Beemaster's International Beekeeping Forum

BEEKEEPING LEARNING CENTER => DISEASE & PEST CONTROL => Topic started by: Robo on July 24, 2008, 10:40:35 am

Title: Are you increasing varroa population with your screened bottom board?
Post by: Robo on July 24, 2008, 10:40:35 am
I know many here believe that the screened bottom board (SBB) helps reduced varroa population because the mites fall through the SBB and can not climb back up or grab onto a passing bee.  This does seem logical, and most people without a scientific degree can visualize this process and easily buy into it. But there are studies that show the benefit of the SBB can be outweighed by the temperature drop if the SBB is left open for ventilation, both in the brood nest where the mites breed,  and in the rate of falling off bees.  So if you're using open SBB, inserting empty frames in the brood nest, using top entrance, or any other method that reduces the hive temperature, are you are helping the population of varroa grow?

I have attached two PDF files showing results of the studies if you want to read them in their entirety.

Quote from: Tucson AHB/Mites Conference RIFA Control
Temperature seems to have more of an impact on Varroa reproduction than most people thought. While 95ºF is "brood nest temperature," that temperature
fluctuates some with climatic conditions. By carefully controlling temperature, Varroa were found to reproduce best at 93ºF. Performance was a bit worse at 88-91 and 95º. At the lower than brood nest temperatures, the post-capping period is extended about one day per 2ºF. At higher temperatures the post-capping period is not shortened significantly. However, at "brood nest" and higher temperatures, mite reproduction drops way off. In the same study it was shown that 53% of the mites on brood held at 59-68% RH (normal) reproduced normally but at humilities of 79-85% only 2% of the mites reproduced. Hot, humid brood nests are tough on Varroa. Studies of Apis cerana brood nests showed drone brood is reared at 92ºF (perfect for Varroa) and worker brood is incubated at 96-98ºF (too hot for Varroa). Purposely cooling the brood nest in Apis mellifera colonies by using a "thin" hive lid, open bottom board, simulative feeding to spread brood out, and splitting the brood nest with frames of foundation doubled the numbers of mites on the bees.



Quote from: Experimentation of an Anti-Varroa Screened Bottom Board in the Context of Developing an Integrated Pest Management Strategy for Varroa Infested Honeybees in the Province of Quebec

The antivarroa bottom board must never be used with its bottom hole opened as this leads to a lowering of cluster temperature resulting in ideal conditions for varroa development. As confirmed in 2000, this situation not only negated the beneficial effects of the bottom board, it also resulted in a net increase in the mite infestation rate (29.2% more varroa mites, non significant) as compared to the control group.



Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: BeeHopper on July 24, 2008, 12:44:47 pm
I'll get back to you  :)
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Vetch on July 24, 2008, 01:13:29 pm
Thanks - good to think about, keep an open mind to different techniques. In the end, I'm for the ones that work.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Cindi on July 24, 2008, 03:07:16 pm
Rob, OK, wow.  I mentioned in another post I switched all my screened bottomboards back to solid bottomboards.  Now I am further glad that I did that.  My reasons for switching back were for ease of vapourizing oxalic acid though.  I don't doubt for a minute that research that you put into your post.  Cluster heat is extremely important. 

I had very low mite counts this spring, probably because I have reverted back to the solid bottomboards and vapourizing last fall.  I had performed one treatment of vapourizing, when there was no brood present, so as to get all the mites.  Vapourizing can be performed when brood is present, it does not kill brood, as the oxalic acid trickling will.  My preference was to vapourize when brood rearing had ceased. 

