Bob Sanford
Middleton, Nova Scotia, wrote:
 
>1.  The label states: "for best chemical distribution, use Apistan
>strips when day-time temperatures are at least 10 degrees C.  Does
>this mean not to use them when the average day is below 10 C (i.e.
>late fall)?
 
Bob: There's a justifiable sensitivity about adherance to the Apistan
 label just now, because of the risk of selecting resistant mites.
See comments after your # 3 and 4 below.
 
>2.  If it is alright to treat in the late fall with Apistan, would it
>be possible to only treat for 10 days and still get an effective
>treatment because of the broodless period that exists at that time?
 
It seems reasonable that you would get faster, better mite kill
during the broodless period. If you have a relatively small mite population,
(100 mites total, maybe 10 falling on day 1) 10 days of treatment may be
as good as longer, and avoid diffusion of fluvalinate into the wax. One
thing late treatment does not do, is provide bees unaffected by mites,
for wintering. As with tracheal mites, the bees once fed on by mites, are
impaired for wintering, whether the mites are killed or not.
 
>3.  Would testing for varroa with Apistan strips and sticky boards be
>effective over a 24-hour period if the average daytime temperature
>was under 10 C (i.e. late fall)?
 
Yes, here is a major problem. Whether the mites are killed at such low
 temperatures or not, the cluster is snug enough, that the mites don't drop
out to be seen. So an inaccurate measure of the mite population is seen.
 
>4.  There has been some discussion here (Annapolis Valley, Nova
>Scotia) that the outside temperature shouldn't matter in the
>effectiveness of the strips because the bees keep the inner
>temperature of the hive constant (above 10 C).  If this is so, why
>has the company included temperature information on the label?
 
The bees don't keep the hive warm, only the cluster (yes, that no doubt
heats the hive to some extent, but not much. The insulation is in the
bees). The strips may be in the cluster (or often may not, depending on
where the cluster forms). But in any case, the bees are neither
moving regularly around the strip, nor allowing "affected" mites to
drop out of the cluster (both conditions that will remove mites
 from the bees).
Treating varroa with Apistan in late fall or winter may be better than
nothing (in the short run), but better results are obtained from
treatments when the bees are more active. There has been a recent article
in ABJ (Roger Hopingarner I think) concluding that early fall treatment
was better than later.
 
 
Kerry Clark, Apiculture Specialist
B.C. Ministry of Agriculture
1201 103 Ave
Dawson Creek B.C.
        V1G 4J2  CANADA          Tel (604) 784-2225     fax (604) 784-2299
INTERNET [log in to unmask]