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Title: Du nouveau dans la lutte biologique contre Varroa destructor

item Meikle, William

Submitted to: Scientific and Technical Review
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2007
Publication Date: 4/1/2007
Citation: Girod, V., Mercadier, G., Meikle, W.G. 2007. Du nouveau dans la lutte biologique contre Varroa destructor. Scientific and Technical Review.

Interpretive Summary: Varroa mites are one of the most important pests of honeybees worldwide and beekeepers are very interested in new ways to treat varroa infestations without using chemicals that contaminate honey and wax. Biopesticides, which use pest diseases to control the pests, are one option, but many diseases of insects and mites are not very specific and might hurt the bees. We found a strain of fungus attacking varroa mites in a commercial apiary in France, and tested the fungus in lab experiments on varroa mites. Results showed that mites were very susceptible to the fungus. We then conducted small scale field experiments and the fungus caused the mites to drop out of the hive at higher rates than normal. We conducted a larger field experiment to see if the fungus hurt the bee colony by weighing the beehives and by monitoring the adult and larval bees and the honey stocks. We found no negative impact of fungus treatment on the bees at all, and we did find that the fungus caused more mites to fall than usual. Commercial and hobby beekeepers should benefit from a new, chemical-free way to kill varroa mites.

Technical Abstract: The European Biological Control Laboratory and the Association for the Development of Professional Beekeeping are working together to find a biological control solution against varroa mites. In spring 2005 the insect pathology team at EBCL found entomopathogenic fungi, Beauveria bassiana, on varroa mites from beehives in the Languedoc-Roussillon region of southern France. Strains of the fungus were tested in laboratory bioassays, and the fungi were found to kill the mites in 5-8 days. Two small field experiments were conducted in the fall of 2005, during which the fungal treatment was found to cause a significantly higher mite fall than untreated hives. A third field experiment was conducted in spring 2006 using 21 hives. The first objective of that experiment was determine whether the fungus, which can attack bees, caused any health problems for beehives. Treatment of hives with the fungus caused signficantly higher mite fall, but did not cause any measurable negative impact on hive health. These results compare favorably with similar work by other researchers. Future experiments are planned with the intention of getting a reasonably inexpensive product on the market in the near future.