# population crash/not varroa........ideas?



## simplyhoney (Sep 14, 2004)

There are a few commerical beekeepers here in Colorado who are experiencing an unknown problem. June was dry and stressfull, so we attributed the failure of many spring nucs to that. However, large established colonies have been losing field bees. We treated for mites early and have kept them under control using thymol or oxylic acid. There is no sign of mite damage. The colonies look like they are sick with foul brood but after closer inspection no foul brood can be found. There are some brood problems, but it looks as though the problems are more due to lack of attendance by bees. Random sac brood, or chalk or both. But these were colonies that have 2 deep supers of honey that they made pretty fast, and then began to decline very rapidly.
If it were just my own bees I would know it was something I had done but there are several commercial guys, all very experienced with similar problems and no idea of the cause. Open for opinions. please post any idea.


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## merops_apiaster (Jul 16, 2005)

<There are some brood problems
Usually when bee population decline the brood has problems, similar to chilled brood. 
It seems pesticides problems:
1.-Strongest colonies decline faster.
2.-It is not necessary to see dead bees around the hives, because any pesticides kill the bees don´t allow the bees return to the hive.
My opinion.


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## BjornBee (Feb 7, 2003)

I just inspected an apiary a few weeks back that had all the signs you said. Chilled looking brood, dead decaying lavae that could be casually seen as AFB, signs of chalk, signs of SAC, shotgun patterns, etc. I went to the next hive, and the next....

I said to the beekeepers "I really don't know what I'm looking at, but I could swear that you had massive pesticide poisoning". He then said that prior to pulling the hives from blueberry, he had seen the farmer spraying a couple days before. I asked if he had bees that did not go to pollination, and after looking at them, not one had any of the symptoms of the first group.

I think merops if correct. Sounds like pesticides. Unhealthy bees will not keep ahead of secondary deseases and will dwindle.


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## simplyhoney (Sep 14, 2004)

thanks for the info, It does seem like pesticide, but the cases are too many in every yard. Not only in my part of the state but in northern colorado also. some yards are miles from agriculture or populated areas. I really believe that it is something to do with Almond pollenation. All the beekeepers I have spoke with had bees in California around Fresno. It is a very puzzling thing. 
Many of the colonies affected have made two deeps of honey and their brood (for the most part is ok, perhaps a little sac, or chalk brood, likely causes by poor care, because of lack of bees) when I harvested there weren't enough bees to fill the deep and medium hive body. Usually the bees are pouring out of the hive body after harvesting the supers this being peak population time. Please email me if you have any similar cases or post here. [email protected]
Thanks again for the opinions.


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## Dave W (Aug 3, 2002)

We have had (and having) record high temps all across the US. TV weather guy says over 1000 high temp records have been broken in July.

How does high temps affect queens' egg-laying?


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## peggjam (Mar 4, 2005)

"How does high temps affect queens' egg-laying?"

It may not have anything to do with the queens ability to lay during high temps, but it may have something to do with the eggs mortality rate. Higher temps would proably increase the loss of moisture from the hive, and increase desication of the eggs. But it doesn't seem like it would cause this kind of sudden decrease in hive population. I would sooner think that it had to do with pesticide posioning than anything else. If these hives stored lots of pollen during almonds and are now using that to raise brood, and this pollen contained a pesticide such as sevin, it would be as leathel now as it was when it was garthered.


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## simplyhoney (Sep 14, 2004)

re: temps.......we move the bees to Southern New Mexico to winter and in the spring temps are regularly around 105-109........never seemed to bother the queens or eggs in years past, so not sure that 95-98, which is what we had in Colorad, in June would bother them. Especially if they had access to water.
The Almond farmers are very careful not to spray pesticides in the orchards while the bees are there and with the shear amount of "bee interest" in california during pollenation, I'm sure any farm would be leary of spraying insecticid for fear of a lawsuite, But a good theory for sure.
Let me ask this: Do you believe that when a varroa mite (or family) is feeding on a larva, it affects the life span of the bee once she has emerged? Gloria De-Hoffman had indicated that this is a large factor in hive collaps even after treatment. Again, any info is welcome. Thanks


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## peggjam (Mar 4, 2005)

It would stand to reason that if a mite fed on a larva long enough, there would be damage that would decrease the lifespan of the bee. I have no idea how long that would be, and if there was enough mites in anyone hive to do this kind of delayed die off, the hive would have succombed to mites long before this. I think I would pull a sample of pollen from a couple hives and have it tested for pesticides, I really think that is where your problem is.


