One thing that is seldom talked about in design of tests, is which precautions were taken to avoid drifting and robbing during registering the data for all the 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 even less than half an hour, it doesn't take long before you have a robbing going on, which makes any measures of figures more or less worthless. And once the bees have learned to rob, the next day (if nectar flow is low) the bees develop a robbing mode even quicker.
We don't know anything about the chemical residues in the wax combs used. Recent tests of wax in combs have shown alarmingly high residue levels from miticides and agricides in brood nest combs. We know too little about the effects of this on the immune system (RNAi, peptides, hemocytes, microbe-balance, etc.) and defense system (defense behaviour like VSH, grooming, cleaning out virus filled bees from the hive) in the bee colony. We do know that a test made by Randy Oliver with HSC (fully drawn plastic small cell combs)(15), which have no such residues, gave a much slower varroa buildup than on large cell size (drawn on plastic foundation).
When a drought is at hand, nectar availability is often scarce. To help the bees they might be fed. We don’t know from the description of the tests what is fed and how much. Is it honey, high fructose corn syrup (HFCS) or sucrose solution fed? Are proteins low in colonies and therefore pollen or pollen substitutes supplied? We know that there is a discussion concerning the nutrition value, or rather lack of, in HFCS.(16), (17) What you feed can influence the performance and behaviour of your bees. This could be part of the explanation why the ending bee populations in some tests were remarkably low in my view.