Since the authors of the "Harvard" study have declined to answer the
list of questions that I submitted to them, and since the Bulletin of
Insectology does not publish letters to the editor, I've decided to
put a slightly abbreviated, and annotized, list of my questions out
for discussion.

I aplologize that all formatting has been lost.  I plan to post a
formatted version to my website.

Randy Oliver

THE QUESTIONS
[I have also added a few comments italicized in brackets]
Readers will likely wish to have a copy of the study at hand.  It can
be freely downloaded at
http://www.bulletinofinsectology.org/pdfarticles/vol65-2012-099-106lu.pdf.
   Remember, these are the typical sort of questions that I would ask
as a peer reviewer when a manuscript is submitted for publication—the
referee is expected to go over the paper detail by detail, check the
math, make sure that previous research is cited, a challenge the
author’s interpretation of the data.

THE AUTHORS’ EXPERIENCE
Q: Could you perhaps briefly state for the benefit of my readers, your
experience as apiarists?

YOUR ASSUMPTIONS AND BACKGROUND RESEARCH
vanEngelsdorp (2009) reported that “Large-scale losses are not new to
the beekeeping industry; since 1869, there have been at least 18
discrete episodes of unusually high colony mortality documented
internationally. In some cases, the descriptions of colony losses were
similar to those described above.”
In my own beekeeping career, losses due to the initial tracheal mite
invasion often reached 70%, and for varroa, up to 90%.  Wilson (1979)
reported losses in the ‘70s to “Dwindling Disease” that were nearly as
extensive as those from CCD (and the reporting at the time was not
fueled by media coverage).  His maps of DD distribution were nearly
identical with those of the 2006/2007 CCD incidence.
Q:  Could you please provide supportive evidence to substantiate your
claim that:  “never in the history of the beekeeping industry has the
loss of honey bee hives occurred in such magnitude and over such a
widely distributed geographic area”

Figure not copied--map from the following paper.
Wilson, WT and DM Menapace (1979) Disappearing Disease of Honey Bees:
A Survey of the United States.  ABJ March 1979: 184-217.
You state: "First, since most of the suspected but creditable causes
for CCD were not new to apiculture, there must have been an additional
new stressor introduced to honey bee hives contemporaneous with the
first occurrence of CCD during the winter months of 2006 and early
2007."
Q: Could you please explain why do you not consider the recent
invasion of Nosema ceranae, the novel ubiquitous presence of DWV, nor
the apparent recent invasion of IAPV to be novel "stressors?
A very similar trial was performed by Faucon (2005), with
substantially different results.  As you are well aware, it is
standard practice in scientific papers to cite previous similar
research.  Yet you do not cite Faucon, nor any other studies in which
spiked syrup or pollen was fed to colonies in situ.  [It is a
scientific obligation for any author to cite previous research on the
subject when he publishes a paper].
Q:  Why did you not cite and discuss previous research, especially
that in which the findings conflicted with yours?

