In article m,
Tim Challenger "timothy(dot)challenger(at)apk(dot)at" writes:
|
| They do protect some aphids. I've seen (presumably) young pale aphids being
| nurtured in a few nests I've dug up in winter. They overwinter them in the
| nest and bring them out onto the young shoots in spring. The ants often
| drive off potential predators, so allowing the aphids to increase. So it's
| not exactly farming, more like shepherding.

Are you sure that you weren't confusing dairy and beef cattle?

Both may well occur, but your "often" is definitely wrong. At most,
"sometimes". I have enquired in several contexts about this, and
even entymologists are very uncertain about exactly what the ants
are doing with the aphids in the UK[*], and in what proportion of
cases. Unlike in the tropics, there is minimal evidence for much
in the way of shepherding, let alone farming - proof of association
(which, as you say, there is) is not even good evidence of causality.

What there is no evidence for at all, and some evidence against,
is that killing ants helps to reduce aphid infestations. This is
pretty strong evidence that, if the protection actions occur, they
are not very effective.
[*] Except that the tabloids' usual innuendo is implausible.


Regards,
Nick Maclaren.