Economic thresholds anyone

[dickm]

This subject was handled in another thread. If anyone wants to contribute for the next go-round Try the link below.

http://maarec.cas.psu.edu/varroaStudy.htm

Dickm

[Kieck]

From what I read on the PSU site, the researchers are planning to study the Varroa threshold for winter survival, which is not the same as the economic threshold. The economic threshold would have to include any reductions in production due to Varroa loads, not just winter survival rates.

Sounds like a great study, though! If I were in their study area, I would volunteer to join the project.

[dickm]

When these guys talk about an economic threshold they mean "At this point I have to treat or lose the hive." In other fields it has to do with yield. I suspect that since the mites are peaking when the population of bees is peaking ... and the bees are hauling in honey... that yields could remain relatively unaffected, and then the hive dies.[ the effects kick in after the honey flow] Besides it's hard enough to get data on hive deaths.

Dickm

[Kieck]

But that's not an ECONOMIC threshold, it's an LD50. We've argued this on other threads.

The key point here, though, is that the researchers themselves are calling this a "Varroa threshold." No where on their site do I find it referred to as an "economic" threshold.

[Michael Bush]

Maybe the economic threshold is the point where they all die with no treatments before consuming the (uncontaminated) stores so you can harvest ALL the honey and buy a package next spring. ;)

[George Fergusson]

>[the effects kick in after the honey flow]

This is often what happens. It is not uncommon for your strongest, best producing hives in the summer to be the ones to succumb to PMS in the fall. I saw it happen with some of mine.

>But that's not an ECONOMIC threshold, it's an LD50. We've argued this on other threads.

And failed at least in my opinion at arriving at a concensus, or at least an agreement to disagree. I understand the distinction you're making between an economic threshold and an LD50 Jon, I just don't happen to agree with you on how these terms relate to varroa and beekeeping.

I agree we're talking insect pests (varroa, corn borers, etc.,) but we're also talking bees here, not corn fields. There's no reason to factor in "survivability" of corn in the sense of the likelihood that it will winter over and reseed itself in the spring, but that is EXACTLY what we're talking about with bees.

With crops, you can consider the cost of treating for a pest versus the percent loss of crop from not treating, but either way, you're going to replant something else in the spring. When fall arrives and the crop is harvested, the game is over and you either made money, broke even, or lost money. Which of those outcomes you attain may well depend on whether you blew money on a treatment or not. An economic threshold, plain and simple.

In beekeeping, if you don't factor survivability into the treatment equation and consider only cost of treatment versus additional honey production or pollination contracts, then you also better include the cost of new bees in the spring because chances are, you're going to need them.

George-

[sqkcrk]

As part of the New York State Apiary Inspection Program we sample one or two colonies in each inspected yard, through out the season. The data is collected and becomes part of the info that we share with the beekeepers during the next season. One problem with this "study", as I see it, is that we are sampling different colonies through the season. Rather than the same colonies each month. So I don't know what the data really shows.The type of study shown in the first post would at least show how varroa grows or ebbs and wanes through the season. From what I've seen one might have 5 or 6 mites in an ether roll sample in May, 3 or 4 mites in June, 7 or 9 mites in July, 3 or 4 mites in August and then 15 or 20 in September. The mite population seems to increase greatly toward the end of the summer. In some ways similar to Bumblebees and Yellow Jackets. Almost like the idea that if we really increase our numbers then some will last through the winter to start the cycle over again. Am I seeing things that others are seeing? Or am I misinterperating what I see?

I know in my own colonies, I can split them in South Carolina in March, have 400 ready for pollination in May and this year I took 40lbs per colony in August. I didn't get a chance to take the fall crop off as early as I would have liked to.(The honey house owner wasn't ready for me) Then because of personal problems I didn't get the fall crop off until friends took it off in November and December. Therefore the bees didn't get to SC until Nov. and Dec. and didn't get a treatment until December. When it was too late anyway. So where I had 730 colonies in May I'm lucky if I have 250 or 300 now. So what do you say about that as a test of the "Economic Threshold" or the "Varroa Threshold"?

