The structure of a high latitude plant-flower visitor system: the dominance of flies

The species richness of insect flower visitors to all angiosperms at a subarctic-alpine site in northern Sweden was described and the plant-flower visitor matrix was analysed and compared to other high latitude systems and with systems from lower latitudes. In the habitat, 23 plant species had a total of 242 interactions with 388 flower-visiting insects, belonging to 118 taxa. Connectance of the plant-flower visitor matrix was 8.9. Comparing our findings with other studies, we get that the proportion of dipteran species of the total pollinator fauna increases with latitude but that the proportions of species of Diptera, Hymenoptera and Lepidoptera do not vary significantly among high latitude systems. Muscidae and Empididae were more abundant and generalised than other dipteran families visiting flowers in the arctic, their proportions of the total Diptera fauna increase with latitude and they are the most widespread Families of flower-visiting insects in the arctic. Several Muscidae species are typical to alpine habitats in the arctic-subarctic zone. These species have special pollen feeding behaviour and an elongated proboscis, which improves access to closed flowers. Compared to other published pollination system studies, the connectance of low latitude systems ranges between 3.4 and 28.1, whereas high latitude and high altitude systems vary between 8.6 and 19 (-60).