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## merops_apiaster (Jul 16, 2005)

When did you treat the varroa? 
If the problem is not pesticide, but stress, "Treat varroa, Feed, Requeen".
By the way, almond pollen is considered bad because low protein levels. But I suppouse that your hives have not almond pollen actually.


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## Kieck (Dec 2, 2005)

This one doesn't sound like Varroa to me. The original post states that they saw no signs of mite damage.

How was the brood-rearing during June? Did the bees continue to raise brood, or did they shut down? How rapid is the decline now? Are we talking about numbers dwindling within a week, or has the decline taken place over the last month?

I'm not sure, either, that you'd get enough Sevin in pollen to kill bees months later. I wonder if Sevin would persist that long, and, more importantly, I wonder whether enough Sevin could be absorbed into the pollen to pose a threat to the bees if all they got was the pollen. The reason beekeepers often close in their bees for 24 hours after agricultural spraying takes place near their bees is to avoid exposure -- if the residue persists that long in pollen, it would persist for much longer periods of time in the field, too.

How often have you been using oxalic acid or thymol? How are they being applied? (Some beekeepers have suggested that oxalic acid is pretty hard on the brood.)


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## BjornBee (Feb 7, 2003)

I'm not sure the number that were up too, but 18 was last I heard. Thats 18 different viruses that are associated with v-mites. I am sure that the total picture is not clear and who knows how many more are out there.

All viruses are not directed related with the mite counts being high. Yes, as mites increase, the chances of one virus or another being profound increases. But thats not to say that viruses need high loads, with obvious damage to be seen, to make an impact on hive health. Every year more is found and the knowledge increases. I am sure there are some things we just overlook. Viruses are going to change with time. 

It seems mite associated viruses cycle every two or three years. Some places, regardless of treatment and mite load, see heavy losses, with no clear cut answer at this time.


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## merops_apiaster (Jul 16, 2005)

--if the residue persists that long in pollen, it would persist for much longer periods of time in the field, too.--
Of course. And really this matter has been a headache for Frenchs beekeepers. (Only for Frenchs?)


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## peggjam (Mar 4, 2005)

Let me direct your attention to this article, which deals with sevin stored in pollen, this is not a research article, but does pose the question and possiblity of this happening. Most of it is on page 2:

http://www.nrdc.org/onearth/06sum/bees1.asp


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## Kieck (Dec 2, 2005)

Well, I read up on Sevin, in particular, and discovered a couple things I didn't realize previously. Most importantly, acidity preserves Sevin. The more acid the environment, the longer Sevin remains toxic. That doesn't help bees any, if they would manage to store it in their honey.

However, I would expect pollen to be stored with pollen, and the pH of pollen almost certainly isn't as acidic as honey. At a neutral pH, Sevin will only persist in the environment (including the inside of a bee hive) for less than three weeks.

Of course, too, Sevin is a neurotoxin. How could bees manage to come into contact with enough poisoned pollen and pack it back to their hives without killing themselves in the process? Sevin doesn't have to be ingested, after all -- contact with Sevin is enough to kill bees.

The other factor that doesn't add up in my mind is the timing in the scenario outlined in this thread. If the pollen from California is toxic to the bees, and the bees faced a dearth in Colorado in June, why would effects from pesticides only be appearing in early- to mid-August? I would have expected any poisoned pollen to have decimated hives at the time of the dearth, when they were using their stored reserves of pollen. In other words, I would have expected the problem to have shown up in June.

By the way, Sevin has little or no effect after less than two weeks on other insects eating plants that have been sprayed by Sevin. Strange that bees would be that much more susceptible to Sevin than other insects.


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## BjornBee (Feb 7, 2003)

Everyone is focused on Sevin. Based on some farmers I know, there are a few out there that have some older chemicals in the back of the barn. Some say the stuff they use today wouldn't kill a flea. (Of course I know nothing of killing a flea) Using banned chemicals by old-timers does happen. Who knows what chemicals the bees were exposed too.

How about a fellow beekeeper poisoning the area after his bees were pulled. Heard rumors of such acts recently. What about a "peta" type who hates beekeepers? Who has the most to gain? Follow the money....What about Bush. Any connections to Halliburton and Cheney. You wouldn't be on any possible oil fields being from Colorado? Is this a conspiracy to have you sell land cheap after the great crash of the Colorado honey industry?

