Varroa question

9753 Views 53 Replies 13 Participants Last post by Michael Palmer, Feb 9, 2010

jmgi

Discussion Starter · Feb 5, 2010

Just getting back in to bees again since pre-varroa days, so I have much catching up to do. With the varroa mite, I guess it is said that they prefer drone cells to worker for reproducing, because of the extra few days of developement time for the drone, the foundress mite's offspring has more of a chance to mature. Now a couple questions, how does the mite know the difference between a drone and worker cell? Or does it use some other way to identify it that we don't understand yet? Surely the mite couldn't know that the drone takes longer to develop, right? However, the mite will use worker cells, either by choice or desperation, which is it? Or does it even matter which cell it uses? If you study the mite life cycle in terms of days to maturity from egg, seems to me there is plenty of time for the offspring of the foundress mite to mate and mature inside the worker cell, so why do they say it prefers drones? Have any of these questions that I have posed been answered by experts, because I can't find the answers. Thanks

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sqkcrk

· #2 · Feb 5, 2010

Did anyone ask the foundress Varroa mite if she PREFERS drone cells to worker cells?

Perhaps it is just the longer capped period of drone brood which allows production of more varroa from the drone cells compared to the worker cells, which some have interpereted to indicate preference. That's the way I see it.

I don't see necassarily a preference. Otherwise we would see cases where an over whelming number of mites come from drone cells and almost none from worker cells. I don't know if that is ever, or has been, observed. Perhaps someone else knows.

Dave W

· #3 · Feb 6, 2010

Mites are ATTRACTED to drone cells by ODOR.

The RESULT is more mites mature in drone cells vs worker (due to longer development time for drones).

Michael Bush

· #4 · Feb 6, 2010

>how does the mite know the difference between a drone and worker cell?

There is evidence to support both cell size and odor. When drone larvae are placed in worker cells they are less likely to invade them than drone larvae in drone cells, but more likely than worker larvae in worker cells. With worker larvae in drone cells they are more likely to invade them than worker larvae in worker cells, but less likely than drone larvae in drone cells.

> Or does it use some other way to identify it that we don't understand yet? Surely the mite couldn't know that the drone takes longer to develop, right?

Of course they don't logical think it would work better, but their instincts are to do exactly what works out to better reproduction.

> However, the mite will use worker cells, either by choice or desperation, which is it?

Probably a combination of desperation and confusion. A typical large cell is closer to the size of a drone than a natural worker cell.

> Or does it even matter which cell it uses? If you study the mite life cycle in terms of days to maturity from egg, seems to me there is plenty of time for the offspring of the foundress mite to mate and mature inside the worker cell, so why do they say it prefers drones?

Because they do "prefer" them. They are more likely to invade them.

>Have any of these questions that I have posed been answered by experts, because I can't find the answers.

Yes. Much research has been done on the subject.

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jmgi

Discussion Starter · #5 · Feb 6, 2010

Michael, Do you foresee the day (say within 10 years) when we will be 99% mite free in the U.S. based on where we are today with a combination of mite research, bee breeding, and the growing number of beekeepers going natural and/or organic? John

peterloringborst

· #6 · Feb 6, 2010

jmgi said:
Have any of these questions that I have posed been answered by experts, because I can't find the answers.

Much of the work done on varroa infestation was done so long ago, a lot of folks are not familiar with it. It appeared that varroa preferentially infested drone brood and that was the basis for many control measures. However, like everything, things are not always what they appear to be. Recent work seems to indicate that the lower number of mites in worker cells may be caused by the bees removing mite infested larvae from worker cells *more diligently* than from drones.

> VSH bees inspected brood cells containing mite-infested pupae of both types of brood, but they removed signiÞcantly fewer mite-infested drone pupae than mite-infested worker pupae after 1 wk. This result suggests that mite populations in VSH colonies could increase more rapidly when drone brood is available.

(2008) Effect of Brood Type on Varroa-Sensitive Hygiene by Worker Honey Bees (Hymenoptera: Apidae) JEFFREY W. HARRIS
Honey Bee Breeding, Genetics and Physiology Laboratory, USDA ÐARS

Barry

· #7 · Feb 6, 2010

peterloringborst said:
Recent work seems to indicate that the lower number of mites in worker cells may be caused by the bees removing mite infested larvae from worker cells *more diligently* than from drones.

Recent to some, but this action of removing larvae and/or simply removing the caps to get to mites was observed by Lusbys years ago and by those of us who started using SC back in 2001. Here is one such photo of my comb from '01.

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peterloringborst

· #8 · Feb 6, 2010

Right, but I was referring to the observation that bees remove larvae from mite infested worker cells much more often than they do from drone cells as a possible reason why mites reproduce more often in drone cells than they do in workers.

