# The Case Against Imidicloprid



## grondeau

Please bee folk, I did a little playing with graphs and looked at various toxicity data on Imidacloprid and plotted on log-log graph to find the power law. It's disturbing to say the least. If you are wondering why we don't see residue in collapsed colonies, the answer is that the effects happen at unobservably small chronic doses.

The post is here: http://squashpractice.wordpress.com/2013/03/03/the-case-against-imidacloprid/

We've got to follow the Europeans and get rid of this stuff!


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## Stromnessbees

An excellent article, thank you for posting it!

The link at the bottom to the work of Rosemary Mason should be followed up as well. 
I was lucky to have Rosemary visit our farm last year, to see a prime habitat of the endangered Great Yellow Bumblebee.


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## johnthefarmer

Very interesting, will follow the links at the bottom of the article to find out more.


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## jim lyon

This is an interesting theory and may well have some validity. It does, though, also seem to be a convenient means for keeping alive the theory that what cannot be detected is actually the problem. It would also seem to suggest that there would only be a single narrow window for neonic exposure. Is that plausible? Maybe, maybe not. I would suggest that if someone is to actually prove such a theory that they need actual data proving this rapid rate of metabolization and excretion.


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## grondeau

jim lyon said:


> This is an interesting theory and may well have some validity. It does, though, also seem to be a convenient means for keeping alive the theory that what cannot be detected is actually the problem. It would also seem to suggest that there would only be a single narrow window for neonic exposure. Is that plausible? Maybe, maybe not. I would suggest that if someone is to actually prove such a theory that they need actual data proving this rapid rate of metabolization and excretion.


This is not a theory. All I was doing is fitting existing data to a convenient toxicity model and extrapolating to the age that bees normally live. The fact the the model works well with the neonics with other species, and fits published bee toxicity data, suggest that actually the chemical is NOT metabolized and excreted, but rather bio-accumulates and continues to produce toxic effects well after exposure.


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## jim lyon

grondeau said:


> This is not a theory. All I was doing is fitting existing data to a convenient toxicity model and extrapolating to the age that bees normally live. The fact the the model works well with the neonics with other species, and fits published bee toxicity data, suggest that actually the chemical is NOT metabolized and excreted, but rather bio-accumulates and continues to produce toxic effects well after exposure.


Then wouldnt you agree that a lack of residue could, among other things, mean either that there never was any residue? How could you differentiate without some sort of data? Again, I am not saying its not a viable theory just trying to understand how showing that something is possible may not be an indication of anything other than that it is, in fact, possible. Please clarify.


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## grondeau

Hi Jim,
We CAN detect residue in pollen in plants grown from treated seed. Typical levels are in the 1-10 ppb range. Problem is, the bees dilute this since they bring in pollen from other sources as well. Plus the stuff does degrade. Our detection limit is around 1 ppb, so we are starting from a point close to the detecion limit anyway. By the time you dilute, you not expect to be able to detect it. This is not a mystery. Nor would you expect that toxins in the sub ppb range would kill bees immediately. There is not a lot of data on how low doses of neonics kill bees. Best paper is Suchiel 2001. There is nice data on how very low doses of neonics kill other arthropods (the other paper I ref.). Both sets of data fit the power law toxicity model very well. The model (and Suchiel's data) show individual bee mortality at sub ppb dose levels when given enough time. (7-10 dyas for Suchiel). 

Please tell me how bees that gather pollen from sources which have ~1ppb residue - could NOT have some residue more than 0.0001 ppb in their bee food. We can't see that, but it would be folly to assume that just those molecules jumped off the pollen load on the way back to the hive.


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## Kieck

> ... suggest that actually the chemical is NOT metabolized and excreted, but rather bio-accumulates and continues to produce toxic effects well after exposure. -grondeau


Fascinating stuff. Do you have any sources that suggest that such bioaccumulation can occur? The chemicals that tend to bioaccumulate are often not as water-soluble as the neonicotinoids are. If it does bioaccumulate, it should be easy to demonstrate. Older bees should have increased levels of neonicotinoids in their systems.