How about a time line showing pollination dates and the possible first signs of problems. Is the poisoning enough to effect queen health and egg laying, transferring the signs to this later date by unhealthy bees raised a few cycles after the queen has layed eggs. Have you tried requeening any hives and what were the results? And do you have any hives for comparision that was not used for early pollination?


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## peggjam (Mar 4, 2005)

I don't believe it would have to take place only in CA, only during almond pollination. If they were exposed anytime during the foraging period, they could have stored enough to cause the affects that are being seen now. A decrease in bee numbers a month ago, could be reflected now due to hives inability to care for all the brood.


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## merops_apiaster (Jul 16, 2005)

The Mystery Of The Disappearing Bees.

Nobody knows the cause. It is generalized along Europe, and USA, and Australia, and...etc.
Bad pollen, pesticides, Nosema, a new nosema called Nosema Ceranae, viruses, Acarapis, stress...
When the answer is very complicated, you have to come back at the begining. 2+2=4 > young queen, food (pollen and honey, or substitutes) and mites control.


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## LSPender (Nov 16, 2004)

I would suggest everyone read the current article in Am Bee Journal, that overview all the VIRUS's that have been identified in the past few years. I have been saying for the past 3 year I do not have a mite problem, and I don,t but I still lose hive to exactly what you are talking about above. The closest thing I relate is SAC BROOD, or a relitive of it. Here is what I did earlier this year when I found one bee yard of 60 hive that had the same symtoms, and I did this because the past 3 years when I saw this all the bees died off. I treated for foulbrood with BOTH Terramycin & Tylan in the powdered sugar and gave 1 big scoop to each hive. All these hive look good now and I will do same treatment but in 3 stages during the fall. As a side note I believe we could have been suppressing something with the terrymacin for many years we were not aware of. I notices a lot of problems after I stopped using it 3 years ago, as did a lot of beekeepers did and went with Tylan(Tylosan). Hope this helps.


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## merops_apiaster (Jul 16, 2005)

http://www.honeybeeworld.com/misc/sadandbad.htm

This article can help you. It is about "bad" and "sad" bees. It is really good.


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## peggjam (Mar 4, 2005)

"By the way, Sevin has little or no effect after less than two weeks on other insects eating plants that have been sprayed by Sevin. Strange that bees would be that much more susceptible to Sevin than other insects."

kieck

I read this when you first posted this, and thought about it for awhile. You are compareing the breakdown of sevin which is exposed to the environmental effects of rain, wind, sun, to the breakdown of sevin stored in a controled envirnment, I really don't see that there is a comparison available here. In the hive, sevin would be protected from the elements, and hence reduce the rate at which it decays. We really don't know what the effects of sevin is on other pollinators that take it back to their nest, we only notice the effect on honeybees because there are so many that are in managed hives.

Bjorn has a good point about other pesticides being store or used that we don't know about.


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## Kieck (Dec 2, 2005)

First, let me say that my comment that it would be strange for Sevin to have an effect on honey bees long after it was sprayed was in response to some of the comments made -- and the article cited -- that implied that Sevin on plants could still be toxic to bees after several weeks after application. I still doubt this.

I also doubt that Sevin would last very long in a hive. A hive really isn't the sort of controlled environment that you imply, Peggjam. At least mine aren't. I try to maintain good ventilation through my hives. Air circulates pretty freely through the hives.

I recommend you go down to your local hardware store or chemical supply place, and look at a bottle of Sevin concentrate (or any other chemical that you're concerned about). Notice that it has an expiration date on it. That expiration date applies even if the seal is never broken. Chemicals, Sevin included, break down even in sealed containers. The rate is slower than in the open, as you would expect, but it does break down.

You're right, we don't really know the effect on other pollinators like we should. We do know, though, that Sevin no longer kills beetles or grasshoppers or other insects feeding on plants that have been sprayed after a short period of time, usually much less than two weeks. That was the comparison I was trying to make: why would Sevin be toxic to bees in much smaller amounts than it would be to aphids, for example?

Bjorn does have a good point. I picked up on Sevin in particular because it seemed that Sevin was being singled out in this thread. Other insecticides can be just as bad or worse. Again, though, unless they're encapsulated, insecticides are usually lethal by contact as well as by ingestion. Bees are unlikely to be able to store up large enough amounts to kill future bees without killing themselves in the process. That means the effects are unlikely to show up months or even weeks after the event. Poisonings by pesticides should show up quickly after spraying.

