Scientists have developed a breakthrough food supplement that could help save honeybees from devastating declines. By engineering yeast to produce six essential sterols found in pollen, researchers provided bees with a nutritionally complete diet that boosted reproduction up to 15-fold. Unlike commercial substitutes that lack key nutrients, this supplement mimics natural pollen’s sterol profile, giving bees the equivalent of a balanced diet.
I expect there are dozens of different things that influence how well a hive does, some good, some bad. Maybe having better nutrition overpowers the effect of pesticides, varroa mites, etc.