> Our detection limit is around 1 ppb, so we are starting from a point close to the detecion limit anyway. -grondeau


I don't know about this one. I've talked to some researchers who work on these sorts of things, and they have all been confident that they could detect presence at the "ppt" level or maybe less. However, most of them caution that such low limits of detection mean that virtually all samples will show up as positive results. 



> ...some residue more than 0.0001 ppb in their bee food. -grondeau


This sort of level is 0.1 ppt, or less than one molecule per bee. PPT is likely less than one molecule per bee. If you have one molecule of neonicotinoid per several bees, I doubt that that single molecule could affect more than one bee, if that.


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## TWall

This is an interesting theory. I'm not as likely to accept a graph that happens to fit a specific hypothesis.

I find the bigger question to be why are many commercial beekeepers successful in maintaining healthy colonies in areas with widespread neonic useage?

I think neonic poisoning is a 'sexy' cause for hive death/CCD. Most people claiming CCD don't regularly monitor varroa mite levels. I think in many cases it is easier to blame a pesticide for the lose of hives than to take the time to monitor and control mites.

Tom


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## grondeau

Today monitoring and treating for mites might be enough to keep colonies healthy enough to overcome bee losses due to pesticides - sometimes. That used to be the case where I live. Seems less so today. Usual CCD losses are associated with any number of diseases. Varroa is a bad one - but not the only culprit. They are visible and easy to blame, however!


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## AstroBee

Taken from your report "Extrapolating the green dashed line trying to reach 50 to 100 days would require reducing continuous exposure to less than 0.0001 parts per billion (ppb). "

You've got one data point 3 orders of magnitude larger than your 0.0001 ppb assertion. You can't expect us to take this seriously? Such simple models (at best) can perhaps describe "local" phenomenon within your data set, gross extrapolation is simply folly. One of my former professors liked the phrase: "Models have limitations, stupidity does not", Michael Athans, MIT


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## cerezha

*grondeau* just use already published scientific data (proper references has been provided) and use logarithmic coordinates to plot EXISTING SCIENTIFIC data. Sometime, the way of data presentation helps to understand the trends. Plotting in different coordinates does not change the data. 

There is acute (one single shot, very high dose) and chronic toxicity. It is misconception that in chronic toxicity the "poison" is accumulated and may be detected. It is *damage* from slow poisoning accumulates and eventually kill. "Poison" has been spent on poisoning, it did not accumulate itself... In case of neonics, it irreversibly bind to Nicotinic acetylcholine receptors and thus disappears from the scene - bind neonic is not detectable anymore by standard technique. Neonics are evil because they are using normal biological pathways.


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## deknow

What justification do you use to rely on the suchal data? No other study has been able to replicate those results. If you are going to use data that is clearly anomolous from everything else done in the 12 years since, there should be a reason other than it is the most convenient to fit a hypothesis.

Deknow


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## grondeau

AstroBee said:


> Taken from your report "Extrapolating the green dashed line trying to reach 50 to 100 days would require reducing continuous exposure to less than 0.0001 parts per billion (ppb). "
> 
> You've got one data point 3 orders of magnitude larger than your 0.0001 ppb assertion. You can't expect us to take this seriously? Such simple models (at best) can perhaps describe "local" phenomenon within your data set, gross extrapolation is simply folly. One of my former professors liked the phrase: "Models have limitations, stupidity does not", Michael Athans, MIT


I actually stand corrected on this. Frankly I was so amazed that the data could be so well modeled by a simple power law that I couldn't resist the extrapolation. Nevertheless, I want my bees living longer than 10 days (0.1 ppb) and I see little reason to expect a sudden turn upward to the curve. What will change the toxicological dynamics? Who's job is it to find where the curve finally turns up? I'd be happy if someone did it in the water crustaceans since it is so much easier than with bees. With those critters, the authors of the study took them out to about 7-8 days with the critter's normal life span ~ 30-35 days and still showing power law behavior. It certainly would be curious to see how many more orders of magnitude you can take this before it breaks down. You want to do it!