As far as pesticides being stored and used, I'm sure they are. Some people probably get away with it. I know I wouldn't want to face the penalty if I got caught applying a chemical that wasn't labeled for use on a crop, though, and those old chemicals are now off-label.


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## peggjam (Mar 4, 2005)

kieck

There are alot of ands, ifs, and maybes associated with pesticides. Labeled breakdowns (expiration dates) are much longer than once the product has been applied. Breakdown depends on factors found within the environment in which it is used. I have found that one fly spary called extiban(sp) has outlived it's expiration date by years, not weeks. It is as effective today as it was when I bought it 10 years ago. So just because it has an expiration date, doesn't mean that it is not as effective after that date, than it is before that date. In order for the labeled breakdown to occur, it has to be exposed to the environment conditions that will cause the breakdown. Just to use sevin as an example, if pollen contained sevin levels that were below the toxic thershold of adult honeybees, but toxic to the brood of honeybees, was carried back to the hive and stored in cells, with additional pollen packed on top of it, which in essence blocked or capped the bottle, so to speak, do you really think that it would continue to degrade without the environmental influances nessacery for degragation? It is possible for this to occur, and just underlines our need to be careful with the use of pesticides on our crops.


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## Kieck (Dec 2, 2005)

"Labeled breakdowns (expiration dates) are much longer than once the product has been applied." -Peggjam

Yes, I agree. Keep in mind, though, that the bees aren't picking up bottles of concentrate to haul back to their hives.

Also, degradation doesn't stop after it has started. You can't expect to open a bottle of Sevin (or another insecticide), use some of it, close the bottle again, and have the bottle remain effective for as long as a bottle with the seal intact. Sevin, and many other insecticides, begin breaking down once they come in contact with water or water vapor. Even the humidity in the air is enough to begin degrading pesticides.

So, taking it to the next step, the Sevin (or another pesticide) gets sprayed on a field and begins decomposing, gets picked up by bees perhaps and keeps decomposing, and gets put in comb where it keeps decomposing. Even sealed, degradation continues once it begins.

". . .do you really think that it would continue to degrade without the environmental influances nessacery for degragation?" -Peggjam

Yes. Like I already said, it might progress at a somewhat slower rate, but I'd even wonder about that. Pollen won't form an air-tight seal, air (and water vapor in the air) will still reach the pollen, and Sevin (and other pesticides) degrade in the atmosphere, too.

As far as the fly spray is concerned, killing flies successfully and being just as potent as it was ten years ago are two different issues. It might still be lethal to flies (and, therefore, as effective as before), but it might be far less potent than it was ten years ago. And, some products of decomposing pesticides are almost as toxic as the original pesticides. If these products are also lethal to flies, you might not even be using the same chemical, but it might be just as effective.

Like others have suggested on this thread, if anyone is concerned that pesticides might be in some of the pollen stored in a hive, simply have the pollen tested for pesticides.

Ironically, I've sprayed soybeans that my own bees were working with Sevin and numerous other chemicals, including many that are far more potent than Sevin. I've never even seen die-offs of worker bees, much less reductions in populations of colonies, from these chemical applications. Of course, all but one of the chemicals was applied as a liquid spray, and they were sprayed over the top of the foliage (like farmers around here spray), so I doubt that much if any even got into or onto the flowers. A few chemicals that were used are systemic, but most are contact (like most farmers around here use).

Really, I think most Americans would be shocked at the number and amounts of pesticides applied all around them. I think most beekeepers would be shocked at how many pesticides are applied within range of their bees, and they never realize it because they don't see any effects on their bees. And, I think it would be next to impossible in the U.S. to keep bees away from these chemicals (maybe that's why "organic" beekeeping is so hard to define -- but that's another thread).


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## peggjam (Mar 4, 2005)

"(maybe that's why "organic" beekeeping is so hard to define -- but that's another thread)."


Tis true, tis true! 

"Like I already said, it might progress at a somewhat slower rate, but I'd even wonder about that."

But at what toxicity level? Remember, were're not talking about full strength here, as degradation begins at the moment of mixing, but at what toxicity level would it be toxic to brood? I would hazzard a guess that it wouldn't have to be very toxic to affect brood. I haven't seen any studies on this at all, and don't know that any have been done, just saying that it is possible, it could happen.

Most Americans don't realize that every square inch of the world shows some level of DDT either. But yet it continues to be manufactured and used in other countries.

