# Shelf life of BT



## Kieck (Dec 2, 2005)

I don't know which form is sold by some of the members of BeeSource; I've asked one of them before and never got a response.

In most varieties of Bt (_Baccillus thuringiensis_), two forms are sold: the purified toxin(s) produced by the bacteria, and the endospores of the bacteria themselves. Usually the endospores are far more expensive because, 1) the "shelf life" tends to be longer, and, 2) once the bacteria are established, they will continue to reproduce whenever conditions are favorable. What that means is that if you were to seed one of your hives with _B. thurigiensis_ endospores of a variety that kills wax moths, every time the bacteria kill the wax moths (through producing toxic proteins, the same proteins that are purified for the other form of "Bt"), more endospores will be produced and remain in the hive, just waiting for future wax moths.

I've seen endospores of a different "Bt" variety sold to control white grubs in lawns (that variety will have no effect against wax moths). All other Bt products for application against insect pests that I've been able to confirm the "form" are simply the purified toxin(s) produced by one or more varieties of _B. thurigiensis_.


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## drobbins (Jun 1, 2005)

doesn't this appear to be the endospore?

http://www.cdms.net/LDat/ld4CM005.pdf

Dave


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## Swobee (May 18, 2007)

Yes, that's the product. Maybe the packaging has expiration dates on it. My order is going to Sundance this week, I was just curious how long I can expect to be able to store the excess product and still be confident it will be viable. We have enough hives and fruit trees that timely disposal shouldn't be a problem. Store it un-mixed in a cool, dark, dry location and I suspect a couple of years of usable life.


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## drobbins (Jun 1, 2005)

Hi SwoBee

my question was really to Kieck
which of the 2 forms he mentions is this?
I believe it's the endospore and it has a quite long shelf life (years)
I have no documentation to back that up
the MSDS does say the shelf life is a couple days after it is mixed with water

Dave


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## Sundance (Sep 9, 2004)

The Xentari I sell has *no expiration date* on packaging. The information does not list a specific shelf life but does indeed mention "years" if keep dry and cool.

*Once the product is re hydrated it must be used within 3 days.*


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## drobbins (Jun 1, 2005)

Sundance

the question in my mind is not shelf life but rather whether it reproduces in the combs and provides long lasting (years) protection
Kieck mentioned the 2 different forms of Bt that differ in this regard
I believe Xentari is the endospore form and does provide this long lasting protection
Kieck seems to be knowledgeable along these line and I hoped he could answer this from the MSDS

Dave


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## Sundance (Sep 9, 2004)

Hey Dave......... I will contact the maker and see what info I can gleen from them.


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## drobbins (Jun 1, 2005)

the MSDS looks to me like it says it's the endospore form ( learned that big word from Kieck)
in the part about "active ingredient"
I'm just not knowledgeable talking about this stuff

Dave


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## kenpkr (Apr 6, 2004)

*Ooops! Guess I shouldn't have stored it in my freezing garage*



Sundance said:


> Hey Dave......... I will contact the maker and see what info I can gleen from them.



Find out whether or not mine is dead now that it's been in below freezing temps. 

Thanks!


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## Kieck (Dec 2, 2005)

drobbins:

From the label in the link you provide, I gather that product is the toxin. The phrase "fermentation solids and solubles" is a tip off, as well as the fact that they can list a "percentage" of active ingredient.

Fungi produce spores. Certain bacteria can undergo a change into "endospores." Think of "endospores" as "dormant bacteria." Once conditions are right, the endospores will revert back.

The "spores" of foulbrood that are talked about frequently in beekeeping are actually endospores.


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## Kieck (Dec 2, 2005)

I checked with some of the people I know at Valent, the company that produces XenTari. According to them, XenTari contains the proteins produced by _Bacillus thuringiensis aizawai_ that are toxic to certain lepidopterous caterpillars, but does not contain active bacteria or endospores.

They pointed out that label indicates repeated applications even in a single season are necessary for effective control of the target insects (another indication that this is the protein, and not the endospores).


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## Swobee (May 18, 2007)

So, when the label mentions 'xx number of Diamond Moth units...' what is considered a unit? Viable spores, endospores...? I'm not a bilogist, but played on on TV. Seriously, if the product works even if it may be accidentally used in what could be construed as a violation of lable what are the concerns? 

Even repeated treatment at say- annual intervals following extraction & cleaning/drying out the combs wouldn't be so bad. Albeit, it's nice to understand a product ingredients which may help explain a price difference from brand A Bt to brand B Bt. If one is endospores, yet they are effective in treating the cabbage loopers that may invade my hives and incidentally kill off some wax moth and/or SHB larvae as collateral damage, I'm one happy guy!