My curious side though.  Why did you make another post, quoting your original post?  Nosey old me.  Have the most beautiful day, loving and living this great life.  Cindi
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: acbs on July 24, 2008, 03:43:29 pm
Robo,
Thanks for posting this.  I think you've saved the lives of a couple of queens.
We have Russians, do not use medication, and up to this point are not having problems with mites.  Some are Russians from a breeder queen, and some are the result of the Russians we purchased in the past and open breeding between established hives and ferals.  Was a big believer in SBB's and had been using them faithfully up until the middle of last year as the number of hives grew and I didn't keep up with converting the used solid bottoms over to SBB's when setting up a new hive.  We now have 48 hives including full hives and a few splits.  Less than half of our hives now have SBB's and have not noticed any difference in mite problems between the two.  I have noticed a couple of mites in our 2 TBH hives and yes, they have screened bottoms.  Not enough of a problem to worry about, just a mite or 2 here and there, more than I've noticed in our regular hives.  Might possibly be mistaken, but I would assume a TBH with open bottoms would be cooler than a 2 deep hive with supers.  Both queens are new this year, daughters of the original TBH colony queen we overwintered and not quite as dark in color as most of our Russians.  I was ready to kill these queens and blame it on bad genetics, but this report gives us cause to wonder if they might do better in a standard hive.  Was planning on using a couple of our breeder offspring to replace them.  Might continue with that plan now, but not kill the other queens, move them into another hive just to see what happens, and see how the breeder offspring do in the TBH's.  Or I could just close up the TBH bottoms. :-\
Have a well established real strong feral hive we cut out of an old building this spring that was healthy and is still in the same condition on solid bottoms.  I realized none of this is proof of anything, but sure gives one reason to wonder.
Thanks again for posting this.
Arvin
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Michael Bush on July 24, 2008, 09:13:33 pm
In my experience, I see no difference in mite levels with or without the SBB.  There is research to support both views (more or less mites).  But I think any difference is at best, negligible.  However with the SBB I can get them to stop bearding without having to buy slatted racks and I can use a tray under it to monitor and if you're using ANY Varroa treatment you will get rid of more.  Research I've seen presented by Dr. Tom Webster has shown that the Apistan resistant mites are knocked down by the Apistan, but with a solid bottom board, they climb back up into the hive again.  With a SBB they do not.  The same is probably true of any kind of treatment.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: KONASDAD on July 25, 2008, 03:38:50 pm
Anecdotaly, my hives have experienced huge mite explosion the past 3 weeks. It has been the hottest, most humid July I can recall. Many, many days above 95F w/ heat indices above 100F. Some of my hives have SBB, some not, some slatted racks and some w/ vented tops-some have all 3. All of my hives are infested right now. If brood temps were as greatly impacted as written, my hives w/ traditional equipment should have less mites given the extreme weather we have been experiencing. I might just do a count this weekend and see.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: SgtMaj on July 26, 2008, 04:02:06 am
Wouldn't keeping the mite board in all the time give, in the now all too immortal words of Miley Cyrus: the best of both worlds?
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Robo on July 26, 2008, 09:19:29 am
Yes, if you keep on top of it and clean it out.  As we have discussed in other threads :roll:,  it makes a great environment for wax moths with pollen and other debris collecting there and is protected from the bees.   You can also find ants and other bugs accessing it too.   It is not practical for large operations,  but if you have a few hives and can take the time to clean them every week or so it does have it's benefits.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: SgtMaj on July 26, 2008, 10:40:27 am
Yup, although coating it with a mix of veggie oil and that wax moth chemical Annette got... you might be able to get away with not cleaning it out quite as often... though, since it's so easy to clean, one might as well do so at every inspection anyway (especially since it's also a great way to monitor problems like varroa, shb, and moths... I would think anyone would be curious enough to at least pull it out and look with every visit to the hive).

Speaking of those moths though, has anyone lined their SBB mite boards with parchment paper?  If so, do you ever find any of the wax moths boring through it?  Or does the thin bit of silicone coating on the parchment paper stop them from boring?
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: suprstakr on July 26, 2008, 09:11:42 pm
[quote author=Robo link=topic=16851.msg123059#msg123059 date=121690683   
I know many here believe that the screened bottom board (SBB) helps reduced varroa population because the mites fall through the SBB and can not climb back up or grab onto a passing bee.  This does seem logical, and most people without a scientific degree can visualize this process and easily buy into it. But there are studies that show the benefit of the SBB can be outweighed by the temperature drop if the SBB is left open for ventilation, both in the brood nest where the mites breed,  and in the rate of falling off bees.  So if your using open SBB, inserting empty frames in the brood nest, using top entrance, or any other method that reduces the hive temperature, are you are helping the population of varroa grow?

I have attached two PDF files showing results of the studies if you want to read them in their entirety.

