Varroa Mite Count on Sticky Boards

[fatscher]

What daily number is enough to prompt you to treat?

20 per day?
50 per day?
10 per day?
5 per day?
Other answer?

[MichaelW]

depends on the method of 'sticky board', location, and time of year.
The stickier the trap, the more mites you will get. We use shelf liner
under a metal screen with wooden frame to keep bees from entering.
I've trapped 'less' using a board with Crisco, and 'more' using that yellow
insect trap paper (forgot what its called). There's at least one study that
says your stickiness has an effect.

[JustBob]

A state apiarist once told us in a class that a 50 mite drop in a 24-hour time period is the threshold to treat so that's what I've gone with. Below that threshold, I continue to periodically monitor.
JustBob

[MichaelW]

Economic threshold for Varroa jacobsoni in the southeastern USA. Delaplane, K.S. & W.M. Hood. 1999. Apidologie 30: 383-395

ABSTRACT This research was designed to determine economic thresholds for Varroa jacobsoni mites in mature overwintered colonies under conditions that encourage or discourage mite immigration. Congruent data from the present study and our earlier work suggest that a true late-season (August) economic threshold for mites in the southeastern USA lies within a range of mite populations of 3 172-4 261, ether roll mite levels of 15-38, and overnight bottom board insert mite levels of 59-187 in colonies with bee populations of 24 808-33 699. Overwintering colonies can benefit from an additional early-season (February) treatment. This benefit was realized in colonies which in February had the following average values: mite populations 7-97, ether roll 0.4-2.8, bottom board inserts 0.6-10.2 and bee populations 12 606-13 500. Continuous acaricide treatment never achieved colony bee populations or brood number significantly higher than in colonies treated more conservatively. There is evidence that minimizing mite immigration has the benefit of delaying the onset of economic thresholds.

http://www.ent.uga.edu/bees/Research/archives.htm

[winevines]

Interesting.

Although if I used an ECONOMIC threshold for anything as a small time hobby beekeeper I may never would have started with it at all.

Just good to note the difference between recommendations based on an economic threshold and what you as a beekeeper are comfortable with as a tolerable/acceptable level of mites and the risk associated.

[beemandan]

10.

overnight bottom board insert mite levels of 59-187

Michael, if the study you're quoting says 59 - 187, why do you recommend treating at 10? I'm not being critical, just curious.

[MichaelW]

Dan,
I'm not recommending ten. I just cut and pasted that off UGA's website
and it was #10 on their list of research articles. I went back and took
out the #10 to prevent confusion.

karla,
Ideally, economic thresholds are going to be the same for hobby operations
as profit oriented ones. Its just a term and calculation used to determine
how much of an infection from a pest it takes to significantly damage the
host. Generally speaking, treating crop/livestock systems that have pests
below 'economic threshold' causes more harm then good. That is how systems
get on the 'pesticide treadmill', which involves a myriad of problems. All of
this can be measured in economic terms, which is a convenient way to make
determinations.

[aszalan]

this is from 'Economic Threshold for Varroa on the Canadian
Prairies'
http://www.capabees.com/main/files/p...athreshold.pdf

based on research done in Manitoba they found that a natural drop mite count (assuming 24 hrs) of 18 mites is appox 3% infestation and 33-43 mites is a 5-6% infestation. they recommend treating in early fall when the mite infestation is >3% and treating in the late fall when the mite infestation is >10%.

[winevines]

Ideally, economic thresholds are going to be the same for hobby operations as profit oriented ones. Its just a term and calculation used to determine
how much of an infection from a pest it takes to significantly damage the
host. Generally speaking, treating crop/livestock systems that have pests
below 'economic threshold' causes more harm then good. That is how systems
get on the 'pesticide treadmill', which involves a myriad of problems. All of
this can be measured in economic terms, which is a convenient way to make
determinations.

THanks for clarifying. I guess I thought economic threshold meant is it worth it cost wise to treat.. and for a hobbiest, at least for me, that is really a non issue or else we never would have started. sort of like my $50 cantelopes! But boy are they good!

[Robert Brenchley]

This is a difficult one. The mites round here are well loaded with viruses, and I worry that they may affect drone performance. On the other hand, if I never let mite numbers rise, I can't spot the more resistant hives. It's a question of finding the right balance somehow.