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## Kieck (Dec 2, 2005)

"Diamondback moth units" are units of measurement for determining how large the pest problem from diamondback moths may be. The number of units per caterpillar vary by the size/age (instar) of the caterpillar and the type of crop. For example, a second-instar caterpillar (young and small) on one cabbage crop might equal "2.0 diamondback moth units (DBMU)." A sixth-instar (older and large) caterpillar on the same crop might equal "48.0 DBMU."

If it works, it works. If it's not labeled for the use, it's off label; and if it's off label, the applicant could face some stiff penalties if he's caught. Don't think that enforcement will look at off label as "accidental" or "misconstrued." The penalties for both are the same as "intentional" or "deliberate."

And don't expect any harm to small hive beetle from _B. t. aizawai_. The strains of _Bt_ are specific enough that the proteins from this one are unlikely to be toxic to SHB.


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## drobbins (Jun 1, 2005)

hmm, not the answer I wanted to hear but very good to know
it would be bad to assume reapplication wasn't needed when it is
the stuff works great, no wax moth around here

Dave


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## BEES4U (Oct 10, 2007)

*Bacillus thuringiensis STORAGE*

THIS SHOULD GIVE YOU YOUR ANSWER:


STORAGE OF B.t. 
http://www.ext.colostate.edu/Pubs/insect/05556.html

HERE IS MY WEB SEARCH:
http://www.google.com/search?hl=en&...1&q=STORAGE+OF+BACILLUS+THURINGIENSIS&spell=1

Effect of storage temperature on the insecticidal activity of a wettable powder formulation ofBacillus thuringiensis var.israelensis onCulex pipiens molestus larvae 
Journal Journal of Pest Science 
Publisher Springer Berlin / Heidelberg 
ISSN 1612-4758 (Print) 1612-4766 (Online) 
Issue Volume 61, Number 2 / February, 1988 
DOI 10.1007/BF01905718 
Pages 31-33 
Subject Collection Biomedical and Life Sciences 
SpringerLink Date Sunday, July 31, 2005 

. I. Farghal1 and Y. A. Darwish1

(1) Plant Protection Department, Faculty of Agriculture, Assiut University, Assiut, Egypt 
(2) School of Agric. and Life Sciences, Departm. of Entomology, North Carolina State University, Box 7613, 27695-7613 Raleigh, N. C., U.S.A. 


Abstract Bactimos was incubated for 30 days under 7 constant temperatures (i. e. –20, –10, 5, 25, 35, 40 and 45°C). The insecticidal activity of the compound was evaluated against 2nd and 4th instar larvae ofCulex pipiens molestus after 1, 3, 7, 10, 15 and 30 days of storage.
No loss in the insecticidal activity of the Bactimos was detected after 30 days at –20, –10 and 5°C. At temperatures above 25°C the insecticidal activity reduced as the storage period increased. The LT50 value of Bactimos for the 2nd and 4th instar larvae at 24 h and 48 h exposure was found to decrease as the temperature increased.

--------------------------------------------------------------------------------

Zusammenfassung DasB. thur. var.israelensis-Präparat Bactimos wurde 30 Tage lang bei konstanten Temperaturen von –20, –10, 5, 25, 35, 40 und 45°C gelagert. Danach wurde seine insektizide Aktivität gegen die Zweit- und Viertlarven vonCulex pipiens molestus, differenziert nach Lagerungszeit (1 h bis 30 Tage) getester.
Nach 30tägiger Lagerung bei –20, –10 und +5°C zeigte Bactimos keinen Verlust seiner Aktivität. Nach Lagerung oberhalb 25°C nahm seine insektizide Aktivität mit der Lagerungsdauer ab. Der LT50-Wert von Bactimos für die Zweit- und Viertlarven bei 24- und 48stündiger Anwendungszeit nahm mit zunehmender Temperatur ab.

- 20 degrees C is = to 4 degrees below 0 degrees F.
In my Medical Bacteriaology class we held our bacterial strains in a chest freezer.Regards,
Ernie
Lucas Apiaries


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## BEES4U (Oct 10, 2007)

*Font Size*

Oops,
A Little Big
Ernie


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## Swobee (May 18, 2007)

Sundance,
My order went to you yesterday evening via USPS money order. I don't do PayPal, my apologies for any inconvenience using snail mail does for you. My questions have been answered reasonably.

Ernie- all I had to do was walk all the way across the house so I could read your reply. It's so easy to get settings in a bind, sometimes. Thanks for your research, too. I hope all interested folks got the info they needed on this product.


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## Sundance (Sep 9, 2004)

In reading the insert, it talks about spraying tobacco leaves for 12 month storage......... not to read into it but that seems to imply some longer term protection.

I re-apply simply because its easy, fast, and really cheap. It takes me 30 seconds to do a 8 frame super/deep (or less).


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