Ruth, three things come to mind:

1. There are different strains of EFB...some are more virulent than others and are harder to clear. Some are oxytet resistant. So one experience is not likely representative of all EFB experiences. Great lecture by Dr. Kirsty Stainton that I think has already been posted here:
https://www.youtube.com/watch?v=z0B9o4GHq7U


2. Boosting the nutrition for an EFB colony also boosts larval survival as EFB competes in the gut for nutrients and dead larvae are starved larvae. So shifting to a better nutritional site would help suppress symptoms. But EFB will still be in the honey and stores. 

3. Randy pointed out to me the Ph.D thesis of Dr. Gordon Waddell, in which he speculated that the alkalinity of blueberry pollen may make the bee gut more susceptible to EFB. I think he suggested acidifying bee feeds, preferring lactic acid, and he went on to develop Megabee pollen sub. In the Megabee literature they discuss the long term deleterious effects of soy flour:

"Soy flour contains two types of sugars (stachyose & raffinose) that are actually toxic to bees as well as something called a trypsin inhibitor, which blocks the honeybees ability to break down proteins. Essentially, your bees get a short boost from the feed, but soy flour eventually ends up dragging them backwards."

And of albumin:

"This is because the albumen in eggs contains avidin, a protein that binds biotin and makes it unavailable to the developing larva. Biotin is a vitamin B complex that is essential for growth and development in animals and insects. Several studies have been done where egg products were put into insect diets and they slowed or stopped growth all together."

So...tinkering with supplemental feeds may alleviate EFB or help prevent it. And I am reconsidering my choice of pollen sub, which I use heavily to boost colonies while prepping for queen rearing, and for producing well nourished queen larvae during queen rearing. 

I would love a good discussion on prevention as I am likely picking up EFB from a local source that appears in early May (two years running, same infection dates...don't think my bees are that smart). I can put robbing screens on to deter infected drift bees, but how can I defend against my girls robbing infected hives or deadouts?

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