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Hygenic test results on breeders

23K views 40 replies 22 participants last post by  John Davis 
#1 · (Edited)
#2 ·
These are just a few of the great results at the 24 hour mark. We arrived at a very hygienic bee by selecting for Varroa tolerance. Dr Royce from OSU came down and showed us how to to the freeze killed brood assay. There were some that did not get 100% in the test so I presume they must have other mechanisms for coping with mites. I have been leaning towards the ones that got 100% for the last few grafts but will continue to monitor the other breeders for mite loads and overall success.
 
#9 ·
What were the mite loads like? Does this indicate varroa mite tolerance or resistance? I can see how it would indicate hygenic behavior, but, does hygenic behavior directly lead to mite tolerance/resistance?

What other traits are you selecting for and how do you go about accessing the degree of those traits?
 
#16 ·
We are looking for hardy mite tolerant bees that are productive. We will be doing some sugar rolls soon to put some metrics on current mite loads. All breeders wintered well and easily made the grade for the almonds. We, of course, are looking for all of the usual economically valuable traits. I like a bee that can pay the bills.
Varroa sensitive hygiene is a well documented trait and does result in lower mite loads. Apparently you can end up with very hygienic bees by selecting from bees that cope with mites well. It is a challenge to keep the selection pressure on but well worth doing. We are taking some steps this year to try to get these traits more "true breeding" throughout the whole population. More isolated mating yards and instrumental insemination will definitely be helpful this year.
 
#11 ·
The OPer can answer from experience, but, you start off w/ a nice patch of capped brood and kill what you can see as an empty circle of brood by applying liquid nitrogen, which freezes the pupae dead. Exactly how this is done, someone else needs to explain. I think a tin can is used somehow, but I haven't done it.
 
#13 ·
@Tazcan
The capped larvae that WERE inside the circles were killed with liquid Nitrogen, as sqkcrk said...then the bees removed the killed larvae within 24 hrs. This is done to test the efficiency with which bees will theoretically remove varroa infested/killed larvae from the comb, thus reducing varroa levels in the hive. (or at least that's my understanding of it)

@irwin harlton
I believe the freeze-killed larvae are supposed to be homologous to mite-infested/killed larvae to the bees... i.e. it's not necessarily "varroa" that the hygiene is sensitive to, so much as "dead larvae" sensitive hygiene...so the same trait should be pretty efficient against EFB too (once again, in my opinion, and according to my understanding of the principles in practice).
 
#20 ·
What is interesting to me is that you said "We arrived at a very hygienic bee by selecting for Varroa tolerance". My understanding is that Marla Spivak and Gary Reuter started the other way, breeding for hygienic bees by using the frozen NO2 test because of the strong correllation of hygienic behavior with bees that remain free of AFB. Yet they make no claim that MH queens are varroa resistant. What percentage of your breeders were that hygienic - if you don't mind sharing.
So, in addition to your bees having hygienic capabilities I suspect they have other positive attributes that make them varroa resistant.
 
#23 · (Edited)
I have heard that also. I have also heard the developers of the VSH and SMR traits ended up with very hygienic bees in the end working from the other direction. Of the ones we have tested, about half were 90 to 100 percent and the other half was all over the place. We plan to monitor mite levels in all but have been grafting off the ones that got 100% lately. The others may still have valuable traits if they test well on the sugar roll later in the week.
 
#26 ·
Could be just as effective I guess, having no experience w/ either. All I know is liquid nitrogen is standard operating procedure, tried and true. So, no one sees the need to change. Try it and let us know how well it works. You may be on to an alternative method. Or it could have been tried and rejected for some reason or other.
 
#27 ·
I attended a queen rearing workshop with Dr. Larry Connor this May and asked him about using the canned coolant, like for freezing off warts. He said it would be really expensive, and not very effective. It wouldn't get the brood cold enough for long enough to kill it. He gave an example of how tolerant the brood is by telling about an alternative method to the LN2. If you use wax foundation, you can cut out a 3"x3" plug of brood and put it in the freezer for 24 hours, then place it back in the brood frame. Then you can do your 24 hour hygenic test. He said someone he knew took their brood out of the freezer after 24 hours and it was still alive! They must have soft ice cream! Anyway, the liquid nitrogen must be the gold standard for freezing and killing the brood. If your home freezer is really cold, you can try the plug method.
 
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