Researchers are closer to understanding how the foraging distances of wild bumblebees vary across landscapes. The findings, published recently in the scientific journal Oikos, are potentially important for landscape managers looking to conserve bumblebee populations and enhance pollination services for crops and biodiversity.
Evidence suggests that many bumblebees have declined across Europe and North America along with the plant species they rely on as foraging resources. Habitat loss is considered one of the main drivers behind the decline and there is considerable interest in developing conservation options that could restore landscapes for pollinators.
Bumblebees live in colonies of at most a few hundred workers and a single queen and have an annual lifecycle. They need safe nesting sites and lots of flowers to forage on. However it is not known how the distribution of nesting and foraging habitats, or habitat structure, affects how foraging workers use these habitats.
Researchers led by the Centre for Ecology & Hydrology (CEH) used a combination of methods to estimate the nest locations and foraging distances of a large number of colonies of two wild bee species widespread in the UK, the red-tailed bumblebee (Bombus lapidarius) and the common carder-bee, (Bombus pascuorum). Using DNA collected from a large number of worker bees they were able to estimate how many different colonies were present foraging across a landscape. These data were combined with highly detailed images of a landscape taken by airborne remote sensing to estimate colony location and individual foraging distances from these locations.
They found that colony-specific foraging distances of both species varied with landscape structure, decreasing as the foraging habitats increased. This optimal foraging activity would maximise the bee’s net energy intake and enhance a colony’s chance of survival.
“Our method offers a means of estimating foraging distances in social insects,” said senior author Dr Matthew Heard, an ecologist at CEH. “This research provides a powerful tool for informing the scale of management required for bumblebees in both agricultural and urban landscapes.”
CEH's Press Office issued this story as a Media Briefing.
The findings are published in the journal Oikos. The full reference is Carvell, C., Jordan, W. C., Bourke, A. F. G., Pickles, R., Redhead, J. W. and Heard, M. S. (2011), Molecular and spatial analyses reveal links between colony-specific foraging distance and landscape-level resource availability in two bumblebee species. Oikos. doi: 10.1111/j.1600-0706.2011.19832.x