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Photo A. A mature adult
female V. destructor. |
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Geographic Range: Northeastern U.S.
The methods discussed in this fact sheet were developed and evaluated in the northeastern U.S. Drone brood removal will benefit beekeepers
throughout the U.S.; however, formic acid and other miticides acting as fumigants work best in areas where colonies are broodless or nearly
broodless for at least four weeks during the fall or winter. When a colony is rearing brood, most mites are present in brood cells where they
are protected from the effects of fumigants. During broodless periods, mites are present on adult hosts and are susceptible to fumigants. Since
fumigants have a relatively short treatment period (about three weeks) compared to other pesticides (about six weeks), it is critical that the
majority of mites be present on adult hosts for fumigants to be effective.
Introduction
This bulletin focuses on the management of the parasitic honey bee
mite Varroa destructor (V. destructor) in the northeastern
U.S. It contains information that will allow a beekeeper to: 1)
identify V. destructor, 2) recognize the symptoms of mite
infestation, 3) determine pest densities, and 4) implement an effective
IPM program for keeping mite populations below the economic injury
level.
The western honey bee, Apis mellifera, was introduced
to the U.S. from Europe in the 1600s. Today, the honey bee provides
essential pollination services for over 45 commercial crops grown
throughout the U.S., adding $14.6 billion to the value of the country's
agricultural production each year. In addition, U.S. beekeepers
produce between 170 and 220 million pounds of honey each year, more
than 50% of total U.S. consumption. Hence, a sustainable supply
of healthy and affordable honey bee colonies is a critical factor
affecting farm productivity and the stability of farm incomes and
food prices.
The parasitic honey bee mite V. destructor (photo
A) is considered to be the most serious global threat to beekeeping
and to the sustainable production of crops that rely on A. mellifera
for pollination. V. destructor, which kills honey bee colonies
of European descent within one to two years, has killed millions
of managed and wild colonies in the U.S. in the past two decades.
Apistan® and CheckMite+® have provided some relief, but control
always has been unpredictable due to the fact that mite populations
often rise rapidly during the honey-producing season, when treatment
is proscribed by label restrictions. Consequently, colonies often
suffer serious damage while the beekeeper waits for a legal treatment
window to open. The threat from V. destructor has become
a matter of grave concern as resistance to both Apistan® and CheckMite+®
has become widespread.
To continue to be viable, the beekeeping industry requires sustainable
management practices that will keep mite populations below the economic
injury level and maintain the high quality of hive products. The
best way to achieve these goals is to use a management program that
relies on multiple tactics, rather than solely on chemicals. One
such approach is referred to as Integrated Pest Management or IPM.
IPM incorporates chemical and non-chemical tactics; however, for
several reasons, IPM minimizes the use of chemicals whenever possible.
First, chemicals add a recurring cost to a beekeeper's management
program. Second, chemicals inevitably show up as residues in hive
products, and that jeopardizes their reputation as pure and natural
products. Third, chemicals can be injurious to the applicator and
may pose a risk to the consumer. This raises the issue of liability,
especially for beekeepers with employees. Fourth, the less a pest
population is exposed to a pesticide, the more slowly it develops
resistance to that pesticide. So, by minimizing the use of a pesticide,
its useful lifetime is extended.
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