I know a beekeeper who doesn't treat and doesn't monitor mite levels. He takes his bees south for the winter, splits the live ones in the spring, adds new Russian queens and produces 80 lbs per colony on average. No waste of money on treatments that don't work and no waste of money putting them on.

Mark

[George Fergusson]

>Am I seeing things that others are seeing?

That's about normal. Drops can vary due to weather and temperature throughout the spring and summer, but the general trend is UP and at an ever increasing rate:

http://www.sweettimeapiary.com/pics/bee_and_varroa_population_graph.gif

If you look at the varroa population growth between April and July versus the growth between August and October, you'll see what I mean. FYI, I think that's a better graph of varroa populations than it is of bee populations, but the trends are correct.

>One problem with this "study", as I see it, is that we are sampling different colonies through the season.

All things (and hives) being equal, which they're not, I'd agree though I wouldn't say the data is worthless. General statewide trends are useful.

George-

[Kieck]

I agree that this is a threshold. Call it that if you want. But it doesn't fit the definition of an "economic" threshold. The researchers recognize that. Otherwise, they'd refer to it as an economic threshold. (An LD50 is also a threshold, just a different, particular type. If you don't like the term, don't call it that.)

As far as the data from NY, if the research is concerned about population trends of Varroa over the season, and I assume it is, the researchers have chosen a statistically valid method of sub-sampling the hives to come up with representative data. Again, statistically, the data will accurately portray how the population of mites in an average hive will change over the season. From the description, it says nothing about establishing thresholds from that data.

The personal example, sqkcrk, doesn't include data on the numbers of mites. Otherwise, it might be an example of a threshold in your hives.

[George Fergusson]

>it doesn't fit the definition of an "economic" threshold.

Please define "economic threshold" as you understand it. Perhaps we're just having a misunderstanding. This site suggests the definition depends on who you're talking to:

http://instruct1.cit.cornell.edu/courses/ipm444/test/NotesThreshold.htm

George-

[GaSteve]

Here's UGa's economic threshold for treatment.

mite populations: 3172-4261
ether roll levels: 15-38
overnight sticky sheets: 59-187

Their definition of economic threshold is:

"the pest level that justifies treatment in order to prevent the pest from reaching damaging levels"

I guess the next step is to define damaging smile.gif

Here's an article that references the threshold. I couldn't find the actual study that establishes it.

http://www.ent.uga.edu/bees/Disorders/Varroa_mites.htm

[Kieck]

The definitions from the Cornell site -- ALL of the definitions that they quoted -- and the "damaging" definition from UGA all use the same concept of an economic threshold or economic injury level: the idea is simply that the cost of treatment is met or exceeded by the increase of production provided because the crop (in this case, the bees) were treated. I go back to my old example: if treating a hive for Varroa costs $20, but you make an additional $21 worth of honey because you reduced the population of Varroa, your hive had surpassed the economic threshold.

Setting up the economic thresholds is another matter. In this case, you'd have to test many hives. Think of it like this (these tests would be replicated many, many times, but the principles remain the same), if you have 100 mites in each of two hives, one gets treated, the other doesn't. How much production do you gain in the treated hive? How much did the treatment cost? What if you have 200 mites in each of two hives? What if you have 500 mites? Etcetera. Statistically, you can calculate economic thresholds without having to directly and precisely control pest levels. Of course, the economic thresholds should account for differences as well. For example, in an area with greater honey production, the gain from treating a hive with a small number of mites might be much greater than in an area with lower honey production, thereby driving down the economic threshold in the high-production area.

Again, like I keep saying, if the hive dies, the economic threshold has been far surpassed. Think about flies on cattle. Studies have shown that high populations of stable flies can reduce the weight gain of cattle by pestering the cattle to point where they don't eat as much. Economic thresholds have been established; you have (this many) flies, you can expect that your beef production declines by (this amount). If the stable flies actually kill off the cattle, the example has reached an extreme end of the economic scale. No longer do you worry about putting an extra 50 pounds, for example, per animal on your cattle, now you worry about keeping them alive.

