For a while I've been wondering why ants are so interested in my
Passion flower plant.

I've been manually picking aphids off this plant - so the ant interest
seems to be due to some other factor.

To cut a long story short, I think I may have found the solution:

I long ago noticed that the ants are interesed in the "fake eggs"
that passion flower plants grow at the base of their leaves.

I'd previously assumed that the function of these nodes was as
imitation Heliconius caterpillar eggs - with the idea of preventing
female Heliconius butterflies from laying eggs on leaves that
appear to be already occupied by other cannibalistic caterpillar
eggs.

However I recently read that the plant produces nectar to attract
ants:

``Passionflower vines may enlist ants to pick off any young Heliconius
caterpillars developing on the leaves. In return the vines supply the
ants with nectar.''

- http://insectzoo.msstate.edu/OrkinZoo/lifeOpen.html

I assume that the "fake eggs" are also ant feeding stations.
That would explain what I'm seeing.
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__________
|im |yler http://timtyler.org/ Remove lock to reply.

On Sat, 23 Jul 2005 19:46:36 GMT, Tim Tyler wrote:

For a while I've been wondering why ants are so interested in my
Passion flower plant.

I've been manually picking aphids off this plant - so the ant interest
seems to be due to some other factor.

To cut a long story short, I think I may have found the solution:

I long ago noticed that the ants are interesed in the "fake eggs"
that passion flower plants grow at the base of their leaves.

I'd previously assumed that the function of these nodes was as
imitation Heliconius caterpillar eggs - with the idea of preventing
female Heliconius butterflies from laying eggs on leaves that
appear to be already occupied by other cannibalistic caterpillar
eggs.

However I recently read that the plant produces nectar to attract
ants:

``Passionflower vines may enlist ants to pick off any young Heliconius
caterpillars developing on the leaves. In return the vines supply the
ants with nectar.''

- http://insectzoo.msstate.edu/OrkinZoo/lifeOpen.html

I assume that the "fake eggs" are also ant feeding stations.
That would explain what I'm seeing.

There are nectar-secreting glands found at several positions on
passion flower plants: on the under sides of the leaves, around the
edge of the bracts, and from glands on the petioles (leaf stalks), and
of course within the flower. Not all passion flowers have them in all
the places. It's quite usual to see drops of nectar oozing from the
glands, and handling the plants can leave your hands quite sticky.


--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net