Thanks for the responses--
To answer everyone's questions:
1. In the past I have seen EFB at random and in drone layers. The
treatment that has always worked was to give the drone layer frames to a
strong hive. The other successful treatment has been to requeen the
hive with a queen cell and the disease has always completely cleared
up. What alarms me this year is the disease reoccurs severely in the
second brood cycle after requeening.
2. Yes the hives are too close together. They all drift into each
other and there is nothing I can do about it. Just part of doing
beekeeping around my area. It does seem likely that they have always
had EFB but it has never expressed itself before. This seems incredibly
more contagious than American foulbrood since last time I had that I
burned two hives and have been clean for 6 years.
3. I last treated for mites in December. The hives that now have the
least EFB appear to have the most mites. The hives with the EFB have
very few mites, I suppose because they are not carrying much brood to
maturity. Believe me, this EFB is very different than what I have seen
with mite collapses.
4. These scales do not pop off the cell wall like normal EFB scales.
They have the raised head-bump and you have to destroy the cell to get
them out. The do not take long to form however.
5. Nutritional stress is the case as we were slammed with wind and rain
all May. Nectar has been coming in heavily but sporadically for a month
now. It alarms me that the EFB brood frames are dripping with nectar
but still have EFB since everything I read says it clears up with a
decent flow.
6. I tried shaking one of the hives out onto foundation and the EFB was
back within two weeks, so I don't think that is going to solve the problem.
7. I treated one yard with OTC and the brood was clean within 24 hours
in many of the hives. I am going to be treating my hives periodically
for the next year or two. I am burning the frames from the hives that
have died.
My feeling is that this outbreak is going to be almost completely
cleared up a month from now because of the increasing nectar flow. My
hives were stressed (but very full of bees) in almonds, then they
experienced a lack of spring pollen flowers, and then a month of wind.
So hopefully improved conditions will make it clear up as fast as it
appeared. Or else I am going to have a lot of equipment to irradiate.
--Jeremy Rose
San Luis Obispo, CA
On 6/18/2011 9:00 PM, BEE-L automatic digest system wrote:
> There are 5 messages totaling 265 lines in this issue.
>
> Topics of the day:
>
> 1. European foulbrood (5)
>
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>
> Date: Fri, 17 Jun 2011 22:10:40 -0700
> From: Jeremy Rose<[log in to unmask]>
> Subject: European foulbrood
>
> A few weeks ago on this list I described symptoms that I thought might
> be a strange looking American foulbrood. Larvae dying extended in
> capped cells, melting down and forming scales that look just like
> American foulbrood scale. In the mean time, USDA lab confirmed that my
> samples are of European foulbrood.
>
> A month ago, I had 8 hives with symptoms and all other hives looked
> great. Thinking it could be AFB I removed them before they died and was
> careful about sterilizing my hive tool etc. Now a month later I am
> finding EFB in pretty much all of my hives, some with classic symptoms
> (larvae yellow or dying in coiled stage) and some with the larvae dying
> under the cappings. Some hives have cleared it up on their own and most
> have become worse. The only hives being killed by it right now are
> splits with new queens.
>
> Since it must be extremely contagious to go from 8 hives to 350 in a
> month I am wondering if anyone else has had an outbreak like this and
> how long EFB typically persists on used comb. I read somewhere on the
> internet that it can survive for 3 years on brood comb, but I haven't
> found a scientific study. Right now I am medicating the worst hives
> with OTC and making honey with most of the decent hives. I am trying to
> avoid medicating all of them since we are going to be making honey
> constantly until October with all the rain this year. As they all
> appear to have it I am no longer concerned about mixing frames from
> infected hives.
>
> --Jeremy Rose
> San Luis Obispo, CA
>
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> ------------------------------
>
> Date: Sat, 18 Jun 2011 05:19:38 -0400
> From: allen<[log in to unmask]>
> Subject: Re: European foulbrood
>
>> A few weeks ago on this list I described symptoms that I thought might
>> be a strange looking American foulbrood. Larvae dying extended in
>> capped cells, melting down and forming scales that look just like
>> American foulbrood scale. In the mean time, USDA lab confirmed that my
>> samples are of European foulbrood.
> AFB scales are hard to remove without deforming the cell. They also
> have a distinctive bump where the tongue was, if the bees have not
> polished it off. They also take quite a while to form and do so in capped
> cells.
>
> EFB is found pretty well everywhere in North America, AFAIK, and historically has
> typically only expressed itself under some stress conditions like mal-
> nourishment. EFB outbreaks were quite uncommon when people routinely treated
> with OTC. EFB has been known to spread through an outfit and cause
> serious loss, although I have never seen that in my forty years of beekeeping
> or when inspecting. Apparently, EFB is comsidered a serious problem in Great
> Britain.
>
> On the other hand, the first indication I had of (what I think was)
> varroa-related collapse of all my hives last year, I first mistook for EFB.
>
> An EFB diagnosis from samples does not necessarily mean that EFB is more
> than an opportunistic participant in the event.
>
> What are your mite levels? What have they been recently?
>
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> ------------------------------
>
> Date: Sat, 18 Jun 2011 07:03:28 EDT
> From: Chris Slade<[log in to unmask]>
> Subject: Re: European foulbrood
>
> Apart from beekeeper action, the usual reason for the spread of EFB is
> drifting of bees between colonies. How close together are your hives? Are
> they arranged in rows or scattered? Are they uniformly coloured or rainbow
> shaded? Are they on a mown sward or arranged among bushes or other
> landmarks?