Back to the Varroa on the bees. Sure, the populations of mites that actually cause hives to die represent a threshold, and it has an economic component, but economic thresholds refer to the point where the gain meets or exceeds the cost of the treatment. Again, why does the threshold used in determining whether a hive dies of Varroa have to be called an "economic" threshold? Why can't we just refer to it as a threshold, or, like some of the researchers, a "Varroa threshold?"

[dickm]

Kieck,
We use the words differently than you scientists do. I think you would be able to adapt to our language, rather than keep telling us we are wrong. If it were possible to treat in July, say, and raise honey yields ... 'keepers would be doing that. The only "threshold" that makes any sense is the overwintering one.

Those [thresholds] that determine yield as colony size, disease etc. usually don't respond to treatment fast enough to have an effect.

George,
I can see you thought you were talking to Jon. I hope he doesn't find this thread. smile.gif

Dickm

[Kieck]

>>I think you would be able to adapt to our language, rather than keep telling us we are wrong.

If you create a term, and I use it differently than you do, should you adapt to me or should I adapt to you? Again, I'm not arguing that it's a threshold. It's just not an ECONOMIC threshold. It's not using a word differently; you're adding a word to term, and the addition of that word changes the meaning of the term. Do you also refer to all bees as "honey bees?" Do you see a problem with calling the little native bees "honey bees?"

George found me. I just changed my screen name. George is still (correctly, even though my screen name changed) calling me "Jon." I don't take offense at his comment or your hope. ;)

[Jim Fischer]

With honey worth at least $2.00 a pound to any
hobby beekeeper, the traditional "economic
threshold" is so low as to simply not be a factor.
The cost of treatment is low enough, and the
economic advantages of a stronger uninfested hive
so much larger, that there simply isn't a point
at which "treatment is not good economics".

That said, treatments that force one to choose
between a honey crop and a survivable hive have
a significant economic impact, as the outcome
is a hive that MIGHT make money next year, or
might once again need to be taken out of
production to be treated.

The graph given is very typical - one CAN take
an overwintered hive and harvest spring crops
in the 90-day "spring" period (in this case,
Apr, May, Jun), but one must harvest early
and harvest often to exploit these flows.

By early July, some hives MUST be taken out
of production, and treated. Perhaps all.
The important factor is the slope of the
curve as shown in the graph:
http://www.sweettimeapiary.com/pics/bee_and_varroa_population_graph.gif

Once the varroa population slope starts to "go
exponential", as it does in the late June
period in the graph, you have a serious problem
building, or have a serious problem in place.
The point of monitoring is that not all hives
will progress at the same rate, nor will all
apiaries have the same level of infestation
(but it is true that one or two hives of a
group of hives are pretty fair representatives
of the group as a whole).

So, all togther, now:

</font> There are no thresholds. There are no easy answers.</font> There are no absolute numbers, there is
only the slope of the curve.</font> The guy giving the slide presentation about
varroa is very likely to be math-phobic, and
will never mention concepts like "the slope of
the curve", as he's not quite sure what the
slope of a curve means.</font> The price of honey is eternal vigilance.</font>

[Kieck]

I agree with most of your statements about thresholds, Jim, but two of your sentences need at least some clarification:

&gt;&gt;The cost of treatment is low enough, and the
economic advantages of a stronger uninfested hive so much larger, that there simply isn't a point at which "treatment is not good economics".

What if you have a hive with zero Varroa? Using this statement, you should still treat the hive. What if you have a hive with 100 Varroa consistently (spring, summer, winter, brood, no brood, etc)? Would treatment still be good economics?

&gt;&gt;1. There are no thresholds. There are no easy answers.

I'll agree that no easy answers exist. No thresholds, though? No thresholds may currently exist for a particular situation, but thresholds do work well for most crops. I guess if you don't believe in thresholds, it explains your comments about treating regardless of presence or population of mites. Personally, my bees seem to tolerate low populations of mites well. I don't have numbers calculated to establish graphs that represent thresholds, but the concept remains the same. Low populations of mites -- I wait to treat. If populations are growing or if hives have very high populations of mites, I treat. Even if I don't have the numbers yet, I use thresholds.

