Hello All
 
I have recently obtained a Varroa Calculator from the British Beekeepers
Association of which I am a member. The calculator has the approval of the
British Ministry of Agriculture and Food (MAFF).
 
The calculator is the result of a considerable amount of research carried
out by Dr S Martin of the NBU.
 
I show below the salient equations from the calculator which will hopefully
help some of the subscribers who asked about converting the number of mites
counted, into an estimate of the mite infestation level in the colony.
 
The calculator goes into far more detail than I could possibly give here. It
gives data on the number of days until control is essential for any month
and for any infestation level.
 
If anybody wishes to obtain a copy of this calculator (which in action
reminds me of the slide rules of old except that it is circular), you could
write to
 
      Dr S Martin
      NBU
      CSL
      Sand Hutton
      York Y041 1LZ
      England
 
or to
 
      BBKA
      NAC
      Stoneleigh Park
      Warks CV8 2LZ
      England
 
SALIENT EQUATIONS FROM THE VARROA CALCULATOR
 
This table converts the daily mites knocked down into an estimate of the
total mites in the colony,and is used in conjunction with a varroa floor, eg
if you count say 50 mites knocked down in one day in May, you have an
estimated 1500 mites in the colony.
 
 
Month   Multiplier
 
Jan     400
Feb     400
Mar     100
Apr     100
May     30
Jun     30
Jul     30
Aug     30
Sep     100
Oct     100
Nov     400
Dec     400
 
The following equations convert the sealed brood or bee infestation levels
into the estimated number of mites in the colony. The first two equations
are used in conjunction with brood uncapping.
 
 
For sealed drone brood:
 
No of drone cells infested divided by the number of drone cells sampled,
multiplied by the total number of sealed drone cells in colony, multiplied
by 10.
 
For sealed worker brood:
 
No of worker cells infested divided by the number of worker cells sampled,
multiplied by the total number of sealed worker cells in colony, multiplied
by 1.8.
 
 
For adult bees in summer:
 
No of bees infested divided by the number of bees sampled multiplied by the
total number of bees in colony, multiplied by 2.9.
 
For adult bees in winter:
 
No of bees infested divided by the number of bees sampled, multiplied by the
total number of bees in colony.
 
 
It is possible that the equations may have climate involvement, which
subscribers outside these islands may need to consider. The species of bee
may also be a factor.
 
I shall be glad of comments on the above.
 
Sincerely
 
Tom Barrett
49 South Park
Foxrock
Dublin 18
Ireland
 
e mail [log in to unmask]
Tel + 353 1 289 5269
Fax + 353 1 289 9940
 
Latitude  53 Degrees 16' North
Longitude  6 Degrees  9' West of Greenwich