Interpreting Those Mite Counts

[beaglady]

I just did 48 hour mite counts on most of my hives. Now I'd love some input on interpreting the results. One of the things I'm wondering about is whether hive size (2 vs 4 deeps, etc) has any effect on mite counts. It seems logical that a large population would drop more individual mites than a small one, but the counts could still be proportional. Mostly, I'm pleased, but would be glad for any input on my results. The nucs were treated with powdered sugar about a month ago. Nothing else has been treated. All are on small cell with screened bottoms. The nucs are not completely regressed. The older colonies are. The swarm was drawing small cells on their own when caught.

#1 Russ Nuc 5 mites/48 hrs (4 med box)
#2 Russ Nuc 8 mites/48 hrs (4 med box)
#4 Swarm 1 mite/48 hrs (2 med)
#5 2nd year from feral 11 mites/48 hrs (4 med)
#7 2nd year from feral 3 mites/48 hrs (4 med)
#8 2nd year Russ 12 mites/48 hrs (6 med)
#9 2nd year Russ 4 mites/48 hrs (4 med)

In general, I'm feeling pretty good about the counts. I'll keep a close eye on the ones with higher counts, but the russian one with 12 was also my highest last fall and they wintered fine and built up hugely this spring.

[Janice Lane]

I am no expert and have had similar results as you. I am pretty sure it is low for spring/summer.

I have also wondered if the population size influenced mite counts. It seems logical that more bees equals more mites, but I'll let the experts chime in.

I have a few ants on boards when I check them. It makes me wonder if my count is wrong because the ants have been removing the mites.

[Maine_Beekeeper]

I am also seeking advice.
24 hour mite drop on sticky board.
Hive 1 (swarm) 16 of 18 frames drawn with bees - 18 mites
Hive 2 (2nd year parent of swarm) 15 of 18 frames drawn with bees - 8 mites
Hive 3 - (2nd year also threw off swarms) - 17 of 18 frames drawn with bees - 12 mites.
I am considering pulling the supers on all three (they haven't drawn them out yet to speak of) and feeding 1 qt each syrup with wintergreen oil - perhaps will interfere with the mites in the brood? "Maybe it will help, can't hurt" kind of theory. Any ideas/opinions on that?

[Dave W]

beaglady . . .

>hive size (2 vs 4 deeps, etc) has any effect on mite counts . . .

Yes. More brood = more mites. But a large bee population is always "recommended".

>treated with powdered sugar about a month ago . . .

Why?

>swarm was drawing small cells on their own when caught . . .

Were they swarms from YOUR regressed hives?


ONE mite count is good, but does not tell you the "whole picture", you also need to know the "trend" of how rapidly the mites are increasing.

All of the above numbers sound OK if the are not increasing.

The following 24-hr drop counts are from a package on large-cell foundation:

2003-Installed package in Apr
6/9 - First mite
6/25 - 5
7/27 - 14

2004
5/9 - 11
5/12 - 14
5/27 - 53
6/15 - 94
7/7 - 108

2005
5/6 - 36
6/6 - 68
7/15 - 34
7/29 - 124

Please give us MORE 24-hr counts from your fully-regressed hives.

Thanx

[Jim Fischer]

> I just did 48 hour mite counts on most of my
> hives. Now I'd love some input on interpreting
> the results.

Well, given that you have only one
data point for each hive, you can't interpret
the results just yet, because the essential
question is:

Is the mite population in each hive "stable",
"slowly growing", or "exponentially growing"?

Clearly, hitting all the hives with another
cloud of powdered sugar "can't hurt", so if
you have any doubts or fears, take a half hour,
and hit them all with more powdered sugar.

But to track mites and make an actual "treatment
decision", you need more than one data point.
You need at least three, preferably with counts
taken at regular intervals. The idea here is
to draw a curve (by connecting the dots) and
look at the slope of the curve, which is
the rate of mite population increase.

> One of the things I'm wondering about is
> whether hive size (2 vs 4 deeps, etc) has any
> effect on mite counts.