[Jim Fischer]

&gt; What if you have a hive with zero Varroa?

This is such a rare case, it barely deserves
mention. I have one very isolated yard myself,
and it remains varroa free to date.
It goes without saying that treatment for
this yard would be a waste of time and money,
but if I found any more hives with "zero varroa",
I'd question my monitoring methodology before I
stocked up on liquor and threw a party.

&gt; What if you have a hive with 100 Varroa
&gt; consistently (spring, summer, winter, brood,
&gt; no brood, etc)? Would treatment still be good
&gt; economics?

This is the sort of speculation that does nothing
but confuse matters. There simply is no such
thing as a varroa infestation that does not
involve inherent varroa population growth.

&gt; I guess if you don't believe in thresholds, it
&gt; explains your comments about treating regardless
&gt; of presence or population of mites.

I don't mind you offering unrealistic "impossible"
conditions as a way to question a statement
intended to apply to the bulk of reality as
experienced by beekeepers, but I do mind when
my words are twisted. I said nothing of the sort.

Its not that I "don't believe in thresholds", it
is that thresholds are a simplistic approach that
dooms hives left and right, a direct result of
an unexplainable lack of respect for the basic
intelligence of beekeepers on the part of those
who promote such concepts, or perhaps a fear of
math at even a high-school level on the part of
those who promote such concepts.

&gt; thresholds do work well for most crops

Of course they do! Why? Simple - the farmer
knows how many PLANTS he has (at least in terms
of average plants per acre), so he can work out
a "pest to plant ratio" using statistical methods
or simple averages. Beekeepers can only
estimate hive populations, as the bee population
is a variable itself - a moving target.

&gt; If populations are growing

Good! The phrase above implies more than one mite
count per hive in a season, which is the simple
and basic point that "thresholds" (as promoted to
beekeepers) attempts to ignore.

&gt; or if hives have
&gt; very high populations of mites, I treat.

"High" as compared to WHAT?
The qualitative term "high" STILL requires
more than one measurement, at least a comparison
to a nearby hive with roughly the same number
of bees in the hive by "eyeball estimate".

You can't control anything you don't measure,
and a single measurement is useless, as it
lacks context, that's the ONLY point I was
making, and the only critique required to
expose "thresholds" as not only "bad science",
but "not even science at all". Needless to say,
bad science makes for poor choices in the apiary.

[George Fergusson]

Well, at the risk of sounding like I'm taking my bat and ball and going home, I'm gonna state MY perspective on this subject and my "economic threshold" and then er... take my bat and ball and go home smile.gif

I agree completely with Jim Fischer's assessment of the situation with one minor qualification. I particularly like his statement that "the traditional "economic threshold" is so low as to simply not be a factor." Stated in my own terms, the value of a healthy over-wintered colony can't be overestimated when compared to the cost of keeping that hive healthy during the previous season, and I'm not just talking replacement dollars, I'm talking hive longevity and all the benefits that acrue from it. Following Jim's logic, I do not arrive at the absurd conclusion that it is therefore worthwhile treating a hive with no mites. That's just silly smile.gif

I *thought* at first that I took exception to Jim's assertion that there are no thresholds, but I realize that Jim has only stated what must become a fundamental premise for beekeepers in this age of varroa, if they're going to keep their hives alive: there are no thresholds. There is only the slope of the line. I would however modify Jim's statement, at the risk of destroying the simplistic beauty of it to "there are no numeric thresholds."

Beekeepers have been BEGGING, shamelessly, for a numeric threshold they can use for deciding whether to treat their hives or not. I did. We weren't using the word "economic" either, and we weren't considering the honey crop. We just wanted to keep our hives alive. What's a safe population level of varroa? The answer, in my humble opinion, and I've said this before and will no doubt say it again, is there is no "safe" population level of varroa. The real question you should be asking is what was the count last week? How about the week before? And the week before that? Is the population growing? How fast? If the population is growing fast, you better treat. If the population is low and stable, keep an eye on it. Keep a *close* eye on it. The price of honey (and a healthy hive) is eternal vigilance (thanks for that gem, Jim).