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## grondeau

deknow said:


> What justification do you use to rely on the suchal data? No other study has been able to replicate those results. If you are going to use data that is clearly anomolous from everything else done in the 12 years since, there should be a reason other than it is the most convenient to fit a hypothesis.
> 
> Deknow


I know of one other study of low-level extended-time experiments. That was Shmuck. Of his four trials one showed similar results to Suchiel, the others did not. Shmuck was a Bayer scientist and chose to disregard the data he didn't really want to have be the truth. Not saying he was wrong, but his data would not fit a power law like that reported by Sanchez-Bayo on crustaceans either. If you can point me to other studies that looked at low levels out to 10 days, I would be grateful.


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## Stromnessbees

Hi grondeau

I would be interested in your opinion on this theory:



Stromnessbees said:


> Some studies have reported that summer bees rather than winter bees were found in colonies going into the winter. The difference is in the smaller fat reserves, leaving summer bees with much shorter lifespans.
> When the fat reserve is used up, a bee leaves the colony to die away from the hive.
> Lots of bees leaving at the same time leave behind an empty hive, the beekeeper calls it CCD or Marie Celeste or dwindling disease.
> 
> The trigger for winter bee production in a healthy colony is the shortening of daylength after the summer solstice, June 21st.
> Depending on your type of bee, winter bee production should commence soon or slightly later after that.
> 
> 
> *If the colony is under the influence of neurotoxins, like neonicotinoids, the bees might not be able to perceive the change of daylight and continue production of summer bees. *
> 
> It has already been proven that neonicotinoids reduce the memory of bees in field studies (reutrn rate of foragers) and in the lab (training experiments).
> 
> A compromised memory would make perception of daylight changes impossible, and as many colonies are exposed to neonics at the *critical time of year for winter bee procuction*, we should look into this possibility more closely.
> ...



It would explain why no or very little residue of neonics can be found in CCD hives.


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## Kieck

> It would explain why no or very little residue of neonics can be found in CCD hives. -Stromnessbees


How so? Are you suggesting that the bees are carrying all of the residual pesticides out of the hives with them in their bodies?


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## grondeau

Kieck said:


> This sort of level is 0.1 ppt, or less than one molecule per bee. PPT is likely less than one molecule per bee. If you have one molecule of neonicotinoid per several bees, I doubt that that single molecule could affect more than one bee, if that.


Not true. NA=6x10^23 molecules/mole. Assume bees are mostly water --> molecular weight = ~20; lets use 60 so more numbers cancel... bee weighs 0.1 g --> N = 6e23 * .1 / 60 = 10^21 molecules in a bee. 0.1ppt --> 10^8 toxin molecules. there is along way to go before we get to the single molecule per bee range - and the bee is long dead from natural causes on the toxicity graph.


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## Stromnessbees

Kieck said:


> How so? Are you suggesting that the bees are carrying all of the residual pesticides out of the hives with them in their bodies?


In a way, yes!


The bees that collect the neonic contaminated pollen & nectar don't 'consume' it, they just transport it. 
It's the nurse bees that ingest the pollen and some of that nectar, the rest of the nectar will be converted to winter food and stored. 

The case where I saw the clearest connection between neonics and CCD was a valley in Austria, where all apiaries near Clothianidin treated maize collapsed from CCD in late autumn and winter. 

This maize/corn would have supplied mostly contaminated pollen, as well as maybe some contaminated guttation droplets earlier in the season.

This pollen would have been consumed by the young bees that emerged in late August and September. Most of those should have done a lot of extra eating in order to build up fat reserves which would turn them into long lived winter bees. The trigger for that is the shortening daylength.