Quote from: Tucson AHB/Mites Conference RIFA Control
Temperature seems to have more of an impact on Varroa reproduction than most people thought. While 95ºF is "brood nest temperature," that temperature
fluctuates some with climatic conditions. By carefully controlling temperature, Varroa were found to reproduce best at 93ºF. Performance was a bit worse at 88-91 and 95º. At the lower than brood nest temperatures, the post-capping period is extended about one day per 2ºF. At higher temperatures the post-capping period is not shortened significantly. However, at "brood nest" and higher temperatures, mite reproduction drops way off. In the same study it was shown that 53% of the mites on brood held at 59-68% RH (normal) reproduced normally but at humilities of 79-85% only 2% of the mites reproduced. Hot, humid brood nests are tough on Varroa. Studies of Apis cerana brood nests showed drone brood is reared at 92ºF (perfect for Varroa) and worker brood is incubated at 96-98ºF (too hot for Varroa). Purposely cooling the brood nest in Apis mellifera colonies by using a "thin" hive lid, open bottom board, simulative feeding to spread brood out, and splitting the brood nest with frames of foundation doubled the numbers of mites on the bees.



Quote from: Experimentation of an Anti-Varroa Screened Bottom Board in the Context of Developing an Integrated Pest Management Strategy for Varroa Infested Honeybees in the Province of Quebec

The antivarroa bottom board must never be used with its bottom hole opened as this leads to a lowering of cluster temperature resulting in ideal conditions for varroa development. As confirmed in 2000, this situation not only negated the beneficial effects of the bottom board, it also resulted in a net increase in the mite infestation rate (29.2% more varroa mites, non significant) as compared to the control group.

Great news but THINK . are you going to put heaters under the hives at night to keep varoa mites down ??? Bees dont like 95 thats why they keep brood temp down , and bees bussy fanning are not cleaning the hive . I will use the SBB in my area becouse it works for me .Everything that smells roses isn't . :)



[/quote]
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Robo on July 27, 2008, 09:26:39 am
Great news but THINK .
That's exactly why I posted this.  We have many new beekeepers here and I wanted to give them more information so that they can make an informed decision for themselves and not just from anecdotal advice.

Quote
are you going to put heaters under the hives at night to keep varoa mites down ???
Bees maintain the brood temperature regardless of the time of day.

Quote
Bees dont like 95 thats why they keep brood temp down , and bees bussy fanning are not cleaning the hive .
From the research I've read, 35°C (95°F) seems to be the optimal brood rearing temperature.

Do you have any issues with the humidity aspect of these findings?

Quote
I will use the SBB in my area becouse it works for me .Everything that smells roses isn't . :)
Glad it works for you. I'm not looking to convert anyone either way,  just sharing information for those who like as much information as possible before making their own decision.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Cindi on July 28, 2008, 01:57:41 pm
Sharing information is a wonderful thing.  It allows the human being to made INFORMED decisions.  I don't see anything about trying to convert anyone to anything here.  It is information sharing, beautiful!!!  Have that great and wonderful day, Cindi
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: NWIN Beekeeper on July 29, 2008, 02:21:32 am
Even though it does take extra effort, I will continue to use SBB. 

In my locations moisture is a serious concern (well actually it isn't because my hives have such good ventilation with the SBB). I don't like dampness in my hives, it leaves too much opportunity to harbor disease and pests. I have not had dampness issues like caulk/stone brood as other local beekeepers have experienced and a significant difference is that I run all SBB, he does not.

Improving hygienic genetics in one's bee stocks helps greatly in minimizing varroa in the first place.
A small level of mites maintains a good genetic 'pressure' to keep mite fighting genes. My heavy mite loads are concentrated in feral swarm colonies or cut-outs, and yet I don't see heavy mite loading as a result of drift.

I see a significant amount of chewed cappings, loose pollen, and other debris that falls through.
These are all things that my bees did not have to waste time in house keeping to be rid of.
That means the bees were doing something more meaningful - like waving to me as I arrive to inspect their hive.  Keep in mind my SBB are custom and span the entire 16x20 area of the box.

Besides, SBB make it easy to smoke a hive before/during inspection.

I think a calculated break in the brood cycle does significantly more to minimize mites then a SBB contributes, but I believe they help.

I am not sold on anyone's temperature theories. I think the thermodynamics of hive are far more complex than most scientists model. I also feel it is far more complex and conditional to other hive conditions (curing honey, pupating brood, fermenting pollen, etc.) than most models could accurately depict (it varies frm hive to hive).

If my bees were suffering from too much ventilation, they would propolize the entrances to compensate.
I have to figure that brood temps are acceptable and correct.

