bacillus thuringiensis shelf life
semjase at aol.com
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 adnc.com
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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