Small Cell Studies

There have been widely reported (and widely misinterpreted, I might add) studies trying to evaluate small cell wrt mite issues. I have some thoughts that I will add later, but I wanted to highlight some of what others are saying about this. Below are comments from Michael Bush and Erik Osterlund:

Michael Bush, Beesource, December 20, 2009

Let's assume a short term study (which all of them have been) during the drone rearing time of the year (which all of them have been) and make the assumption for the moment that Dee Lusby's "psuedodrone" theory is true, meaning that with large cell the Varroa often mistake large cell workers for drone cells and therefore infest them more. The the Varroa in the large cell hives during that time would be less successful because they are in the wrong cells. The Varroa, during that time would be more successful on the small cell because they are in the drone cells. But later in the year this may shift dramatically when, first of all the small cell workers have not taken damage from the Varroa and second of all the drone rearing drops off and the mites have nowhere to go.

In the end, as Dann Purvis says, "it's not about mite counts. It's about survival". No one seems interested in measuring that. What I do know is that after a couple of years the mite counts dropped to almost nothing on small cell. But that did not take place in the first three months...

Erik Osterlund, Organic Beekeeping list,  January 2, 2010

Response to J Berry on small cells

In the November issue of Bee Culture 2009 there is an article by Jennifer Berry with the message that there is no value in small cell size as a tool against Varroa mites. As I live in Sweden and mail is taking extra long time during Christmas I got my Nov issue of Bee Culture late in December. (The new option of subscribing on a digital copy of the magazine is really great!)

I read the article of Jennifer Berry about three investigations of small cell size (SC) effect on varroa population build up during a short period of time, half a year to a year. The end of the article is highlighted. She there clearly gives the message that her article is kind of the final word, through unforgiving objectivity of the scientific method, demolishing and ship-wrecking the idea that small cell size foundation, which is an arm-chair science presupposition, will reduce Varroa mites.

I strongly defend her right to have and to argue for this opinion. But mine is closer to the opposite.

All three tests described in her article were not focused on colony survival, but on development of the varroa population during a relatively short time. This is of some interest of course. But the results from all of these three tests give in no way ground for the bold statement at the end of the article. This statement gives the impression that the tests show that small cell size gives no advantage in the fight against varroa, BUT, that is not the conclusion in any of the tests. They only talk about varroa population build up during a restricted period of time. There are more factors to colony survival than mite population build-up during circumstances that is not a natural situation for the bee colony, or rather a natural situation for a population of bee colonies.

The first test described is her own, published in different journals. She began the test with bees from a beekeeper succesfully keeping bees on 4.9 mm cell size without using treatments. That is note-worthy. She kept the test (SC) and control colonies (LC=large cell) in the same yard. The resulting mite population was too small to give any real figurers able to show reliable eventual differences in varroa population growth. This test is comparable with the first year result presented in a small cell size test by Prof Fries in Sweden (see the small upper left part of graph showed in the jpg-file on this url: – The urls given here are made short through the help of ) It's in the file section of Organic Beekeepers discussion group on Yahoo , named Two cellsize tests.jpg.

ONE THING that is never talked about in any of these (and other) tests is which precautions were taken to avoid drifting and robbing during taking the measures to get all these figures in tables and graphs! I know through experience (when nectar flow is low) that if these kind of thorough lifting up of combs and measures taken in a yard is done continously during more than half an hour, it doesn't take long before you have a robbing going on, which makes any measures of mites more or less worthless. And once the bees have learned this, the next day (if nectar flow is low) the bees come even quicker in a robbing mode.

ALSO, we don't know anything about the chemical residues in the wax combs. Recent tests of wax in combs have shown alarmingly high quantities in brood nest combs. We know too little about the effect of this on the immune system and defense system in the bee colony. We do know that a test made by Randy Oliver with HSC (fully drawn plastic small cell combs), which have no such residues, gave a much lower varroa buildup than large cell size bees did. See the lower graph on the above mentioned url:

The second test (by Ellis/Hayes/Ellis) described can be found through this link: It is the best designed scientific test I've seen so far on this subject that have negative conclusions against small cells. The test had the major fault of being performed during too short a time too. Why should modern scientific tests almost always just run one season at the most?

