Georgia Bee Letter

[TwT]

here the quarterly news in Georgia.... it says this in the news letter, isn't this high for those who take mite counts

"Varroa mite treatments may be unnecessary if your colony
mite level is below the economic threshold of 60-190 mites in a 24-hour sticky sheet test".


http://www.ent.uga.edu/bees/Newsletter/06_03_GBL.pdf

[Jim Fischer]

> "...below the economic threshold of 60-190 mites
> in a 24-hour sticky sheet test..."

Here we go again...

First of all, there is no such thing as a
"threshold" when all one is counting is pests.
One needs to also count the bees. So, while
a drop of 60-190 mites may not be a big hairy
deal when dealing with a largish colony with
8 frames of brood, it certainly may be
a sign of a need to treat a much smaller colony.

Thresholds are inherently ratios. Pests per plant
or pests per acre for farmers, who have the
advantage of knowing how many plants or acres they
have.

Second, the MARREC group (mostly Penn State)
proved years ago that one cannot trust a
24-hour drop test, as weather events and other
"transient events" tend to impact varroa drop.
That's why they suggest doing a 3-day test, and
dividing one's total count by 3. It results in
more accurate counts.

Third, any single measurement is useless!
What one wants to know is the rate of change
of the varroa population. Is it slowly growing,
is it stable, or is population increasing
rapidly? What's the "slope of the curve"?

So, monitor mites on a regular basis, and track
your numbers by graphing them. Ignore the
temptation to use approaches that don't even
stand up to a brief application of rational
thinking, and this includes trying to make a
treatment decision from a single number in
isolation. (For math heads, varroa cannot be
described by a scalar, one needs a trend.)

I said it before, and I'll say it again -
The price of honey is eternal vigilance!

[George Fergusson]

What he said.

[naturebee]

I would go further than what Jim stated and say that even many mite count measurements are totally useless. For instance, take two colonies of equal size.
If you think you have a resistant colony in hive #1 because it has low mite counts, you could be mistaken because colonies with spotty laying or poor performing queens are known to have low mite counts.

If you treat or requeen colony in hive #2 because it has high mite counts, you could have made a mistake again. There is evidence that show resistant colonies will tend to have a higher mite load, larger brood patterns and produce more honey. Here in the link they describe so called susceptible colonies with high mite counts actually had a higher average honey crop.

http://www.beeculture.com/storycms/index.cfm?cat=Story&recordID=480

[GaSteve]

Remember, that threshold is not the "most effective threshold for treatment", it is the "economic threshold for treatment". It's not to maximize effectiveness, but to minimize costs.

Just my opinion, but I believe that study was done specifically for a lot of the big commercial beekeepers who seem to want to treat at the drop of a hat with the strongest chemicals possible. The most effective way to influence their decision making is to show how it affects the bottom line. That seems to hit home much better than studies about long term resistance to chemicals or contaminated honey.

Bottom line is if you treat before you reach a certain number of mites, you're wasting money. Follow on studies were conducted on IPM practices (defined as SBBs, Russian queens, etc.) The goal wasn't to show how it decreased chemicals in the honey or how it delayed the onset of resistance. The aim was to show how it delayed the economic threshold for treatment. Again, direct effects on the bottom line grabs the most attention.

The question has been asked many times if the threshold applies to single deeps, double deeps, mediums, nucs, etc. and the answer is always a befuddling "yes".