"Pollen won't form an air-tight seal, air (and water vapor in the air) will still reach the pollen, and Sevin (and other pesticides) degrade in the atmosphere, too."

This i'm not so sure about. Mold needs moisture, air and darkness to grow, an I don't see alot of mouldy pollen in strong colonies.

All i'm saying is this is possible, it could happen, proably has happened, an nobody knew it, just chalk another one up to mites.LOL


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## Kieck (Dec 2, 2005)

"Remember, were're not talking about full strength here, as degradation begins at the moment of mixing, but at what toxicity level would it be toxic to brood? I would hazzard a guess that it wouldn't have to be very toxic to affect brood." -Peggjam

Could be. I would think, too, that Sevin would be toxic to brood at lower levels than it would be toxic to adult bees. I would guess, though, that (based strictly on size or body mass) that small amounts of Sevin should be just as toxic to aphids as to young honey bee larvae, yet after just a few days on plants, Sevin (and many other pesticides) have no effect on aphids -- even very young, small aphids.

In my experience, mold doesn't do well in well-ventilated spaces. It might need air and moisture to grow, but it doesn't seem to do well in places with good ventilation. Bee hives (at least mine) have pretty good ventilation, and the same air currents that ventilate the hives are likely to help degrade any pesticide residues in the hives.


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## peggjam (Mar 4, 2005)

Kieck

I enjoy these conversations even if we don't agree on anything. I view events from the past, where the current thinking was the metheod of disposal or application was ok, and then we find out that it wasn't ok years later. Present thinking on longevity of pesticides in pollen is just begining to take shape, and I am certain that future studies and thought will provide the oppertunity to prove one of us wrong.


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## Kieck (Dec 2, 2005)

I enjoy them, too, Peggjam. I always appreciate your comments, even when I don't agree with them. The differences in opinions among beekeepers on this forum is really what makes this forum so valuable.

I agree with you that we don't know what the long-term effects of many of the chemicals we put into the environment are. Having said that, though, what we're talking about here is short-term: bees come into contact with pesticides in some manner, and wind up dying from the exposure. We're not talking about long-term changes here. The directions of this thread, anyway, is discussing the possibility of some problem from no more than a few months previous to the observed effects.

One of the reasons I take issue with some of these threads is the tendency to lay blame on an "easy" source, whether or not the blame is justified. Read through most of the threads that are titled [paraphrasing here], "My bees died/are dying: why?" and you'll see two common culprits that get blamed: 1) Varroa mites, and 2) pesticides. I'll agree that Varroa are a serious problem, as well as pesticides, but these two tend to have the blame pinned on them even when all the evidence suggests neither was involved.

For example, in this thread, many of the hives are dwindling without recent (known) exposure to pesticides, yet beekeepers on this forum are going so far as to suggest that they might have picked up pollen laced with pesticides months before, stored that pollen, and later were poisoned by the pesticide residues in the pollen. What about the possibility that dry conditions prevented the bees from collecting adequate amounts of nectar and pollen to continue brood rearing? What about the possibility that repeated treatments of oxalic acid or thymol or both might have some impacts on colonies (these treatments were mentioned in the original post, after all, and if they're hard on mites, they're probably not too great for the bees, either)? How about some other possibilities?

I guess the way I see it is that mites and/or pesticides are easy to blame because it tends to give us a specific problem to blame, rather than a combination of factors that collectively might stress colonies, and, to some extent, it takes the blame off of us as beekeepers. Pesticides? Well, that's that guy who was spraying who killed my bees! Not me! Mites? Everybody's got mite problems! Not much I can do on my own about mites!

Other problems have been killing mites all along, too, and may be just as much to blame as the most popular problems of the day. Reading through the literature from some years ago, trachaeal mites were the popular pest to blame. Some beekeepers seemed to believe that every hive that died at the time, or would die in the future (which would be now), must have died because of trachaeal mites.

In this specific case (the subject of this thread), I don't think pesticide poisoning sounds very likely. The large numbers of dead bees around the hives typical of pesticide poisonings haven't been mentioned, many of the bees are said to be in areas far from pesticide applications, and the dwindling populations are occurring long after any theoretical exposure to pesticides -- and it's the oldest bees that are dying now, rather than the youngest.


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## peggjam (Mar 4, 2005)

Kieck

Things discussed in this thread:

High temps, egg mortility, verro mites, pesticides in the pollen, virus associted with verroa mites, queens ablitiy to lay in hot temps.

