The Basingstoke Beekeeper

Autumn 2007

Contents

Apiary Update

by Gordon Scott

This year seems to have been so pressured and so frenetic that I hardly remember what has happened in the apiary.

Both colonies have had more than their share of problems, but that goes for most bees this year, I think. The larger colony near the apiary entrance raised a good new queen and built up nicely. We've had a bit of a crop from them, which is bucking the trend for most of us. The colony round to the left raised a drone-layer, which after a few tribulation we finally managed to get replaced with a good queen and they've been doing fine since, though inevitably no crop.

This year for the first time we tried Exomite Apis in these colonies for our August anti-Varroa treatment. I'd originally planned to treat one with Exomite and one with Apiguard, to demonstrate both treatments, but a sudden rush of customers ran me out of stock for a while of ApiGuard.

Whilst it's possible that Apistan will still work, we have now had more years from it than even the most optimistic predictions and the longer one uses it "just one more time", the higher the risk of a problem. Like a mild version of Russian Roulette, each click reduces the chance of "making it through".

Treating with Exomite is quite interesting and has some similarities with the talc and icing-sugar techniques that we have occasionally used for varroa control. Exomite, of course, also has an active ingredient in the form of Thymol.

Exomite comes is sachets with a plastic tray. One bends down the corners of the tray and empties the contents of one sachet into the tray, spreading out the powder and breaking up any compacted lumps. The tray is slid into the hive entrance until the folded-down corners stop it going in further and the hive entrance is closed so that the only route in or out is over the tray. The instructions say with strips of foam, but pushing the entrance block across worked fine for me.

The powder is statically charged and as the bees pass over it, they pick up a quantity of the powder. This is a technique explored a few years back as a means of delivering treatments selectively to crops, now "turned on its head" so that the treatment is now applied to the bees. Once the bees have passed over the powder, they become quite covered in it and large numbers of bees appear all dusted in white, some flying and some running around on the hive front.

It's quite clear that the bees are not exactly enamoured of this powder as large numbers come out of the hive and congregate outside. Looking in the colonies a week later, it's also clear that this treatment is more than some bees can handle as there were quite a few casualties, though in the context of the colony as a whole, not a serious number. It's even possible that these been were just natural mortalities that the others are a little reluctant to throw out of the hive.

The second sachet of powder is put into the tray two weeks later. I was unable to be present during this process, but presume behaviours were similar.

One attraction of Exomite is that the whole course is finished in four weeks, rather than the six to eight weeks of ApiGuard. I suspect but have not yet investigated, that the amount of Thymol smell may be lower as the treatment appears to be two individual "hits" on the Varroa, rather than a sustained treatment. It's notable that ApiGuard's first tray is used primarily to aclimatise the bees to Thymol before increasing the dose with the second tray.

Both colonies seem to have come through the ordeal OK. What the impact has been on Varroa remains to be seen. There wasn't a huge drop during treatment, but then we believe the number of mites was already quite low, due in no small part to the breaks in brood rearing due to swarming and raising new queens.

I understand from David Purchase that one of the colonies was attacked by vandals. Bees are tough creatures, though and were getting on with life in their knocked-over hive with few complaints. Dave restored the hive and tidied up and the colony is up and running just as it should be.

I remember well an incident in an apiary of mine a few years back. A huge oak branch a full 25cm in diameter had fallen right between two hives, knocking one of them over like a stack of dominoes. Remarkably nothing was broken and the bees had just built new comb in whatever places they could. As with the Association colony, I tidied and reassembled them and they were fine. It took me some time to do and I was amazed at just how tolerant the bees were about it, almost as if they recognised that I was helping.