Keep in mind that 50% of all satistics can be manipulated 90% of the time to slant towards the results that creates the most controvesy and press (right or wrong).
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: suprstakr on July 29, 2008, 12:56:20 pm
NWIN. Thanks could not said anny better  ;)
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Robo on July 30, 2008, 12:01:48 pm

In my locations moisture is a serious concern (well actually it isn't because my hives have such good ventilation with the SBB). I don't like dampness in my hives, it leaves too much opportunity to harbor disease and pests. I have not had dampness issues like caulk/stone brood as other local beekeepers have experienced and a significant difference is that I run all SBB, he does not.
Sounds like the anecdotal advice I referred to previously.  How about other climate differences like elevation, wind, sun exposure, etc.  or even basic differences in management styles.  Could any of these have a larger affect than you assume?   I have yards just miles apart that have enough differences in weather to affect their productivity.

Quote
Improving hygienic genetics in one's bee stocks helps greatly in minimizing varroa in the first place.
A small level of mites maintains a good genetic 'pressure' to keep mite fighting genes. My heavy mite loads are concentrated in feral swarm colonies or cut-outs, and yet I don't see heavy mite loading as a result of drift.
Sure, hygienic behavior plays a part in it as well. My experience has also been that some feral colonies can have fairly high mite levels.

Quote
I see a significant amount of chewed cappings, loose pollen, and other debris that falls through.
These are all things that my bees did not have to waste time in house keeping to be rid of.
That means the bees were doing something more meaningful - like waving to me as I arrive to inspect their hive.  Keep in mind my SBB are custom and span the entire 16x20 area of the box.

Or possibly spending their time and resources keeping the brood temperature up?

Quote
Besides, SBB make it easy to smoke a hive before/during inspection.

true

Quote
I think a calculated break in the brood cycle does significantly more to minimize mites then a SBB contributes, but I believe they help.

Absolutely,  I personally think that plays a large roll in how the ferals are surviving.  Every swarm they throw is a break in the brood cycle.

Quote
I am not sold on anyone's temperature theories. I think the thermodynamics of hive are far more complex than most scientists model. I also feel it is far more complex and conditional to other hive conditions (curing honey, pupating brood, fermenting pollen, etc.) than most models could accurately depict (it varies frm hive to hive).
I don't necessarily disagree that it is more complex than what we know.  But I do consider it higher than "I use SBB and he doesn't, so that is why" when deciding on my approach.

Quote
If my bees were suffering from too much ventilation, they would propolize the entrances to compensate.
I have to figure that brood temps are acceptable and correct.

Or they are burning additional resources maintaining the core brood temperature.  B Heinrich determined that even free swarms regulate their core temperature to 35C.  It may even be that a large portion of the honey they gorge on before swarming is used for this thermoregulation.

Quote
Keep in mind that 50% of all satistics can be manipulated 90% of the time to slant towards the results that creates the most controvesy and press (right or wrong).
Agree, that is why each needs to make their own decision.  Hopefully based on data from multiple sources and not just anecdotal advice.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: SgtMaj on July 31, 2008, 03:53:57 am
Or they are burning additional resources maintaining the core brood temperature.  B Heinrich determined that even free swarms regulate their core temperature to 35C.  It may even be that a large portion of the honey they gorge on before swarming is used for this thermoregulation.

Unless your average daytime temps were above 35C, in which case it would seem logical that it might help them keep from consuming more resources to provide A/C for the brood.  Of course, day and night temps. vary greatly, so even then if one was going for maximum efficiency, I guess they would need to be constantly inserting and removing the mite board... which would be very tedious.  On the other hand, armed with that knowledge, a thermostat, and a clock, an observant person could figure out how long the temperature remains above 35C at different daytime highs in your area.  Then you can figure out at what point the temp stays at or above 35C for exactly 1/2 of the day.  Then for example, if you see the temps being forcasted are at or above that level all week, you could leave the mite board out to gain efficiency.  The rest of the time you could leave it in.  And this probably only applies to tropical and subtropical climates only, as I would think that most US climates stay below 35C most of the time.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: pdmattox on July 31, 2008, 11:50:12 am
Well I have both types of bottom boards, some are screened and some are solid Pressure treated plywood on clipped pallets. The hives with the highest mite counts in May were the ones with SBB. The SBB hives also took longer to draw the frames out to the bottom bar but did not need to have the bottoms cleaned like I always have to do on the solid ones. I prefer the clipped pallets over a single hive configuration any day. just a 2 cent observation.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: poka-bee on July 31, 2008, 12:11:52 pm
Dallas, Don't laugh but what is a "clipped pallet?"  :oops: (well, you can snigger a bit if you want..) :roll:  Jody
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: pdmattox on July 31, 2008, 01:04:23 pm
The pallets that I built basically will allow me to place 4 hives on it and pick them up at one time with a loader. They are similar to a fork lift pallet you see behind stores except that they are smaller and have a solid bottom for use as a bottom board for the colony. The clips are used to keep the box from shifting on the pallet keeping it all together. I also have seen some made with screen in the bottom board. I will try to get a couple of pics for ya.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: SgtMaj on August 01, 2008, 07:16:35 am
Dallas, Don't laugh but what is a "clipped pallet?"  :oops: (well, you can snigger a bit if you want..) :roll:  Jody

