Dear Bee-L members:

Tracheal mites continue to be a problem. It depends on where you are
located.  Colonies with high infestations in the south do not suffer from colony
mortality by tracheal mites. Colonies with similar high infestations in
the north experience high winter mortality. The experienced colony
mortality in the north has become cyclic. Look at previous years' records,
you will find that high winter mortality of bee colonies with tracheal
mites occur every 3-5 years in the northern states. It depends on winter
conditions.

I conducted  a survey in NJ when I was at Rutgers University. I found that
colonies wintered in the south (Florida) had high levels of tracheal
mites. As soon as these colonies moved up north to New Jersey in early
spring for Blueberry pollination, you can find dead bees in front of the
hives. Those dead bees had high infestation levels with tracheal mites.
Meanwhile, colonies that wintered and survived the winter in New Jersey,
they had very low mite levels. By fall, we sampled again bee colonies that
were going back to Florida, we found that the mite levels were up to
20-40% infestation. This high level of tracheal mites could explain why
beekeepers have to move their bees quiet fast to Florida for wintering to
avoid winter losses in New Jersey.


Looking at the chart posted in Allen's web site, you will find that out of
5 tested commercial operations:
1. Two operations (Operation 3 & 5) could be considered good
2. Two operations (operation 2 & 6) are no good
3. Two operations (Operations 2 & 7) are moderate
This could explain that the tracheal mite problem still exists. Beekeepers
will have different opinions about the problem based on their location and
wintering conditions and source of queens used (resistant vs. susceptible
stock). Remember, the USA and Canada have wide range of climatic
conditions.



Medhat

Medhat Nasr, PH. D.

Pest Risk Management Unit
Crop Diversification Centre North

RR 6, 17507 Fort Road
Edmonton, AB, Canada T5B 4K3
Tel: (780) 415-2314    Fax: (780) 422-6096
Mailto:[log in to unmask]


 Allen Wrote:

Some of us were saying we never treat any more, that TM is no longer a
threat.

Then, several years ago, TM related losses were again reported  and we
changed our tune.
A chart I saw at Baton Rouge sheds light on why some say TM is no threat
and
others say that it is eating their bees alive, and the rest of us are not
sure.