Data from: Interaction between Varroa destructor and imidacloprid reduces flight capacity of honeybees

Current high losses of honey bees seriously threaten crop pollination. Whereas parasite exposure is acknowledged as an important cause of these losses, the role of insecticides is controversial. Parasites and neonicotinoid insecticides reduce homing success of foragers, e.g., by reduced orientation, but it is unknown whether they negatively affect flight capacity. We investigated how exposing colonies to the parasitic mite Varroa destructor and the neonicotinoid insecticide imidacloprid affect flight capacity of foragers. Flight distance, time and speed of foragers were measured in flight mills to assess the relative and interactive effects of high V. destructor load and a field-realistic, chronic sub-lethal dose of imidacloprid. Foragers from colonies exposed to high levels of V. destructor flew shorter distances, with a larger effect when also exposed to imidacloprid. Bee body mass partly explained our results as bees were heavier when exposed to these stressors, possibly due to an earlier onset of foraging. Our findings contribute to understanding of interacting stressors that can explain colony losses. Reduced flight capacity decreases the food-collecting ability of honey bees and may hamper the use of precocious foraging as a coping mechanism during colony (nutritional) stress. Ineffective coping mechanisms may lead to destructive cascading effects and subsequent colony collapse.当前蜜蜂种群的大规模锐减严重威胁了农作物授粉工作。尽管寄生虫侵染被公认为是蜂群锐减的重要诱因之一，但新烟碱类杀虫剂（neonicotinoid insecticides）所扮演的角色仍存在争议。寄生虫与这类杀虫剂会降低外勤蜂（foragers）的归巢成功率，例如通过削弱其定向能力，但目前尚不明确二者是否会对其飞行能力产生负面影响。本研究探究了蜂群暴露于寄生瓦螨（Varroa destructor）与新烟碱类杀虫剂吡虫啉（imidacloprid）后，其外勤蜂飞行能力所受的影响。研究人员利用飞行磨（flight mills）装置测定外勤蜂的飞行距离、时长与速度，以此评估高负荷瓦螨侵染与田间真实剂量的慢性亚致死吡虫啉暴露的单独及交互影响。暴露于高负荷瓦螨的蜂群，其外勤蜂飞行距离更短；若同时暴露于吡虫啉，则该抑制效应会进一步增强。蜂群体重变化可部分解释本研究结果：暴露于上述胁迫因子的蜜蜂体重更高，这可能源于其外勤行为提前启动。本研究结果有助于进一步解析可导致蜂群锐减的多重胁迫因子间的交互作用。飞行能力下降会削弱蜜蜂的食物采集能力，同时可能阻碍蜂群在（营养）胁迫期间通过提前启动外勤行为作为应对机制。失效的应对机制可能引发破坏性级联效应，最终导致蜂群崩溃。