"A decrease in bee numbers a month ago, could be reflected now due to hives inability to care for all the brood."

I posted that in one of my earlier posts, and now I will explain it because I don't think you picked up on it. If a pesticide had been used within the foraging area of a hive, and it was a lethel level on the foragers and they couldn't make it back to the hive, and died in the field, that would stress a hive enough to cause this type of decrease in hive numbers. Maybe it has been low for awhile and nobody noticed it. It would effect the hive in all levels from brood rearing to foraging. And would proably cause the queen to reduce laying until the population recovered.

Truth is nobody knows, and we all have therioes, and that's about all. But we have discussed more than just pesticides, and their lethel affect on the hives.


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## Kieck (Dec 2, 2005)

"Things discussed in this thread:

High temps, egg mortility, verro mites, pesticides in the pollen, virus associted with verroa mites, queens ablitiy to lay in hot temps." -Peggjam

Yes, but go back and read the posts. Most of the blame is being pinned on pesticide poisoning. Some are trying to blame mites. Most of the rest got only a brief mention, and were discarded as unlikely.

Some of that makes good sense to me. For example, "high temperatures." My bees have shown no problems, despite living in a climate with higher temperatures than the bees described (over 100 degrees Fahrenheit, versus 95 to 98 degrees described in the post). I'd imagine that beekeepers farther south keep bees in much higher temperatures without killing off bees. I've kept bees in Kansas through weather over 110 degrees.

Viruses? Possibly, but those seem to be associated with Varroa again.

Egg mortality could be caused by any number of things, but the post suggested that only the field bees were really dwindling. That doesn't sound like egg mortality to me.

"I posted that in one of my earlier posts, and now I will explain it because I don't think you picked up on it. If a pesticide had been used within the foraging area of a hive, and it was a lethel level on the foragers and they couldn't make it back to the hive, and died in the field, that would stress a hive enough to cause this type of decrease in hive numbers." -Peggjam

Actually, I did pick up on it. It's plausible. But so would other explanations. For instance, a drought could make the bees cease rearing brood for a while. When the older foragers begin dying off, no bees would replace them. Why is this any less (or more) likely than pesticide poisoning?

Like you said, we don't know, and we're speculating here. We have discussed pesticide poisoning, and the effects on hives of pesticides. This problem sounds much more widespread than any sort of pesticide poisonings that I've ever seen, though, which made me doubt that theory. I got the idea that hundreds of hives were involved in this scenario, across some pretty great distances. I suppose all of them could have bee poisoned by pesticides, but how likely is that?


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## Velbert (Mar 19, 2006)

was wondering could it be in the feed you are feeding.

With the newer planting of the GM corn could they be making corn syrup out of it that may be causing the problems.

Just a thought


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## peggjam (Mar 4, 2005)

Not a bad one at tha Velbert. What say you Kieck? (Here we go again  )


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## Kieck (Dec 2, 2005)

Well, for starters, I'll assume that the GM corn you're referencing is Bt, not all GM corn. Why RoundUp-Ready corn (which is also GM, of course) would make more of a difference than the nectar from the RoundUp-Ready soybeans that are planted so widely isn't logical to me, so I'll stick with the assumption that you're talking about Bt corn.

Possibly. I'll say that it's possible. But I have a couple reasons to suspect it's not a problem. First, Bt corn has been around for more than 10 years, and, in South Dakota, is widely planted and used for just such things. We haven't seen this same problem with honey bees here. Since South Dakota is the leader in the number of acres planted in GM crops (especially Bt corn) and the amount of GM crops produced, I would expect it to show up here first. It hasn't.

Secondly, many beekeepers use Bt products (Certan) in their hives to control wax moths. These products don't kill the bees -- they're specific for wax moths. In fact, different types of Bt corn target different pests. "YieldGuard - Rootworm" targets rootworms (beetles), but has no noticeable effect on the moths or other insects that feed on corn. "YieldGuard - Corn Borer" (or Herculex 1) is the most commonly-grown type of Bt corn, and it only targets corn borers (moths in the same family as wax moths); it won't even kill other types of moths feeding on the corn.

But it's possible that corn syrup made from Bt corn is having an effect.

More likely, in my mind: what about the effects that treating with OA and thymol may have had on these hives? In the original post, Simplyhoney stated, "We treated for mites early and have kept them under control using thymol or oxylic acid." Even staunch advocates of OA say that it can damage open brood. Is it possible these products might be causing the problems seen in these hives?


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