When you've been doing this long enough- and I've got a ways to go before I can say that about myself- you get a feel for what is a worrisome drop or sugar shake count and what isn't. That's fine, that comes from experience but this should not be a reason to become complacent or assume your magic number will always be valid or applicable, nor can you assume that what works for you will work for everyone, or anyone else for that matter. Share it, by all means, but qualify it as what works for YOU.

So. There is a threshold in sense, just not a hard, unchanging numeric one. Obviously, at some point, you decide to treat. Some threshold has been reached. Is your decision to treat based on an arbitrary and isolated number? Hopefully not! Hopefully, it's a decision based upon your understanding of your varroa population, where it's going, and how fast. If it's not, you may be treating needlessly, too soon, or worse, too late.

Did that come out right?

Finally, regarding the use of the term "economic"... I like it. It's a good term and not at all ambiguous to me. It pertains to the dollars in my pocket, where they come from, and how I choose to spend them. The cost of replacing a dead hive, whether from a package or a split, because I failed to handle the mite problem, is a very real cost to me and every bit a part of my decision treat or not treat. So is the cost basis of the hive, which might be high (a purchased nuc), low (a split), or virtually zero (love dem swarms!). So I'm going to use the word "economic" in MY definition of a threshold for deciding when to treat a varroa infested hive which is:

That point in time when based upon a series of observations it is apparent that MY mite population has achieved lift-off.. and about to go ballistic.. and failure to treat will likely result in the death of the hive and treating will help the colony make a surplus if there is a surplus to be made and likely assure they'll go into winter with a strong healthy cluster and sufficient stores to successfully winter over.

I could probably clean that up, but it works. That's my "economic threshold", and I'm sticking to it, until I change it, which is my perogative. Anyone else is welcome to use it, but remember, your mileage may vary smile.gif

I'll stick around and kibitz now smile.gif

George-

[George Fergusson]

Um... my previous post referred to Jim's initial post, for those of you that follow such things.

&gt;George found me. I just changed my screen name. George is still (correctly, even though my screen name changed) calling me "Jon." I don't take offense at his comment or your hope.

Well Jon, when you first changed your screen name I didn't pick up on it right away and as I read the new posts I thought "Oh God, now there's TWO of them!". I finally figured it out, and I'm glad to say, that while two of you is too much, one of you is just right and none of you is nothing I want to see. I'm sure you'll agree smile.gif

That's just my round-about, backhanded way of saying welcome to the group Jon smile.gif

Pssst... Dick... he found the thread smile.gif

[Ian]

&gt;&gt;onsuming the (uncontaminated) stores so you can harvest ALL the honey and buy a package next spring. [Wink]


The boys in Aulstrailia would love to hear that point stated louder!! smile.gif


Not sure how exacley we are to determine the "economic threshold" of varroa populations in a hive, becasue there no real constants to work off of. Hives all differing in every aspect you can think of, including the tolerace of v mites.

So I can only take the threshold of varroa in a colony as a bench mark, or an estimated acceptance of the point where mites will teater the balance and overrun the current averagely run hive. I have never yet treated my hives on an individual basis due to thier average daily mite drop. But I have treated my yards/and or operation due to the average daily mite drop on a random sampleing. And that "benchmark" or "threshold" gave me the ability to measure the populations and severity of the mites in the hives.

Economic thresholds on a crop are also in a way estimated, to predicted population expectations and damage severities, and applied over the entire acres, although usually confined to individual fields. But these thresholds are worked off more concrete information, from, weather, plant pop, life stage, and insect trap counts.

Show me where these variables are included in your varroa "economic threshold" calcualtions.

Anyhow, I dont care wheather it is called economic or not.

