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

Also, it's a common sales pitch for ant killer sellers to point out
that ants protect and cultivate aphids.

I think you may be under-estimating the attention which
gardeners with aphid problems give to ants.

No, I am not. I am stating that it is based on prejudice.

I was referring to this claim:

``I know that aphid infestations are a major agricultural problem,
and I knew people working on defences, but not one was even
considering attacking the ants. This indicates that they knew
it was an irrelevance.''

Maybe the people you consulted didn't pay attention to the ants -
but I reckon there are quite a few others who do. After all,
the UK Organic association and the The Royal Horticultural
Society, publicly state that ants protect aphid infestations -
and IMO, their relationship mythical or not, is pretty common
knowledge.

There is considerable evidence that ants milk aphids of honeydew,
at least in the UK, but effectively damn-all that they cause or
enhance aphid infestations. [...]

It would be possible to test this, say, for Lasius niger and Aphis
fabae (a VERY common combination and claimed symbiosis). Make a
21'x21' concrete slab with 6" walls, put 100 3' by 1' diameter tubes
on it, fill them with gravel and soil, put 3" of water and a film
of paraffin on the slab, a broad bean plant in each tube, string to
connect each black square (assuming a chequerboard) and ensure that
there were Lasius niger nests around.

Then measure the Aphis fabae infestation of each plant and the crop
of beans, and analyse them. My prediction is that there would be
damn-all difference. Yours is that the ant-accessible plants would
do worse.

The equivalent - with a tarred cloth around a tree - might be simpler
still.

There are some drawbacks to this kind of experiment - since there
is at least one cofounding factor: the ants may protect the aphids
against other creeping aphid predators, which would also have their
access to the plants inhibited by any such physical barrier.

I'm not sure "the establishment" is likely to perform such an
experiment - since the symbiosis between ants and aphids is
common knowledge, and not exactly newsworthy.

However, this *is* the sort of experiment those wanting to
vindicate the ants might like to consider.

What I am saying is that, until such an experiment (or equivalent)
has been done, there is damn-all evidence that ants either cause or
enhance aphid infestations in the UK. There is some weak evidence
supporting it (the research you mentioned and your earth walls), and
some weak evidence opposing it (mine on distributions and relative
crops), but both are too indirect to be definitive.

It would be nice to see an analysis of the type in:

``Friend or foe? A behavioral and stable isotopic investigation of an
ant-plant symbiosis.''

- http://calorierestriction.org/pmid/n=15179580

....for a range of UK plants.

However, I'd be pretty suprised if a fairly major link between ants and
aphids was not established in the process. Ants get a good fraction of
their diet from honeydew - and IMO, the question is a *lot* like asking
what would happen to the number of cows in the UK if the humans were
removed.
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