On Wed, 13 Aug 2003 13:58:38 +0100, Oz
posted:

Mooshie peas writes

Bottom line though is that BT expressed is no more likely fo cause
resistance development problems than intemittent application of BT.

Hard to answer.

The persistent and uniform use of any pesticide tends to lead to some
level of resistance. The speed resistance arrives is rather variable and
varies from locally almost immediate (eg dimfop) to hugely delayed (eg
hormone weedkillers). Others allow decades of use before resistance is a
problem (eg OP's).

I suspect it depends on how easily the organism can bypass the pathways
blocked by the pesticide.

In the case of dimfop, a single change on a single gene seems to be
enough. For OP's tolerance seems to develop by multiple gene changes,
each of which confers a small tolerance, so resistance development is
slow. In the case of hormones the auxin systems are so fundamental and
old that it takes many rather large changes for true resistance to
develop and we only see a partial tolerance.

I would suggest from the evidence we have (ie no complete control
failures) that Bt resistance is most likely to follow the second or
third routes. Alternative GM insecticide molecules would, however, be
advantageous, IMHO.

--
Oz
This post is worth absolutely nothing and is probably fallacious.

You're too modest. Thanks