[tecumseh]

Mr keich adds:
The definitions from the Cornell site -- ALL of the definitions that they quoted -- and the "damaging" definition from UGA all use the same concept of an economic threshold or economic injury level: the idea is simply that the cost of treatment is met or exceeded by the increase of production provided because the crop (in this case, the bees) were treated. I go back to my old example: if treating a hive for Varroa costs $20, but you make an additional $21 worth of honey because you reduced the population of Varroa, your hive had surpassed the economic threshold.

tecumseh replies:
well first of all I am using my sister computer and I cannot access the highlighted link at the first of the thread, so the comments that follow are of a general nature and are not in any way shape or form a criticism of your remarks.

let me state right off the bat that I have two degrees (one advanced) in economics/finance and in all my days of studing these subject I have never heard of the concept of economic threshold. what the concept does sound like (via your above comment) is what is most commonly know as break even analysis and or cost-benefit analysis. Both of these analysis are extremely sensitive to the cost side of the equation (I believe a number of folks-George and Jim- have suggest the same idea)which typically are much more difficult to define than the benefit or income side of the equation.

furthermore an LD50 (a common concept present in entomology)is a weight to weight (mg to kg if memory serves)analysis of pesticide effectivenes and is by definition the point at which 50% of the exposed population dies. first I would find it difficult to believe that someone might even think about weighting mites or bees and the relationship of these at which 50% of the sample hives perish? just sounds implausable to moi...

just wondering.... really

[George Fergusson]

&gt;Anyhow, I dont care wheather it is called economic or not.

Neither do I really, it's just that Jon is so adamant that the term "economic" doesn't belong in our concept of "threshold" (which is and isn't a threshold) that I just have to do it smile.gif

[Jim Fischer]

&gt; Beekeepers have been BEGGING, shamelessly, for
&gt; a numeric threshold they can use for deciding
&gt; whether to treat their hives or not. I did.

Exactly! Everyone wants a magic bullet, a
single simple thing that they can do without
any thought or much trouble. It is a very
seductive ideal.

Sorry, that is the exact opposite of the entire
philosophy of "Integrated Pest Management".

It would also be wonderful to have the perfect
job, the perfect mate, the perfect ratchet wrench.
All I can say is that one either keeps looking
forever in vain for "Easy Answers", or one rolls
up one's sleeves, and makes do with whatever is
lying around to deal with reality as it exists
as best one can.

There are no "Easy Answers", but there are
"Elegant Solutions". The elegance takes
hard work. This is because the elegance
itself is 100% pure hard work.

Sorry to be so "zen" about it, but some things
are very, perhaps uncomfortably, "zen".

[Fusion_power]

They are missing one of the most important concepts in varroa population. It is alluded to above but never stated clearly.

When a very large and populous colony goes through a varroa increase, then the colony slows or stops brood rearing, the population of varroa in that colony may be too great relative to the number of new bees being raised. This puts extreme pressure on the colony that has A DECLINING BEE POPULATION.

This is one of the reasons why a huge and productive colony collapses at the end of the season.

They must measure the bee population, the amount of brood present, and the varroa population. Otherwise, the results will be useless.

Fusion

[George Fergusson]

&gt;They must measure the bee population, the amount of brood present, and the varroa population. Otherwise, the results will be useless.

Fusion, I agree that these things are important to consider, but I can't say that without a really good handle on them that the results will be useless. A general idea of the relative bee and mite populations and the amount of brood is useful, even interesting, but it's not crucial IMHO and can cause one to get buried in details and lose sight of the bigger picture.

A lot depends on the manner of mite sampling you're doing. Sugar rolls directly generate a percent level of infestation of phoretic mites, subject to various errors of course which Jim has nicely described in another thread. Given a reasonably accurate percent level of infestation and historic data showing the changes in that population over time, of what use is knowing how many bees are in your hive? Only if you want to know how many mites are in your hive do you need to know how many bees are in your hive, but what are you going to do with this information? You're falling back to a hard number- the very thing we're trying to get away from!

