Oxford Bees

Bee diseases

The value of a feral colony

Submitted by will on Fri, 30/03/2018 - 19:13

People value things more when other people value them. Price is a useful proxy for judging what other people value, but price reflects usefulness and abundance and status and cultural history.

It takes experience and time to learn the value of that which is abundant, cheap or free. It takes no time to be influenced by someone.

I value feral bee colonies. Established feral colonies are where natural selection is allowed to happen. Established feral colonies are survivors.

Bee Keepers in England have valued the Italian strains for decades, particularly those which were selectively bred from 'Italian' stock at Buckfast Abbey: the Buckfast Bee. Professional and mainstream bee keepers value the Buckfast Bee because it is easy to manage and produces lots of honey. It's a product of modern agricultural thinking.

Honey bees now face new challenges: new invasive species; new pests; invigorated diseases; changing land use leading to less forage, or seasonal variability in the amounts of forage; new pesticides.

The Varroa mite is a significant challenge. It is a pest which was in balance with its' original host, the Asian Honey Bee (Apis Cerana). The move to the Western Honey Bee (Apis Mellifera) changed the mite's life-cycle so that it now infests worker brood as well as Drone. This has increased its' virulence. The mite has also super-charged existing viral diseases -- particularly Deformed Wing Virus which is implicated in the increasing number of failing colonies (Colony Collapse Disorder). The Varroa mite is a parasite which is out of balance with its' host, the Western Honey Bee.

The popular Buckfast Bee does not cope well with Varroa.

Feral colonies are probably either descended from, or related to Buckfasts. What sets ferals apart is that they have interbred freely and been subject to natural selection. Newly escaped colonies which cannot cope with the new challenges will die within 2 or 3 seasons. My best survivor colonies have been untreated for at least 5 seasons.

Oxfordshire is unlikely to be the place where Western Honey Bees evolve a resistance to Varroa. Evolution is not that convenient. Oxfordshire can be a place where natural selection is allowed so that the bees can reach a survivable balance with Varroa. My low intervention approach is intended to support that.

Deformed Wing Virus appears to be seasonal in Hive A

Submitted by will on Wed, 31/05/2017 - 06:40

For at least the last 2 years I have observed a definite pattern in Hive A. In spring there are lots of crawling bees outside the hive. Some are clearly affected by Deformed Wing Virus (DWV); others maybe by another paralysis virus or by exhaustion.

They crawl around near the hive. If you launch them into the air they fall back to earth. They never make it back to the hive and have probably been ejected by the other bees. The Sparrows eat some of them. The others presumably die out of site.

By mid-May they have all disappeared. Mite drop on the hive floor has diminished so much that I've started wondering whether Ants are removing them.

I don't have an explanation. Maybe there is greater transmission of viruses when the bees are confined to the hive during the early spring build up. Maybe these bees have been in the hive for a while and are only ejected in spring.

I'm going to write to a DWV researcher to ask whether seasonal expression of DWV and other diseases is usual, and if she has an explanation.

An early morning viewing

Submitted by will on Mon, 29/05/2017 - 08:50

I went to the visit the bees at my out-apiary this morning. I took the lids off the hives but left the brood area alone (except for Hive F) because the air temperature was cool. Everything was finished by 0630.

A side effect of looking at hives in the early morning is that all their flying bees are still in the hive. These are the bees which are most likely to defend the colony. As a result the bees seemed noticeably more angry when I opened the hives.

All the hives have plenty of space, with the possible exception of E.

Hive D. The hive floor had evidence of a lot of activity: comb building; hatching of brood; Varroa mite drop and a couple of dozen antennae. The antennae are interesting. Gareth says that when brood are ejected from the nest the antennae are pulled off first, where they fall to the hive floor. The body is then removed and will be disposed of by undertaker bees away from the hive. The brood may have been diseased or have been chilled. I would expect disease - specifically the effects of Varroa and their diseases. This hive needs further inspection into the brood nest. In any case, this is the hive where I was having difficulty with the Queen excluder so I ought to check that all is well.