JUSTIFICATION OF THE IMIDACLOPRID IN HFCS HYPOTHESIS
The central tenet of your paper is your hypothesis that HFCS (high
fructose corn syrup) in 2006 was tainted with residues of
imidacloprid: “The widespread planting of genetically engineered corn
seeds treated with elevated levels of neonicotinoid insecticides, such
as imidacloprid since 2004 (Van Duyn, 2004), and their acute toxicity
to honey bees led us hypothesize a link between CCD and feeding of
HFCS containing neonicotinoid insecticides.”
In response, Bayer Crop Science claims that imidacloprid has never
been used on more than about ½ of 1% of corn plantings in the U.S.
Q: Do you have evidence to the contrary, or evidence to suggest that
the harvest of that 0.5% of corn seed would have been preferentially
used to produce HFCS?
You state: "it was the timing of the introduction of neonicotinoid
insecticides to the cornseed treatment program first occurring in
2004/2005 that coincides with CCD emergence"
Dr. Eric Mussen observes that several California beekeepers (including
myself) experienced CCD in our operations beginning as early as the
fall of 2004. This does not appear to fit with your introduction of
seed treatment timing.  Nor did Dr. Bromenshenk's CCD survey find any
correlation between CCD and the feeding of HFCS.
Q: Do you have supportive evidence that apiaries fed HFCS were more at
risk for CCD?
A major problem with your study, in the minds of many, is the lack of
support for your core hypothesis that imidacloprid contamination of
corn syrup indeed actually occurs.
Q:  Your hypothesis is that CCD was caused by residues of imidacloprid
in HFCS fed by beekeepers to their bees.  Since CCD still occurs
through the current time, it seems then that you should be able to
find it in 2012 syrup.  Yet in your own testing, there was no trace of
imidacloprid in your samples of HFCS.  Some reviewers feel that your
own testing disproved your hypothesis!
Q:  Could you please give an explanation for this inconsistency?
Q: Could you please explain your reasoning as to what had changed in
the process of HFCS manufacturing between 2007 and the time that you
purchased your HFCS (2010?) that would have caused pesticide residues
to disappear?
One would assume due diligence on your part to check to see whether
the commercial corn seed from which HFCS is manufactured actually
contained residues of imidacloprid.  As an “ad hoc panel member of the
US EPA Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)
Scientific Advisory Panel,” your lead author (Dr. Lu) would certainly
be aware that any residues of pesticides in corn grain would have been
published in the USDA’s readily available “Pesticide Data Program
Annual Summary, Calendar Year 2007”  [].
In Appendix F of that document (Distribution of Residues by Pesticide
in Corn Grain), one can easily find that in 2007 the USDA tested 655
samples of corn grain (from which HFCS is made) and found absolutely
no detections whatsoever of either imidacloprid or clothianidin!  Is
seems odd to base your entire study on a hypothesis which the main
author had every reason to know was unsupported by simple facts!
Q:  Could you please explain why you did not mention the absence of
residues in corn seed in USDA testing?
You state: "It should be noted here that the residue levels of
imidacloprid, or other neonicotinoid insecticides, have not been
routinely monitored in HFCS."  You call for us to note this as a fact.
Q:  Do you have documentation HFCS is not tested by the USDA or the
HFCS manufacturers?
A simple internet search [] reveals that the ARS Tucson Bee Lab tested
HFCS for both bee toxicity and contaminants in 2008.
Q:  Why do you not mention this, nor cite their results in your paper?
You state: “One apparent deficiency, in addition to the small number
of honey bee hives used in this study, is that we were not able to
obtain HFCS manufactured in 2005/2006 for use in this experiment.”
Q:  In light of the fact that the HFCS manufacturers are livid over
your accusation that their product was contaminated by a pesticide,
implying that they threatened the U.S. populace with pesticide
exposure in common food products, did you actually ask the
manufacturers to supply archived samples for testing?
Q: And if not, have you yet done so?
Perhaps the most controversial aspect of your study is the statement:
“Since there is no tolerance level for imidacloprid in HFCS, we
applied a 10-fold concentrating factor, or 0.5 ppm (500 μg/kg) of
imidacloprid in HFCS, by taking into account the uptake by corn plants
from seeds that are treated with imidacloprid.”
This is a pretty strong assumption, and implies that the EPA, the
USDA, the FDA, and the corn syrup manufacturers were all derelict in
their duty to protect the public from exposure to high levels of an
insecticide in a ubiquitously-used sweetener in the American diet!
Frankly, it appears that your 10-fold “concentrating factor” was
simply dreamed up!
Q: What supporting evidence do you have that would suggest that the
insecticide would be concentrated by a factor of 10 (as opposed to
being removed) in the manufacturing process of HFCS from corn kernels?

