Submitted to: Journal of Economic Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/30/2006
Publication Date: 2/1/2007
Citation: Meikle, W.G., Mercardier, G., Holst, N., Nansen, C., Girod, V. 2007. Duration and spread of an entomopathogenic fungus used to treat varroa mites in honeybee hives. Journal of Economic Entomology 100: 1-10. 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. In this study we used a strain of fungus, that we had previously found attacking varroa mites in a commercial apiary in France, to treat beehives in two field experiments. The percentage of mites infected with the fungus was much higher than the control hives after treatment, and remained higher for at least two weeks, but the number of mites that fell per day was not significantly different between treated hives and control hives. Although further work will be needed to improve the mite kill by the fungus, commercial and hobby beekeepers should benefit from a new, chemical-free way to kill varroa mites.
Technical Abstract: A strain of Beauveria bassiana isolated from varroa mites was used to treat bees against varroa mites in southern France. Fungal treatment was associated with a considerable increase in the percentage of infected varroa mites over baseline levels in two field experiments. The percentage of infected varroa mites also increased in the nontreated (control) hives, suggesting a movement of conidia, probably via bee drift, among the hives. However, the mite fall, measured using sticky boards placed under the hives, was not significantly different between treated hives and control hives. Live bees were sampled from within the hive and washed to determine the density of fungal colony-forming units (cfu) on their bodies.