Hive E. There seems to have been bearding yesterday. Bearding is when bees gather in large numbers outside the hive. This behaviour allows more space to cool the hive and suggests overcrowding. There were still bees outside the hive this morning looking wet and unhappy from the overnight showers. The hive floor had several splotches which I assume are bee poo. They may be pollen which has become wet. If they're poo then this suggests dysentry. Bees normally evacuate outside the hive. I need to read about dysentry and maybe have another look in the hive. I didn't look at the brood comb so I don't know whether there is more poo on the comb.

Hive C. There are signs that there's been a lot of activity in the hive. There are quite a few Varroa on the hive floor. This hive has a super which can be taken off.

Hive F. This is the recently established colony which swarmed from Helen's Top Bar Hive. There are still lots of Varroa on the hive floor but the rate of drop seems to be decreasing. This may not be a good sign because they're probably reproducing inside brood cells. It will be interesting to see how this colony fares. They have plenty of space. I get the strong impression that this colony is more aggressive than the others.

Hive G. This is the recently established colony which was caught as a swarm on the tree in front of my apiary. I gave them a Commercial hive with a super on top - and a Queen excluder. They have built loads of comb including new comb in the super. This shows a preference for building vertically through the boxes, rather than across the brood box as we might want. The colony looks very healthy. It has plenty of space and is dropping very small numbers of varroa.

Anticipating a balancing of the host-parasite relationship

Submitted by will on Thu, 25/05/2017 - 19:40

Parasites rely on another organism for aspects of their feeding and/or reproduction. Whilst parasitism is a complex subject, the relationship between Western Honey Bees and Varroa mites is relatively simple. The mites live entirely with and on the bees. Food, reproduction and transport is all provided by bees. In this case, if the host dies so does the parasite.

Some parasites have periods where they are hosted by a different organism - for example Influenza or Malaria. Some parasites have long lived dormant phases - for example Anthrax. These can fatally damage their hosts without killing themselves. Anthrax depends on killing its' host so that decay releases it from the body cavity. Varroa is not like this.

Until recently I have been looking for an increase in the tolerance or resistance of bees to Varroa and its' diseases. I now see that the virulence of the mite should also decrease. This will bring the relationship into a balance where the parasite will not kill itself by killing its' host.

The Varroa mite became much more virulent when they crossed to the Western Honey Bee (Apis Mellifera) from the Eastern Honey Bee (Apis Cerana). It started to infect worker brood, rather than just drone brood. This gave it many more opportunities to reproduce and so overwhelm colonies. I don't expect the Varroa to stop infecting worker brood, but I do expect some change in the rate of reproduction or the effectiveness of viral infection.

My untreated hives have survived for extended periods without suffering Colony Collapse Disorder. Maybe collapsing colonies are subject to multiple stresses: Varroa plus intensive apiculture and/or another disease. I don't see evidence of resistance but I do see tolerance and patterns of disease expression which don't have significant effects on the colony.

Hive F still shedding lots of Varroa

Submitted by will on Thu, 11/05/2017 - 05:53

I looked at Hive F's removable floor again on Tuesday 9th May. I counted 24 Varroa mites which had fallen out of the colony. That's 8 per day. Will they survive?

UPDATE: I visited the hive on 12th May after dark. There were another 32 mites. I've counted 88 mites in 7.5 days, an average of about 12 per day. That's very high. This colony has been untreated for a couple of years but it was from a bought queen before that. I don't think much of its' ability to manage Varroa.

Hive F settling in and shedding lots of Varroa

Submitted by will on Sat, 06/05/2017 - 12:37

I put the a swarm from Helen into Hive F on the evening of 2nd May. I had a look at the entrance and the removable hive floor this morning.

The colony appears to be settling in well, despite the colder May weather. There is shed wax on the removable hive floor; there are bees coming and going. It appears that they've been building comb and orienting themselves to their new area. I didn't look for pollen, but I wouldn't expect to see it this soon anyway.

I was very suprised to see a large number of Varroa on the hive floor. I counted 32, which is approximately 9 per day. A conventional bee keeper might urgently treat for Varroa in this situation. I'm inclined to wait and see what happens.