JUSTIFICATION OF THE CLAIM OF “FIELD RELEVANCE” OF DOSAGES
You state: “The range of dosages used in this study from 20 to 400
μg/kg were not only environmentally relevant to those reported
imidacloprid levels by studies that are cited previous…”
In a recent review, Cresswell (2011, whom you also oddly do not cite
in your references) suggests that “the field-realistic range of
imidacloprid concentrations is assumed to be 0.7–10 μg L-1.”
[forbenefit of the reader, μg/kg  is equivalent to ppb (parts per
billion); μg L-1 is similar, but by volume, rather than weight].
I commend you on your initial range of doses (0.1, 1, 5, and 10 ppb),
which do indeed reflect typical levels found in nectar, with 10 ppb
being at the far high end.
But after four weeks of feeding these field realistic doses, without
explanation in the paper, you switched to much higher concentrations
of the insecticide (20, 40, 200, and 400 ppb)—levels which would be
considered to be overtly toxic to honey bees!  This is a key question,
and a major criticism of the study.
Q: Could you please elaborate as to why you changed the dosages mid
study, and why you apparently changed your minds as to what
constituted “environmentally relevant” levels.
In an excellent recent review  on the ecotoxicity of neonicotinoid
insecticides to bees (which you also inexplicably failed to cite),
Decourtye and Devillers (2010) note that “acute exposure [100 ppb]
cannot probably occur in the realistic conditions since the
concentrations of imidacloprid and its metabolites, to which honey
bees are exposed always have been measured lower than 10 [ppb].”
Q:  Could you please explain how you arrived at the range of high
doses that you used, since they appear to be far above (up to 40 times
higher than) field-realistic doses?
Q:  Could you please specifically cite studies that have found 400 ppm
of imidacloprid in nectar to which bees would normally be exposed to
the extent that it could be associated with widespread CCD?
You state: “Considering that honey bees were diluting the
concentrations of imidacloprid fed to the hives with natural nectars
foraged during the HFCS feeding months (July to September)…”  Yet
earlier in the same paper you state that the colonies experienced a
nectar dirth [sic] during this period of time. These two statements
appear to be contradictory!
Q: Do you have any daily weight gain data to support your contention
that the treated syrup was indeed diluted by nectar during the feeding
period?
You state: “Therefore, we are confident that the imidacloprid dosages
applied in this study would be comparable, if not lower to those
encountered by honey bees inside and outside of their hives.”
I find it difficult to believe, by any stretch of the imagination,
that nine weekly feedings of  half gallons of 67% sugar solution (for
a total of 51 pounds per colony) spiked at 400 ppb (or even 20 ppb)
imidacloprid, during the nectar dearth, could be construed to mimic
any field-realistic exposure of colonies to the insecticide!
Q: Would you care to comment?

QUESTIONS ON PARASITE MONITORING AND MANAGEMENT
You state that: "Hives were monitored weekly, and managed using
standard beekeeping techniques."
As I’m sure you know, there are few observable signs for varroa
infestation, and there are no field signs of Nosema ceranae infection.
 Standard beekeeping management these days involves the monitoring of
varroa mite levels, typically by natural mite fall, either roll, or
alcohol wash [3].
 [Since all the colonies in the trial (test and control) started going
downhill (and since a quarter of the control colonies also died), it
is difficult not to ignore that something was seriously wrong with the
entire experimental design!
More to the point, the field investigators should have taken a few
nosema or varroa counts, rather than simply assuming that these common
parasites weren't killing the colonies!  For all we know, all the
hives could have been crawling with varroa or badly infected with
nosema.  One statement suggests that varroa was evident: "nor a large
number of Varroa mites was observed in hives during the summer and
fall seasons," which suggests to me that the investigators are
admitting that mites were indeed observed!
Let’s look at varroa:  the study states that 3-lb packages were
installed on March 28.  Surprisingly,  “By May 21st, 2010 all twenty
frames in each of 20 hives were drawn out into comb and contained at
least 14 frames of capped brood.”  These colonies really took off,
meaning that they were virtual varroa breeding factories.  By late
July they averaged about 25,000 cells of sealed brood.
Strange and Calderone (2009) found Eastern package bees to contain
about 3 mites per hundred bees, which would work out to about 300
mites in a 3-lb package.  When colonies are rapidly expanding, mite
populations double each month.  So from late March through late July,
we’d expect the mite populations in these hives to reach 4,800 by late
July.  This is a very serious mite infestation level!  Yet, the
researchers waited until October 5 to treat with Apistan strips (which
are ineffective against mites in many areas of the U.S.)!  Any
experienced beekeeper would suspect that these colonies died from a
varroa/Deformed Wing Virus epidemic, which leaves deadouts, as the
authors observed, “remarkably empty except for stores of food and some
pollen left on the frames.”  Unfortunately, the authors only included
a photo of a honey frame, rather than a brood frame, which might have
been helpful in diagnosing the actual cause of death!  Note also that
the dosing with high levels of an insecticide would be expected to
cause the treated colonies to suffer more from varroa than the
untreated controls.]
Q: Did you monitor mite levels during the trial?  If so, could you
please elaborate on your testing method and share the results?
Nosema is a common pathogen, currently infecting about 50% of
colonies, and can be deadly to colonies during winters such as yours.
Q:  Did you take any samples of bees from the colonies to monitor for
nosema levels?  If so, could you please share the results?
You state: “Since all hives were considered healthy as they went into
fall season, those pathogens posed very little threat to the health of
honey bee hives.”
Q: Could you please elaborate on how you determined that the colonies
(hives are the wooden boxes) “were considered healthy,” especially in
light of the “systematic loss of sealed brood” that you report in your
Discussion?
I am surprised that the investigators waited until October 5 to treat
for varroa.  This is a much later date than recommended by most
authorities (most successful beekeepers strive to treat by
mid-August), as viruses can go epidemic in colonies with high mite
levels in late summer, leading to midwinter collapse, as occurred in
your colonies.
Q: Could you please explain why you waited so late to treat for varroa?
Your choice of Apistan strips as a mite treatment is of interest,
since the mites in your colonies would be expected to be descended
from those present in the original package bees.  Mites in most
commercial operations exhibit high resistance to the active ingredient
of Apistan.
Q: Do you have any data on what the actual mite levels were in the
colonies in October, and whether the strips were actually effective at
reducing the mite infestations to below economic thresholds?

