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Is EFB Becoming More Common and Difficult in North America?

Posted: July 26th, 2018, 11:49 am
by Allen Dick
Peter send me this and I don't have time to deal with it in depth at the moment, so maybe others can contribute experiences and thoughts. I'll write when I have the time.
EFB in my operation has been creeping up in severity (% of colonies and severity per colony) and I need a more effective way to deal with it.

A July 2018 ABJ article by Alison McAfee talks about a potential link between EFB flare-ups and pH of the bee gut. Apparently Gordon Wardell's PhD thesis was related to this and he apparently made his MegaBee patty recipe more acidic to help protect against EFB.

Have you ever looked into the pH of your/Global Patties patty recipe? If you were going to make the recipe more acidic, how would you go about it? My first thought would be to add ascorbic acid (vitamin C) since it is relatively low cost, human food grade, not toxic to bees, mixes easily, and the amount needed can be computed with some knowledge of chemistry. However, I realize the possibility that making the food more acidic might not make the gut that much more acidic because the ascorbate could move across the gut wall or be broken down by digestion.

The more I look into EFB, the more complexity I see. It is almost the perfect parasite in that it rarely kills its host. I do suspect that there might be a co-evolution thing happening between EFB and varroa which might be a factor in why EFB is becoming more troublesome in North America. Common patterns suggest that hive stress and changes in pollen sources affect the disease. Hives usually recover on their own, but the reduced bee populations result in a reduced honey crop. EFB can persist, without symptoms, both in live bees and in brood comb. Therefore, cleaning the disease out of a hive requires replacing the brood combs and administering an antibiotic. Hives that need to raise a new queen during a serious EFB infection may not be successful at that.

It is possible, in theory, to breed a line of bees that are strongly resistant to EFB, but the variability of the disease makes it difficult to create a challenge condition to measure EFB resistance. I buy my queens from HoneyBee Genetics and they are strongly disease resistant. The owner/operator of that breeder recently inherited an EFB-infested beeyard from a friend and is doing an experiment by requeening the symptomatic EFB colonies. I've told him that the outcome of that experiment will be difficult to interpret. I have a number of EFB hives headed by his queens (marked). I requeened one such EFB hive with a new HBG queen and 30 days later observed a near-perfect brood pattern. I think the improvement was caused by a combination of reduced brood rearing during the transition to the new queen, plus general reduction of brood rearing post-solstice, plus a complete changeover in pollen sources. I don't believe 9 days of hatchout with slightly different genetics can!
account for all the capped brood having a great pattern.

From a practical commercial honey-producer beekeeping perspective, I think a good EFB management approach would have two components:
1) identified EFB cases get shookswarmed plus Oxytet
2) a special feed or resistant genetics reduces the severity of any EFB infection.

Re: Is EFB Becoming More Common and Difficult in North America?

Posted: July 26th, 2018, 9:50 pm
by Allen Dick
Personally, I have never seen much EFB either in my own hives or when inspecting all around Alberta over decades and when lifting lids in the USA.

In my experience, EFB was a seasonal matter where a few cells might show in spring, then promptly disappear. Also, we used OTC prophylactically for AFB prevention in those days and OTC cures EFB instantly.

The consensus was that EFB was a symptom of malnutrition and it is very common on blueberry pollination in particular. I've heard it can be a scourge in Britain.

As for the contamination of comb, it is not spore-forming, so I should think it cannot last in comb and the source is more likely environmental.

EFB is also opportunistic and is maybe the most obvious but last arrival of several co-infections. If the others are viral, they are bound to be harder to detect and EFB would be the diagnosis, even if it is the only end point of a series of infections. I wonder how much of the 'EFB' seen these days is actually snotbrood and actually only a visible symptom of the infections spread by varroa.

Re: Is EFB Becoming More Common and Difficult in North America?

Posted: July 26th, 2018, 9:56 pm
by Allen Dick
pH in patties. Interesting point. Andy Nacbbaur used to say that the secret ingredient in homemade supplement was Tang.