Submitted to: Apidologie
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/1/2003
Publication Date: 9/1/2003
Citation: Pettis, J.S. 2003. A scientific note on varroa destructor resistance to coumaphos in the united states.. Apidologie. 2003 35:91-92. Interpretive Summary: The honey bee is the major pollinator of many agricultural crops in the U.S., and the beekeeping industry has only a limited number of chemicals to protect honey bees from a destructive parasitic mite. Scientists at the Bee Research Laboratory in Beltsville have developed a field technique to determine whether or not parasitic mites are resistant to chemical treatment. This information will be used by state regulatory personnel to monitor chemical resistance and thereby offer alternative methods of control.
Technical Abstract: The beekeeping industry has limited products to control the parasitic mite Varroa destructor. Varroa resistance to fluvalinate in Italy in 1995 was followed in 1998 by fluvalinate resistant Varroa in the United States. In response to the loss in effectiveness of fluvalinate, the United States Environmental Protection Agency granted CheckMite+, a slow release strip form of coumaphos, a section 18 "Emergency Use" permit in 1998. In the fall of 2001, a commercial beekeeper in who moves bee colonies from Florida to Maine complained of high Varroa populations following treatment of his colonies with CheckMite+. To determine if acaricide resistance was involved, experiments were conducted on mite populations in Maine and Florida and compared with mite populations in Maryland using a field assay originally developed to detect fluvalinate resistance that was modified to detect coumaphos resistance. The assay indicated only 13% mortality of the mites in Maine while mites in Maryland exhibited 80-100% mortality and the mite mortality in two Florida apiaries were 6.8% and 80%. The appearance of mites resistant to coumaphos, the active ingredient in CheckMite+, in only three years of use is disturbing in light of the limited control alternatives. The current study documents high levels of mite resistance in Florida and Maine. The U.S. currently has Varroa populations that are resistant to fluvalinate and coumaphos and few mite control alternatives are on the horizon. Identification of resistant mites and rotation of control products is needed to limit the spread of resistant mites.