A systems approach to understanding the impacts of sublethal doses of neonicotinoids on bumblebee and honeybees

新烟碱类杀虫剂现在是世界上使用最广泛的杀虫剂之一，通常用于保护一系列开花作物，如油菜和向日葵免受食草动物的侵害。在英国，2010年有127万公顷的作物使用了类烟碱，其中噻虫胺、吡虫啉和噻虫嗪是最常用的类型。大多数用作拌种，作物在生长时吸收化合物，从而保护作物免受草食性害虫的侵害。新烟碱类也用作软果作物的叶面喷雾剂，并作为花园用的喷雾剂或颗粒剂广泛销售于花卉、水果和蔬菜作物上。由于它们是内吸性化学物质，在处理作物的花蜜和花粉中发现低浓度的类烟碱，因此它们被传粉昆虫消耗。它们还具有水溶性和持久性，因此在处理过的作物附近的树篱/田边野花中发现了可检测的数量。越来越多的证据表明，蜜蜂暴露于类烟碱会产生亚致死效应，如降低导航能力，这在实验室测定或田间试验中不会被检测到，在田间试验中，蜂箱被放置在紧邻经过处理的开花作物的地方。只有当蜜蜂在远处觅食时，它们才明显，就像自然界中发生的那样。PI负责人最近的一项研究表明，大黄蜂巢暴露于已知存在于种子处理油菜的花蜜和花粉中的吡虫啉水平，导致新蜂王产量减少85%（Whitehorn等人，2012年）。大部分野生大黄蜂巢穴和管理的蜂群都可能在经过处理的开花作物的觅食范围内，因此，这类杀虫剂可能对备受讨论的野生蜜蜂数量下降有很大贡献。有迫切需要了解的亚致死性影响的类尼古丁的行为和群体水平的表现大黄蜂在野外条件下。该项目将量化英国可耕地作物和野花中发现的类烟碱水平，并将其纳入花卉资源分布的景观地图（在一个平行项目中制作，BB/J 014753/1，从2013年开始）。我们将量化蜜蜂和大黄蜂在农田中自然觅食时暴露于类烟碱的剂量，然后继续评估这种暴露对大黄蜂群体性能的可能影响。将通过实证研究和建模方法审查接触和影响。奥斯本博士和贝彻博士开发了一个蜜蜂群体的综合模型，该模型预测了放置在真实的或模拟景观中时觅食行为和群体表现。在BB/J 014753/1项目中，我们将为大黄蜂群体开发该模型的一个版本。这些模型将使我们能够预测蜜蜂和大黄蜂工人将在哪里觅食，从而预测他们的暴露，这将与放置在景观中的真实的巢穴所接受的暴露进行比较。然后，我们将研究是否暴露在现实领域的水平改变或损害觅食行为，使用罗森斯特德的独特谐波雷达设施。这些数据将用于为蜜蜂和熊蜂开发一个子模型，其中包括类烟碱对蜂群成功预测的影响，该模型将在田间实验中用真实的熊蜂蜂群进行测试，并可用作用户的风险评估工具。最后，数据和模型结果将使我们能够制定管理建议，以最大限度地减少类尼古丁对管理蜜蜂和野生熊蜂种群的影响。

Neonicotinoid insecticides are now among the most widely used pesticides in the world, and are routinely used to protect a range of flowering crops such as oilseed rape and sunflowers against herbivores. In the UK, 1.27 million ha of crops were treated with neonicotinoids in 2010, with clothianidin, imidacloprid and thiamethoxam being the most frequently used types. Most are used as a seed-dressing, with the crop plant absorbing the compound as it grows, and hence becoming protected against herbivorous pests. Neonicotinoids are also used as foliar sprays on soft fruit crops, and are widely sold as sprays or granules for garden use on flowers, fruit and vegetable crops. As they are systemic chemicals, low concentrations of neonicotinoids are found in nectar and pollen of treated crops, and hence they are consumed by pollinators. They are also water soluble and persistent, so that detectable quantities are found in hedgerow / field margin wildflowers near treated crops. Evidence is mounting that exposure of bees to neonicotinoids produces sublethal effects such as reduced navigational ability that would not be detected in laboratory assays, or in field trials where hives are placed immediately adjacent to a treated flowering crop. They are only apparent when bees are foraging at distance across the landscape, as occurs in nature. A recent study by the lead PI demonstrated that exposure of bumblebee nests to levels of imidacloprid which are known to occur in the nectar and pollen of seed-treated oilseed rape resulted in an 85% reduction in output of new queens (Whitehorn et al. 2012). A substantial proportion of both wild bumblebee nests and managed honeybee colonies are likely to be within foraging range of a treated, flowering crop, so it seems likely that this class of insecticide may be contributing substantially to the much-discussed declines in wild bee populations. There is an urgent need to understand the sublethal impacts of neonicotinoids on behaviour and colony-level performance of bumblebees under field conditions. This project will quantify the levels of neonicotinoids found in crops and wildflowers in UK arable farmland, and feed these into landscape maps of the distribution of floral resources (produced in a parallel project, BB/J014753/1, starting 2013). We will quantify the doses of neonicotinoids that honeybee and bumblebee colonies are exposed to when naturally foraging in farmland, before going on to assess the likely impacts of this exposure on bumblebee colony performance. Exposure and impacts will be examined by both empirical studies and modelling approaches. Drs Osborne and Becher have developed an integrative model of a honeybee colony, which predicts forager behaviour and colony performance when placed into a real or simulated landscape. In project BB/J014753/1 we will develop a version of this model for bumblebee colonies. These models will enable us to predict where both honeybee and bumblebee workers will forage, and thus predict their exposure, which will be compared to that received by real nests placed in the landscape. We will then examine whether exposure to neonicotinoids at realistic field levels alters or impairs foraging behaviour using Rothamsted's unique harmonic radar facility. These data will be used to develop a sub-model for both honeybees and bumblebees which includes impacts of neonicotinoids in predictions of colony success, which will be tested with real colonies of bumblebees in field experiments, and can be used as a risk assessment tool by users. Finally, the data and model results will enable us to develop management recommendations to minimise the impacts of neonicotinoids on both managed honeybees and wild bumblebee populations.