Monitoring for Varroa & Nosema

by Nick Delaney

Notes from a talk by Nick Delaney given at our 15th May 2010 meeting:

A. Varroa Destructor
Follow this link for images of varroa  destructor.

Summary

• Varroa is an external parasitic mite, distributed particularly in Asia (origin site), the US, the UK and continental Europe.
• Varroa infestation provides a context for significant weakening of a colony through infection, disease and shortened lifespan.
• Varroa control is therefore viewed as a primary aim of much beekeeping activity, although methodologies vary greatly.

Description

Photo © Wikipedia

Adult females are reddish brown in colour, have eight legs and a flattened ovoid body of 1 – 2 mm in diameter. They attack both brood and adult bees, sucking blood and leaving open wounds, which weakens the bees and spreads disease/infection.

Adult males are about half the size of females and yellowish in colour. They only attack sealed brood.
Mites have a preference for drone brood, probably because the pupation period is longer.

Impact
As noted above, the feeding habits of the mite results in parasitic weakening of the host and, most importantly, cross-contamination of disease. The major disease indicators of varroa infestation include deformed wing virus, acute bee paralysis virus and slow paralysis virus.

Bees can tolerate varroa at low levels and are believed to have co-existed with the mite for decades in Asia, where hive mite populations do not increase exponentially throughout the season as is the case in Europe.
However, once a critical mite population threshold is reached hives will be affected by a combination of:

• Decreased adult bee weight
• Decreased adult bee lifespan
• Virus spread
• Deformed wings
• Reduction in drone numbers
• Increase in drone infertility

Photograph © Wikipedia

It is probable that a fatal mite threshold is reached in European (mellifera) honeybees because the pupation period of the European honeybee is two to three days longer than that of the Asian (cerana) honeybee. In Asia, therefore varroa mites, which breed in capped brood, only have time to produce one offspring. In Europe between 5 and 6 offspring are produced on average.

It is this hyperbolic increase in mite population throughout the brood season in
Europe which creates the critical infestation threshold and typically overcomes
a colony during the cold season due to a fatal weakening of the winter bees.

Monitoring
Due to the destructive nature of varroa infestation it is essential to monitor mite population throughout the season and take action if levels breach a safe threshold.

The standard monitoring methodology is to count mites falling to the floor of a hive using a sticky board, preferably in conjunction with a mesh varroa floor.

The sticky board is left on the hive floor, ideally for seven days, and the number of varroa stuck to the board is then divided by the number of days the board has been in place.

This calculation gives an average daily mite count which is then multiplied by a season-dependant constant to provide an estimate of mite numbers in the hive. In the UK, typical seasonal multipliers are as follows:

• May to August 30 times average daily mite drop
• September to October 100 times average daily mite drop
• Rest of year 400 times average daily mite drop

Thus, if one counts 28 mites on a sticky board left in place for 7 days during May, this gives an average daily drop rate of 4 which, using the May to August multiplier estimates the mite population to be 120. The same drop rate in March would suggest a mite population of 1,600.

The National Bee Unit (NBU) recommends mite control intervention when the estimate infestation level based on such a calculation exceeds 1,000 mites (although the old MAFF guidance was 2,500 mites, so some leeway).

Treatments
There is little disagreement about any of the above discussion. Where practices begin to diverge is in the treatment used to bring mite levels down and/or maintain them below a critical level. Possible treatments fall into 4 broad categories:

1. Hard chemicals
Varroa has traditionally been treated with Apistan (fluvalinate) or Bayvarol (flumethrin) which was initially successful in radically reducing mite populations.

However, eventually the blanket application of these chemicals meant that mites were effectively selected for resistance and these treatments are no longer effective.

The use of chemicals is also likely to contaminate honey.

Whilst new chemical treatments are being developed and, notably in China and the US, illegal chemicals are widely used inevitably such practices will simply create further resistant strains of mites.

