In article ,
"Tumbleweed" writes:
|
| 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.

Piranhas attacking something dropped in the water. The grasp reflex
of human newborns. If I recall, Gould has other examples.

| 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.

Yes, of course. Don't be silly. The ants were 'milking' precisely
the aphids that the ladybird larvae were feeding on. And the
coexistence went on for a long time.

| 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,

Nobody has so far shown ANY evidence that ants cause an increase
in the number or severity of aphid infestations, let alone that
killing the ants will reduce the latter. But there HAS been some
evidence that (a) is true in at least the majority of cases.

| b)theories of organic gardening re controlling pests with predators (or more
| specifically aphids by ladybirds) is bunk?

Well, I have not seen it work. Ladybirds reproduce fairly slowly
and don't eat huge numbers of aphids, so I am unconvinced that
they make much difference in controlling infestations. Things
aren't as simple as that, because you can also control pests by
restricting sources (e.g. I am spraying my philadelphus with soft
soap now to protect my broad beans later).


Regards,
Nick Maclaren.