sublethal effects ● Risk assessment ● Bee monitoring ● Site selection ● Spatial analysis ● GIS
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Pollinating insects are a key component of terrestrial
ecosystems and provide an essential ecosystem service to
wild plants and agricultural crops. The annual value of
insect pollination to agriculture was estimated to be worth
US$ 153 billion globally in 2005 (Gallai et al. 2009) and the
demand of pollination services is high (Aizen and
Harder 2009; vanEngelsdorp and Meixner 2010). However,
many factors are suspected to impact pollinator health,
including parasites, the loss of habitat and decreasing
diversity of foraging resources (Goulson et al. 2008; Potts et
al. 2010; vanEngelsdorp and Meixner 2010; Winfree et al.
2009). Furthermore, the use of plant protection products
(PPPs) has been suggested to harm pollinating insects. In
particular the neonicotinoids, a group of systemic
insecticides, have been the subject of much discussion about
whether they cause adverse effects in pollinating insects
under field conditions (e. g., Godfray et al. 2014, Schmuck
and Lewis 2016).
Before a new PPP gets authorization for use in Europe, it
is subject to an extensive ecotoxicological risk assessment
in order to minimize the potential of adverse effects on
nontarget organisms (European Commission 2009). These risk
assessments follow a tiered approach based on worst-case
assumptions to ensure cost-effectiveness and
proportionality, ranging from laboratory toxicity tests to
more complex higher tier studies under field realistic
conditions (European Food Safety Authority 2013). The lower
tier studies are an important tool to assess intrinsic
mechanisms and identify potentially adverse effects of
PPP exposure in a set of model organisms. The strength of
these studies is their well-defined exposure under controlled
laboratory conditions. However, these studies apply
artificial conditions regarding the concentration and
duration of the exposure to the PPP (Carreck and Ratnieks 2014;
Godfray et al. 2014) and simplify or disregard processes
which might be of relevance in the field (Cutler and
Scott-Dupree 2014; Godfray et al. 2014; Liess et al. 2005).
Particular uncertainty exists about the actual exposure of
pollinating insects to the focal PPP under field conditions
because, for example, bees forage on a wide array of
pollen and nectar sources or may actively avoid pollen
and nectar from treated crops which might reduce their
exposure to the PPP in question. Furthermore, the
vulnerability of a species might differ from the model species
due to different ecological traits (Decourtye et al. 2013;
Liess et al. 2005). Due to these uncertainties, monitoring
studies at the landscape level may be needed in addition to
the common sequential testing in risk assessment to
gain a sound understanding of the actual environmental
effects of PPPs under current agricultural practice (Liess
et al. 2005).
In the case of clothianidin, a neonicotinoid insecticide
which is used in seed dressings of a number of crops e.g.
sugar beet, maize and oilseed rap (...truncated)