Current guidance even in forward thinking traditional environments such as the NBU is therefore to avoid hard chemical treatments.

2. Soft chemicals
There have been attempts to develop chemical treatments which are not systemic and which will not therefore build up resistance. A key group of such treatments are naturally occurring acids such as formic (fumigant) and oxylic (liquid) acid.

Whilst effective in controlling varroa, dosage is extremely difficult to control and both acids are harmful to bees in the wrong dose.

Even at the right dose, the acids appear to shorten bees’ lifespan and whilst a colony can cope with this during the summer, a shortening of the lifespan of winter bees can cause colony collapse.

3. Natural
(a) Powder dusting
Usually powdered sugar, dusted over bees and combs, which results in a 30% drop of phoretic mites in first hour after treatment. Also thought to stimulate grooming which can improve mite fall.

Whilst this simple mechanical treatment undoubtedly reduces the number of mites in the short term, the 30% efficacy rate means that frequent and repeated treatments would be necessary to control a hive suffering true
hyperbolic mite population growth.

This treatment also does not attack the breeding and juvenile mites still in capped brood at the time of treatment.

This treatment is probably therefore only suitable to maintain mite populations in colonies which already display signs of natural mite resistance.

(b) Essential oils/plant extracts
There are a number of products based on essential oils and plant extracts, predominantly thymol, which have been used with varying degrees of reported success.

Whilst a natural extract, bees dislike the smell of thymol and may be disturbed by its use. It will also taint honey if used before harvesting.

For an essential oil recipe and methodology visit this link.

(c) Integrated Pest Management (IPM)
IPM is an attempt to bring together various methods of pest control that, in combination, contain mite levels more effectively than any single treatment.

The following combination of activities would be in line with a generally ‘natural’ approach, and should be successful without the need to resort to chemicals.

• Free cell size
• Powder dusting
• Drone trapping in traditional hives or culling in horizontal Top Bar Hives
• Interruption of brood cycle through hive splits
• Varroa floors
• Essential oils

(d) Behavioural breeding
This isn’t really a treatment but it is probably the long-term solution to the varroa problem.

In nature, parasites co-evolve with their hosts. There is no advantage to the varroa in destroying its host colony, quite the contrary, and it is likely therefore that over time it would evolve to moderate it population growth in European bee colonies. Bees also would naturally select for mite-resistant traits.

The blanket use of hard chemicals when varroa first appeared in managed European bee apiaries means that such co-evolution has not yet properly begun. However, some European bee strains, notably Russian, have a natural resistance to varroa built from a propensity to groom aggressively to remove mites from adult bees, and to detect the mites in capped brood and eject the infested pupae from the hive.

Several projects are now underway to breed from these strains and in time it is likely that naturally resistant bees will be made available to commercial beekeepers and hobbyists.

In the meantime we should all monitor our own colonies and, where possible, actively look to split and expand our more robust populations.

B. Nosema
Follow this link for images of Nosema

Summary
A common, host specific unicellular parasite of the class microsporidian, which affects all insects. Nosema apis is the species which affects the European honeybee.

Description

Under a microscope the parasite looks like a grain of rice. It develops and multiplies in the cells of the epithelium in the mid-gut of adult bees and is mainly transmitted through the transfer of spores when young bees clean up faecal material on contaminated comb.

Impact
Reduces the lifespan of infected bees, increasing winter mortality and causing poor spring build up.
There are no specific symptoms but the disease is linked with dysentery and virus diseases indicated by bees crawling outside the hive.

Infected colonies can appear to recover during summer when bees defecate away from the hive and infected bees die without transmitting the disease.

However, the spores persist on contaminated comb and often trigger a more severe infection the following winter.

Monitoring
Due to the lack of direct symptoms there is no specific monitoring programme but where bees display any of the linked indicators noted above a simple diagnosis test should be performed.

