Bumblebees live on the edge
21 May 2009
Researchers have identified which types of farmland are most attractive to queen bumblebees looking for both nesting sites and wildflowers from which to gather nectar.
The buff-tail bee.
The research, published in Biological Conservation, could help stem the decline of Britain's remaining native bumblebee species.
Pollinators around the world are in trouble. Populations of honeybees, bumblebees, butterflies and other pollinating insects are dropping steadily and scientists widely acknowledge that intensive farming and disappearing biodiversity are behind the decline. Vast fields of single crops produced by intensive farming are unable to support many pollinating insects.
Of the 25 bumblebee species native to Britain, three have already become extinct and the populations of ten other species have dropped drastically in the last 60 to 70 years.
Bumblebees are important pollinators of wildflowers and crops such as oil seed rape and green beans. 'Honeybees, while important for the pollination of many crops, aren't good at pollinating tomatoes or soft fruits like strawberries, which means that bumblebees are just as vital,' said Gillian Lye of the University of Stirling who led the study.
'Wildflowers pollinated by bumblebees have disappeared faster than other wildflowers,' she added.
In recent years, on the back of an increasing awareness of the negative effects of intensive farming on biodiversity, the government has funded numerous schemes to help restore habitats that will support native wildlife.
But schemes designed to conserve bumblebees have tended to focus on providing habitats that will support bumblebees during the summer. 'This might not be the best approach,' said Lye.
Bumblebee queens come out of hibernation in the spring and raise their first batch of workers single-handedly. To be successful, they need to find a suitable nesting site surrounded by wildflowers that they can gather nectar from.
Lye looked at farms supported by the Scottish Rural Stewardship scheme, seeking to find out which habitats are most attractive to bumblebee queens emerging in the spring - hedgerow, field margin or grassland.
She found that hedgerows are the least attractive habitat for spring queens. Grassland managed under the rural stewardship scheme is good for bumblebees searching for nest sites, while abandoned grassland contains more flowers, so attracts bees searching for nectar.
But emerging bumblebee queens are most attracted to field margin habitats, because these areas provide plenty of nesting opportunities as well as flowers for nectar.
'The bees use old mouseholes in tussocky grass as nests. The land is left alone in field margins, so wild flowers grow up, which the bees like,' said Lye.
She sees this new information being used to develop farmland management strategies that could increase the number of bumblebee colonies, which would in turn improve biodiversity.
'I'm hoping this work will inspire more badly-needed research in this area,' added Lye.
Lye, G. et al.
Assessing the value of Rural Stewardship schemes for providing foraging resources and nesting habitat for bumblebee queens (Hymenoptera: Apidae).
Biological Conservation (2009).
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