[GregV]

Hmmmm.
Anyone care to elaborate?

Effect of Propolis against Varroa Mite has been investigated and showed lethal effect. Propolis extracted with 70% ethanol was found to be highly toxic, at 20% (w/v) of propolis resulting in 94.44% mortality with a brief contact time of 5 sec.

https://www.academia.edu/27745720

Occurrence and Distribution of Varroa Mite and Antivarroa Effect of Propolis in Walmara District of Oromia Special Zone Around Finfine, Ethiopia

https://www.academia.edu/27745720/O...d_Finfine_Ethiopia?email_work_card=view-paper

 

[Akademee]

So...was it the propolis, or the ethanol that killed them? I understand that propolis is basically part of the bees' immune system/strategy. do highly propolized hives experience lower mite loads?

 

[GregV]

So...was it the propolis, or the ethanol that killed them? I understand that propolis is basically part of the bees' immune system/strategy. do highly propolized hives experience lower mite loads?

Was my immediate question.
But from skimming the writings does no appear so.
Ethanol was used to extract some fractions of the propolis; the extract was later dried BEFORE using on the mites (water solution, I think).
But I did not read too closely, just glanced over.

 

[msl]

bad study

Te filtrate was dried in an incubator at 40°C toweight constancy, which was achieved in two weeks’ time. Te 70%ethanol extract was used in 55% ethanol in the bioassay to reduce theeffect o strong ethanol solution on the experimental organisms.

Te control solution o 55% propolis extract with distilled water,at different concentrations (5%, 7.5%,10%, 15% and 20%), at specifiedtimes (5, 10, 20, 30, 40, 60, 75, and 90 seconds) had no effect at al

propolis and water no effect, propolis and 55% ethanol dead mites..... must be the propolis !!!

 

[GregV]

bad study
propolis and water no effect, propolis and 55% ethanol dead mites..... must be the propolis !!!

I thought maybe I was missing something.
Why such stuff is even printed?

 

[little_john]

bad study
propolis and water no effect, propolis and 55% ethanol dead mites..... must be the propolis !!!

There have been other studies (which appear almost identical :scratch, such as: The varroacidal action of propolis: a laboratory assay (2002)

Which reached exactly the same 'logical' conclusion - which is crazy - imo, of course.
LJ

 

[little_john]

I found a recent Marla Spivak 'umbrella' paper covering all that's currently known about propolis, which imo is worth a read - but -

However, a recent study using raw propolis, not extracts, found no effect of propolis exposure on mite survival in the laboratory [ 22 ]. Given that ethanolic extractions of propolis are essentially chemically enriched fractions because they contain no wax, it is unclear when using raw propolis how much of the material is bioactive. Furthermore, the propolis used in the study was a year old and so likely lost a portion of its bioactive compounds.
Propolis Counteracts Some Threats to Honey Bee Health (2017) Spivak et al

https://pdfs.semanticscholar.org/354e/01422cf75813accf03c624e56fb0c7cf5738.pdf

Although the propolis is extracted with alcohol and then dried - it is then being reconstituted with known concentrations of alcohol before being administered (!) - but for some strange reason the alcohol is not being identified as being a likely candidate for acting as a miticide. For when mixed with water - exactly the same propolis fails to work. How is it that this is being overlooked ?
LJ

.

 

[grozzie2]

do highly propolized hives experience lower mite loads?

Anecdotally I can say quite definitively, no. If anything, the ones with the most propolis in my yard also have the most mites, but there can also bee lots of other factors at play.

 

[grozzie2]

propolis and water no effect, propolis and 55% ethanol dead mites..... must be the propolis !!!

There is a reason alcohol is used for the mite wash...

 

[msl]

yes and no
took me a day to find the right video to make sure I was remembering right, they will live threw a 50% Isopropupal wash (unsure about ethanol)
https://youtu.be/zXjDSD92ILs?t=2865

dosen't explane the use of water as a controal