But maybe they failed to register the shortening daylength whilst under the influence of the neonics and didn't gorge themselves enough.
*
The toxins themselves would mostly be metabolized by the time winter arrives*, and all the short lived bees leave the hive to die. - Which is unfortunately the bulk of the bees, as no proper winterbees have developed, creating the appearance of CCD - an empty hive with just a small cluster and possibly the queen and some remaining brood left behind.


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## Kieck

> Not true. NA=6x10^23 molecules/mole. -grondeau


I was considering it from the standpoint of the number of _cells_ in a bee, not the number of molecules. You're right.

Of course, that all assumes perfect solubility, perfect transfer of molecules across cellular membranes, perfect retention within the cells after permeating the membrane, and ability to affect the organism if the molecules are locked in cells throughout the body.



> This maize/corn would have supplied mostly contaminated pollen, ... -Stromnessbees


I'm not rejecting or denying what you say, but I will reiterate: I'm convinced that bees do not collect much corn pollen under normal conditions. I've spent thousands of hours counting various insects in corn throughout the season. Honeybees are largely absent from cornfields at most times. I suspect that bees only collect corn pollen when other sources of pollen are very scarce or have failed. Teasing out the pesticide effect from the effects that might induce bees to collect corn pollen would be difficult, I think.



> ... as well as maybe some contaminated guttation droplets earlier in the season. -Stromnessbees


That one keeps coming up as a possible source of poisoning. I've never observed honeybees collecting guttation droplets from corn. Guttation occurs only occasionally here, typically in the early morning hours. Most bees that I've observed are not seeking sources of water at the time of day that guttation tends to occur, and guttation in corn tends to occur in conditions that cause guttation in any number of other plants. I've read that droplets collected from corn guttation can contain amounts of neonicotinoids that could cause bees problems. The difficulty I see is how infrequently honeybees are likely to collect guttation from corn.



> The toxins themselves would mostly be metabolized by the time winter arrives, and all the short lived bees leave the hive to die. -Stromnessbees


Makes some sense to me. What about the stores left behind in hives that have died from CCD? My understanding is that leaving behind adequate to large amounts of stores is a symptom of CCD. In fact, I've read and heard that new bees put into a hive that collapsed from CCD are also likely to suffer the same fate rapidly (if they can even be enticed to take up residence in the hive). What would cause such a symptom if the pesticide residues are all gone?


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## grondeau

One thing I'm still trying to puzzle out is why the big difference in toxicity between the two crustaceans in the Sanchez-Bayo paper. If this stuff acts on a nervous system, _what's so different_? Both absolute level and time dependence _are_ very different. One thought I had was either an absence or presence of another pathogen. The particularly strong time dependence is associated with the decay of the host immune system and the growth of pathogen organisms. You might expect very different results depending if pathogens are present or not. This kind of goes along with the very different results for toxicity from different researchers on bees, and also with the "outbreaks" of CCD that tend to happen. You might expect very different outcomes depending on exposure levels, pathogens, and time the bees need to live.


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## Stromnessbees

Kieck said:


> I'm convinced that bees do not collect much corn pollen under normal conditions. I've spent thousands of hours counting various insects in corn throughout the season. Honeybees are largely absent from cornfields at most times. I suspect that bees only collect corn pollen when other sources of pollen are very scarce or have failed.


My experience from keeping bees with fields of maize nearby:

During maize flowering time lots of bees coming home with very large pale pollen packs in during a few hours in the morning. 
The pollen collection on maize only happens during a short daily window, but the amounts brought hoe during that time are large, as nearly every pllen load is from maize. 
The flowering period is the middle/late summer, a time when few other pollen sources are available. 

As for observing bees whilst they collect the pollen: 
The maize fields are usually huge, so you would need a major apiary nearby to see bees out in force and you would need to be there just at the right time. 




