Article

Neonicotinoid Pesticide Reduces Bumble Bee Colony Growth and Queen Production

School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK.
Science (Impact Factor: 33.61). 03/2012; 336(6079):351-2. DOI: 10.1126/science.1215025
Source: PubMed

ABSTRACT

Growing evidence for declines in bee populations has caused great concern because of the valuable ecosystem services they provide. Neonicotinoid insecticides have been implicated in these declines because they occur at trace levels in the nectar and pollen of crop plants. We exposed colonies of the bumble bee Bombus terrestris in the laboratory to field-realistic levels of the neonicotinoid imidacloprid, then allowed them to develop naturally under field conditions. Treated colonies had a significantly reduced growth rate and suffered an 85% reduction in production of new queens compared with control colonies. Given the scale of use of neonicotinoids, we suggest that they may be having a considerable negative impact on wild bumble bee populations across the developed world.

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    • "Laboratory and semi-field studies are often dismissed as using unrealistically high doses of pesticides. For example, Whitehorn et al. (2012) experimentally exposed bumble bee colonies to pollen containing 6 ng/g of the neonicotinoid imidacloprid, plus 0.70 ng/g in their nectar, and found an 85% drop in queen production compared to controls. However, it has since been argued that this dose was higher than bumble bees are likely to receive in the field because colonies will be feeding on a mix of contaminated crops and uncontaminated wildflowers (Carreck and Ratnieks, 2014). "
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    ABSTRACT: There is considerable and ongoing debate as to the harm inflicted on bees by exposure to agricultural pesticides. In part, the lack of consensus reflects a shortage of information on field-realistic levels of exposure. Here, we quantify concentrations of neonicotinoid insecticides and fungicides in the pollen of oilseed rape, and in pollen of wildflowers growing near arable fields. We then compare this to concentrations of these pesticides found in pollen collected by honey bees and in pollen and adult bees sampled from bumble bee colonies placed on arable farms. We also compared this with levels found in bumble bee colonies placed in urban areas. Pollen of oilseed rape was heavily contaminated with a broad range of pesticides, as was the pollen of wildflowers growing nearby. Consequently, pollen collected by both bee species also contained a wide range of pesticides, notably including the fungicides carbendazim, boscalid, flusilazole, metconazole, tebuconazole and trifloxystrobin and the neonicotinoids thiamethoxam, thiacloprid and imidacloprid. In bumble bees, the fungicides carbendazim, boscalid, tebuconazole, flusilazole and metconazole were present at concentrations up to 73 nanogram/gram (ng/g). It is notable that pollen collected by bumble bees in rural areas contained high levels of the neonicotinoids thiamethoxam (mean 18 ng/g) and thiacloprid (mean 2.9 ng/g), along with a range of fungicides, some of which are known to act synergistically with neonicotinoids. Pesticide exposure of bumble bee colonies in urban areas was much lower than in rural areas. Understanding the effects of simultaneous exposure of bees to complex mixtures of pesticides remains a major challenge.
    Full-text · Article · Mar 2016 · Environment international
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    • "The unintended negative effects of neonicotinoids on non-target bumblebees has led to increased focus on delineating the environmental fate of this class of insecticides (Cameron et al., 2011; Cresswell and Thompson, 2012; Henry et al., 2012; Osborne, 2012; Whitehorn et al., 2012).Soil serves as the predominant sink for pesticides, which make their way to soil through deliberate field application, water leaching, or air deposition(Fenoll et al., 2011). Once in soil, pesticides and their metabolites are dissipated to form extractable residues(ER),and bound residues(or non-extractable residues, BR), or are mineralized (converted to 14 CO 2 ) (Craven and Hoy, 2005). "
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    ABSTRACT: Cycloxaprid (CYC) is a novel broad-spectrum neonicotinoid insecticide that has been developed for agricultural pest control. The fate of the (14)C-labeled racemic and enantio-pure CYC isomers in flooded and anaerobic soil was investigated using radioisotope tracing techniques. After 100d of incubation, only a minor portion (<1%) of the applied CYC isomers is mineralized by each of the four tested soil types. The fraction of initially applied radioactive CYC dissipated into the bound or non-extractable residues (BR) increases with increase in the length of the incubation period, reaching up to 53.0-81.6%. The dissipation of the CYC through mineralization or formation of BR is strongly influenced by soil properties, such as humic content, pH value, and retained microbial activity. Amongst the soils studied, the fluvio-marine yellow loamy soil displayed the highest tendency to mineralize CYC while the coastal saline soil exhibited the strongest tendency to form BR. The observation that the water phase retained the large portion(>60%) of the radioactivity attributed to the total extractable residue suggested that under the experimental condition, the initially applied (14)C-labeled CYC residues were readily available for leaching or offsite transport. Additionally, no enantiomer-specific behaviors are observed. The results from this study provide a framework for assessing the environmental impact resulting from the use of this pesticide.
    Full-text · Article · Feb 2016 · Science of The Total Environment
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    • "Neonicotinoids, a relatively new class of insecticides in use since 1991 (Elbert et al., 2008) have been under scrutiny in recent years due to research indicating negative impacts on non-target species, both directly (bees: e.g. Whitehorn et al., 2012; aquatic invertebrates: Beketov and Liess, 2008) and indirectly (insectfeeding birds: Hallmann et al., 2014). Presently, there is a moratorium on neonicotinoid use as seed treatments, or as granules, on certain " bee attractive crops " such as maize, sunflower and oilseed rape in the European Union (EU) due to " high acute risks " to bees (Europa, 2013). "
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    ABSTRACT: Neonicotinoid insecticides have been under scrutiny in recent years due to their potential to harm bees. The European Union recently imposed a two year moratorium (2014-2015) on their application as a seed-treatment for certain bee-attractive crops. In this study we investigated the effect of mature plant size on residual neonicotinoid concentration in two widely grown, bee-attractive crops: oilseed rape (. Brassica napus) and maize (. Zea mays). Plants were collected from four commercial farms in Sussex, United Kingdom, three growing oilseed rape and one maize. All were grown from seeds treated with the neonicotinoid thiamethoxam. For both crops there was a significant negative relationship between mature plant mass and residual neonicotinoid (thiamethoxam and its metabolite clothianidin) concentrations (. p<. 0.001). Concentrations in plant tissues roughly halved with a four-fold increase in plant weight. These results indicate that agronomic practices that result in larger mature plants might have the potential to reduce the exposure of bees to neonicotinoid contamination of pollen and nectar.
    Full-text · Article · Jan 2016 · Agriculture Ecosystems & Environment
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