The situation with drop counts is somewhat different- you're essentially measuring the mite population directly rather than a percent level of infestation. There are errors associated with these measurements too, more than with sugar shakes probably- drop counts can vary due to a variety of influences, the main one being whether there is brood in the hive or not, and how much so you're going to need to do more head-scratching and figuring, or not. In any case, with drop counts you come much closer to figuring the total mite population in your hive.

If you want to derive a percent level of infestation from your drop counts then you need an estimate of the number of bees in your hive, and the more accurate the better. However, is this really necessary? As with the sugar roll, the information you're really interested in is the rate of change in the mite population over time. It's not necessary to derive the percent level of infestation unless you want to take that extra step and if you do, you need to remember that the uncertainty of your conclusions increases with each assumption you make.

If you want to compare the data from the two methods of sampling, you've got to adjust your numbers- the percent level of infestation of phoretic mites doesn't include actively breeding mites, and drop counts do include mites actively breeding. Both methods give you a picture of what's going on in your hive but from different perspectives. Both are valid. Both are sufficient for coming up with rates of change in mite populations. Neither is really comparable.

George-

[sqkcrk]

Economic threshold, Varroa threshold, whatever. Beekeeping is an art not a science. Granted science enters into it. But when it comes right down to it there are too many variables for anyone to come up with consistantly accurate recommendations on when is the exact right time, the exact right amount of varroa or tracheal at which you or I should treat or not. That's where you have to know your own situation and act accordingly. Then again, most of my hives are dead, so what do I know. I guess I missed the threshold, economic or varroa. Whichever you wish to pick. At least I've had an effective treatment for a change. Only the live hives have varroa.

Mark

[Dave W]

&gt;That's where you have to know your own situation and act accordingly . . .

How DO you KNOW?

Much of beekeeping IS science. How do you teach an "art"?

[Michael Bush]

&gt;Much of beekeeping IS science.

Science is a "I do this and this happens" kind of thing. I've never known the bees to cooperate that well. smile.gif The best you can say is "if I do this, this is PROBABLY what will happen".

&gt;How do you teach an "art"?

Part of the art is just paying attention and seeing patterns. For instance, with Varroa (the main suject here) if you're paying attention and doing counts or other assesments you'll know if things are changing. If you don't, you won't know when things are changing. Maybe sometimes you'll be wrong about your assessment of the situation, but, if you pay attention and think about it, you'll learn from it.

[George Fergusson]

I believe beekeeping is largely an art, not a science. Certainly there are elements of science, biology, statistics, genetics, botany, chemistry, and physics involved, to name a few, more than enough to satisfy the most inquisitive of scientific minds... but if that's all your perspective includes, you're missing the best part of beekeeping.

Enjoy your bees smile.gif

George-

[Jim Fischer]

&gt; They must measure the bee population, the amount
&gt; of brood present, and the varroa population.
&gt; Otherwise, the results will be useless.

Not to indulge in necrophiliac equine sadism,
but the varroa count (no matter how you do it, as
long as you are consistent in your method) will
"go exponential" well before the colony population
dwindles. This graph is a fairly good model:
http://www.sweettimeapiary.com/pics/bee_and_varroa_population_graph.gif

So, you don't really need to track bee population
if you are doing your varroa counts on a regular
basis, as it should be obvious that a serious
varroa population increase cannot happen without
a significant brood area.

Sure, a very weak hive is going to look like
it has less of a varroa problem if one depends
on simplistic numeric "thresholds", even though
it might be in serious danger, but a graph of
the varroa counts taken over time will STILL
show a curve that "goes exponential", even
though the brood area is much smaller, and
the number of mites much smaller.

I would offer that estimating bee population and
brood area is not a waste of effort, as it allows
one to see other trends, but the lack of such
data does not make one's graph of varroa counts
"useless". In fact, time spent looking at brood
and bees could be better spent doing varroa counts
on more hives more often.

[Kieck]

Sorry, I've been away and haven't been able to respond to some of these comments. From Ian's comments, I believe he understands how economic thresholds work and how to apply them. How many of the rest of you have ever really looked at an example of an economic threshold (or any other threshold besides the threshold of a door, for that matter)? Now we're confusing things still more by refering to them only as numeric thresholds. Sure they're numeric; as people have pointed out before, qualitative measurements don't really work.

