Nick Maclaren wrote:
Tim Tyler writes:

| Sap suckers:
|
| ``Some ant species, such as the common Black garden ants
| (Lasius niger) found in the UK, farm aphids. They have
| aphid livestock which they transport between plants and
| protect from enemies in return for a sugary substance
| called honeydew, excreted from the aphids as they suck
| on plant sap.''

All of the references I have seen, and my observation over many
years, indicate that is at best an urban myth. More bluntly, it
is just plain wrong. I don't know whether there are any 'farming'
ant species in the UK - most references are evasive on that - but
Lasius niger is not one of them.

It does do some desultory herding, but that is about all. I have
seen one decent reference that indicates that it may assist aphids,
but the research had a fair number of possible flaws, and it was
done so long ago that I couldn't check with the author.

The best first hand evidence I have of UK black
ants doing more than exploit existing aphids is
the earth castles they sometimes build to protect
them from overheating:

http://sprouting.org/temp/ants/

....has photos.

I have now seen these things built six inches high.

When the growing point is too high off the ground,
for a tower to reach, the ants can still carry moist
earth up and stick it on around the target area.

http://cat.inist.fr/?aModele=afficheN&cpsidt=15221511

....has Lasius niger excluding predators from aphid
colonies:

``Large predators were excluded by both ant species from the
aphid colonies, while they were abundant in ant-excluded colonies.''

http://jeb.biologists.org/cgi/content/abstract/35/4/703

....has Lasius niger sucking twice as much juice out of
beans when attended by ants.

....and this looks pretty conclusive to me:

http://www.brown.edu/Departments/EEB...00_ecology.pdf

``The presence of workers of the ant Lasius niger
had a strong positive effect on the fitness of
individuals of the aphid Metopeurum fuscoviride.
Ant-tended individuals lived longer, matured earlier,
had a higher rate of re-production, and a higher
expected number of offspring than aphids not tended
by ants. An aphid’s longevity was significantly
correlated with the daily mean number of workers
tending it.''
--
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