Survival of bumblebee families improved by flowers
16 March 2017
Flower-rich habitats are key to enhancing the survival of bumblebee families, according to new research involving UCL scientists.
The team led by the UK's Centre for Ecology & Hydrology found that increasing flowers provided by spring-flowering trees, hedgerow plants and crops across the landscape - in combination with summer flower resources - can increase the probability of family survival to the next year by up to four times.
The discovery comes from the largest ever study of wild bumblebee colonies and will help farmers and policy makers ensure the countryside is better suited to the needs of these vital but declining pollinators.
Published today in the journal Nature, the study used DNA technology and remote sensing to identify, map and track mother, daughter and sister bumblebees over two years to reveal that access to high-quality food resources is vital to the survival of their populations.
Three species - Bombus terrestris, the buff-tailed bumblebee; Bombus lapidarius, the red-tailed bumblebee and Bombus pascuorum, the common carder bee - were investigated by tracking more than 1,600 families across a farmed landscape in Buckinghamshire.
Colonies located within 250-1,000 metres of habitats with high-quality food resources produced more daughter queens that survived to the following year. This is because spring- and summer-flowering plants provide pollen and nectar throughout the bees' life cycle.
In the UK, most bumblebee species have an annual life cycle; colonies are formed in the spring by a single queen and produce up to a few hundred daughter workers. At the end of the summer new queens are produced which, after mating and hibernation, go on to start new colonies the following spring.
Until now, understanding survival between these critical life cycle stages has proved challenging because in the wild, colonies are almost impossible to find. To overcome this, the team matched daughter queens to their mothers and sisters using genetic sampling that didn't harm the bees, and estimated the locations of colonies in the landscape from the locations of their workers.
Co-author Dr Seirian Sumner, from UCL Life Sciences (formerly University of Bristol), who led the genetic component of the study, said, "This scale of experiment would be impossible without the use of genetic markers: as well as providing important insights, the study also showcases the power of molecular ecology in guiding our management of our natural resources."
The results provide strong support for conservation measures such as the enhancement of flowering hedgerows, meadows or flower strips along field margins under agri-environment schemes implemented by farmers. They will also help with decisions on where to place these intervention measures in the landscape.
Lead author Dr Claire Carvell, a Senior Ecologist at the Centre for Ecology & Hydrology, said, "By decoding the clues hidden within the DNA of bumblebee queens and workers, and combining these with detailed landscape surveys, our research demonstrates that the survival of bumblebee families between years is positively linked with habitat quality at a landscape scale."
Senior author Dr Matthew Heard, a Principal Ecologist at the Centre for Ecology & Hydrology, said, "While there is an urgent need for more robust data on the patterns and causes of pollinator population decline, our study strongly suggests that conservation interventions can have a lasting, positive impact on wild pollinators in agricultural landscapes."
The study involved scientists from UCL, the Centre for Ecology & Hydrology, University of East Anglia and the Institute of Zoology at ZSL (Zoological Society of London) and UCL. It was kindly funded by the £10 million UK Insect Pollinators Initiative, a joint initiative from the Biotechnology and Biological Sciences Research Council, Defra, the Natural Environment Research Council, the Scottish Government and Wellcome.
- Red-tailed bumblebee (Bombus lapidarius) on the prickly sow-thistle (Sonchus asper). Keila, Northwestern Estonia (credit: Ivar Leidus, source: Wikimedia)
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