HBA 125

by David Purchase

David Purchase
(Delegate to HBA) 

Open Mesh Floors

by David Purchase

  I am often asked questions about `open mesh floors'.  More and more of us are substituting them for solid floors, mainly as part of our Integrated Varroa Management (IVM) strategy.  Up to 20% of live mites fall from bees.  If they fall onto a solid floor, they can climb back up onto the brood comb.  If they fall through a mesh floor onto the ground, there is no way back and they perish.   What do we mean by `open mesh floor'?  Well, in its simplest form it is a square or rectangle of plastic or wire mesh with a wooden frame on three sides, the fourth side being open to form the hive entrance.  It can be used on its own to form a true open mesh floor.  Placed above a solid floor with the entrance to the solid floor facing to the rear, it can be used for monitoring natural mite mortality, an essential part of IVM.  A sheet of stiff paper, card, plastic or hardboard is inserted through the rear-facing entrance to the solid floor to catch the mites that fall through the mesh above.  Most of them will be dead but there are sometimes a few live ones.   It is likely that many of the live mites that fall through the mesh onto the solid floor are able to climb back up to the comb.  Some beekeepers coat the insert in Vaseline or similar to prevent that from happening.  Unless the insert is cleaned regularly it will quickly become a breeding ground for wax moth whose larvæ feed on the detritus that collects there.   Though more expensive to buy and more difficult to make, a varroa floor is more flexible and more effective than the arrangement described above.  It consists of a mesh with a tray beneath that can be inserted periodically for monitoring purposes and left out at other times to achieve the full benefits of an open mesh floor.  A solid floor is not required.  For monitoring mite fall as part of IVM, the tray should be inserted periodically throughout the year and left in for about a week.  At the end of the week (or thereabouts) the number of mites is counted and divided by the number of days of mite fall.  By using either the tables in DEFRA's Varroa Management Handbook or the National Bee Unit's on-line calculator at www.nationalbeeunit.com you will be able to determine the approximate level of mites in the colony and whether or not treatment is required. The insert should not be in place continually as it would negate the benefits of an open mesh floor and become a breeding ground for wax moth, as described above.   I have described the two most common types of open mesh floor (given different names by different people, just to confuse us!), but, as is so often the case with beekeeping equipment, there are `variations on the theme', so watch out for those.  It is worth mentioning that solid floors can be converted to open mesh by cutting out the centre and replacing it by mesh.   Colonies will overwinter very well on open mesh floors.  A former bee inspector colleague regularly and successfully overwintered colonies on open mesh floors in Northumberland.  Apart from the mite control benefits, it does help to improve ventilation and reduce the likelihood of mould on the outer brood comb, especially when the frames are aligned the `warm way' (ie, parallel with the entrance).  However, based on my own trials over the past four years, I would advise covering up the holes in the crown board to avoid a through draft (the so-called `chimney effect').  Also, if your hives are on an exposed site, I would recommend placing an empty super or similar beneath the mesh floor to act as a baffle to the wind.  A deep framed hive stand would do just as well.   Many of us are now using Apiguard in preference to Apistan or Bayvarol.  The insert must be in place for the duration of the treatment, or the mesh floor replaced by a solid one for the same period, as Apiguard works partly by evaporation and the vapour is heavier than air.  If the mesh floor remains open the treatment will be less effective.   I hope I have been able to allay some of the fears and remove some of the confusion surrounding this subject.  

David Purchase

Another Odd Season

It's been another odd season this year. Again warm in March, cool and wet in April, becoming very wet indeed during the summer, with rainfall typically twice the average. It's hardly surprising, then, that we and our bees have also found this a tricky year to handle.

I suspect most of us struggled to manage swarming as most of us will have found it difficult to manage our bees with weather that seemed to fluctuate in extremes. Too cold, too wet, too windy both for us and for the new queens.

It's often been said that if you lose the swarm, you also lose your honey crop. That isn't 100% true, but it isn't so far away .. provided you don't also lose the after-swarms and your new queen mates OK.

I guess many of us will have to acknowledge that the year's typically poor crop is as much down to our own failure to manage the bees properly, all be it so much determined by weather and opportunity, as it was by the direct effects of the weather on crops and nectar flows.