Don't feel bad Jody, I was wondering the same thing.  From the sounds of his description though, it seems like I wouldn't know or need to know anyway, because it sounds like a commercial beek thing instead of a home beek thing.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Robo on August 01, 2008, 09:28:02 am
Here are two different types of pallet clips.  one lets you stack hives back to back and the other leaves a 1/2" space between hives.   They just get screwed to the pallet and the deeps are placed over top. The clips prevent the hives from sliding off the pallet.

(http://www.mannlakeltd.com/images/catalog/hd-648.gif)(http://www.mannlakeltd.com/images/catalog/hd-649.gif)
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: poka-bee on August 01, 2008, 11:05:08 am
Thanks Robo, now I understand.  Makes sense if you have a lot of hives & move them differrent places.  I have no way to lift the whole pallet but am thinking about those little trailers you put together to use, to see how many I could get on one of those W/room to work em to take to the organic farm I buy from or other places so I can tow & drop.  Have a solar charger for fencing that I could put around the whole thing to keep critters out. What are the pros & cons of each type of clip?  I would think that the 1/2 apart would give a little wiggle room to take tops & supers on & off..Jody
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: pdmattox on August 01, 2008, 06:48:36 pm
In Rob's picture the clip on the left is a "w" clip and gives space for the hive bodies to dry out and not rot. The other is a "u" clip and boxes can be placed close together.  A trailer is a great way to go if you don't have a way to pick them up all at once.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: poka-bee on August 01, 2008, 07:27:10 pm
Thanks Dallas, here in the PNW we have to really work at keeping things dry! :roll:  BUT it's better than 90 degrees w/90 humidity!  If it gets over 70 w/50 humidity we think we are "braising"! 8-)  Jody
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Gware on August 20, 2008, 10:44:11 pm
well if this temp theory is true it sure did not help the feral bees that was inside a thick tree trunk with only an opening the size of a silver dollar. I am sure it got hot in that tree trunk but it seemed to not stop the mites from reaching a level enough to kill the hive.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: annette on August 21, 2008, 12:18:11 am
Ok, I feel pretty happy with my SBB on the hives. I know that mites drop off and through the screen and are gone far away from the hive. It just seems cleaner to me than closing up the bottom. Whenever I place my tray in to monitor the hives, I find so much debris falling down. I like knowing it is away from the hive.

So I believe it helps with the varroa mites that naturally fall off the bees. I do not know if the temperature differences between open SBB and closed SBB  make any difference in mite population. Maybe it doesn't matter either way.

One thing that I noticed this summer is my bees have gotten much smaller due to letting them draw out their own combs. And I have not had to do any powder sugar dusting this summer because the mite population is also very little. My bees are regressing in size and this may have something to do with the mite population. I will have to check this out further to be sure.

Annette
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Robo on August 21, 2008, 10:21:22 am
well if this temp theory is true it sure did not help the feral bees that was inside a thick tree trunk with only an opening the size of a silver dollar.

Another anecdotal response.  That is like saying wearing a seatbelt didn't help the guy who died going off a cliff when his brakes failed.  Unless you know what was the demise of said colony,  and the other issues involved,  your are just using your bias in judgment.

The ferals around here are booming.  I know others on the forum have strong feral populations as well. All the survivor stock (been in the location for more than 1 year) that I have removed have sealed up every little hole in the cavity except the entrances. 

Quote
So I believe it helps with the varroa mites that naturally fall off the bees. I do not know if the temperature differences between open SBB and closed SBB  make any difference in mite population. Maybe it doesn't matter either way.