Now whether the mites "know" they will be left alone more often in drone cells is an interesting question. Maybe they just end up there after being chased off the worker brood.

jmgi

Discussion Starter · #9 · Feb 7, 2010

Peter, please correct my understanding of what you said if I'm wrong, but are you saying that back in the earlier days when mites first showed up in significant numbers in colonies, the worker bees may have been more hygenic than we gave them credit for? Because my understanding is that drone brood preference was said to be the case right from the start. I have been doing much reading on this subject lately, and I never came across research that showed that workers from feral or hived common European honeybees removed mite infested worker brood, let alone removing it better than drone infested brood. I am aware that the more recently developed VSH bees engage in that activity to some extent, but never heard of non-VSH European bees doing it.

peterloringborst

· #10 · Feb 7, 2010

jmgi said:
Peter, please correct my understanding of what you said if I'm wrong, but are you saying that back in the earlier days when mites first showed up in significant numbers in colonies, the worker bees may have been more hygenic than we gave them credit for?

Well, i was quoting work by others, but yes, that is exactly what I was intending to say. This should not surprise us, however, as bees normally are pretty good at getting rid of pests in the hive, and they value queens, workers, and drones in that order.

However, there is good evidence that insects may be capable of learning new behaviors and associations, so it is possible that honey bees can develop new ways of controlling pests over time that have nothing to do with inheritance.

jmgi

Discussion Starter · #11 · Feb 7, 2010

No, it does not surprise me at all, actually what surprises me is the fact that mites ever became an issue with honeybees in the first place. I've kept bees long enought to know that they are, like you say, very hygenic naturally. I have observed them on many occasions, as I'm sure you have too, how they are attracted to investigate any particle, tiny bug, or anything that does not belong at the entrance to the hive or even inside the hive. If the foreign body is a living thing, such as a tiny ant or fly, they proceed to chase it, attack it and/or remove it.

jmgi

Discussion Starter · #12 · Feb 7, 2010 (Edited)

As to your statement about bees learning or developing a way to handle a new pest, as in the mite, I totally agree that it can and will happen, but there is something hindering or slowing the process currently, that is the use of acaracides, and other substances introduced into the hive to eradicate the mite that are not natural and healthy. If we want to speed up the process of bees learning to deal with them, we have to basically leave them alone, a tactic not supported by many beekeepers, especially large commercial guys, and I can understand why. I do however think that we have possibly created multiple problems over the last 130 years or so by artificially enlarging the cell size from what naturally occurs. It is anyone's guess how many separate negative problems have popped up in the hive over time regarding just this one mistake.

peterloringborst

· #13 · Feb 7, 2010

jmgi said:
I do however think that we have possibly created multiple problems over the last 130 years or so by artificially enlarging the cell size from what naturally occurs.

I doubt that. View thread "Natural Cell Beekeeping"

jmgi

Discussion Starter · #14 · Feb 7, 2010

I'll do that and then get back with you.

Barry

· #15 · Feb 7, 2010

An interesting observation, I never saw bees uncapping pupae, chewing down pupae, until I had bees on smaller cells. Coincidental? I don't think so. Dennis Murrell also observed the same thing and he worked commercial for many years.

peterloringborst

· #16 · Feb 7, 2010 (Edited)

Dear Barry
I have numerous photos of this behavior but I don't have any photos of any small cell hives. See above

Barry

· #17 · Feb 7, 2010

http://beesource.com/forums/showthread.php?t=208226
http://beesource.com/forums/showthread.php?t=227902

peterloringborst

· #18 · Feb 7, 2010 (Edited)

4

Pictures of uncapped and chewed pupae

Bee trying to remove varroa

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jmgi

Discussion Starter · #19 · Feb 7, 2010

Well, I can see that I have entered into a discussion topic that has been going on for 25-30 yrs. with no total agreement or solutions. Plenty of experienced beekeepers on this site have told me that they have healthy productive bees with a minimal amount of mites that have survived many years without any treatments whatsoever. A common denominator among these beekeeper's hives is that they generally use screeened bottoms, natural or small cell, and survivor queens adapted to their region. My bottom line opinion based on my limited knowledge of this subject is that the solution to getting our bees healthy again is to let the bees do what their instincts tell them to do naturally, we must stop forcing our will on them to accomplish out goals, thinking that we can bend and shape them without any repercussions. Giving the bees a crutch to lean on may make us feel like we are helping things work out for our best interests and theirs, but I disagree.

peterloringborst

· #20 · Feb 7, 2010

jmgi said:
Plenty of experienced beekeepers on this site have told me that they have healthy productive bees with a minimal amount of mites that have survived many years without any treatments whatsoever. A common denominator among these beekeeper's hives is that they generally use screeened bottoms, natural or small cell, and survivor queens adapted to their region.

My friend Mike Johnston has varroa resistant bees without small cells, nor screened bottoms. It's all about the bees.

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