It's quite noticeable that most people have done poorly, but that a few have done really rather well. For sure, some of that is fortuitousness and some is "getting it right" when the rest of us got it wrong.

Quite a lot seems to be down to having your bees in the right place at the right time and this year the right place may just have been where your nearest OSR or field beans were on a south facing slope when it was yielding, or on a north facing slope earlier so it was held back a few days.

Certainly those who did well seem to have managed their swarming well. I know though that there are some very experienced beekeepers around who this year have had a tough time keeping things under control, so I guess those of us who have done less well are at least in good company.

My own crop this year has been pitiful, but at least all the bees have now built up fit and healthy again and they have been putting on colony weight just fine from the late flows. They're all nicely up to the weight and should be fine through the winter. So at least I don't have to feed them.

Thymol

by Gordon Scott

Thymol is, of course, the active ingredient in ApiGuard and Exomite-Apis. It's one of the aromatic phenols found in oil of thyme and in it's pure form is a white crystalline substance that is largely insoluble in water.

In that pure form it can be harmful, but in the low concentration to which we're normally exposed, and handled sensibly, it's quite safe.

Obviously it is toxic to Varroa mites. It can also be toxic to bees, though their tolerance to it is substantially higher than the mite's tolerance. I remember from one of Max Watkins' (from Vita Europe) talks, a toxicity ratio of around 600:1 between the species. That gives a reasonable range for safety, but not exactly a generous range, considering the differences in evaporation due to heat and humidity variations. I seem to remember that with Apistan and Bayvarol, the toxicity ratio was around 2000:1 or more.

ApiGuard is formulated to stabilise the evaporation rate and make Thymol easier and safer to use than the bare crystals would be. It works well and should continue to do so long into the future. The mites are unlikely to become resistant anything like as early as they would or did to the synthetic pyrethroids in Apistan and Bayvarol. These latter treatments are effectively anti-mite `nerve gasses', that kill in a very specific way. Thymol has a broader action, killing mites through a number of effects, each of which would have to have the resistance develop.

It's true though that Thymol is less effective than the synthetic pyrethroids were, being somewhere around 93% effective rather than the 98% or 99% effective to which we are accustomed. Those few percent different may not sound like much, but they are quite significant. Thymol alone will not totally control Varroa.

There's also another disadvantage to Thymol that will now be familiar to those who have used it. It's a strong aromatic that leaves a distinct smell in the hive and can also leave the smell in wood, wax and honey. The last of those is, in truth, the main reason that Vita and others advise removing the honey crop during treatment. Tiny traces of Thymol in honey may be harmless to health, but they may not be so harmless to your sales figures.

We're a little limited on options for controlling this aroma. Even removing the crop during treatment doesn't necessarily guarantee total freedom from it as bees can and will move honey stores around. We have to try and ensure that any tainted honey gets consumed by the bees and any that's left in the spring is either in small amounts or perhaps we remove it. This is probably another good reason for considering the shook swarm methods of Varroa control in the spring.

It is of course also quite possible to control Varroa without using aromatics like Thymol or indeed Formic Acid. There are a number of techniques available to us that use manipulations only to control the mite. I'm thinking here specifically of drone trapping and Queen trapping as well as the shook swarm and modified Pagden method artificial swarm techniques.

These too have some risk, though. Drone trapping, where we encourage an area of drone brood in which the mites prefer to raise they young, will never totally control mites. Worse still is that if the drone cells are not removed when sealed, rather than controlling the mites we start actively to breed them!

Queen trapping, where we cage the queen onto one frame at a time for three consecutive weeks/frames, then destroy each of those frames when they're sealed, it extremely powerful, giving mite kills comparable with the synthetic pyrethroids. But of course you must find and move the queen three times and you lose three weeks worth of brood production. Done at the right time, though, this does slow the colony and reduce the swarming tendency.

Rare Bee

Recent new member spotted an article in The Times about the RSPB's recent discovery of 11 previously unidentified nest sites for a rare species of bee.

