Medycyna Wet. 67 (11), 757-759, 2011

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Howis M., Chorbiński P., Janiszewska K., Nowakowski P.
Efficacy of oxalic acid used in honeybee colonies to remove Varroa destructor mites
Oxalic acid 3.2% in water saccharose (1 : 1) solution was applied in 20 bee colonies (25 ml per colony) in October 2010 to control Varroa destructor infestation. The mite fall on the bottom board of the hive was scored after the second and seventh day of oxalic acid use. During the treatment with oxalic acid, the colonies included an average of 0.23 dm2 (from 0 to 0.8 dm2) of sealed brood, which can be a source of new populations of mites. The degree of the mite infestation of the sealed brood ranged from 0 to 55% of comb cells with pupae. The efficacy of the treatment was evaluated on the basis of the number of fallen mites after oxalic acid application and the number of fallen mites after a subsequent single fumigation with amitraz (Apiwarol AS). The average efficiency of oxalic acid in removing the parasites was estimated at 69%, which means that a single application of this acid in October reduces infestation but cannot ensure the removal of over 95% of mites, which is the level recommended for medicines.
Keywords: oxalic acid, honeybee colonies, Varroa destructor