QUESTIONS ON UNPUBLISHED DATA ON COLONY STRENGTH
You mention that “notes were also made of the number of frames of
adult bees observed.”
Those data would be of great interest, and allow the reader to track
any treatment effects upon the colony size over time.  Unfortunately,
the results are not included in the paper.  All the treated colonies
survived for at least three months after treatments were completed.
I’m curious as to when adverse effects due to treatment became
apparent.
[In the study, poisoning the colonies all through late summer and
early fall likely hampered the ability of the colonies to prepare a
healthy population for winter.]
Q: Could you share your data on cluster size?  I’m especially
interested in how colony cluster size was affected during the initial
four weeks of treatment at true “field relevant” dosages of
imidacloprid.  Of note is that the initial field-relevant doses of
imidacloprid appeared to stimulate broodrearing in proportion to the
dose!
Q:  Do you have any comments about this surprising finding?

QUESTIONS ON STORED HONEY
In the trial, you fed a large amount of HFCS to the colonies
(approximately 71 lbs).  I’m very curious about the apparent delayed
effect due to the feeding of treated syrup.
Q: Did you test any of the stored honey in the dead colonies for the
presence of imidacloprid?
In late December, you began feeding supplemental sugar in patty form.
Q:  If the colonies contained adequate stores, why was this necessary?
Q:  Do you have data on how much supplemental sugar was consumed by
the various colonies during winter, and did this correlate with either
treatment or mortality?

