Either natural cell size helps with Varroa or it does not. If it does not, there is no evidence that it is detrimental. If it does, and there are many anecdotal references that would indicate it might, then it would be well worth doing. So there appears to be no downside to using natural cell and a huge possible upside.
We know that the foundation supply is contaminated with acaracides (fluvalinate, coumaphos and amitraz among others). I believe this is at the point of being beyond dispute. We also know that contaminated comb is contributing to shorted lives of queens and the infertility of drones. The effect of shortening worker lives might be up to debate as to how significant that is, but we know the hive depends on the queen and a queen who is failing or getting superseded repeatedly is not contributing to the success of the hive.
We know that natural comb is not going to be contaminated with acaracides. We know that it is the ďrightĒ size. We know itís possible to induce the bees to build it in a frame (see historical references from Huber on until the early 1900s).
We know itís possible to put wire in foundationless frames when getting natural comb for reinforcement if strength is an issue.
We know that the current cell size of foundation is NOT natural (see historical references from Huber on until early 1900s).
We know that artificially large cell sizes changes the anatomy of the bee (see historical references from Huber on until early 1900s, particularly writings of Baudoux et al).
Therefore since there is no reason from the point of view of the health of our bees that I can see NOT to use natural comb and at least one KNOWN reason (contamination) that foundation is detrimental, at least one LIKELY reason (the effects of artificial enlargement on the health and vitality of the bee) it could be detrimental and at least one POSSIBLE reason (more Varroa reproduction) that it could be detrimental, I think the most prudent choice would be to stop using foundation and use only natural comb.
We know we canít breed for resistance to any disease or pest if we are artificially eliminating that threat to our bees. Obviously if we kill the pest we donít know if they could handle that pest. And since the first step to handle any of our issues should be bees that can handle that issue, the obvious first step is to stop treating.
We know that acaracides are also poisonous to insects. Certainly organophosphates are insecticides and yet we are using them in a beehive. This seems like a very bad plan.
We know that a stable parasitic relationship is one in which the parasite does not kill its host. The development of this stable relationship with any of the parasitic mites of the honey bee is impossible to develop as long as we keep treating the bees. The mites that survive will be the ones that manage to kill a colony so that the rest of the colonies will rob it out and carry hitchhikers back to their colony, or the ones that can breed so fast as to make up for the number we kill. So as long as we treat we will continue to breed weak bees and super mites.
We know that the acaracides we are using kill off some of the 30 benign and beneficial mites that normally live in a beehive and we donít know how many beneficial insects.
We know that every treatment we use kills off or injures entities other than the target. For example using oxytetracycaline will kill many of the other 8,000 beneficial or benign microorganisms that live in the beehive. Fumidil will also kill some of those. We know that microorganisms in the hive help with digestion of pollen, crowd out other brood and gut diseases and live together in a complex network that we barely understand. A few of those relationships have been mapped out however so we know that at least some of them are important.
So, while treating for what we perceive to be the problem (the pest, the pathogen etc.) treating only masks the underlying problem which is that genetically our bees canít handle the pest, and upsets the natural web of life, both micro and macro, that makes up a beehive.
Therefore, if we want to have genetically strong bees and a healthy balance in our hives, the only way to accomplish that includes not treating.
We know that most of the pathogens that are a problem in a hive (EHB, AFB, Chalkbrood etc.) multiply better at the pH of syrup than at the pH of honey.
At worst honey is as nutritious as syrup, and at best, itís more nutritious. I often wonder why beekeepers argue that there is no difference. Why are you raising honey if there is no difference? Maybe you should sell sugar syrup to your customers?
We know that bees raised on pollen out live bees raised on substitute.
We know that it takes much more labor to harvest all the honey from a hive and then turn around and make and feed syrup than it does to just leave them enough honey to winter instead.
So why do we insist on all this extra work when, at best honey is better for the bees and at worst itís no difference? And why feed pollen substitute only to end up with short lived bees for the effort?
Therefore, why not just leave the artificial feed out of the hive and use proven natural food?
Locally adapted survivor stock
We know that bees that do well in our climate are what we want. Package bee outfits are all in the South and are breeding bees for their operation, which is a package bee outfit in the South. That means bees that explode very early in the spring and are brood rearing fools from there on so there are lots of bees to package and ship. In the North we are better off with bees that are more frugal and make better decisions when to build up and when not to. Getting queens that are well adapted to raising package bees in Georgia (or California etc.) are not going to be well adapted to honey production in Minnesota (or Nebraska etc.).
We know that the local feral bees are adapted to the local honey flows and frugal enough and hardy enough to winter in our location.
We know that we canít get bees that can survive as long as we keep treating and we know that the feral bees have not been treated. So they are able to withstand whatever they have been exposed to. If we want resistance to Tracheal mite, Varroa mite, AFB, Nosema etc. we want those kinds of stock.
We know that the gene pool of domestic bees is quite narrow and that the feral bee population is often somewhat different in makeup and this broadens the gene pool.
Therefore, we should be breeding our own queens from our own survivors with traits we want and letting them mate with feral survivors. This will maintain a broader gene pool and it will infuse our bees with hardiness and a sense of the timing of our area.
How do we get all of these?
Foundationless frames (a frame with a comb guide) would be how to get this. Simply turn the wedge sideways and nail it back on. Or, if there is no wedge, glue a strip of wood in the groove. Or, if there is already comb in the frame, cut out the center and leave a row of cells all the way around.
Easy enough. Just donít treat for anything. If some die, say ďgood riddanceĒ to bad genes.
Just leave them enough honey. Trap some pollen if you like and feed it back in the Spring.
Locally adapted survivor stock
Just donít treat and breed from the survivors. Open mate to get the feral population included.