>
> In times of prosperity (lots of nurse bees and a good income) EFB often
> goes unnoticed by the beekeeper as there isn't heavy mortality and the bees
> can easily clean up those that do die. The corpses can be removed whole by
> the bees without passing on the infection. In times of prosperity, infected
> larvae get enough food to enable them to pupate successfully, but still
> carrying the infection which they pass on. The symptoms you see: misshapen
> larvae usually, are those of starvation as the bacteria out-compete the larva
> for the food supply.
>
> As far as I know, I have had it only once, in July 2000. I spotted a couple
> of larvae looking uncomfortable in their cells in a nucleus. I called the
> bee inspector at once. He took a look and told me he thought it looked
> more like sac brood, but took a sample for the lab anyway. The sample proved
> positive for EFB. That was at the time when treatment with antibiotic
> (Aureomycin) rather than burning first became permissible in the UK. The
> Inspector treated them while I was away at Gormanston and when I came back I
> found in the hive the green dye with which he had mixed the syrup. The nuc
> weakened and died anyway. Of course I kept a close eye on the other 6 nucs in
> the mating apiary but none showed any sign of EFB.
>
> It appears that there may be some strains of bee that may have some
> resistance to EFB. A retiring professional beekeeper once told me that, after he
> had brought all his hives back from pollination contracts and had gathered
> them together in a holding yard, he found EFB in one hive. It took some
> time to arrange a massive bonfire and he couldn't move them away because
> there was a 'standstill order' on the apiary. In the meantime the EFB very
> rapidly spread from hive to hive and was everywhere except in one particular
> hive that never showed any sign of it; but it had to be burned with the
> rest.
>
> That is one reason why I number my queens rather than my hives. If I make
> the time I can provide a 'family tree' on the female side of those that
> didn't arrive with swarms this year, just in case any heritable qualities,
> good or bad, show up.
>
> Chris
>
>
>
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> ------------------------------
>
> Date: Sat, 18 Jun 2011 12:55:57 +0100
> From: Peter Edwards<[log in to unmask]>
> Subject: Re: European foulbrood
>
>> Since it must be extremely contagious to go from 8 hives to 350 in a month
> I would suggest that it has been in all 350 for some time. EFB has been
> called the disappearing disease because clinical symptoms can disappear and
> then re-appear. They usually appear at the start of a flow when many bees
> are recruited to foraging and larvae are fed less generously.
>
> In the UK it is a notifiable disease and can only be treated by our Bee
> Inspectors.
>
> For many years it was treated with OTC - rather unsuccessfully (27%
> re-infection rate) - with compulsory destruction for bad cases (over 50%
> visible infection), or at the beekeeper's discretion in light cases. In
> recent years treatment has moved to shook swarming, where all the bees are
> shaken into a clean hive with new frames and foundation. A queen excluder
> is placed under the brood box to for a few days to prevent absconding. At
> first the shook swarms were fed syrup with OTC, but the thinking now is that
> OTC is not needed. It is recommended that whole apiaries are shook
> swarmed - not just the colonies showing clinical symptoms as the thinking is
> that it will be in all the colonies. Re-infection rates are now around 4%.
>
> More information here:
> https://secure.fera.defra.gov.uk/beebase/index.cfm?pageid=89
>
>
> Best wishes
>
> Peter
> 52.194546N, -1.673618W
>
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> ------------------------------
>
> Date: Sat, 18 Jun 2011 08:15:10 -0700
> From: randy oliver<[log in to unmask]>
> Subject: Re: European foulbrood
>
>>> I am wondering if anyone else has had an outbreak like this and how long
>> EFB typically persists on used comb.
>
> Jeremy, you and I seem to observe similar phenomena in our apiaries (we are
> several hundred miles apart), although not necessarily in the same year.
>
> Historically for me, I'd see EFB occasionally during springtime when rain
> kept bees inside, or when colonies suffered from lack of forage or high mite
> levels. It is also very common in laying worker hives.
>
> But since about 2005, I'm seeing much more "EFB-like" symptoms, and
> especially "corn yellow" larvae. Unlike the "old" EFB, which nearly
> invariably went away with a good nectar/pollen flow, the "new" EFB lingers
> on, and infected colonies simply do not grow.
>
> As Allen noted, I suspect that EFB may be an opportunistic parasite taking
> advantage of bees stressed by mites, malnutrition, and viruses.
>
> More to the point, this season I've also seen a number of cases of the
> "watery brood" that you observed. It generally went away when the weather
> improved. In cases where it didn't, it responded to a single dose of OTC.
>
> I've been restocking the infected combs for a number of years now, burning
> anything that I suspect has AFB involved. I allow the combs to dry out for
> a few weeks first. I have not noticed the infection to spread, although I
> can often find an infected larva in hives.
>
> I sell hundreds of nucs each spring, and carefully inspect each one for
> brood disease when we are making them up (we don't nuc up diseased hives),
> and then again later when I am selling them with the new queen (mated in the
> nuc). It is extremely rare to find diseased brood in the new nucs. I
> suspect that the break in the brood cycle is the reason.
>
> I don't have advice for you other than that you may wish to treat at least
> one yard with OTC as an experiment. I'd be very interested in hearing your
> results.
>
--
Jeremy Rose
Sr. Apiculturist
The California Bee Company, LLC
www.californiabeecompany.com
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