HERO HOVERFLIES: tiny travellers with big potential
A new study into the migratory behaviour of hoverflies reveals their usefulness as pollinators and pest controllers amid the decline of other insect species.
NRI’s Dr Don Reynolds together with a group of international scientists, used entomological (insect-monitoring) radar, to study hoverflies flying up to 1km high, in the skies above southern England. Over a ten-year period, Dr Reynolds and his colleagues examined the seasonal flux in numbers and the biomass of migrant hoverflies.
The study, led by the University of Exeter, was a collaboration between the Natural Resources Institute (NRI) at the University of Greenwich, UK, Nanjing Agricultural University, China, Rothamsted Research, UK, and the Max Planck Institute, Germany.
The scientists found that up to four billion hoverflies migrate to and from Britain each year, significantly more than previously thought, and unlike other species of pollinators which are in decline, hoverfly numbers have been relatively stable over the last decade.
Dr Reynolds says: “Migratory hoverflies contribute significantly to ecosystem services – their larvae prey on aphids making them important biocontrol agents, and the adults are effective pollinators of various fruit and vegetable crops. As pollinators, hoverflies are considered second only to bees, but their dual role makes them uniquely beneficial to humans.”
“The hoverfly migrations into and out of Britain are clearly adaptive. The flies showed a strong seasonal preference in their migratory flight direction (e.g. southward in autumn), and they tended to wait for favourable wind directions for their mass movements between Britain and mainland Europe.”
Scientists say that this study proves that hoverflies are very mobile and this allows them to locate the best habitats. They are also known as “generalists”, meaning that the adults feed on many different kinds of pollen and the larvae are not fussy about the type of aphids they consume.
The study used data on the marmalade hoverfly and another closely related species (collectively termed ‘migrant hoverflies’) gathered by radar equipment at Rothamsted Research, funded by the Biotechnology and Biological Sciences Research Council (BBSRC).
The study, published in the journal Current Biology, is entitled: “Mass seasonal migrations of hoverflies provide extensive pollination and crop protection services.”
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