Nick Maclaren wrote or quoted:
In article , Tim Tyler wrote:

Ants are the aphids' friends - and you know what they say about the
friends of your enemies:

Sigh. Do you have any REAL evidence for that - in the UK?

``And ants directly defend the aphids from predators, the
aphids having lost their own defenses as domesticated
animals often do. The ants' success in protecting their
flocks is attested in the lengths that green lacewing larvae
(Chrysopa glossonae) go to sneak past ant defenders to catch
woolly alder aphids (Prociphilus tesselatus). ...

An extreme example cited in The Ants is that of the American
corn-root aphid (Aphis maidiradicis) and an ant (Lasius
neoniger). Colonies of this ant keep the aphids' eggs in
their nests over the winter, ...

- http://nationalzoo.si.edu/Publicatio...antfarmers.cfm

All that refers to North America. While we may be a vassal state
of the USA, that does not mean that we have a subset of its ecology.

Yes, I know perfectly well that the phenomenon occurs in the tropics,
and occasionally in the temperate zones. Even there, I doubt that
"ants are the aphids' friends", because it is probably that there
is more ant predation on aphids than ant protection of them. [...]

AFAICS, that doesn't seem to make sense :-(

IMO, the ants are *farming* the aphids - in similar ways all over the
world.

Just because the ants eat the aphids, that doesn't mean the aphids are
/not/ being farmed. You might just as well argue that humans are not
farming pigs because people have been observed to eat bacon.

But, whatever the situation, it is irrelevant to the UK.

To the best of my knowledge, there has been NO serious research on
whether ants EVER (a) cause or (b) enhance aphid attacks in the UK.

The size of the UK makes it harder to find research on the ant-aphid
symbiosis which is demonstrably applicable. However:

Here's a UK paper showing that the ants are defending the aphids:

``Soldiers effectively defend aphid colonies against predators in the field''

- http://calorierestriction.org/pmid/?n=9514674

....and here's a UK paper showing aphids produced more soldiers when ants
were not in attendance - which strongly suggests the ants were protecting
the aphids:

``Ant tending influences soldier production in a social aphid''

- http://calorierestriction.org/pmid/?n=11052537

How I interpret what I see in my garden is ants farming aphids, by
protecting them, raising them, carrying them up to the tops of plants,
and using them as a technological tool to attack the plants, and steal
their juices - both by sucking the honeydew, and by eating the
resulting plump and juicy aphids.

I fully expect the ant-aphid symbiosis to be global in extent and ancient
in origin.

That doesn't /necessarily/ mean that the ants have an overall negative
influence on the plants the aphids prey on. The ants depend on keeping
the plants alive as well, and their farming may conceivably have
beneficial effects on the plants - as well as on the aphids that
feed on them - perhaps by deterring other predators.
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