1. Accumulating evidence shows that landscape fragmentation drives the observed worldwide decline in populations of pollinators, particularly in species of Lepidoptera and Hymenoptera. However, Little is known about the effects of landscape fragmentation on hoverfly (Diptera, Syrphidae) communities. Hoverflies provide varied ecosystem services: larvae contribute to waste decomposition (saprophagous species) and pest control (aphidophagous species), and adults pollinate a wide range of flowers.
2. To determine how the diversity and quantity of resources for larvae and adults affect hoverfly abundance and species richness at three spatial scales, we recorded insect visitors of five target plant species in Belgian heathlands, habitats that have decreased considerably due to human activities.
3. Hoverflies represented the most abundant visitors on two plant species, and the second most abundant visitors (after bumblebees) on the other target plant species. A large proportion of hoverflies observed were aphidophagous species associated with coniferous and deciduous forests. Resources for the larvae and floral resources for the adults influenced interactions among hoverflies and plants, but acted at different scales: larval habitat availability (distance to larval habitat) was relevant at the landscape scale, whereas adult resource availability (floral density) was relevant at the plot scale.
4. Hoverfly abundance and species richness decreased with distance to larval habitat but increased with floral density. Moreover, landscape structure and composition had different effects according to hoverfly ecological traits. Landscape composition influenced aphidophagous but not saprophagous hoverflies, in that their abundance and species richness decreased with distance to forests. Maintenance of the interactions between plants and their hoverfly visitors requires complementary resources at both landscape and local scales.

中文翻译：

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食蚜蝇（双翅目、食蚜蝇科）的保护需要景观和当地规模的互补资源。

1. 
   越来越多的证据表明，景观破碎化导致了全球范围内观察到的传粉媒介数量下降，特别是鳞翅目和膜翅目物种。然而，人们对景观破碎化对食蚜蝇（双翅目、食蚜蝇科）群落的影响知之甚少。食蚜蝇提供多种生态系统服务：幼虫有助于废物分解（腐食性物种）和害虫控制（蚜虫性物种），成虫则为多种花卉授粉。
2. 
   为了确定幼虫和成虫资源的多样性和数量如何在三个空间尺度上影响食蚜蝇丰度和物种丰富度，我们记录了比利时荒地中五种目标植物物种的昆虫访客，这些栖息地由于人类活动而大幅减少。
3. 
   食蚜蝇代表了两种植物物种上最多的访客，以及其他目标植物物种上第二多的访客（仅次于大黄蜂）。观察到的大部分食蚜蝇是与针叶林和落叶林相关的蚜虫种类。幼虫资源和成虫花卉资源影响食蚜蝇和植物之间的相互作用，但作用范围不同：幼虫栖息地可用性（到幼虫栖息地的距离）与景观尺度相关，而成虫资源可用性（花卉密度）与景观尺度相关。情节规模。
4. 
   食蚜蝇的丰度和物种丰富度随着距幼虫栖息地的距离而减少，但随着花卉密度的增加而增加。此外，根据食蚜蝇的生态特征，景观结构和组成也会产生不同的影响。景观构成影响食蚜蝇，但不影响腐食食蚜蝇，因为它们的数量和物种丰富度随着距森林的距离而减少。维持植物与其食蚜蝇访客之间的相互作用需要景观和局部尺度上的互补资源。