Oxford Bees

Pests and Diseases

No crawling bees outside Hive A

Submitted by will on Mon, 07/05/2018 - 07:19

For at least the last 2 years there have been flightless bees crawling around outside Hive A. These bees were clearly suffering from Deformed Wing Virus or another disabling virus. This year there are none.

The cause was explained to me by a researcher at University of Salford. All winter the Varroa mites feed from worker bees. They accumulate DWV virus particles. In spring, when brood production increases they rush in to infest the new brood and transfer more virus to them. These bees show visible signs of DWV -- deformed wings or an inability to fly.

The absence of crawling bees can be explained in several possible ways.

  1. There are fewer Varroa mites in the hive. I usually check this by looking at the removable floor of the hive. I've found dozens of ants on the floor so I don't know whether they've been taking the Mite bodies away. I don't think that this is what's happening.
  2. The overall number of virus particles has fallen in the hive. It was very cold in April this year. This should have stopped the bees rearing brood. Virus is removed from the hive by bees or mites leaving the hive. If more mites died during April then it might explain some of the reduction.
  3. There are fewer brood this year. This seems most likely. The activity at the hive entrance is quite slow. I did look inside the hive and found only one frame of brood which was capped. I may have overlooked uncapped brood but it points to there being fewer bees and fewer brood. They're taking longer to build up this spring.

On reflection I think that Colony 01 is smaller this year which would mostly explain the absence of crawling bees.

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.

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.