> What about the stores left behind in hives that have died from CCD? My understanding is that leaving behind adequate to large amounts of stores is a symptom of CCD. In fact, I've read and heard that new bees put into a hive that collapsed from CCD are also likely to suffer the same fate rapidly (if they can even be enticed to take up residence in the hive). What would cause such a symptom if the pesticide residues are all gone?


I agree that the guttation is not usually a problem.

With regards to the leftover stores I think we simply lack data:

Most beekeepers are told that if they suspect poisonig they need to send in bees. 
With most of the bees gone from a CCD hive this is usually not an option. 
If all beekeepers were encouraged to have leftover stores analyzed we might see interesting results, but from what I have read in studies it is somewhat difficult to analyze sticky liquids like HFCS for traces of neonics at the ppb range. 


My advice: 

Look for the maize pollen arriving at the hives during flowering time, you could also set up a pollen trap for a day. 
You might be surprised at the amounts actually brought in!


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## Stromnessbees

My own observations are backed up by some studies:



> ...
> Malerbo e Couto (1992) studied the activity of bees Africanized, Jaboticaba l, São Paulo State, noted that *about half of the pollen was collected in the field until 10:00 a.m.*
> ...
> According Sabugosa-Madeira et al. (2007), bees do not show great interest in the fields of corn plants when there are other good sources of pollen to ensure close and their livelihoods. However, the bees come to feed almost exclusively on corn pollen when in case of famine or when apiaries are located in areas with large plantations of corn (MAURIZIO; LOUVEAUX, 1965). These authors found apiaries in the area of the Landes, in France, *satisfying about 90% of its needs for flowers with pollen from corn*, extending this for almost a month until the end of August.
> ...


http://www.scielo.br/pdf/asagr/v33n4/20.pdf


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## Kieck

> The flowering period is the middle/late summer, a time when few other pollen sources are available. -Stromnessbees


Difference in location may explain a lot here. Corn tassels and produces pollen during a window of about two weeks each year around here. And enough other flowers are usually in bloom during that time.

In the fields where I've collected data, an apiary of 64 hives was within a mile each time, often within 1/4 mile depending on the field. Flowers around the corn fields were often humming with bees. They just don't seem to venture into corn much here.



> Most beekeepers are told that if they suspect poisonig they need to send in bees. -Stromnessbees


The recommendation I've seen, most recently from our state apiarist, is to collect honey and pollen samples from hives where CCD is observed to submit the samples for pesticide and pathogen testing.



> According Sabugosa-Madeira et al. (2007), bees do not show great interest in the fields of corn plants when there are other good sources of pollen to ensure close and their livelihoods. -contained in quote posted by Stromnessbees


That matches with what I've observed. How do you tease out "poor nutrition" from "trace amounts of neonicotinoids" in an analysis of bees in this sort of situation? Which one is more important than the other?


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## Stromnessbees

Kieck said:


> How do you tease out "poor nutrition" from "trace amounts of neonicotinoids" in an analysis of bees in this sort of situation? Which one is more important than the other?



The bees in the valley where CCD appeared suddenly had been feeding on maize pollen for years and were thriving.
Bees tend to compensate for low amino acid content by collecting more of the pollen, and in our experience this worked fine, colony losses over winter were virtually unknown.

After the introduction of Clothianidin treated maize whole apiaries were lost to CCD in the following winter, nothing else had changed and the weather had been quite average. 

This seed treated maize had been banned in Germany where it had caused massive colony losses, and remaining stockpiles were sold over the border to Austria, making sure it _wouldn't go to waste_. :waiting:

As one could have expected, CCD 'arrived' just as it had in the years before in Germany.


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## Kieck

> Bees tend to compensate for low amino acid content by collecting more of the pollen, .... -Stromnessbess


Sure, but from corn (maize)? From everything I've observed, they only seem to collect significant amounts of corn pollen in times of desperation. Your observations suggest that my generalization based on what I've seen in this region does not extend to that valley in Austria, at least.



