On Wed, 19 May 2004 07:08:25 +0100, Tumbleweed wrote:

"Nick Maclaren" wrote in message
...
In article ,
Tumbleweed wrote:
I have watched ants attacking ladybirds near aphids, effectively
protecting
them. They may not do it deliberately, but if the ants get some benefit
from
the aphids (why else follow them around) then protecting them in this way
would help the ants. OTOH if the aphids gain nothing by being protected
from
ladybirds and the like, then so much for aphid control by predators or
selective spraying.

Not at all. It is very common for animals to perform actions that have
no useful effect because they had an effect earlier in evolutionary
history.

Can you give an example? As people research things more, it often turns out
that behaviours or attributes that were thought to be incidental, arent.

I have watched ants walking over ladybird larvae, completely ignoring
them.

But were there any aphids about? :-) And organisms arent perfect, I have
watched ants running about and missing small bits of food. That doesnt
indicate they dont pick up food.

There might not be any evidence that it makes a major difference, but is
that because people have done the experiments and observations and seen
no
relationship, or because no one looked?

Some people have done experiments and found no difference. Nobody
so far has reported an experiment that detects a difference in the
UK.


So if I notice ants consistently attacking ladybids&larvae on my apple tree,
and the aphids therefore being left alone, should I draw the conclusion that
;
a)killing the ants wont help reduce the aphids, or that,
b)theories of organic gardening re controlling pests with predators (or more
specifically aphids by ladybirds) is bunk?


There's a summary of a paper he
http://www.blackwell-synergy.com/lin...d=hvenKPRD9TVh
One would *think* that ants protecting aphids would damage the plant more
than without ants. In some cases, they could be beneficial, by driving off
other herbivores (weevils etc), which would cause more damage.

You might also see on some plants, (particularly roses in our garden) a
coating of fine earth particles around parts of the stem. Break one open
and you'll find the thing full of aphids and ants. Certainly an number of
european ant species overwinter aphids and carry them or their eggs out to
feeding grounds in the spring. That doesn't meant to say that those plants
suffer more or less.

--
Tim C.