Or maybe it does.  Maybe the mites that naturally fall off are insignificant compared to the increase of mites that are raised in the cooler/drier environment. You can easily get the so-called "advantages" of SBB mite separation without taking the heat away.

It amazes me some of the hoops people will jump through to be "more natural" in their beekeeping but will just ignore, or justify to themselves it is not important, that the natural temperature/humidity aspects of feral colonies.   I don't know if it is just "we know better", the human need for visual stimulation, or we are just sheep to what others believe.  My experience has shown me that heat definitely plays a big role in a hive. I admit it is not "the answer" and I don't know the full extent, but I'm not willing to discount it. The bees seem to think it is important, and despite all our knowledge,  I tend to believe them more than man.  When I put a 7 watt night light on the bottom board,  the queen will move right down above the light to lay. Hives that I heat build up faster in the spring than those that I don't.

Here is an interesting read on nest scent and heat -> http://forum.beemaster.com/index.php/topic,17318.0.html

 Sometimes I just wonder if we are just cutting the nose off to spite the face.  My ancestors where fishermen and I can remember my grand dad telling me that when they clammed and caught a star fish,  they would cut it up to kill it, because star fish eat clams, and throw it back into the water.  What they didn't realize was that each piece would regenerate and they where actually increasing the star fish population. 
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Gware on August 21, 2008, 05:30:56 pm
There also has been scientific  quote quote research done on screened bottoms as well. You can find any research to support a particle veiw.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Brian D. Bray on August 23, 2008, 02:48:30 am
I nearly lost my bees to starvation this spring (lost 3 of 5) and have checked for mites weekly using a mite board.  I have yet to find a single mite on either board.  I have bottomless hives, using a slatted rack as a spacer board at the bottom.  I also use natural sized comb as I use foundationless frames.

I could argue that I am miteless due to having bottomless hives.
I could argue that the smaller cell size of the natural comb limits the mite population.
I could argue that I am miteless due to the brood interrupting during the near total starvation.

I credit all three.  The smaller the cell means there is less room and time for mite reproduction.  What mites are coming back to the hive from being passed bee to bee are falling out of the hive and unable to climb the 8 inches of open space between the ground and the hive.
 
I've found, in my 50 years of beekeeping, that there is never a silver bullet and it's a waste of time looking for one.  However, a combination of several ideas can work just as well as the proverbial silver bullet.

If you're using only one approach to the problem you're being myopic and narrow minded.  If you rule out something you don't think will work, you're being myopic and narrowminded.  I wear glasses, I'm myopic, but I'm not narrow minded,
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: NWIN Beekeeper on August 23, 2008, 03:58:00 am
[Another anecdotal response. ]

I just find this whole post a little brain damaged.
You can post your opinion, but its crap listed because its 'anecdotal'.

Excuse me, but you aren't going to get university study responses asking the crew that posts on this board (no insults meant to any of us!)

So what sort of response are you looking for?

Or purhaps this is posted to cause some sort of uproar?

Just because a paper has some words typed on it just doesn't make it so.
And your avoiding believing anyone's opinion because it isn't proven in a scientific method.
But when the replies come back in quantity saying one thing, it has to imply a little truth.

I don't understand the purpose of this thread...
There's no reasonable room for reply or expression of opinion.
If I was the moderator, I think I'd move myself to: [REPRINT ARTICLE ARCHIVES]

[ I wear glasses, I'm myopic, but I'm not narrow minded]

Well my eyes were laser corrected, so I'm a little better then where I started from.
Some days if I was any narrower minded my ears would rub together and catch fire.
Other times I don't know how to wrap my mind around everything.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: SgtMaj on August 28, 2008, 07:59:30 am
Either way I think it warrants further investigation.

No matter which way you lean in the debate over whether SBB does more to reduce or promote varroa... doesn't really matter, so long as you're aware of the other side of the coin... while it may not prove to be valuable info for beeks in Arizona or Florida, where the outside temps are close to the brood temperature anyway... it might make a big difference for a beek in Alaska who's dropping the hive temp. by 20+ degrees by opening up the bottom of the hive.