COULD THE HFCS THAT YOU USED HAVE BEEN THE CAUSE OF MORTALITY?
You state: “the systematic loss of sealed brood in the
imidacloprid-treated and control hives may indicate a common stress
factor that was present across all 4 apiaries.”
I heartily agree, especially since one would expect nutritional and
pathogen factors to vary from apiary to apiary!
I feel that it may be premature to reach the conclusion that
imidacloprid-induced CCD occurred until you determine the cause of the
reduced brood rearing, which you observed was “vastly different from
that normally seen in honey bee hives” in your area.  Perhaps the
reason was that the HFCS that you fed in the trial was a poor bee
food, independent of any pesticide residue.
In your trial, you fed an extraordinary amount of HFCS to the colonies
(13 feedings of ½ gal at 11 lbs per gallon = 71.5 lbs of HFCS).  Few
beekeepers that I know of have ever fed this amount of HFCS to
colonies.
You cite a study by Dr. LeBlanc from the Tucson ARS lab, who found
that storage of HFCS in warm conditions, especially in metal
containers, could result in toxic levels of HMF formation.
Q  Could you please tell us how you stored your HFCS and whether you
tested to confirm that HMF was not present in toxic levels in your
syrup toward the end of the trial?
 LeBlanc and his coworkers also determined that there were no
imidacloprid residues in any of the several brands of HFCS that they
tested! Of note though is that they found that some brands of HFCS
caused increased mortality in caged bees.  You state that you used
“food-grade HFCS.”
Q: Was it a brand that is normally fed to colonies by beekeepers in
your area as winter feed, and do you have previous experience with
feeding this brand to your colonies?   Could you please tell us which
brand you used, as this is of great interest to beekeepers?
Q:  Did you perform any cage trials to see whether that brand of HFCS
exhibited toxicity to bees?
Q: I’m curious as to why you did not feed sucrose syrup as a control
group, to see whether the HFCS that you used caused colony morbidity
for reasons other than your hypothesized insecticide contamination.
Comments?
You state: “the delayed mortality in honey bees observed in late
winter months remains puzzling.”  I agree that this is the key issue
in your study.  The question is, was it due to the dosing with
extremely high levels of the insecticide, the prolonged feeding of
HFCS, or to nosema or varroa buildup in the colonies.  Without
eliminating the other plausible causes, I feel that it is premature to
place the blame for the observed colony mortality solely upon the
insecticide.

QUESTIONS ON DWINDLING OF BOTH TEST AND CONTROL COLONIES
Regarding Figure 1 (brood area tracking), you mention that there were
no significant differences in broodrearing due to treatment.  I find
this point noteworthy, as well as surprising, given the high dosages
of imidacloprid given!
Q: Any comments?
You state: “It should be noted that the steady decreasing trend of
sealed brood during the summer months as observed in this study is
vastly different from that normally seen in honey bee hives residing
in the central Massachusetts area.”
It appears that all the colonies, including the controls, were
suffering from some sort of morbidity.  The most likely suspects would
be the poor nutrition of the HFCS (independent of the added
insecticide), nosema, or the varroa/virus complex.
Although you were monitoring brood areas weekly, and clearly noted
that something was apparently wrong in all colonies, you waited until
October 5 to begin any standard parasite treatments.
Q: Could you please explain why?
Figure 2 (the chart of colony survival) is striking, and clearly shows
that colonies fed very high dosages a pesticide died sooner than those
not fed pesticide.  I do not find the results surprising.  What would
be of interest is the starting cluster sizes of the colonies going
into winter cluster.  Smaller colonies are well known to exhibit
poorer winter survival than strong colonies.
Q:  Did the treated colonies enter the winter with smaller cluster
sizes, and could this be the reason for their early mortality?