Kill 30 to 35 bees and mash the bodies in a pestle and mortar with a few drops of water. Observe a drop of the resulting soup under a x400 microscope to identify the distinctive rice-shaped spores per the photo above (the NBU will do this test for you).

Treatment
The only effective treatment for nosema apis is Fumidil © B, an antibiotic fed to the bees through treated syrup.

It is difficult to use correctly, and combs will also need fumigating with acetic acid or replacing using a shook swarm technique as the spores persist in the comb even if reduced in the bee population.

by Nick Delaney
May 2010

Bumblebee Rescue Programme

Being interested in all species of bee YABeeP will often attend calls as part of our swarm collection duties where the householder has a problem with bumble bees. Most beekeeping groups don't do this as bumbles don't produce honey in sufficient quantity or of a taste acceptable to the human pallet. 

Moving the humble bumble

Buff tail - Photo © Wikipedia

Bumbles nests are quite small building up to only a maximum size of around 200 bees in high summer - compare this to the 50,000 plus bees in a summer honeybee colony. The bumble is an annual species where the nest dies out each autumn and only the newly hatched queens, around 10 - 15 of them, survive the winter. These new queens leave the nest and hibernate in the ground ready to start a new nest afresh next year while all the males and female workers die off. Another good reason to leave your garden tidying to spring when the hibernating bumbles have safely emerged.

Typical bumble rescue box

When on a bumble call-out we always try to educate the caller to try and persuade them to keep and enjoy the bees, in the knowledge that they won't sting and will be gone come the winter. Please note I said that they don't sting - bumbles can sting, but they won't unless their nest is attacked or you violently antagonise them by flailing your arms around in an attempt to knock a curious bee away. In fact bumbles are probably the most passive stinging insect and will just fly around a person who takes up camp in immediately front of their nest. Most of the 250 species of bee in the UK don't have stings, it's only the bumbles and honeybees that do. The best advice if a bee, or wasp for that matter, flys around you is to stand still and ignore it. It has no interest in attacking you but is just checking you out to see whether you are a source of pollen or nectar. Once it has finished checking it will fly off.

Photo © Wikipedia

Sometimes, however, the householder  for their own personal reasons will be too worried and insist that the nest goes - what a shame that our modern excessively health and safety concious society means that folk are brought up to fear these charming gentle creatures that are responsible for so much of the pollination of our crops and flowers. Did you know that commercial glass house and polly-tunnel growers import bumble nests to pollinate their crops and kill the bees when the job's done - what a crazy world!

A nest of Red tail bumbles in a rescue box

Provided the bumbles are readily accessible YABeeP will remove them and relocate into a safe location, usually our member's gardens. The main species we get called to around North Somerset are ground nesting Buff-tailed, White-tailed and Red-tailed which prefer to nest in old mouse nests - these are easily relocated by placing them in a purpose built bumble box and moving them to their new location. Amazingly they immediately learn where their new home is and come and go quite happily. The other less common species we sometime have to move is the Common Carder which lives in the open in plant mass and is far harder to relocate successfully.

Examples of bees moved

May 2010 - Milton Buff Tails
One of the calls we attended in mid-May 2010 was to a garden in Milton where, following advice seen on a CBBC programme, they had successfully attracted a Buff-tailed bumble queen to nest in a very small nest box which they had hung on the wall. Unfortunately, the box was too small to contain a full nest of Buff-tail's and they had nowhere in their small garden to re-site them into a bigger box so we relocated them.

23 May 2010 - Milton bumbles moved into their new home

The original nest box now inside the new one.
As the nest outgrows the smaller box it
can expand into the larger box which has
 a perspex viewing window on top

Returning Buff-tail bumble (Bombus terrestris) forager lands at entrance

May 2011 - Clifton Tree Bumble Bees (Bombus Hypnorum).
The owners of a house in Clifton were having extensive building work done, so rang YABeeP. The Bristol Museum's Etymologist had confirmed that these were rare so the owner asked that they be moved. Jo and Ali were happy to oblige.