> After the introduction of Clothianidin treated maize whole apiaries were lost to CCD in the following winter, nothing else had changed and the weather had been quite average. -Stromnessbees


The title of the thread is specifically about imidacloprid, not clothianidin. However, I recognize the similarities of the two insecticides, and I won't belabor that point.

I envy the sort of conditions where you must have been keeping bees. I have yet to have a year of keeping bees that I could point to as being "average." Each year here seems to provide some sort of remarkable climatic condition: too wet, too dry, too hot, too cold, wet spring and dry summer, up-and-down temperatures during the winter, deep snow, and so on.

Having said that, did you submit samples of honey and/or pollen from those collapsed hives for testing to see if clothianidin was detectable in them? Seems to me that that would have provided ****ing evidence, given everything else that you outlined here.


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## jonathan

Stromnessbees said:


> The bees in the valley where CCD appeared suddenly had been feeding on maize pollen for years and were thriving.[/I]. :waiting:
> 
> As one could have expected, CCD 'arrived' just as it had in the years before in Germany.


Looks like Austria has quite regular events like this.



> Heavy colony-losses during the winters 2002/2003 and 2003/2004, as well as bees showing unusual behaviour raised the question whether virus infections may be involved in these conditions.



And the good news is that things look better this winter.



> Currently, the bees are doing comparatively well, said Gottfried Wenzel, Vice president of the Regional Beekeeper Association. "This year we have rarely had any reports of losses and we hope that it will be better than the previous year."


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## BlueDiamond

grondeau said:


> If you are wondering why we don't see residue in collapsed colonies, the answer is that the effects happen at unobservably small chronic doses.


In the USA we don't see a pattern of consistently more collapsed colonies in states where acreage of crops planted in crops grown from neonic treated seed is high (e.g. North and South Dakota) vs States where the acreage is low. So it stands to reason that if neonics were banned in the USA, the ongoing problem of 25% of the beekeepers losing 40-100% of their colonies each year would continue.

Here's a 2012 University of California at Davis article downplaying the role of pesticides in bee health problems: http://www.universityofcalifornia.edu/news/article/27351


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## PanchoBee

I think neonic poisoning is a 'sexy' cause for hive death/CCD. Most people claiming CCD don't regularly monitor varroa mite levels. I think in many cases it is easier to blame a pesticide for the lose of hives than to take the time to monitor and control mites.

Tom[/QUOTE]

I had my hives near treated imidicloprid orange trees for Orange Blossom honey production, I harvested some supers, and extracted some of it and others I stored for winter feed. hives that i gave a super of orange blossom lagged to build up as they went into the honey stores, where other hives build up quickly because they weren't given that Orange Honey super. It didn't kill the colony but they were behind in population compared to my other hives that they weren't ready for Avocado pollination/honey production, it was until then they began to explode in population after they consumed the stored honey (I havent tested the honey, no Lab wanted to do it, would have been Interesting to see). I also had hives near young lemons treated with Imidicloprid they made some honey, but didn't get sick at all, even if I left it there for them. All this was before the trials and suspicions of Imidicloprid on bees, i now avoid keeping bees near such treated fields especially if they bloom heavily and were treated way before bloom. It takes a while for imidicloprid to be taken up by the plant via the roots into the twigs, leaves, flush, bloom, etc........

It appears its the dosage and the crop's physiology of the bloom, Oranges blooms quick and at once, lemons all year round, also the timing of the application of Imidicloprid is a factor as well. They did an experiment in california in regards to Imidicloprid on bee health, (some good data) Lindcove research center. It was Orange blossom, does imidicloprid appear in the nectaries of the plant, yes it does, does it cause harm to a colony(reaches the LD50), yes, but it must reach certain ppb to do so. I will try and find the information online and post it here.

