BEE-L Archives

Informed Discussion of Beekeeping Issues and Bee Biology

BEE-L@COMMUNITY.LSOFT.COM

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Seppo Korpela <[log in to unmask]>
Reply To:
Informed Discussion of Beekeeping Issues and Bee Biology <[log in to unmask]>
Date:
Tue, 28 Sep 1999 11:39:58 +0200
Content-Type:
text/plain
Parts/Attachments:
text/plain (42 lines)
> I gather that 1 kilo of oxalic acid hydrate, and 10 kilos of water and 10 kilos
> of sugar would make about 2.5 litres and treat 2500/50 = 50 strong colonies
> using the drizzle method.  The spray (Pulvérisation) The instructions are to
> dribble 5 ml of the mixture onto the bees along each gap between occupied
> frames.  With 9 frames of bees that would be 8 gaps and 40 ml.

This solution is the so called original italian solution. However, mixing 1 kg
oxalic acid dihydrate, 10 liter of water and 10 kg of sugar gives you 16.8 liters
of solution, which is enough to treat  336 strong colonies with 50 ml/colony.
>
> The only 'cons' I've heard about it is that it must be practiced on hives with
> no brood (hence November in Switzerland) and the bees are a bit upset for
> several weeks after treatment. There were some reports of unexpected winter loss
> afterwardes, but the researchers mentioned that local yards not treated with
> oxalic also suffered losses.
>

I am a member in the european group of researchers in a project
"Coordination in Europe of research on integrated control of Varroa mites in
honey bee colonies" (see http://www.entom.slu.se/res/proj16b.html for
description and reports of meetings). Within this program ca. 300 colonies
were treated fall 1998 in Nordic countries with either 2.1 or 4.2 % (original
italian) oxalic acid solutions using the trickling method.  This experiment did not
show in most cases differences in colony strengths in spring between
experimental groups and the control group. Tests planned for this fall should
show whether doses somewhat lower than the original italian solution (Dose in
the italian instructions was given as 5 ml/comb well covered by bees on Dadant-
Blatt frame size. For Langstroth frames the dose would correspondingly be 4
ml/comb.) still show a good efficacy and are well tolerated by the bees. It was a
tendency in all european experiments within the program that groups of
colonies treated with 2.1% solution were even stronger in the spring than
untreated colonies (only treated with Perizin as well as the oxalic acid treated
groups).

 It is important to know that overdosing  causes problems. In my autumn 1997
test I applied oxalic acid solution with a 40% larger dose as some instructions
gave wrong formula for the solution (instead of 1 kg oxalic acid solution in the
above formula, 1.4 kg was given as the oxalic acid dihydrate amount
corresponding to 1 kg of pure acid). With this overdosing 39 out of the 63
treated colonies died in the winter and 16 were very weak. Only 1 out of 14
control colonies was lost in the winter.

ATOM RSS1 RSS2