Tree Bumble Bees are quite rare at the moment, having colonised Britain in 2001. It is suggested that they prefer to live in holes in trees. However, this colony decided upon a disused, rather large wasps' nest in a loft in Clifton. Link (scroll down to 'Rarer Bumble Bees' section). They are now safe and rehoused at Ali's.

Bombus Hypnorum, the Tree Bumble bee

taken residence in old wasps' nest.

At a guess, they started nest-making at the bottom of an old

 wasps' nest and the weight of their honey cells made the bottom break off.

They made their nest from the roof insulation!

There is a lot of nest unseen under this little lot.

Boxed and ready for relocation.

Bye bye Bristol, hello Yatton.

For more information on this species see the Bumblebee Conservation Trust website.

Also see this BBC video on bumble bee flight patterns.

See also YABeeP's main Bumblebee page.

Honeybee Cut-out

As part of YABeeP's swarm collecting duties Ali and I performed a 'cut-out' of bees from a window hip roof of a property in a nearby village yesterday. These were wild bees that had been living there for a year. The whole operation and surrounding story is detailed below - click on any image to enlarge it.


Background
The story starts in June last year (2009) when, as part of our swarm collection duties, I had been called to a property in the next village. The owner had bees coming & going from the hip roof  of a downstairs window. At the time I was able to confirm that it was a established colony of honeybees, however, I was unable to remove them as this would call for the dismantling of part of the roof and a builder would be needed to make good. I gave the usual explanation about the honeybee life-cycle and advised that, in my opinion, the bees would probably not be a problem for the householder. However, there was also a wasp nest in the same roof which were clearly a concern to the owner. We left it that I would be happy to attempt a 'cut-out' once she had spoken to her builder and had agreed to their costings to repair the roof.

Bees entrance under top corner of tiles

Like most amateur beekeeping groups, YABeeP normally just collects swarms which by their nature reside in the open. Once a swarm has moved in to its new home it ceases to be a swarm and becomes a colony. Removal of a colony is a far trickier business and an established colony requires a lot of time and care if one is to preserve the bees.

In the event the builder didn't manage to speak to me until the autumn when it was clearly too late in the year for a cut out to have the chance to rebuild their colony and survive the winter.

2010

First peep at the prize

Move forward one year and, just as we were settling down for last week's monthly YABeeP meeting, the owner arrived reporting that a swarm had issued from her roof colony, darkened her sky's and alarmed both her and her neighbour. A wild swarm, what an exciting prospect for us so we agreed to attend as soon as the meeting ended. It is worth mentioning here that as a sustainable bee group we particularly appreciate wild or feral bees as they managed to survive without being subjected to the chemicals, additives and butchery that many conventional beekeepers practice. 

Does my bum look big in this?

As soon as the meeting ended a small party of YABeePers went a-swarm-hunting – a bit like Morris dancing but with bees, not bells! Unfortunately, the swarm had high-tailed away and could not be found but arrangements were made to meet up with the owner's builder to discuss the cut-out to remove the bees. 

Yesterday

As subsequently arranged Ali & I attended yesterday morning, planning to avoid the full heat of the sun as the weather had turned hot. We  arrived with ladders, bee vac, swarm boxes, comb boxes, buckets, and all the paraphernalia necessary for collecting an established colony of bees. We were exhausted before we even started just carrying in all the equipment and setting up!

Healthy and strong despite earlier swarm

The exercise started with the removal of the mortar sealing the top tiles which entailed multiple hard blows with a hammer to break the rock hard line of sealing mortar. All this bashing on their roof meant the bees knew full well that something was up so sent their guard bees out to greet us. 

