bacillus thuringiensis shelf life

Semjase semjase at
Fri Jun 26 20:29:15 EDT 1998

>While it is true that B.t. is a spore forming organism it is not the spores
>that are responsible for most of the mortality.  (Forgive me if I'm stating
>information you already know, but others reading may not).  The vast
>majority of death is caused by the protein toxin (crystal in form) found
>within the bacteria.  Commercial formulations are grown to maximize the
>amount of this protein so you get a nice bang on the bugs for the first day
>or two it's in the field and then those proteins break down in the
>sunlight.  Any mortality caused by remaining spores is virtually
>negligible.  This stuff does not go hog-wild after being sprayed and
>proliferate like crazy in the soil.  Rather, it quickly fades to background
>levels and is of little further concern.  Also, if still worried, you can
>buy formulations of B.t. that do not contain spores and therefore cannot
>proliferate.  Examples of this are products sold under the trade names MVP,
>Mattch, M-Trak and a few others.  I hope this helps and I get the feeling
>it won't be my last post on this (I had to go and open my mouth!).
>conlan at


The toxin is produced by the living bacteria.  The spores germinate in the gut,
produce the toxin (thurien I believe) which causes paralysis of the gut, then
the bacteria proliferate in the gut destroying the larvae. 

A pure toxin prep would be limited much more in its effect and by deteriorate
quickly.  I do not at the moment have the information on how long it will last.

I would never buy or use the stuff.  So you spoke up?  That is not a bad thing
this stuff needs discussion.



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