At 11:51 PM 5/27/99 -0700, sanjer at televar.com wrote:

>> >there is a >beetle, genus Gallicaria,
>> that apparently feeds exclusively on purple loosestrife, and this beetle
>> is just now being >introduced into the fill.

>Ha--until all the purple loosestrife is gone--Opps--we didn't think it would
>eat other plants.

The cinnabar moth has been spectacular in ridding Oregon (and perhaps
Washington) of tansy ragwort. My childhood job of whacking them for $0.50/hr
while horses tried to eat them out of the wheelbarrow is gone.

I remember when this noxious weed covered field after field in western
Oregon. Now, I'm startled when I find one.

The moth is very specific to tansy. This is typical of moths and butterflys.
If you doubt it, you might ask yourself why so many butterfly species are in
trouble (hint: the very limited range of the quite specific veg species
they're
adapted to is disappearing).

I don't know if beetles are as specific in their "prey plant" selection as,
say, the cinnabar moth (it's not a pest, I don't see them crawling over
everything ala starling or housesparrw).

You shouldn't be so pessimistic, Jerry. It is true that in SOME cases
evolution has bound eating species to very specific eaten species. Most
of our introduced species problems stem from 1) past ignorance of the
evolution of eater/eaten and other environmental relationships, an
ignorance which some seem to wish to propagate, even today 2) specific
ignorance of a particular species' needs (the pest species turn out
to have needs which are present in many seemingly unrelated
microenvironments).
3) the "not give a shit" syndrom, i.e. bass fishermen like bass and they don't
care what havoc results, even if it affects salmon sports fishermen.

And 4-whatever, it's late and I'm too tired to offer more examples,
examples that you probably do (or should) know.

Yet, you should also know (without being told) of the success of the
cinnabar moth/tansy ragwort story (and this is not the only success
story). And you should DEFINITELY know that once an insect species
runs out of target plans, it won't necessarily just start eating
other plants. If it had a taste for other plants, it wouldn't
necessarily target loofestrife. Usually, these bindings are
caused by very specific chemical characterists in the plant and
very specific receptors in the insect species involved. Unless
you know something specific that proves the premise false, you
really don't have anything to say. There's tons of data showing
that many insects are very, very, specialized in terms of the
plants they eat.

>
>Maybe they will just disappear when they are no longer needed. ;-)

This has pretty much happened with the cinnabar moth. Do you
have a problem with this?
>
>


- Don Baccus, Portland OR <dhogaza at pacifier.com>
Nature photos, on-line guides, and other goodies at
http://donb.photo.net