Once a few tiles were removed we established that the comb was attached to the rather old and disintegrating roofing felt which was now now sagging under the weight of a years worth of very laden and sticky honeycomb. With the assistance from a very brave and willing Jenny, the household gardener who I loaned a beekeeper's suit to, 3 of us attempted to cut out the felt trying to rescue at least some of the brood comb.  It may have been the hot weather weakening the comb though more likely it was the weight of honey combined with a weak and flexing felt but we totally failed in rescuing any so it ended up as a damage limitation exercise removing slabs of oozing comb a piece at a time without crushing bees, especially the queen who we needed to preserve to keep the colony viable - what a sticky exercise ending up with cardboard sheets of rescued comb littering the floor! 

Given that this colony had only swarmed a few days earlier there was a mass of bees remaining and a loads of honey, it was a truly healthy colony. Their health is all the more surprising given that last summer the owner had called a pest company to poison the massive wasp nest which was just inches away from the honeybees - see photo. This just goes to prove that bees left alone and not interfered with by the beekeeper can and do make really strong colonies. They know what they are doing, just give them the space and allow them to do it; as with many things in nature man really does not know best! What a nonsense that some, more ignorant, beekeepers are calling for wild swarms to be destroyed – and yet they they still wonder why the bees are having problems!!!

After a while we had managed to remove all the comb and, for the most part, had left the bees undamaged – although there were a couple of hundred honey-drenched bees on the ground wondering what had hit them. With some improvisation we rigged up a Warré box above the void of bees hoping that the bees and queen would move up into it so that we could return at dusk and remove the bees and hive them up in a members hive – in effect they would have made a wild bee shook swarm. 

With honey everywhere it was time to clean up ourselves and all the equipment used – boy does the sticky stuff get everywhere! Then, in the full heat of the day, we had to remove all the imported equipment all the way back to the car. Arrangements were made to call back at dusk and, if successful, remove the bees. There was a nagging fear that the bees might ignore the box we had so helpfully provided for them and just move further into the roof space, though we had a contingency plan should this happen to return the following and and vacuum them up in out YABeeP patent bee vac.

Warré box in situ

We managed the whole exercise with just a couple of stings each taken through our gloves – so much for Ali's kevlar protection! I had one exciting moment when we were clearing up when a bee flew into my ear canal. The sound and tickling makes it very frightening and I probably acted like a total woose but I had experienced the same thing last year when I also took a sting when trying to extract the bee so, with Ali's caring demeanour (she laughed her socks off really), we waited and allowed it to reverse out and fly off with no harm done to either of us – phew!.

The story develops

Just inches from poisoned wasp nest!

Later that afternoon I received a further call from the owner reporting that a swarm had been found in a neighbour's garden. Could this be last Saturday's swarm, that would be 5 days outside so not likely but just in case I got there asap to retrieve the prize. In the event I got arrived just too late – they had been there half an hour beforehand but the swarm had just left with just a few stragglers remaining on the rose bush. Scout bees had been seen earlier nosing around two spots on the nearby house and upon investigation we found them at the second spot still in the process of 'moving in' to a rainwater drain that entered a really substantial porch roof-space. Cursing that I'd just missed this swarm I advised the owner of their options then left. 

The Prize

Job done

Ali and I returned as promised that at dusk to hopefully remove the bees from the original site only to find that they'd totally absconded; not in the box or the rest of the roof space. Disappointing for us not to get those bees given all that hard work we'd put in but the owner was happy that they'd gone at last and at least we have helped contribute to the local feral population.

Post script
We'll never know for certain but piecing together all the evidence it is highly likely that the swarm I just missed earlier that evening was probably the absconded bees from our cut-out. It's surprising that they found their new abode so quickly but then they knew the area and, after all, had just exchanged one roof space for another. So much for the recession, these bees had bucked the economic trend and moved up market!

I just marvel at how healthy these wild bees were and only hope that their new landlords accept them and allow them to stay and they can then throw off swarms which we will happily collect in the future.

Robin
22nd May 2010

Bumble bees going cheap! Or should that be buzz?

