story to find out more.
Beekeepers now have a simple assay to determine if
varroa mites can resist two compounds (coumaphos and fluvalinate) used to
control them. The information will help ensure use of appropriate control
measures. Click the image for more information about it.
New Test on Tap for Detecting Pesticide-Resistant
By Jan Suszkiw
April 15, 2005
Commercial apiarists and state bee
inspectors now have a fast new way to check Varroa mites for this honeybee
parasite's resistance to the pesticides coumaphos and fluvalinate.
Agricultural Research Service (ARS)
entomologists in Beltsville, Md., have developed a "do-it-yourself"
bioassay that determines, within six hours, whether Varroa mites are fully
resistant to the pesticides, are approaching resistance, or are still
Varroa mites are blood-sucking parasites of honeybees that can weaken or
destroy hives. Continuous use of coumaphos and fluvalinate to prevent such
damage has prompted the emergence of resistance among some Varroa populations,
Pettis, in the ARS
Research Laboratory at Beltsville.
In studies there, Pettis and other ARS entomologists sought to devise a
faster, cheaper and more user-friendly alternative to current methods of
checking for pesticide-resistant Varroa mites. These methods are
labor-intensive affairs that require specialized equipment and the shipping of
The ARS scientists' bioassay is intentionally low-tech. Its main parts
include glass canning jars in which to contain honeybees, mesh lids through
which mites on the bees can fall out and be counted, and index cards that hold
strips of either coumaphous or fluvalinate.
A mathematical formula determines the mites' resistance levels or
susceptibility to the pesticides. For example, if the chemicals kill 25 percent
of the mites, then the parasites can be considered fully resistant. However, if
more than 50 percent are killed, then the mites are still vulnerable to the
pesticides. This means the pesticide treatments should still be effective
against the mites.
According to Pettis, some state bee inspectors have already used the
bioassay to document mite resistance in applying for emergency-use exemptions
on alternative control products. They're also using it to monitor the spread of
pesticide-resistant mite populations.
more about the research in the April 2005 issue of Agricultural Research
ARS is the U.S. Department of
Agriculture's principal scientific research agency.