And Varroa.......I lose more bees to varroa than anything else including pesticides, and maybe a rival beek in my area. but pesticides are a lot more easier to blame than other issues such as mites, disease, poor forage which will lead into poor nutrition and succumb much more easier to viruses vecotred by varroa as a result of poor forage.


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## Stromnessbees

Kieck said:


> Sure, but from corn (maize)? From everything I've observed, they only seem to collect significant amounts of corn pollen in times of desperation. Your observations suggest that my generalization based on what I've seen in this region does not extend to that valley in Austria, at least.
> ...
> Having said that, did you submit samples of honey and/or pollen from those collapsed hives for testing to see if clothianidin was detectable in them? Seems to me that that would have provided ****ing evidence, given everything else that you outlined here.


Maize pollen is taken in much more frequently than beekeepers think:




> ...*the degree to which honey bees in our study gathered maize pollen was surprising*.
> 
> The finding that bee-collected pollen contained neonicotinoids is of particular concern because of the risks to newly-emerged nurse bees, which must feed upon pollen reserves in the hive immediately following emergence.
> 
> Pollen is the primary source of protein for honey bees, and is fed to larvae by nurse bees in the form of royal jelly.
> 
> A bee will consume 65 mg of pollen during the 10 day period it spends as a nurse bee [27], therefore a concentration of 20 ng/g (ppb) in pollen would correspond to a dose of 1.3 ng (65 mg 620 ng/g) or almost 50% of the oral LD50 of ca. 2.8 ng/bee [23].
> 
> Some of our pollen concentrations were even higher, although it is important to note that LD50 is measured as a one-time dose, while exposure through contaminated pollen would be spread out over the 10 d period and that there is likely substantial metabolic decay of the compounds during this time.
> 
> Lethal levels of insecticides in pollen are an obvious concern, but sublethal levels are also worthy of study as even slight behavioral effects may impact how affected bees carry
> out important tasks such as brood rearing, orientation and communication.


http://www.moraybeedinosaurs.co.uk/neonicotinoid/routes of pesticide exposure for honey bees.pdf



My Austrian beekeeping friend didn't submit samples, but a large scale study confirmed the correlation between apiary deadouts and neonics:



> DAFNE Project Nr. 100472
> MELISSA
> 
> Investigations in the incidence of bee losses in corn and oilseed rape growing areas of Austria and possible correlations with bee diseases and the use of insecticidal plant protection products
> 
> Projektstart 01.03.2009
> Projektende 15.03.2012
> 
> ...
> Summing up, the results of the MELISSA-project give evidence that in Austria regional clustered bee damages had occurred in the years 2009 – 2011, which were *frequently associated with the use of maize and oilseed pumpkin seeds coated with insecticides, as proved by residue analysis*.


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## grondeau

When Varroa first came on the scene, did any of you ever just sit and watch a colony go down? What I recall is MASSIVE numbers of mites - in the thousands, mulitple per bee - and YES the colony died. Today the colony is dead - often blamed on Varroa when you can barely find mites without a sugar role. What's different today? Shouldn't the bees be getting more resistant to the mites with time rather than less. What's up here? (I guess you know where I stand.)


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## jonathan

A quotation from project melissa re the Austrian situation:

Page 33




> Another monitoring project with focus on neonicotinoid seed treatment products is the MELISSA Project
> in Austria. In this project, particular attention is directed to the investigation of any damage to bees that is
> reported in association of growing maize. (Latest report: Girsch and Moosbeckhofer, 2011). According to
> preliminary results, the safety of neonicotinoid seed treatment products to honey bees can be sufficiently
> ensured when the prescribed security measures for the use of these products are complied with.


As reported many times regarding the risk from Maize/corn, the main problems for bees are due to planter dust incidents during drilling. When seed drilling is done properly, the ongoing risks appear to be minimal.
A bigger risk with corn is monoculture, lack of bee forage and subsequent poor nutrition.


