Data from: Low dose of neonicotinoid insecticide reduces foraging motivation of bumblebees

Widespread use of neonicotinoid insecticides, such as imidacloprid, is often associated with diminishing populations of bees; this loss of pollinators presents a concern for food security and may cause unpredictable changes in ecological networks. However, little is known about the potential behavioral mechanisms behind the neonicotinoid-associated pollinator decline. We quantified the effects of low dose (1 ppb) imidacloprid exposure on the foraging behaviour of bumblebees (Bombus terrestris). Individual bumblebees were released into a flight arena containing three patches of robotic flowers whose colour (yellow, orange, blue) indicated whether the flower delivered a reward (sugar solution). Exposure to imidacloprid had no significant effect on measures of bumblebee physical performance (such as flight speed) or learning (identifying rewarding flowers). However, pesticide treated bumblebees had reduced foraging motivation compared with the control bumblebees, as they visited fewer robotic flowers, were slower to start foraging and did not visit all three flower colours as often. Neonicotinoid concentrations of 1 ppb, often reported in plant nectar near agricultural lands, can thus affect the foraging behaviour of bumblebees. Even without a notable impact on flight performance and learning, a reduction in foraging motivation could explain the poor performance of colonies of bumblebees exposed to neonicotinoids.新烟碱类杀虫剂（neonicotinoid insecticides）如吡虫啉（imidacloprid）的广泛使用，常被认为与蜜蜂种群数量衰减密切相关；这类传粉者的减少不仅对粮食安全构成潜在威胁，还可能引发生态网络的不可预知变化。然而，学界目前对与新烟碱类杀虫剂相关的传粉者衰退背后的潜在行为机制仍知之甚少。本研究量化了低剂量（1 ppb）吡虫啉暴露对熊蜂（Bombus terrestris）觅食行为的影响：将单个熊蜂放入设有三组仿生机械花的飞行竞技场中，这些花朵的颜色（黄、橙、蓝）可指示其是否会提供蔗糖溶液奖励。研究发现，吡虫啉暴露对熊蜂的身体机能指标（如飞行速度）以及学习能力（识别奖励性花朵）无显著影响，但与对照组熊蜂相比，经杀虫剂处理的熊蜂觅食动机显著降低：它们拜访的仿生机械花数量更少，启动觅食的速度更慢，且较少造访全部三种颜色的花朵。农田附近植物花蜜中常被检出的1 ppb新烟碱类杀虫剂浓度，即可对熊蜂的觅食行为产生影响。即便未对飞行性能与学习能力造成显著影响，觅食动机的降低也可解释经新烟碱类杀虫剂暴露的熊蜂蜂群表现不佳的原因。