more than just honey v&f sept 2010
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a female might spend her entire life span
of five to six weeks to complete only one of
these astonishing little structures.
Pollen analyses of nest provisions and
female scopal pollen loads (the scopa consistsof specially adapted hairs on the females
ventral side of the abdomen which transport
pollen into the bees nest) carried out by
Kim Timmermann showed that the Resin
Bee collects pollen exclusively from flowers
of the daisy family (Asteraceae). Pollen
specialization (oligolecty) is common among
solitary bees and can lead to co-evolution
between plants and their pollinators.
This is presumably the case in the other
bee species, the Oil-collecting Bee and their
long-spurred, oil-secreting host plants of the
genus Diascia. There are 24 Rediviva species
that are all endemic to South Africa. The
females of some of the species have greatly
elongated forelegs with their tarsi densely
covered with velvet like hairs. These hairs
efficiently absorb the oil secreted at the tips
of the long spurs of the Diasciaflowers. Floral
oil is mixed with pollen instead of nectar and
used to provision the nest cell to nourish
the larva. However, it might also be used to
line nest cells with a thin waterproof layer
like some South American oil-collecting
bees do to protect the developing larva and
the provision from moulding. The elongate
forelegs that can be as long, or even longer
than the body are a unique feature of some
Rediviva species, like R. macgregori. For a
species in the Drakensberg, it has been
shown that length of Diasciafloral spurs and
Redivivaforelegs varied between populations
but was always correlated indicating a co-
evolutionary process.
These are only two examples illustrating
the striking diversity of adaptations bees
have developed in the South African winterrainfall area, making it a unique laboratory
where evolutionary processes can be
studied under natural conditions. Climate
change, intensified farming and landscape
fragmentation have a large impact on the
entire ecosystem and might fundamentally
change it before we are able to fully
understand its origin and the processes that
ultimately shaped it.
ACKNOWLEDGEMENTS
I thank the Northern Cape Department of Tourism,
Environment and Conservation and the Western Cape
Nature Conservation Board for permission to collect
specimens for research. I am deeply indebted to
the late Neil MacGregor and his wife Neva for their
exceptional hospitality, their interest in and the
constant support of my bee and pollination research
on their former property. I dedicate this article to the
memory of Neil.
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Michael Kuhlmann is research entomologist at the
Department of Entomology of The Natural History
Museum in London. He has a special interest is in sub-
Saharan African solitary bee taxonomy, systematics,
ecology and biogeography as well as global diversitypatterns and plant-pollinator interactions as a
driving force in evolution and speciation. Contact him
ABOVE: Female Oil-collecting Bee (Rediviva macgregori) with
the right elongate foreleg stretched out. Photo: NHM.
RIGHT:The author collecting bees near Nieuwoudtville.
Photo: Kim Timmermann.
BELOW: The long-spurred, oil-secreting annual Diascia
floribunda is one of the host plants of the Oil-collecting Bee
(Rediviva macgregori). Photo: Michael Kuhlmann.
SEPTEMBER 2010 | VELD&FLORA 121