One of my hives had a (seemingly) massive amount of drone cells in the spring. I considered culling them to help with varroa but I left them thinking that I would let them do as they pleased. Now I have a big varroa problem with that hive - mite fall count yesterday was 50+ for 24 hour period.
@AugustC - How do you know "Drones are also essential for rapid genetic responses to threats such as environmental changes, diseases, even varroa?"
Seems like fairly obvious genetic conservation across generations.
Genetics are only conserved and perpetuated at the point of reproduction.
A change occurs in a system!
1) The individual survives to reproduce and passes on its genetics to the next generation OR the individual dies and doesn't.
2) A group of individuals have an advantage over another group of individuals so out-reproduce the other group cornering resources and removing all but a few of the other group.
Varroa I think have a lifecycle of about 10 days. That means every 10 days a new generation of varroa are born. Every 10 days the varroa population have the opportunity to respond to the selection pressures exerted on the hive.
Removing drone comb from a hive removes the varroa that prefer drone comb thus reducing the stress on varroa that prefer worker comb and making it easier for them to proliferate.
Restricting drone comb building places a direct selection pressure on the varroa selecting for those that prefer work brood. Which "may" replicate at a slower rate due to worker lifecycle but will ultimately increase in numbers.
Queen bees live for 3-5 years. The genetics of worker bees are multi-factorial. They have the queens genetics along with the genetics of any one of perhaps 17 different drones. It may be that some of these super-sisters have traits that provide varroa resistance but at hobbyist level it would be very difficult to identify select for them. Drones are pure offspring from the queen. They are haploid so have only half the number of chromosomes of the queen and workers. Drones which display traits which allow them to survive to sexual maturity and mate will pass on those traits. Those which do not suit the hive "environment" will not survive to mate, or will survive in lower numbers. Since the drone only lasts for a single session the colony has an opportunity each year to pass on the genetics which best (or at least sufficiently) match their requirements as a colony. The genetics of the colony don't change until a new queen takes over at which point she will be mated with local drones.
I don't KNOW any of this it is admittedly purely conjecture, but conjecture based on a number of years of scientific study in genetics and drug resistance.
Plus we make this massive assumption that drones are nothing but a hindrance to a hive but we don't really know whether they play an important role in hive dynamics. They would not have developed to the size they are unless that size provided some advantage, it may be that advantage is in their ability to catch the queen during mating but who knows. I do know that bees have been being bees for ~70 million years and they have a better idea as to whether they need drones or not.