DID YOU ACTUALLY OBSERVE CCD, OR MERE DWINDLING
You state: “The magnitude and the pattern of honey bee hive loss
during the winter months in this study resemble the reported symptoms
of CCD.”
Frankly, this is where the CCD researchers that I’ve spoken with have
questions.  They do not find the “symptoms” that you reported to be
consistent with the markers for CCD!
Q: Did any of the members of your team have any actual previous
experience with observing CCD in the field?
The CCD Working Group deliberately named CCD colony collapse to
distinguish it from colony dwindle.  vanEngelsdorp (2009) suggests an
operational case definition of CCD “characterized post hoc by a common
set of specific symptoms: (1) the rapid loss of adult worker bees from
affected colonies as evidenced by weak or dead colonies with excess
brood populations relative to adult bee populations; (2) a noticeable
lack of dead worker bees both within and surrounding the affected
hives…”
To the contrary, you describe the dwindling of the treated colonies in
your study as: “the strength of hives treated with the highest
imidacloprid dose appeared to be weakening as observed by smaller
clusters and frozen dead honey bees scattering (on snow) in front of
the hives.”  You also show in Figure 3 a lack of sealed brood in a
dead treated hive.
Since the “symptoms” that you report do not appear to match those that
distinguish CCD, I cannot fathom how you can conclude: “Data from this
in situ study provide convincing evidence that exposure to sub-lethal
levels of imidacloprid causes honey bees to exhibit symptoms
consistent to CCD months after imidacloprid exposure.”
Q: Could you please explain how you can state that the signs that you
observed were “consistent” with those of CCD, rather than being
typical signs of dwindling due to parasites or poor quality feed?
You state: “Snow usually fell between weekly hive examinations making
the observation of scattered dead honey bees in front of individual
hives noticeable. Although this observation is not quite reminiscent
of the reported CCD symptoms…”
“Not quite reminiscent” is certainly an understatement—either you
observed the signs of CCD or you didn’t!  In my personal beekeeping
experience in a cold winter area, scattered dead bees on snow in front
of hives during winter are normal, due to aging bees flying out to
die, and is indeed not at all “reminiscent” of CCD symptoms.
Q: Why do you bring up this observation—is it not normal in your area
to see dead bees in the snow following flight days during winter?
It appears that you consider the lack of dead bees in the hive to be
unusual.  When I check the weather history for Worcester for the
winter of 2010, it appears that there were an adequate number of days
warm enough for bee flight through early December to allow virus- or
nosema-infected bees to fly off to die.
So I’m not clear as to whether the dwindling of clusters reflected the
normal self removal of sick, aged, or infected bees, or was due to
unusual flight behavior in cold weather due to imidacloprid exposure
(which your discussion hints at).
Q: Do you have any observations that could help clarify when the bees flew off?

YOUR DEFINITION OF “SUB-LETHAL”
You state: “Data from this in situ study provide convincing evidence
that exposure to sub-lethal levels of imidacloprid in HFCS causes
honey bees to exhibit symptoms consistent to CCD”
I think that everyone would be in agreement that the doses used during
the first 4 weeks of feeding would be considered to be “sub-lethal.”
You did not report any adverse effects from those dosages, as
expected.
But then, without explanation, your team ramped up the doses
considerably.  Yet you still claimed that they were “sub-lethal.”  I
must question whether the dosages that you used in 9 weeks of
late-summer feeding would be considered to be “sub-lethal.”
Givens:
Your team added to the syrup for each weekly feeding doses of
imidacloprid ranging from 51.9 μg to1038 μg.
You report that each colony covered about 20 frames.  There are
typically about 1750 bees per covered frame, so that would suggest
colony populations in the range of 35,000 bees.
You do not report how quickly the colonies emptied their feeders, but
in my practical beekeeping experience, a half gallon of syrup is
typically consumed in less than 24 hours, so unless you tell us
otherwise, we can assume that the administration can be treated as
24-hr dosings.
Cresswell (2011) in his meta analysis of imidacloprid toxicity trials,
found that observable toxic effects began to occur at doses exceeding
about 2 ng per bee.  Bayer scientist Maus (2003) states that acute
oral LD50 of imidacloprid to honey bees is as low as 40 ng/bee.
Let’s convert your four dosing regimines to ng/bee:
51.9 μg/colony =     	     51,900 ng/colony = 1.5 ng/bee
103.8 μg/colony = 	   103,800 ng/colony = 3 ng/bee
519 μg/colony = 	   519,000 ng/colony = 15 ng/bee
1038 μg/colony = 	1,038,000 ng/colony = 30 ng/bee
So by my arithmetic (based upon previously published research), even
your lowest rate of dosage gave a marginally toxic dose of
imidacloprid to each and every bee in the hive, and your highest dose
approached the LD50  for all the bees in the hive!
This is a key question.  It appears to me that the high doses of
imidacloprid that you used hardly be considered to be “sub-lethal.”
Could you please explain how your team can consider such
concentrations to be “sub-lethal”?