There may be exceptional reasons for the high level of mite drop in this new colony. They were contained for in the skep with a sheet under them before I collected so the varroa may have been shed over a longer time. I whacked the skep to dislodge them so that they fell in a heap on the hive floor. The fall of around 50cm may have dislodged more mites than would otherwise fall. Perhaps this colony is tolerating a higher number of mites. The parent colony seems to be thriving.

Introducing a new swarm to the apiary does raise concerns for me. This colony has not been feral for as long as the colonies from hives C, D and E. They may have genes which help tolerate Varroa and their attendant diseases but it is less likely. This colony may also introduce new strains of viruses which are present in the existing hives. There are known several strains of DWV. I consider this risk low because these strains tend to be geographically separate. It would be unlucky to introduce a new one. There is a risk of exposing the new colony to diseases already present in the apiary. I have seen evidence which suggests ABPV in Hive D.

I'll have to see what happens.

Wax Moth

Submitted by admin on Sat, 25/03/2017 - 12:08

Hive B has a wax moth problem - or they're unusually good at coping with it. I'm betting that it's a problem. I'll know when it's warm enough to have a look inside.

I have found 4 wax moth larvae on the removable floor of the hive. I've been keeping the floor clear of debris so I don't think they hatched on the floor, unless there is more debris that I can't see.

My expectation is that this colony is tolerant of wax moth. That's not a good thing. This colony is small and has superseded at least once. It hasn't shown any characteristics which are obviously good from my point of view. I'm not going to destroy it but I wouldn't be sad if the hive became available during swarming season.

 

Identifying Chronic Bee Paralysis Virus

Submitted by will on Thu, 09/03/2017 - 19:09

Do some of my bees have CBPV? Today I watched 5 bees at the entrance to Hive D. They were on the ground below the landing board. They weren't moving much. Two or three of them were considerably darker than I'd expect.

Could it be the weather? Perhaps these bees were just chilled. Am I a Bee Hypochondriac? Certainly I have no idea whether this hive has this disease.

I took a moment to read the CBPV factsheet from Beebase. The virus is often present in the European honey bee at low levels. Stress causes the expression of the virus, usually in 'the peak of spring and summer'. I don't think that today is the peak of anything. There is a litter of decaying bee corpses outside Hive D. The hive was notable for its' prolific production of brood at the expense of stores. I hefted the hive and it feels ok for stores. What, if anything, could be causing this stress? Could they be too cramped?

There are more questions than answers. I shall revisit the bees and try to take pictures. I'll take an extra super and put that on. If they're too cramped then extra space could ease the problem.

An inspector calls

Submitted by will on Sat, 27/08/2016 - 20:50
The Regional Bee Inspector looks at brood

The Regional Bee Inspector visited my out-apiary today.

We went through all 3 hives and checked all the brood. There were occasional dead brood which had advanced DWV - evidence of varoosis - but thankfully there were no other diseases. Best of all, the colonies are clear of AFB.

The major threats to honey bees from pests in the UK are varroa and AFB. We await the arrival of the Asian Hornet and Small Hive Beetle. The Asian Hornet is in France, and has been found in Guernsey but has so far not come been found on the mainland. Small Hive Beetle originates in Africa and has spread to several countries including USA. There was a small outbreak in Italy which, it's hoped, has been contained.

There was a thunderstorm as we left my out apiary. We'd hoped to inspect my home hives but it hasn't happened. Next year...

Joining the ReViVe project

Submitted by will on Thu, 02/06/2016 - 19:32

BBKA News ran an article in June about a new project to study Deformed Wing Virus in untreated hives: the ReViVe project*. This is part of Professor S. Martin's research group in University of Salford.

I contacted the PhD student who is undertaking the study and offered my two new hives. These have come from a feral swarm and have not been treated or controlled for Varroa.

The two hives are now part of that study. I have sample tubes to fill with bees for testing. I'm wondering how to persuade the live bees into the tubes. It's going to be tricky.

* Rolling out the Evolution of resistance to Varroa and DWV