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From: Patrick Connell <[log in to unmask]>
To:                              [log in to unmask]
Subject: Fw: Varroa jacobsonii, resistance to miticides and
Dr.CYS Peng
Date: May 22, 1998 3:52 PM
 
Mites are notorious for building resistance to chemicals.
Therefore all beekeepers must observe directions on the
labels of the chemicals we use.   If we sample & find mites
we must treat or we will loose increasing numbers of colonies
yearly.   My losses have swung between 15 to 30% annually.
Others may be able to achieve better results with assiduous
attention to management.
I am suspicious of the current recomndations for  Apistan.
The original recomendation was one strip for each five frames
of bees to a total of four strips for a two brood chamber colony,
for 42 days.   I believe that any less than this original recom-
mendation may contribute to resistance.   We have heard of
resistance to fluvalinate in Italy and now in parts of the SE US.
I understand that Apistan strips cost little to manufacture,
yet the cost to beekeepers is $2, the treatment per colony is $8
plus the cost oftwo visits to the yard and labour.
It is essential to vary our miticides using Formic Acid in the
spring and Apistan strips in the fall, this will prolong the efficacy
of both miticides.
James Bach informed the members of the BCHPA in October 1997,
that another synthetic miticide in strip form was in preperation.
Just in time with resistance appearing.   I hope this company
challenges the makers of Apistan by pricing their strips at a
fairer price.
I believe the best hope for the survival of Apis mellifera and com-
mercial beekeeping and pollination services lies in the behavioural
biochemical studies being conducted on the interaction between
Apis cerana workers and Varroa by Dr.CYS Peng at U of California
at Davis.   Dr. Peng told those who attended the CAPA & Canadian
Honey Council meeting in Kelowna, BC in January, 1992 that Apis
cerana workers are able to groom a fellow  worker bee in one minute
(60 times faster than Apis mellifera workers can) and within two days
Apis cerana workers can kill most mites in their colony by the
second day.   Female mites can lay two extra female offspring in
drone brood over worker brood.   So  Apis cerana expell their drone
brothers after new queens are fertilised on their spring pollen flow,
so there were no drones found in Apis cerana colonies she looked
at in June in China.   Apis mellifera expel drones at the end of
summer.
Dr.Peng is currently doing further work on these interactions.
Perhaps the editor of the List will invite Dr. Peng to bring us up to
 
date.   I know she deserves the support of all N.American bee-
keepers and the agricultural sector who depend on honeybees
for pollination.
Patrick Connell
North Okanagan, British Columbia.