Recently, I wrote to Dr. Harbo, posing the questions that have arisen here,
and also mentioning that I would like to be able to quote his reply.  Here
are his comments, followed by my note to him.  I appreciate his taking time
to respond, and hope this helps clarify a question that likely will not be
answered definitively in the near future, but which provides fertile ground
for further work.

allen

--- Dr. Harbo's reply ---

Dear Allen,

Bees with the SMR trait will remove cells of worker pupae (starting
about when the eyes begin to turn pink and usually completed by the
purple-eyed stage), but they do not remove the cells that have
nonreproducing mites.We were fooled into thinking that all the mites
had become nonreproductive because we only found nonreproducing mites.

Marla Spivak noticed that the SMR bees were hygienic, and it seems that
the entire mechanism of resistance of SMR bees is the disruption of
reproductive mites via the removal of bee pupae by adult bees. Equally
important is the fact that they do not disturb mites that produce no
eggs.  Bees with the SMR trait did remove freeze-killed brood very
rapidly, but so also did many of the bees that did not express the SMR
trait.

At this time, my opinion is that the SMR trait and hygienic behavior
are not identical, but they certainly have some commonality. I say this
for three reasons: (1) people were not able to produce bees with high
levels of varroa resistance by selecting only for the removal of
freeze-killed brood, (2) I could not find a correlation between the SMR
trait and the rate of removal of freeze-killed brood, and (3)
Rothenbuhler's hygienic behavior was recessive. The SMR trait seems to
be additive.

I do not know who first coined the term "hygienic behavior" in bees,
but I think that Rothenbuhler used this term to describe the behavior of
adult bees that removed larvae that were infected with American
foulbrood. Hygienic behavior was further separated by Rothenbuhler into
a factor for uncapping the cells and a factor for removing the larvae.

We are still interested in P-MIB (percent mites in brood). However,
when we did single-drone inseminations to isolate this trait, it did not
jump out at us as the SMR trait did. Also, we had the SMR trait in some
of the bees as we were selecting for P-MIB because when we started this
work, we did not see how the two traits could be related. Now, as we
know more about the SMR trait, the disruption of mites could shift the
proportion of mites from brood onto adult bees. Therefore, we are in the
process of selecting the P-MIB trait from bees that do have the SMR
trait. At this point we do not know if the two traits are independent.


Best regards,

John


John Harbo
Honey Bee Breeding Laboratory
1157 Ben Hur Rd.
Baton Rouge, LA  70820   USA
TEL 225 767-9288
FAX 225 766-9212

--- my question to Dr. Harbo ---

 Hi John,

We're having a discussion, and some are claiming that SMR=HYG.

I understand that there is a commonality, however, last I heard there
is not an exactly identity.  My understanding is that the two sets overlap,
but are not coincident, unless the term HYG has been expanded, if it was
ever clearly defined. (Who decides these things?)

Although it has been known now for some time that the manner in which
'SMR' bees manage varroa is a form of hygienic behaviour, and not a chemical
effect as expected, the last time I heard you speak your opinion was
that the traits exhibited in the SMR tests are not identical to the traits
previously demonstrated by Marla's bees -- or Steve Tabor's -- but went
beyond them in some important respects, (and perhaps fell short in
other regards?).

Maybe you can correct me, but my understanding is that 'HYG' has been a
term that is used to specifically describe the set of characteristics that
Marlas's bees exhibit -- relating to discovery and elimination of dead
pupae -- and that those bees have demonstrated only a very limited
ability to manage varroa on live pupae.

On the other hand, the bees you developed are adept at discovering
reproducing mites on live pupae in capped cells and removing them -- in
addition to having the HYG characteristics.  (I'm not sure if they have
full HYG properties.  If so, then your stock should perhaps be called HYG+)

Has the definition of HYG been extended to include this characteristic,
or are the SMR bees (or whatever they are now called) now included in HYG.
 If so, then are the bees that do not have this trait still called HYG?

The SMR bees you released have been incorporated into some commercial
lines, and last I heard, were still offered by some breeders.   Are they
still
available, and is there a name change in the works?

FWIW, 'SMR' still works for me, since they still suppress mite
reproduction, by interrupting it using brute force!  What could be more
disruptive to
varroa and less prone to evasion?

One other thing.  Several years ago, Tom was listing P-MIB at the top
of the heritability list and a top candidate for further work.  Have recent
discoveries changed this?

Hope you can clarify this for us, and I'd like to be able to quote your
reply.

Thanks in advance, and best regards,

allen dick

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