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My name is Candace Gaylen and I am a professor in biological sciences at the
University of Missouri in Columbia.
The site that we are looking at is a view
of our field site at about thirty seven hundred meters so that's roughly
around twelve thousand feet.
You can see polemonium viscosum, it has very showy purple to blue
For decades now we've studied plant
relationships with their animal pollinators.
Well, we're very interested in how they communicate with one another
how is it that the bumblebee knows where rewarding flower is? What signals
is that plant sending
that the bee can perceive? And so
part of that is
work that we've done with floral fragrances and,
to ask that question about fragrances or volatile
signals we need to take, essentially, electronic noses
out into the high alpine with us,
and those are simplified fragrance collectors that we can take apart
when we get back to the lab
and get a sense of the key compounds that a bee might be finding
attractive or, in some cases as our work has shown, repellent
and the concentrations of those sorts of
We've noticed that the fragrances of polemonium viscosum, the alpine sky
pilot, while the flowers at the species have more than twenty volatiles
that they produce
there's one in particular called 2-phenylethanol which accounts for about
ninety five percent
of that fragrance stream.
This species of bumblebee is bombus balteatus.
It is the biggest bumblebee that we have in
the Colorado Rocky Mountains
at these high elevations, and it has the longest tongue.
This is important ecologically because
the longer the tongue of the pollinator, the longer the tube of
the flower. And they are closely matched to provide
the pollinator with a tongue long enough to reach to retrieve the nectar
and the flower
long enough to force the pollinator into the flower to do the pollinating.
And that becomes important
because the 2-phenylethanol, as I mentioned, is at the base of the flower.
So the bumblebee is being able to slurp that up without sticking her head in
where she would be breathing in great amounts of the 2-phenylethanol.
Now imagine an ant. The ant in particular that we're looking at
formica neorufibarbus gelida, so an ant crawls into the flower and
crawls down to the base it's completely surrounded by whatever fragrance that
flower is producing.
The ant is,
because of its size and its behavior, getting a much different dosage if you will
than the bumblebee is.
Now that becomes important because 2-phenylethanol, in fact,
is a volatile that has a deleterious or negative effect,
a defensive effect in these flowers.
So it's very interesting that the volatile compound which is accounts for
ninety five percent of the flower fragrance is not an attractive at all.
So that this fragrance compound has a defensive role and it actually is highly
repellent to ants and
somewhat less repellent to bumble bees.
We find that the plants that ants visit produce very little 2-phenylethanol.
The plans that they avoid produce a lot.
Now why wouldn't all plants produce a lot of 2-phenylethanol?
Bees find this compound repellent at high concentrations but will tolerate it at lower
What happens at lower concentrations of 2-phenylethanol which is
very interesting is they will drink less of the nectar
then they will if you just give them sucrose solution that has no 2-phenylethanol.
So 2-phenylethanol has a way to
to be what we call an ecological sanction.
If a bee is too greedy,
then it'll get a stronger dose of the 2-phenylethanol because it will remain in
and exposed to the volatiles that are released
from the base.
One of the wonderful strengths of the University to an ecologist
is that diversity that we see in the ecological web is
mirrored in the diversity of
faculty expertise, graduate student expertise and even undergraduate passion
for research experiences here at MU.