Was enough precaution made to avoid robbing and thus averaging out the mite populations? We don't know that. The test and control apiaries were located 700 m from each other (quite good), but during a period without flow, which they had, and if you work through the apiary measuring all these figures in one colony after the other till all are done, then enough stirring up is made to make 700 m no hindrance at all to cross for robbers.

And what about chemical residues in the wax foundation used? We know nothing about that.

They say mite load was big. At the end of the test it was about 3000 in total. Maybe today with more viruses in the mites this is big. Ten years ago and more it wasn't a big load, especially when mites first arrived to a location. Then 10-20,000 was a big mite load.

ONE resistance factor not taken in account is virus resistance with the bees. This is a very important factor for the bee colony to be able to survive a high virus- and mite load during an initial time of mite infestation when the most susceptible colonies in a population of colonies will die. Before they die they spread a lot of mites and viruses to neighbour colonies, which then have to be able to survive this until natural selection has gone through its first steps. Today we know there is a difference in virus resistance among individual bees. This is necessary for selection to be possible. At least one reason for this resistance is the existence of peptides. These are short chains of amino acids. Proteins are also chains of amino acids, but longer, containing more than 50 amino acids.

THE OTHER important resistance factor was already presented as probable in 1996 by Remy Vandame in his doctorate thesis "The Importance of Hybridization in Host-Parasite Tolerance" (translation of the title from French by Malcolm T. Sanford). A graph is included in it showing the varroa population dynamics in susceptible EHB and tolerant (resistant) AHB colonies. (AHB:s live normally on small cell size.) The AHB phoretic mites (mites on the bodies of bees) being stable in number with about 500 during a year, while mites in brood varies a lot with a maximum of about 2500. (In total at most about 3000 mites in a colony then, this being about the same as the end population in the test of Ellis, Hayes and Ellis, so their test was too short for testing suvivability.) The Vandame thesis tells us the bees in AHB-colonies must have been doing something about the mites in the brood before it emerged, or soon after. The AHB:s were most probably what we today call VHS bees, which identify brood with mites and disturb the mite reproduction through opening the brood capping and maybe also clean out the puppea.

The Ellis2/Hayes test talks about total amount of mites. But that is not totally fair, as the final bee population differed in the groups, being almost the double in the SC-group. Almost certain due to more compact brood nest because of smaller cell size. The varroa population in relation to bee population is a much more relevant figure. At the end of the test mites on adault bees were 35% lower in SC-colonies (about 9% and about 14% respectively). Mites in brood were 23% lower (13% and 17% respectively). There is then a tendency for a similar situation as in the thesis of Vandame, thus a probable occurance of more VHS in SC, which then would mean SC stimulates VHS. But to make such a conclusion this test is not enough.

Actually, if survivability is interesting, a test for virus resistance when selecting varroa resistance would be most valuable. I myself work with observations on the occurrence of (or absence of) bees with crippled wings, being a sign of DWV-virus, probably the most devastating of varroa related viruses. None of these two tests described here have been going on long enough to observe DWV-bees(?).

The third test is originally a report to the beekeeper association in New Zealand from HortResearch by M.A. Taylor and R.M. Goowin in 2001, recently published in IBRA publications. It is not a research done 2008, but 2001. It's easily understood through correspondingly exact number of data points, 1636, in both publications. The original report, a pdf-file, can be found through this url:

It's enough to quote from the introduction in the test report: "Ten nucleus colonies were established with mosaic frames containing five different cell sizes and sister queens." – LC-bees drew out all sizes in the same colony, no wonder the resulting combs looked so miserable. "Because the smaller sized cells were drawn out unevenly, with the base of the cell sometimes larger than the top, the trial should be repeated using 4.8 mm foundation that has been drawn out in hives that have undergone a step-down process from the standard 5.4 mm sized cells." – The authors here stating that if another test were to be made it should be made with 4.8 mm foundation correctly drawn and tested in a colony of 4.8-bees.

Why make the test situations so unnatural. Why not make an apiary with SC-bees and another one two miles away with LC-bees and run them separately for survival, taking out the losers before they infest the other colonies too much. Keep the number by making splits of the best ones and let these make their own queen which mate in the apiary. The apiaries then being placed in as remote an area as possible.

- Dean