> In 2004 I began using the Heilyser oxalic vaporizer....He told me to vaporize three
>times, seven days apart. I spent the month of September vaporizing my bees.
>...Mite numbers were 15-25 approx. Vaporized
>that day and twice more at seven day intervals. Then waited seven days
>and did another alcohol wash. The mite numbers stayed the same or went up.
> ... I could see no brood damage or break in brood rearing. I also didn't see any mite
>control.
Thanks for the report, Mike. I have now treated five times this fall with oxalic vapour,
twice with the Cowan blower unit and three times with the Heilyser units (*). So far, the
hives do not show any visible signs of harm from the treatments. I have peeked to verify
cluster size and condition and there are pictures in my online diary.
As for assessing control, I wonder if you compensated for the fact that during
September and October, at least in our latitudes, the phoretic varroa counts typically
can increase by a factor of four or five due to the reduction in brood rearing and the
continuing emergence of drones. Some hives continue raising brood longer than others,
but the trend is up -- drastically at that time. In such an situation, merely maintaining
the same counts could indicate a measure of control. Also, alcohol washes can yield very
different estimates of mite load between hives with brood and broodless hives evne when
the mite load is the same.
Evaluating treatments can be tricky as I found this fall. I documented my experience at
http://www.honeybeeworld.com/diary/files/drop.htm and there are as many questions as
there are answers, but I think that some trends can be seen. We'll know more next spring
when we examine these hives for mite levels and survival.
Please note that my hives are in 3 EPS boxes, and it seems they raise brood a month or
more longer that hives in wood boxes. When I was using wood boxes, and running doubles,
I often found hives shut down in late September. This year, my hives kept emerging brood
into late November
What I found was that the evaporations appeared to merely hold the mite populations
steady in the fall until the brood all emerged, at which time, it appears the treatments
drove mite drops to near zero. You can form your own conclusions from the individual hive
charts at the above URL. (5 minute load time on dialup, but fast on high-speed).
Of course there are problems with my observations since they are just that, and came
as an afterthought when I had treated and are not the product of a planned experiment.
As Randy pointed out, there were controls. I had not thought of controls since I was
merely following a recommended procedure and monitoring results, but now, at this
point of time, it would be most interesting to see what the mite levels would be in
untreated hives.
My conclusions are that the treatments worked after there was no more brood. Of
course, the mite populations will naturally diminish any time they cannot reproduce for
a period of time as the life expectancy of a phoretic mite ranges up to 90 days and
theoretically half the population would die naturally during a 45 day broodless period
(This is greatly oversimplified).
(*) I inserted two strips of Apivar into two of the six test hives in place of doing
evaporation on them when doing the fifth treatment to attempt to establish the
mite populations remaining in those hives after the previous oxalic treatments. I picked
a hive which appeared to still have a significant drop and one which seemed to be deleted.
To date, 2 days after inserting the Apivar, the total cumulative mite drops are 105 and 3.
Allen Dick, RR#1 Swalwell, Alberta, Canada T0M 1Y0
51°33'39.64"N 113°18'52.45"W
http://www.honeybeeworld.com/diary/
***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software. For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html
Guidelines for posting to BEE-L can be found at:
http://honeybeeworld.com/bee-l/guidelines.htm
|