I feel sure the RSPB will forgive me for including the following from their website:

Remote Scottish islands a stronghold
for one of the UK's rarest insects

Multiple nest sites of one of the UK's rarest bees have been discovered by RSPB staff and enthusiasts on the Uists, revealing the islands to be the most important habitat in the UK for the species.

More than ten colonies of the northern colletes (Colletes floralis) were found on sandy dune sites including Berneray island off the north tip of North Uist, making it the most northerly nesting site for the threatened insect in the UK.

The northern colletes is a solitary variety of so-called mining bee, and burrows underground into soft soil to build its nest where it stores nectar and pollen for its larvae. They differ from bumblebees and honey bees in having no workers. Although they do not co-operate with each other, they nest in what are termed 'aggregations' - the insect equivalent of rookeries.

Because of this it prefers gently sloping sandy banks and dunes, close to the herb-rich machair meadows familiar on the islands. The meadows host an enormously rich variety of wild flowers due to the fertile calcareous, shelly sand. It is because this soil produces a much higher diversity of flowering plant species that the bees appear to thrive in the habitat.

Jamie Boyle, RSPB Scotland's Uist warden, said: "This is really great news and extremely encouraging for this struggling and very rare species. As well as in the Uists, there are only a few other isolated UK locations that the northern colletes bee occurs, such as on the Ayrshire coast - where it was first discovered in the UK more than a century ago - on the Cumbrian coast, on Irvine Moor and on Machrihanish as well as off the northern coast of Ireland."

Previously, there were also just a handful of known nesting sites for the threatened bee in the Western Isles. But this year there has been a much more concerted effort to find the colonies, resulting in discovery of eight nests in one small area of north Uist, separate from another huge colony on north Uist and a further two large colonies on south Uist. RSPB Scotland staff have been joined by other wildlife enthusiasts searching for the bees, and have even found nests on some of the small islands such as Berneray.

Adults of the northern colletes bee are active from mid-June to late August. The male bees emerge first a day or two before the females. The females are probably mated soon after emergence. The male then dies and the mated female constructs a nest burrow which can be up to 26 centimetres deep - a considerable excavation job for an insect just over one centimetre long. The females tend to lay in proximity to others, so the nest 'aggregations' are formed.

They produce a secretion from glands in their mouths which they use to coat the inside of the burrow before laying their eggs in individual sealed cells. Each cell contains a food reserve comprised of regurgitated nectar and pollen that will feed the larva and then support the pupa through the winter while the bee develops.

In June, the male bees emerge first and fly around the nests waiting for the females to emerge, and for the lifecycle to begin again.

International significance

Jamie added: "Outside the UK it is really quite an unusual insect in that it occurs in very low densities around the Baltic at sea level in Finland and in Sweden and in southern Norway in the Oslo area. But bizarrely, this little bee is also found in alpine habitats, although with very limited distribution in the Pyrenees, Carpathians and eastwards into the Altai."

"The populations in Britain are of international significance because they are the only places that it occurs in the Atlantic bio-geographical zone, so they are of huge importance. What's more, we are talking about a bee that, as far as its European range is concerned, is likely to be threatened by climate change as a result of being driven off the tops of mountains in the south and finding its habitat no longer available as sea level in the Baltic area where it is present in very low numbers. As part of the big picture for the species, the population on the Hebrides is of enormous significance and worth making every effort to conserve."

The northern colletes is so rare that it is one of the species listed on the UK's Biodiversity Action Plan (BAP), with RSPB as a lead partner in efforts to try and conserve its UK population.

What can I do?

Join the RSPB from only \pounds 2.67 a month

The photographs that relate to this article were from the "Bees Wasps and Ants Recording Society" website: http://www.bwars.com.

Again I'm sure BWARS would welcome further members. \pounds 15 per annum and their website is excellent.

You can find out more by searching Google with "northern colletes" or "colletes floralis".

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