Build-A-Bee:
The Effects of Body Size and Coloration on Bee Activity I. Principles introduced in this exercise A. How are bee bodies adapted
to different environments? B. The importance of thermoregulation
and flight. C. The concept of keystone
species. II. Introduction Many nectar gathering
insects, like bees, are sensitive to temperature. They can’t function
when it is too cold and can overheat when temperatures are too hot. The general size and color of a bee affects
its body temperature (think about wearing a black shirt vs. a white
shirt on a hot day!), so knowing what color and what size a bee species
is can help us figure out when (what time of day) and where (hot or
cold climate) a certain bee will be active (Pereboom & Biesmeijer
2003). As far as size is concerned, it takes larger bees longer to get
hot and longer to cool down, but they can reach higher overall body
temperatures than smaller bees. Smaller bees heat up and cool down more
quickly, and they can’t get as hot as larger bees (Willmer 1983). Looking
at body color, we find that lighter colored bees heat up slower than
dark bees, but also can’t get as hot their darker colored counterparts
(Pereboom & Biesmeijer 2003). Thus, we would expect lighter, smaller bees to
be active at higher temperatures and in warmer lowland habitats (the place where an animal lives characterized by certain
factors such as temperature, water distribution, and species composition.
For example a mountain, desert, rainforest, or coral reef). Alternately,
we would expect to see more activity from larger, darker bees at lower
temperatures and cooler wetter habitat types such as mountains.
From this information
we can see that bees, like many organisms, are very specifically adapted
to a particular habitat. If the
temperature of a bee’s habitat changes (such as in the case of global
warming) bees in that area may go extinct if their bodies cannot adjust
to the new conditions. This can be bad news, not only for the bees,
but for many other forms of life as well.
That’s because many types of bees are the only pollinator for
certain plants, which makes them a keystone species (an organism that has
a strong influence on the species composition of a habitat). To better understand the concept of a keystone
species, lets consider the sea otter. In the ocean sea otters eat sea
urchins, and sea urchins eat kelp. When
the otter is over hunted by humans, there are less otters eating urchins,
so the urchin populations grow large and eat all the kelp. In turn, kelp forests are feeding and nurturing
grounds for fish, so with less kelp, there are less fish and thus less
food for many of the sea creatures that eat fish. As you can see, the
loss of a keystone species has a cascading effect that can influence
many organisms and perhaps even lead to the extinction of some species. The loss of a keystone bee species could have
similar drastic effects on a habitat.
If a bee is the only pollinator for a plant (let’s call it “plant
X”) in its habitat, and the bee is lost (it is out competed by honeybees
introduced by humans for example), plant X can no longer reproduce since
it is not being pollinated by its bee.
Thus, plant X will start to disappear, and any other organisms
that depend on plant X for food or a home will start to disappear as
well. This exercise will
focus on identifying which types of bees are most likely to be active
at a given temperature or found in a given habitat. III. Materials & Methods
A.
Look at the pictures and decide which
one is more likely to be active in a hot dry habitat.
Remember to pay careful attention to whether the bee is large,
small, dark, or light.
B.
Select the bee that would most likely
be active in each of the given habitats.
IV.
Sample Results V. Sample Discussion Questions VI. Sample Conclusions
VII.
References Gerling, D., Hurd,
P.D., Hefetz, A., 1983. Comparative behavioural biology of two Middle
Eastern
species of carpenter bees (Xylocopa
Latreille) (Hymenoptera: Apoidea). Smithsonian Contributions to Zoology 369: 1-33 Pereboom, J.J.M.,
Biesmeijer, J.C., 2003. Thermal constraints for stingless bee foragers:
the importance
of body size and coloration. Oecologia
137: 42-50 Ricklefs, R.E., 2001. The Economy of Nature, Fifth Edition. New York, W.H. Freeman and Company Willmer, P.G., 1983.
Thermal constraints on activity patterns in nectar-feeding insects.
Ecological Entomology 8: 455-469 Willmer, P.G., 1985.
Thermal ecology, size effects, and the origins of communal behaviour
in
Cerceris wasps. Behavioral Ecology and Sociobiology 17: 151-160 Willmer, P.G., 1988.
The role of insect water balance in pollination ecology: Xylocopa and Calotropis. Oecologia 76: 430-438 |