GENTECH archive


answer to Rick on diversity+Bt

Hi Rick and all,

Rick Roush wrote :

> For example, resistance to kurstaki in
> diamondback moth has been shown to be due to a single gene conferring
> resistance to Cry 1A and relatives.

OK for a given resistance. But other resistances to the same toxin may
be due to  an other genes.

> In no way have 140 toxins been used to
> date!!
Right. Although they are getting known, they are not all used. I made a mistake.

> In CONTRAST to Bt sprays, which have effectively developed only a few
> toxins, transgenic crops are looking to develp a WIDER range of Bt
> proteins, including  Cry 2 (already in cotton trials in the field) and Cry
> 9C (already in maize in field trials). Herve, diversity is being led by the
> developers of transgenics, NOT those who use sprays!

Diversity is not multiplicity. I already explain that : if you consider
all the point between two points, whatever they may be far away one from
the other, you will have less diversity than if you have LESS points in
a plane or in the 3D space.
In case of Nature, it's not finite dimensional, so the rule is even
more drastic.

Confusion between multiplicity and diversity is typical of americans
(sorry for some of the list).

Moreover, at the time when Bt toxins were developed, they did not know
all those 140 toxins (and surely much more right now). That must be the
reason why they did not use this whole range of Bt that is large and
so diminishes the probability of appearance (and of propagation) of
a resistance.

The main point here is the INDUSTRIAL use of Bt that is not only a
quantitatice change, nbut a qualitativ change.

Moreover, production of Bt wil b e all year long. It's not the very
same as 2 to 4 aspersions (i've been confirmed that in France it's the
order of magnitude).

> Far more relevant as a cause of lack of resistance is that Bt is used so
> little, the best proof of which is widespread resistance in the one case in
> which Bt is used much at all (for diamondback moth).

False : on may only compare the frequancies of appearance of resistance for a 
very same toxin, a very same insect, under the very same  conditions. The more 
the toxin is present on a wider area, the more appearance is likely.
Aspersion puts in the field a definite quantity of (instable) toxin once.
While production of a (stable) toxin inside the tissues of teh GMO puts
it all day long.