YOUR HYPOTHESIS AND CONCLUSIONS
Quite a number of trials worldwide have been performed to apply Koch’s
third postulate in an attempt to create disease in healthy bee
colonies by the feeding of field-relevant doses of neonicotinoid
insecticides.  To date, that goal has eluded all other research teams
other than yours!
 For example, in a similar but more thorough study (Faucon 2005) the
conclusion was that “In any case, during the whole study, mortality
was very low in all groups, with no difference between
imidacloprid-fed and control colonies.”
Q: Could you please elaborate as to why you feel that your results
were different than all other trials to date? [this is normally done
in the Discussion section of a scientific paper].
You suggest that: “The survival of the control hives managed alongside
with the pesticide-treated hives unequivocally augments this
conclusion.”
“Unequivocally” is a pretty strong statement!  In actuality, your
Figures 1, 2, and 4 suggest that the control hives were suffering from
serious morbidity, and on the same path to mortality as the treated
hives, only to be rescued by the infusion of pollen in spring!  Note
that the control group suffered 25% mortality (which hardly
constitutes “survival”), which raises serious questions about any
conclusions to be drawn.
Q: Could you please provide your cluster size observations to help the
reader to determine the degree of morbidity in the control colonies
relative to that of the treated colonies?
Q: Did you inspect the brood combs of the deadouts for guanine
deposits, which would indicate that varroa was present at high levels
as the colonies dwindled?
Q: Did you sample any of the dead bees in the snow for nosema?
Since all colonies in your trial suffered from unusual morbidity, the
question is raised whether such morbidity was due to the unnatural
feeding of the particular brand of HFCS that you fed to the colonies.
You state: “It is likely that CCD was caused by feeding honey bees
with low levels of imidacloprid in HFCS throughout their lifecycle in
which toxicity occurred during the larval/pupal stages and was later
manifested in the adult honey bees.”
I find a paucity of published data on the toxicity of imidacloprid to
bee larvae, or whether residues in syrup even make it into the larval
food.  [The neonicotinoids are apparently virtually nontoxic to larvae
(Lodesani 2009); Piotr Medrzycki, pers comm]
Q:  Could you please cite research to support your claim that “it is
likely” that “toxicity occurred during the larval/pupal stages”?
Q: Similarly, could you please cite research to support your claim
that “it is likely” that any such toxicity would be “later manifested
in adult honey bees”?
SciTech Daily’s article [4] on the paper says, “Strikingly, said Lu,
it took only low levels of imidacloprid to cause hive collapse — less
than what is typically used in crops or in areas where bees forage.”
In actuality, it appears to me that the initial, field-realistic,
levels of imidacloprid that you feed the first four weeks did not
cause observable adverse effects.
Q: How can you state that “it took only low levels of imidacloprid to
cause hive collapse” when in your own paper you refer to it as “high
imidacloprid dosing”?
Then even after feeding clearly lethal levels of the insecticide for
an additional nine consecutive weeks, you still did not observe colony
mortality!
It was only three full months after you ceased feeding the insecticide
that you observed the first mortality, following a period in which the
“systematic loss of sealed brood [in all] hives may indicate a common
stress factor that was present across all 4 apiaries.”
[The authors state: “Considering the sensitivity of honey bees to
imidacloprid as demonstrated in this study.”  Actually, no such
“sensitivity” was demonstrated at all!  Even the lowest fed dosage (20
ppb) is about 5-20 times higher than that commonly found in nectar,
and the other three doses were far higher--it is amazing to me that
the colonies were not killed outright!  Yet no treated colony
apparently showed any ill effects even after 13 weeks of continuous
feeding with insecticide-spiked syrup!]

AN ALTERNATIVE EXPLANATION FOR THE RESULTS
Your proffered hypothesis is that: “Data from this in situ study
provide convincing evidence that exposure to sub-lethal levels of
imidacloprid in HFCS causes honey bees to exhibit symptoms consistent
to CCD 23 weeks post imidacloprid dosing.”
To many, your evidence is actually less than convincing.
I suggest an alternate hypothesis that all the colonies were on a
downhill track by late summer, and dwindled due to either HFCS
toxicity or parasite loads, and that the feeding of unrealistically
high doses of an insecticide merely accelerated the decline of the
treated colonies.
Q: Do you have any evidence that would help to falsify this
alternative hypothesis?
Feel free to make any additional comments at this point.  Thank you in
advance for taking the time to answer these questions for the benefit
of the beekeeping community!

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html

Guidelines for posting to BEE-L can be found at:
http://honeybeeworld.com/bee-l/guidelines.htm