Bee numbers have been falling
Bumblebees can navigate their way home over distances of up to 13km (eight
miles), a UK research team has shown.
The study also found only worker bees seemed to have this homing ability.
Bees pollinate flowering plants and therefore play a crucial role in food webs,
but numbers of the insect in Britain have been declining recently.
The team said the homing research would inform conservation strategies that
sought to adapt landscapes to create optimum habitats for bees.
The University of Newcastle-led group took some 100 bumblebees belonging to
the common species Bombus terrestris and tagged some of them with tiny identification numbers.
The bees were then dropped in different places around north-east England and left to make their way back to the nest. The scientists set up a webcam in the hive to record the homecomers.
Early results show the bees will fly varying distances but some that were left
at a garden centre in Heddon on the Wall in the Tyne Valley - about 13km from their nest - could get home safely.
"The current scientific literature shows that bees normally forage within 5km,
and this is probably correct," said Steph O'Connor, one of the researchers.
The scientists tagged some of
the bees before releasing them
"What we are showing is it is eminently possible for bumblebees to forage more
than 5km from the nest." Dr Mark O'Neill told the BBC News website.
Only about 20% to 30% of the tagged insects actually completed the journey.
But, explained Dr O'Neill: "Don't forget that a lot of bees got killed by predators and hitting car windscreens."
It is not entirely clear how the insects navigate but their vision seems to
help keep them on course and recognise landmarks.
"We believe there will be a difference, because they use vision, especially
the horizon edge for guidance. So a cluttered environment is liable to be more problematic and challenging to the bees than
a green field environment," said Dr O'Neill.
The insects' "maps" also include odours, but these are limited to less than
2m (7ft). For example, when a bee has emptied the nectar in a flower, it leaves chemical "post-it notes" to tell others where
it has been.
The countryside has a more varied scent composition than the urban landscape,
and researchers are now plotting bee routes to see which kinds of environment the insects prefer.
The great yellow is on the UK's Biodiversity Action Plan
"We are trying to find out more about how bees forage, or look for their food,"
explained Dr O'Neill.
"We're particularly interested to see if they find certain environments easier
Britain and Ireland have 25 native species of bumblebee. Five are currently listed in the UK Biodiversity
Action Plan because of their precarious status: Bombus distinguendus (great yellow bumblebee); Bombus humilis
(carder bumblebee); Bombus ruderatus (large garden bumblebee); Bombus subterraneus (short-haired bumblebee)Bombus
sylvarum (shrill carder Bee).
Many of the other bee species have undergone major range contractions. "We believe bees are very sensitive to having their foraging
range interfered with, such as fragmentation due to housing development," said Dr O'Neill.