Economic thresholds really are comparable to break-even analyses or cost-benefit analyses. They work on the same principles. But, even in the most simplified examples, producers can't go out, count pests once, and know whether or not they need to spray. They have to factor in the time of the year, the trends of the populations, how much yield they can reasonably expect, weather trends, etc. A lot of this is based on probabilities. Thresholds are generally represented as series of graphs, trying to account for pest population trends, times of year, potential yields, climates, etc. The slopes of lines on these graphs are the important points, too. If the conditions in a producer's crop match a point on one of the graphs at which the pest population has peaked and is likely declining in the time ahead, applications of pesticides no longer make economic sense.

My problem, again, on this thread was with the addition of the word "economic" when it didn't apply to the situation. I know it's petty in a way, but what if you arbitrarily added a different word to the threshold for mites? What if you called it a "door threshold?" ;)

As far as LD50s, it's true that they generally are used in examples of pesticides, as well as other chemicals, and rates are often expressed in terms of amounts per mass of animal. More importantly, though, is that they refer to levels that kill the organisms, much like the thresholds we've been discussing for Varroa on this thread. Maybe we should call the threshold for Varroa a "mortality threshold?"

[tecumseh]

kiech adds:
Economic thresholds really are comparable to break-even analyses or cost-benefit analyses. They work on the same principles. But, even in the most simplified examples, producers can't go out, count pests once, and know whether or not they need to spray. They have to factor in the time of the year, the trends of the populations, how much yield they can reasonably expect, weather trends, etc. A lot of this is based on probabilities. Thresholds are generally represented as series of graphs, trying to account for pest population trends, times of year, potential yields, climates, etc. The slopes of lines on these graphs are the important points, too. If the conditions in a producer's crop match a point on one of the graphs at which the pest population has peaked and is likely declining in the time ahead, applications of pesticides no longer make economic sense.

tecumseh replies:
thanks for the added detail.

with the addition of the above information the process sounds a bit like a regime that I utilzed many years back which I will loosely tags as simulation cost/benefit analysis. that is you vary certain variables to generate a rage of possible outcomes (an outcome with a probablility statement). you repeat this process over and over again making changes to variables (some of these you have control in terms of level and some are totally outside of your control).

as you have suggest it is the slope (not change but rate of change) that should be specifically noticed.

[Hillbillynursery]

Real world. I had some very bad results this year because assuming the bees at the house were doing good so would the bees at the yard 6 miles away. Mite counts were low checked by drop test. My highest fall drop test for 48 hours was 23 with most hives being 2 medium hive bodies very full of bees as I shock the bees from the extra empty boxes into them. Mites did not kill my hives. It was starvation. I did treat all my hives for V mites with OA to try and give them a better chance of making it through winter and started feeding.

Why I bring this up was a few times during this discussion people are saying sooner or later all hives will need treating for mites. I ask why? With natural cell/foundationless my counts have stayed low for 3 years on these hives. The hives with large cells were treated until I got rid of the large cell with OA with good results. I hope to have SBBs on all my hives this year as they do help keep the mite counts stay even lower. So with good genetics, small cell/natural cell, and SBBs I feel all hives should be able to take care of the mites on their own but I will keep checking every month or so during the season. If I do not check mite counts I would not know which hives handle the mites the best to use them for my next generations.

Since my major in college was horticultue and I had economics I understand the mixed feelings over this being called an economic threshold. It is a cost/benefit to me. I do think with any livestock that is producing offspring though you have to figure replacement cost of that animal equal to what you may or may not loose. A package is not a good over wintered hive yet it may have better genes and be better in the long term. So you can decide for yourself what the cost of replacing that hive next year will cost to use.

I thought IPM would have been a bigger part of this thread. I know it works but it is not a silver bullet either. I still have mites but so far the bees are taking care of that problem for me.

[Ian]

Are you going to continue the use of OA treatments on your Small celled hives?