I keep noticing on here that people frequently forget that other beeks don't live in the same climate... I've been guilty of it, too.   Those differences have huge impacts on the methods used that are successful.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: TwT on August 30, 2008, 08:29:11 am

I keep noticing on here that people frequently forget that other beeks don't live in the same climate... I've been guilty of it, too.   Those differences have huge impacts on the methods used that are successful.

this happens some times but not much, most questions on here have little to do with climate or location but there are some, what works best in your area sgtmaj? have of my hives had SBB's and the others had regular BB's, I still use SBB every now and then but not much, I have gone to what I call a pollinators BB, it is open on 2 sides, they still beard a little but not as much as a regular BB.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Mickey on October 09, 2008, 06:56:06 pm
Hi Rob Mickey here , Just had the State Bee Inspector here and was told I have  a weak colony with fairly heavy Varoa Mite population... Do have a sbb  . But more importantly I would like to treat the mites with some Oxalic Acid i had for a few years now. Couldn't give me the exact dose or exposure time, but did mention someone he knew heated up a large spoon , filled it with OA and put it under the sbb. Do you have any thoughts on this? Also got info on health certificate but I'll Email separately
thanks
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Michael Bush on October 09, 2008, 09:49:34 pm
Do NOT heat a spoon and fill it with Oxalic acid.  You will get a faceful of fumes.  The safest is to buy the evaporator from Heilyser http://members.shaw.ca/orioleln/Vaporizer.htm and stand way back.  But I've made evaporators from brass pipe fittings, drilled a hole in an old shallow super and threaded it in and heated it with a torch while standing (carefully) up wind, using a smoker to validate that direction.  You do NOT want to breath the fumes.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: DayValleyDahlias on October 09, 2008, 10:04:17 pm
I will continue with SBB'd as well.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Robo on October 18, 2008, 09:27:17 pm
Do NOT heat a spoon and fill it with Oxalic acid.  You will get a faceful of fumes. 

I lent Mickey my vaporizer to use.  I think it is kind of interesting that the state bee inspector would recognize oxalic acid as a viable treatment since it isn't register.  The scary part is that he tells of heating on a spoon :-X
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Cindi on October 19, 2008, 11:28:22 am
Do NOT heat a spoon and fill it with Oxalic acid.  You will get a faceful of fumes. 
I lent Mickey my vaporizer to use. 

Nosey ol' me, who is Mickey?  Beautiful day in this great life, Cindi
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Robo on October 19, 2008, 11:58:07 am
Nosey ol' me, who is Mickey?  Beautiful day in this great life, Cindi

http://forum.beemaster.com/index.php/topic,16851.msg133357.html#msg133357
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: Cindi on October 20, 2008, 10:13:20 am
Rob, oh brother!!!  Sometimes one can't see for lookin'.  Have a great and wonderful day, Cindi
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: BjornBee on October 23, 2008, 10:49:29 am
I see beekeeping as being a "nickel and dime' approach to success. The right management strategy, the right genetics, and the right equipment, all go together in making differences between 10% loss and 60% loss.

Studies I have seen, suggest a mite decrease from 7 to 15%. Nothing unto itself being able to solve any mite problems. One study out of Cornell, because it fails within the statistical realm of being negligible, has said SBB as useless. But I'll take that 7% decrease in mites. I'll take every 5% advantage I can get.

I think for much of SBB impact on mite levels, it is directly in relation to what type bees you have. Not the labeling of bees. but how hygienic they are from a grooming standpoint. Bees obviously that are good groomers, will knock off more mites. Bees also stimulated with trigger mechanisms (smoke, oils, etc.) also will groom off more mites.  To just slap on a SBB and not have good grooming bees is not going to cut it. And not all bees are equal when it comes to grooming.

People always ask me about leaving the screen open or closed. I keep all mine open year-round. Of course, I am also big on the importance of selecting a good apiary location where wind is not an issue. And when retained heat means the most, that being late winter/early spring, most clusters are up in the second box, far from the SBB. So this issue of lost brood is always questionable to me. It may be an issue when some swap boxes in the spring. But that's just something to guard against and know with SBB, you can not do it too early.

I think SBB are worth it for many reasons, including mite drop (using good grooming bees), increased air flow, etc.
Title: Re: Are you increasing varroa population with your screened bottom board?
Post by: mountainvalleybee on October 25, 2008, 12:27:39 pm
The Stiffness and hair type on both the thorax and abdomen can play a role with the mite problem also if it is a type hair which aids grooming by making it harder for the mites to maintain a purchase on the bee. That is stiffer type hairs as on the Mellifera which also seem to get harder quicker upon the initial hatch of the young bee,or maybe that is a new adaptation on the surivivin mellifera bloodlines.