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Foraging habitats and foraging distances of bumblebees,
Bombus spp.
(Hym., Apidae), in an agricultural landscape
Foraging habitats and foraging distances of bumblebees, Bombus spp.
(Hym., Apidae), in an agricultural landscape
Walther-Hellwig, K.; Frankl, R. Correspondent
Department of General and Special Zoology - Animal Ecology, University
Giessen, Germany
Abstract
In selected foraging habitats of an agricultural landscape flower visits
of bumblebees and community structure of foraging bumblebees were studied,
with special regard to the role of crops as super-abundant resources.
Most crops represent temporal foraging habitats with high abundance of
bumblebees but mainly with low diversity in the bumblebee forage community,
in contrast to permanent foraging habitats such as, for example, a hedgerow.
The high numbers of bumblebees in the monoculture of crop plantations
consisted mainly of short-tongued bumblebee species. The role of foraging
distances for the visitation rate of foraging habitats was studied by
performing capture-recapture experiments with natural nests of B. terrestris,
B. lapidarius and B. muscorum. Differences were found on
the species as well as the individual level. The foraging distances of
B. muscorum were more restricted to the neighbourhood of the nesting
habitat than the foraging activity of B. terrestris and B. lapidarius.
High percentages of B. terrestris workers were recaptured while
foraging on super-abundant resources in distances up to 1750 m from the
nest. Isolated patches of highly rewarding forage crops, in agricultural
landscapes, are probably only accessed by bumblebee species with large
mean foraging distances, such as the short-tongued B. terrestris.
Species like the rare, long-tongued B. muscorum depend on a close
connection between nesting and foraging habitat. A restricted foraging
radius might be one important factor of bumblebee species loss and potential
pollinator limitation in modern agricultural landscapes. Furthermore,
long-distance flights of bumblebee pollinators have to be considered in
the present discussion on gene flow from transgenic plant species on a
landscape scale.
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