Our 1st swarm of 2010

A message to all YABeeP members:

Whoopee, the swarm season has started for us!

As you know we already operate a honeybee swarm waiting list.

However, if you built a bumblebee box which didn't attract any bees this spring so is currently vacant and you still want some tenants then bring it along to tomorrow's meeting - please write your name clearly on or under the box in weatherproof ink. The calls have started and Ali and I have already been to 3 bumble calls this week - she is now the proud mum of a nest of buff tails.

YABeeP's bumble recovery service!

We will then use your box on any future calls when we recover bumbles which you can then place in your garden and enjoy - again they'll be offered on a first come first served basis.


Robin

Bees of Yatton

[Note: This YABeeP webpage records the bees seen in and around the local area. Started in April 2010 the development of this page is very much a 'work in progress' - species will be added as members photograph, research and record them - please be patient.]

Bees are classified in the family Aculeata, part of the order Hymenoptera and are listed below according to their 3 general groupings - Solitary bees, Bumble bees and Honeybees. We have decided to also include other species of interest either because they mimic the bees (e.g. Bombylius major, a parasite of the solitary bee) or because they evolved from a similar species - e.g. wasps.      Click on any photo to enlarge it.

A. Solitary Bees

There are over 200 species of Solitary bee in the UK and are generally grouped as ground nesting, cavity nesting and parasytic bees.

Species: Hairy-footed flower bee - Anthophora plumipes

Description: Active from March to late May. Flys with a darting movement - moving quickly then hovering. The male can be easily confused with a bumble bee although the female is all black with orange-yellow hind legs. The male is similar to Bombylius major, although the latter only has 2 wings being a fly which mimics a bee.

Female Anthophora plumipes entering nest in the mortar of Yatton church. Note orange hairs on hind tibia

Link to BWARS pictures

Genus: Mining bee - Andrena

Description: There are over 60 species of the Andrena mining bee in the UK. Mostly active April to early June. The female tunnels into ground to make nest in soil, often unnoticed in the grass of our gardens though they can have volcano like mounds surrounding the holes which are glued by a substance the bee excretes.  The tunnel can be up to 12" deep with many branches where the female stores pollen & nectar and lays eggs in individual cells. The eggs do not hatch until the following spring.  Some species share a common entrance but build separate branching chambers below. Whilst they do posess a sting it cannot puncture human skin so is harmless to children. 
Pictures - Species probably Andrena nitida or Andrena haemorrhoa nesting in lawn in Yatton during May

• Link to the Garden Safari website for identification of the more common species of Mining bee. 

 B. Bumble Bees

There are around 20 species of bumble bee in the UK.

C. Honeybees

Apis meliffera

There is only one species of honeybee in the UK known as Apis Meliffera - our native bee being from the race European Honeybee or Black bee. However, because of the commercial interest attached to honeybees different races of Apis Meliffera have been moved around the world by beekeepers in search of a 'better', ie more commercially productive, bee - a practive YABeeP strongly disagrees with. These races have all interbred and the true native British bee, which had over the millenia adapted to our  environment and climate, is only found in a couple of pockets. The honeybee you see in your garden will be a mixture of several races of bee.

Species: European honeybee - Apis meliffera

Apis meliffera with full pollen baskets

Description: A true social bee common in the area and active year round though the colony goes into winter cluster so is rarely seen flying over the cold winter periods.

D. Bee mimics and others
Species: The Common Bee-fly - Bombylinus major

The Common Bee-fly (Bombylinus major)

hovering to feed on Myosotis (Fotget-me-not)

Description: This fly which mimics a bee acts like a cuckoo and flicks her eggs near to the entrance of solitary bee nest sites. The larvae are brood parasites of these bees esp. Andrena species.

Adults feed on nectar, using their long proboscises whilst hovering beside a flower. Aubretia is one common garden plant frequently visited.



Note: All photographs on this page are originals © YABeeP