Of course it does, which is why the whole idea
of a "threshold" or any single mite count is
such a bogus basis for any treatment decision.

> It seems logical that a large population would
> drop more individual mites than a small one,

Yep! Exactly!

> but the counts could still be proportional.

Yes, and one could do some sort of rough estimate
of "number of mites versus bee population" or
"versus brood area", and at least have a slightly
more defensible silly-wild-guess, but with only
one data point, and nothing to compare to except
other hives, one has no more than a wild guess
no matter how one attempts to dress it up.

Think about it - comparing different hives only
has value if the majority of them are in no
danger. If the majority are in danger, you will
compare the different-sized hives, and decide
that they have "proportional" mite counts, and
therefore are "ok", when they are all on the
verge of collapse.

So, if another round of powdered sugar will
make you feel better, go for it!

But if you want to know the actual situation,
and want to make an informed decision, do more
mite counts at regular intervals. (Of course,
that may be more trouble than simply blinding
hitting all your colonies with powdered sugar
at the same intervals, which is yet another
level of decision facing the enlightened
beekeeper.)

Ain't science fun? Sometimes the drudge work
of "doing science" makes one realize that one
really can transcend the question altogether!

[ July 11, 2006, 01:33 PM: Message edited by: Jim Fischer ]

[Dave W]

One thing smile.gif that gives NewBees a problem (its kinda problem for me) is the "threshold" number we hear so much about.

Let say that threshold is "50". We do only ONE mite count, say in July, and get "14". Things seem OK, maybe even great because we havnt reached "threshold".

But, without a "history", trend or "curve" that ONE number only tells you that your hive is below threshold NOW.

Look at my counts made in 2003.
Starting w/ zero mites on 6/9 and "connecting the dots" to 5 (6/25) then 14 (7/27), see a trend?, guess what happened on Aug 18th.

PLEASE give us MORE 24-hr counts from your fully-regressed hives. No one w/ regressed hives seem to volunteer this info.

[Aspera]

"Ain't science fun? Sometimes the drudge work
of "doing science" makes one realize that one
really can transcend the question altogether!"

Tell us please! I have my comps tomorrow and wish to transcend right now. :(

[beaglady]

I've been too busy assembling frames so far, so I have not been doing mite counts. This was the first for the year, but I can keep everyone updated.

Oh, and FWIW, the swarm that was drawing small cells on its own was from a colony living in an old camper for the past year.

I had sugared the new nucs for the same reason I would give a new dog a bath. Even though they came from a reputable source, I 'just wanted to make sure they were clean'.

[Jim Fischer]

> Tell us please! I have my comps tomorrow and
> wish to transcend right now.

Do what I eventually did, and "transcend" the
whole mess - quit physics, become a beekeeper! smile.gif

Just kidding.
Good luck with the comps.
Get some sleep. At this point, being well rested
is the only "edge" you can gain.

[naturebee]

Assembeling frames? Don't forget them side nails Diane! smile.gif

Mite counts are correlated with the amount of brood in a colony. I find that my best colonies will tend to carry a bit higher mite load, and this is a direct result of fecundity in the broodnest. Mite counts can mean many things, colonies that tend to have a low mite count could be the result of a poor performing queen, OR it might indicate a mite resistant colony. So it is really difficult to make any kind of accurate assessment using mite counts alone.

To illustrate the point, read this fascinating article:

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

The key in mite counts I have found is to ignore them and assess your colonies as they have been assessed for hundreds of years, ‘on overall performance‘ (the article above seems to suggest this). For example, last season my colonies that tested above 98% brood viability and 100% hygienic behavior were my top 20% performers, but they also carried a moderate mite level (which I didn‘t count, but casually observed a few more mites on bees in these colonies). So by selecting from your best colonies, you would likely be selecting many of the essential traits needed for mite resistance without having to do mite counts and hygienic tests etc.

Best Wishes,
Joe

[Dick Allen]

Vermont beekeeper Kirk Webster did a 2 or 3 article series in one of the bee magazines a couple of years ago on his thoughts about developing mite resistant bees. He admitted in his article that he did not do mite counts.