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Alastair

BT kills varroa

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This, an interesting article i found on another web site.

 

BT ( Bacillus thuingiensis) can be purchased in your garden center or hardware store, it is a dried bacteria in powder form and is mixed with water and sprayed onto crops such as cabbages to control pests such as white butterfly caterpillers. It grows on the caterpillars and kills them

 

Beekeepers sometimes spray it onto stored combs because it kills wax moth larvae but is harmless to bees.

 

It has now been found to kill varroa mites. Thinking i may try it on a few hives this coming autumn.

 

https://www.sciencedirect.com/science/article/abs/pii/S0147651317301914

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Is the garden centre stuff the same strains of BT? It seems very specific.

I would be very surprised if something that promising hadn't had further testing over the 2+ years since publishing. 

Good info on spraying onto stored comb.....does anyone here do it?

 

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Has been tried over several years, but the NZ commercially available one had a with-holding period where it comes in contact with food - particularly vegetables growing in garden which was it's original use, and I am pretty sure that that would mean that all traces of it would need to be removed from the frames if used, before frames could go back on a hive, although product label may have changed, have not checked recently.

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just a side note: the BT product europeans (occasionally!) use against wax moths on bee equipment is called "B401"

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I did some research some years ago on the overseas product called B401 (recently reformulated and given a new name) and Certan both a Bt aizawai.

The local caterpillar organic treatment is Bt kurstaki, a slightly different strain, but just as good and it works.

I have been using it at the end of the honey season for the past 5 years on dried off frames going into storage in a well venterlated but well meshed area and , after 6 months in storage I have had no infestation of wax moth when getting them out for the new honey season in September.

https://www.vita-europe.com/beehealth/products/b401/

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Where do you get it locally Martin?

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This BT sounds like a lot more fun than my hitherto late summer/autumn plan of sprinkling citric acid all over my bees. Might even work better too !! I wonder why I haven't thought of the stuff before......

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Posted (edited)

I'll certainly be trying it Yesbut. It says no witholding period, but in anycase if it is applied to the hive as an autumn varroa treatment straight after the honey harvest, it will be the best part of a year before the next harvest so should surely have dissipated by then.

 

I suspect the best mode of application would be to mix as per label instructions, then lightly spray each side of each brood comb, bees and all. 

 

In the wild it is a soil living bacteria, so it may also survive on a dirty bottom board.

Edited by Alastair

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1 hour ago, yesbut said:

I wonder why I haven't thought of the stuff before......

 

Caterpillars are probably something a pink cat would not have problems with.

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I might be wrong but I understood that this type of product could lead to very high cfu counts in honey making the honey ineligible for many export markets.

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Good point, but what if it is applied almost a year before honey harvest?

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7 hours ago, kaihoka said:

 What about spinosad , I have been using it for yrs in the garden .

.

'.http://npic.orst.edu/factsheets/spinosadgen.html

 

Best i can tell with my non scientist mind Kaihoka, spinosad is a toxin extracted from bacteria, where BT is actual living bacteria.

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10 hours ago, Alastair said:

 

Best i can tell with my non scientist mind Kaihoka, spinosad is a toxin extracted from bacteria, where BT is actual living bacteria.

In theory spraying stored frames with it should kill wax moth and phoretic mites and the frames  safe to put back in hives when dry.

I have read phoretic mites can remain dormant for 6 mnths in a hive and become active when conditions become suitable .

Could they survive on frames taken from a hive for storage .

When I was reseaching ways to control the spider mites on my aubergine s in my tunnel house most of the internet was full of controling mites in cannabis grow rooms.

The info suggested that mites could live on in a dormant state for months on stuff,  lights etc in a room when it was unused . Waiting for the right conditions to return .

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Would one of our Scientist members be able to clarify the situation with regard to Bacillus thuringiensis Var. Kurstaki please, both chemically and legally. I am fairly sure that there has been research done on various Bt isolates that have been found to be toxic to a number of non-target Insect Orders.  (As per Dansar's post above.) 

 

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21 minutes ago, kaihoka said:

I have read phoretic mites can remain dormant for 6 mnths in a hive and become active when conditions become suitable .

Could they survive on frames taken from a hive for storage .

 

There is some contradictory advice out there about that. However what we do know is that in places like Canada where bees have a broodless period for 3 + months, the varroa do survive, they cannot reproduce but feed on the adult bees. 

 

Re varroa surviving on combs without bees, I saw a youtube video which unfortunately i cannot now find, where they tried exactly that. The mites with no bees started dying in the first day, and the last ones died on day 3.

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You dont use B401 on the bees. Read my post! Spray it on dried off frames after last harvest when frames put in storage over winter. Bt will be gone after 6 months in storage but the frames will be wax moth free!

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Martin the thread is not about killing wax moths, the purpose was to discuss using it to kill varroa, and as such would have to be applied to a living hive.

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6 minutes ago, Alastair said:

Martin the thread is not about killing wax moths, the purpose was to discuss using it to kill varroa, and as such would have to be applied to a living hive.

 

Not only that, but bacillus go into a period of encystment and form spores when there is not enough nutrients or other limiting factor to reproduction, and those spores remain dormant but viable for long periods of time eg AFB spores, so Bt of any sort does not simply get used up, so if it is toxic, it will revive and rapidly reproduce when the next food supply etc arrives.

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55 minutes ago, Sailabee said:

 

, so if it is toxic, it will revive and rapidly reproduce when the next food supply etc arrives.

And even if not toxic it will do the same . = good !! ?

Edited by yesbut

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1 minute ago, yesbut said:

And even if not toxic it will do the same . = good !! ?

 

Yep.

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