One fly to rule them all—muscid flies are the key pollinators in the Arctic

Global change is causing drastic changes in the pollinator communities of the Arctic. While arctic flowers are visited by a wide range of insects, flies in family Muscidae have been proposed as a pollinator group of particular importance. To understand the functional outcome of current changes in pollinator community composition, we examined the role of muscids in the pollination of a key plant species, the mountain avens (Dryas). We monitored the seed set of Dryas across 15 sites at Zackenberg, northeast Greenland, and used sticky flower mimics and DNA barcoding to describe the flower-visiting community at each site. To evaluate the consequences of shifts in pollinator phenology under climate change, we compared the flower visitors between the early and the late season. Our approach revealed a diverse community of insects visiting Dryas, including two-thirds of all insect species known from the area. Even against this diverse background, the abundance of muscid flies emerged as a key predictor for seed set in Dryas, whereas overall insect abundance and species richness had little or no effect. With muscid flies as the main drivers of the pollinating function in the High Arctic, a recently observed decline in their abundances offers cause for concern.

全球变化正引发北极传粉者群落的剧烈改变。尽管北极花卉可被多种昆虫造访，但蝇科（Muscidae）蝇类被认为是一类尤为关键的传粉类群。为厘清当前传粉者群落组成变化带来的功能后果，我们研究了蝇科蝇类在关键植物物种——山地仙女木（Dryas）传粉过程中的作用。我们在格陵兰东北部的泽纳博格（Zackenberg）地区的15个样地中监测了山地仙女木的结籽率，并利用粘性花模拟物与DNA条形码技术，对每个样地的访花昆虫群落进行了表征。为评估气候变化下传粉者物候改变所带来的影响，我们对比了早季与晚季的访花昆虫类群。本研究方法揭示了访花昆虫群落具有较高多样性，涵盖该区域已知昆虫物种总数的三分之二。即便在如此多样的昆虫群落背景下，蝇科蝇类的种群丰度仍是山地仙女木结籽率的关键预测因子，而昆虫总丰度与物种丰富度的影响则微乎其微，甚至无影响。鉴于蝇科蝇类是高北极地区传粉功能的主要驱动者，近期观测到的其种群丰度下降现象值得警惕。