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## Michael Palmer

grondeau said:


> When Varroa first came on the scene, did any of you ever just sit and watch a colony go down? What I recall is MASSIVE numbers of mites - in the thousands, mulitple per bee - and YES the colony died. Today the colony is dead - often blamed on Varroa when you can barely find mites without a sugar role. What's different today?


Viruses. In the early days of varroa, the virus load in the hives was low, and the colony could survive with huge varroa populations. Now the virus load is way higher and it doesn't take much to tip the balance and kill the colony.


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## jonathan

Michael Palmer said:


> Viruses. In the early days of varroa, the virus load in the hives was low, and the colony could survive with huge varroa populations. Now the virus load is way higher and it doesn't take much to tip the balance and kill the colony.


Exactly.

This paper by Martin et al explains how the arrival of varroa (in Hawaii) changes the viral landscape.
In the case of Deformed Wing Virus (DWV) there are several variants and when varroa arrives it leads to the dominance of the DWV strain which causes maximum damage to bees. The other strains of DWV are less harmful.


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## jim lyon

Posts #33 and 34 are really informative and make perfect sense to me. Grondeau is correct in that mite collapses really aren't as dramatic and easily recognizable as they were 20 years ago though clearly keeping mite numbers low are crucial to keeping your hives strong.


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## TWall

jonathan said:


> A bigger risk with corn is monoculture, lack of bee forage and subsequent poor nutrition.


Monoculture has the biggest impact on bee foraging/health. The problem is beekeepers are dependant on other people to provide forage for their bees. We cannot dictate to other people, at least in the US today, how they manage their land.

Tom


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## jonathan

TWall said:


> Monoculture has the biggest impact on bee foraging/health. The problem is beekeepers are dependant on other people to provide forage for their bees. We cannot dictate to other people, at least in the US today, how they manage their land.
> Tom


That's true, but best practice could involve providing some intercropping with forage plants useful to bees and other pollinators. Beekeepers and landowners need to work together to help bee populations.


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## TWall

jonathan said:


> That's true, but best practice could involve providing some intercropping with forage plants useful to bees and other pollinators. Beekeepers and landowners need to work together to help bee populations.


Jonathan,

It has been almost 18 years since I've been to Ireland. But, agriculture is very different in the US and has changed recently to be come even more monoculture in nature. The fence rows of the past are gone and it is not unusual to see field planted almost to the roadside. Intercropping and leaving forage for pollinators is a thing of the past in a large part of the US.

There are areas such as the northeast and others where farms and fields are smaller and there is more diversity in crops and fields.

The other problem is most landowners don't farm their land or live on their farmland. In some areas of the country cash rent for farmland is over $500/ac. The farmer renting the land wants to farm all the land. The landowner wants rent paid on all the land. The end result is reduced bee/pollinator forage.

Tom


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## gmcharlie

But yet every beek in the country is looking for that almond field or sunflower land for the bees......(okay not every one but you get my point) Really bad as a farmer to drive that combine around all the flowers to pick certian spots of corn so you can have bacon with your eggs...... but back to ima clorapids......


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## camero7

gmcharlie said:


> But yet every beek in the country is looking for that almond field or sunflower land for the bees......(okay not every one but you get my point) Really bad as a farmer to drive that combine around all the flowers to pick certian spots of corn so you can have bacon with your eggs...... but back to ima clorapids......


Based on some studies I'd steer clear of the sunflowers.


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## Kieck

Almond orchard or sunflower field, either is still a monoculture or close to it.


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## gmcharlie

camero7 said:


> Based on some studies I'd steer clear of the sunflowers.


Canola maybe... sunflowers are freaking great...... 3 solid weeks of pollen and nectar...... And yes i know there monocultures but good ones!


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## camero7

Might want to take a look at this study.

Detection of Pesticides in Active and Depopulated Beehives in Uruguay
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3210585/


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