In the July edition of 'Bee Biz' are three articles describing the
use of thymol as a treatment for colonies infested with Varroa.  One
of the articles describes a trial by Mariano Higes and Jesus Llorente
at the Regional Apiculture Centre,  Agarian Investigation Service
Joint Communities of Castilla - La Mancha.
 
The following are the highlights of the article for the benefit of
those who may be interested in this form of treatment.  I hope this
does not infringe anyone's copyright.
 
The trial was carried out on 16 colonies in Langstroth hives divided
into 4 groups.
 
Each treatment was applied in the 'upper part of the boxes'  (I
assume on the top bars).
 
Mite fall was measured for each of the 4 7 day periods of the trial
followed by two applications of Perizin 7 days apart,  with the aim
of recovering remaining mites.
 
Effectiveness was calculated by comparing mite fall during the 4 7
day periods with total fall during the 4 7 day periods and the
Perizin treatments.
 
At the end of the trial the total amount of thymol evaporated was
calculated for each hive.
 
Group 1
16g thymol powder placed in a Petri dish 90mm in diameter,  in which
16 holes 2mm in diameter were made.  Two applications with an interval
of 14 days between them.
 
Effectiveness %
33.2
8.1
6.3
8.1
Av. % 13.9
Av. Evaporation 1.1g
 
Group 2
8g thymol placed on a watchglass.  Four applications at 7 day
intervals.
 
Effectiveness %
93.6
98.8
100.0
98.1
Av. % 97.6
Av.  Evaporation 31.5g
 
Group 3
8g thymol powder placed in a porous cotton fabric bag.  Four
applications at 7 day intervals.
 
Effectiveness %
47.4
33.0
73.7
38.4
Av. % 48.2
Av.  Evaporation 3g
 
Group 4
Control - no treatment.
 
Natural Mortality %
11.3
3.1
17.0
21.7
Av.  % 13.3
 
 
Comments
 
No side effects from the treatments were observed.
 
Mentioned within the article several times - that within each group
the treatments giving the highest effectiveness also showed greatest
thymol evaporation and it was concluded that there was a direct
relationship between thymol evaporation and acaricidal effectiveness.
 
Group 1 with an average thymol evaporation of 1.1g showed an
effectiveness of 13.9%,  similar to the figure obtained for natural
mortality.
 
The authors suggested that a treatment has to be more than 95%
effective to be considered useful and that the results in Group 2
confirms that thymol is a valid alternativefor controlling Varroasis.
 
The article appeared in 'Bee Biz' (July 1997) and was reprinted by
permission of Vida Apicola.  The authors were Mariano Higes and Jesus
Llorente (Regional Apiculture Centre,  Agarian Investigation
Service Joint Communities of Castilla - La Mancha).
 
Joe Hemmens