Hoverfly ecology

As adults, hoverflies feed exclusively on nectar and pollen which makes them important pollinators. Many show a remarkable mimicry of bees and wasps. They do this as a method of defence; although they are harmless, by looking like an insect that can sting, they can scare away predators.

One of our PhD students, Andrew Lucas, studies the role of hoverflies as pollinators in an iconic Welsh habitat: the marshy grasslands known in Wales as rhôs pastures. Across Britain, over 97% of such species-rich grasslands have been lost to agricultural intensification since the 1960s. Hoverflies are likely to be important pollinators in this increasingly fragmented habitat, as well as providing a pollination ‘ecosystem service’ to the wider countryside. However, little is known of the role they play in pollen transport.

Hoverflies have been collected and the pollen washed from their bodies. These samples are then DNA barcoded to identify the plants the hoverflies visited. The results give an indication of the range of pollen carried by hoverflies. The most frequent pollens carried include species of the family Apiacieae, such as whorled caraway and angelica, as well as bramble, thistles, elder, devil’s bit scabious, meadowsweet and heather. So far, the pollen from over 60 plant species, or species groups, has been found carried by hoverflies. The results will give an insight into flower choice by individual hoverflies, and the role these insects play in pollen transport in these important grassland habitats.