Date: Thursday 15 February 2007
Venue: Church Rooms, Stow on the Wold
Notes:
Jeremy Voaden
The Past-For beekeepers to succeed, those days are gone.
For the last
10 years, we beekeepers have had to learn how to deal with varroa. We have done
this principally through the use of our “Magic Bullet” – Apistan and Bayvarol
Strips. But time always tells, and our bees have become resistant.
Michael wants
this talk to be interactive. He wants to find out what, if anything, we are
doing to manage resistant varroa. If we don’t, and we have resistant mites,
then our bees will die.
Cheltenham and
Gloucester Branch (C&G B) of the Gloucestershire Beekeepers Association
(GBKA) have a thriving Branch Apiary. They have been testing for resistant
varroa on a monthly basis.
From May until
August 2006, the varroa tested negative for resistance.
In September the
hives were treated with pyrethroid strips.
In October,
resistance was found!
“We thought we
were on top. But no, they were on top”.
How can
resistance come into the apiary?
1. Mismanagement by the beekeeper e.g. Not
treating with, or removing strips in an appropriate manner. As pyrethroid
chemical treatment has increased over time, so has the prevalence of
resistance. Our Regional Bee Inspectors have visited sites and found hives with
strips pinned all around the inside.
2. Carried in my the bees
10 years ago,
pyrethroid treatment would result in 100% knock-down of mites. Now, in their
resistant hives, C&G B obtain just 10% knock-down. This was forecasted by a range of information
sources including the British Beekeepers Association (BBKA) and Bee Craft.
The only way
to check for resistance is to take samples and test.
When you get
to 1/3rd resistance, you need to start to be totally pro-active. The
challenge for us is that pyrethroid treatment didn’t teach us HOW to manage our
bees and work with them. For some beekeepers, the annual system has remained
that they visit their bees in the spring, throw on a Queen Excluder and some
Supers then return in the autumn to remove them and stick in some strips. That
is it! Those days are gone.
In the C&G
Branch Apiary, they knew there were resistant mites 3 miles away. Two years
ago, Michael said “this is the last year we will be using Apistan”. He was one
year out.
During 2006,
Channel Four Television were filming at the apiary. It was a programme about
two women who had a phobia about bees. At the end of the day’s filming, one
woman was holding a frame of bees. Whilst the film crew and women were
examining the frame, Branch members noticed a lot of mites on the bees. In
addition, they had tattered wings and shrivelled bodies. They knew they had a
big problem.
Michael had already done a test on his own bees, and followed this up treating them with Exomite. Following the Branch Apiary resistance, he telephoned the Rep who sent a number of packets of Exomite with which Michael treated every hive in the apiary.
Michael was
interested to try and determine which hives had resistant mites. There was not
100% prevalence. Some hives had huge mite drops whilst some had none at all.
Why?
The hives with
low numbers were late nukes which were building up i.e. They didn’t have a
surplus of workers wandering around and robbing other colonies.
Those with a
high mite drop were very strong, with lots of spare workers “out robbing”.
The source of
the incoming resistant mites were the resistant colonies three miles away.
These had swarmed over the previous years and the swarms established short-life
colonies elsewhere. These new colonies in turn swarmed, getting weaker over
time as they had not been treated for varroa. C&G B bees flew out from the
Branch Apiary and robbed these weak, heavily resistant colonies.
So, colonies
are more likely to be resistant if they are strong at the end of the season and
rob-out other colonies.
Michael then
asked the 14 beekeepers present what they did to protect their bees from
varroa. Respondents did the following:
Leave our bees
alone 9
Check drone
brood with fork 12
Sample test
the bees 1
Can I see the
mites on the bees 3
Using a mesh
floor 5
Michael
disagrees with “The Ministry” about the losses through drop-down using a mesh
floor. He doesn’t think that their figure of 20% loss is accurate, feeling it
to be more like 5%….which he acknowledges is still better than nothing! Michael has replaced all 50 of his hives
with mesh floors.
So, to summarise the current situation and treatments:
No Magic
Bullet Now!
Synthetic
Pyrethroid (out of the picture)
Apiguard
(thymol) – may be too cold (Aug/Sept/Oct)
Lactic Acid
(requires no brood)
Oxalic Acid
(requires no brood). There is a very small window from the end of December to
mid-January when it can be used. Very effective on varroa but it MUST not be
used when there is brood.
Formic
Acid (Kills mites in sealed cells but
application difficult: July-Oct). Very good treatment for varroa but it must be
skillfully administered. There is a possible history of making the colony
Queenless. The beekeeper needs a special pad or administrator to use it.
Personal protection is also essential.
Exomite
(Thymol) – may be too cold? Treat Aug/Sept/Oct. It was developed by a beekeeper
in Bournmouth and a chemical company. It uses Thymol and electrically charges
it. The beekeeper puts a plastic tray of the Exomite in the front of the hive
entrance. There is a massive roar from the bees inside as the Exomite “jumps up
and hits them” due to the static electricity. The bees run away from it and
they shoot out of the hive like “little white bees”.
When Michael
treated the hives in the Branch Apiary, the hive removable floor was
“absolutely black with drop-down”.
The
disadvantage is that the bees don’t like it!….and can abscond. If you use it in August, you may lose your
bees. Michael treats his bees in September and October when it is a lot cooler
and he has brought his bees back from Yorkshire. Mites dropped for 7 continuous
days during the first application. After 12 days, the 2nd
application was made but there was not a lot of drop-down 2nd-time
round. Exomite must be applied when bees are active and flying. The Hive must
not have any leaks / gaps or other exits as the occupants must pass across the
Exomite tray.
Our NCBKA
Member Roy had a drop of 100 mites with Exomite, having used it after treating
with Bayvarol!
Mesh Floors –
It is simple: These are a must!
2 Super Frames
– These should be inserted into the Brood Box from April onwards. Once the
first is drawn down, insert a second. After 14 days, remove the drone brood and
replace. This technique should be used until the end of June then remove the
Super Frames as they will draw worker brood after that. One C&G Branch
members used this technique with 3 Super Frames. At the end of the 2006 season,
they could hardly find a mite as they ran the colony on a cycle of removing 1
slab of drone brood every 7 days.
Icing Sugar –
After going through the bees, sprinkle icing sugar over the bees. The suckers
on the bottom of the feet of the mites are prevented from working and the mites
fall through. Then remove the floor board and scrape out the drop-down and
remove from the apiary.
Daily Mite
Drop – 12 or more/day : You have a serious problem and must take urgent action
to keep the level down. You must:
Ø Use your 2 Super Frames between April
and July every 14 or 7 days
Ø On every visit to your bees, shake
icing sugar over them. Remove the mites-they are not dead yet!
In these
difficult times, we need to “think outside the box”!. When your bees want to
swarm, try doing a shook swarm and place the brood on another colony. Treat the
swarm with Oxalic Acid. This is
administered in a liquid form using a little syringe. Run the acid along the
top of the frames or onto the bees themselves. The bees will lick it up as it
is mixed with sugar.