Med. Weter. 2013, 69 (12) 744 Praca oryginalna Original paper Varroa destructor is a dangerous parasite because honey bee colonies infested with the mite die out within 3-4 years (13, 39). This is due to the fact that V. destructor exerts its adverse effect on bees in many different ways. When feeding on bees or brood, mites use their mouthparts to puncture the lining of the host’s body. The wounds become an entrance for numerous patho- gens present on the body of brood or on bees (15) as well as those transmitted by V. destructor (2, 16, 17, 28, 29, 33, 42). According to some authors V. destructor contributes to such honey bee conditions as American foulbrood and chalk brood (42). It has been proved that it promotes the development of acute bee paralysis (1). Martin et al. (24) discovered that the presence of V. destructor in diseased colonies is accompanied by the following viruses: deformed wing virus (DWV) and slow paralysis virus (SPV). Infestation with the mite leads to quantitative and qualitative changes in hemolymph. Weinberg and Madel (44) report that 1-3 mites feeding on a worker bee pupa cause a reduction in the host’s hemolymph volume by 23.6%; in the case of a drone pupa, the volume of hemolymph decreases by 18.2%, on average. An attack of the mite brings about changes in the level and composition of proteins (41), which results not only from hemolymph loss but also from the effect of substances excreted by V. destructor. The substances damage some hemolymph proteins (17) or hinder protein synthesis in the fat body (18). In broods, the activity of lisozyme drops by 30-40% as compared to its congenital level (18). In order to prevent such a destructive effect of the mite on honey bees and broods, and consequently also on the whole colony, it is necessary to control the mite regularly every year. Abandoning anti-Varroa proce- dures in one season may have a negative effect on the condition of the whole apiary and its productivity in subsequent years even when anti-Varroa procedures are taken up again (5). Presently, no medications for varroosis show 100% eficiency. Besides, even if colo- nies are successfully cured of the mite in a short time they are usually re-infested by mites from neighboring apiaries not simultaneously treated for varroosis (38). However, carrying out yearly anti-Varroa procedures makes it possible to control the mite population at a level harmless to the bee colony. Medications used in the treatment of varroosis are based on acaricides and essential oils. Presently, among the preparations registered in Poland are such medications as: Apiwarol, Biowar 500, Bayvarol, and Api Life Var. The irst three preparations are chemo- therapeutic agents containing amitraz and lumethrin as active substances. Some residues of these substances may be found in bee products (3, 4); therefore it is recommended to use them not earlier than after the last honey harvest. Efficiency of Varroa destructor management with medications used in Poland* ) BEATA BĄK, JERZY WILDE, MACIEJ SIUDA Apiculture Division, Faculty of Animal Bioengineering, University of Warmia and Mazury, ul. Słoneczna 48, 10-710 Olsztyn, Poland Bąk B., Wilde J., Siuda M. Efficiency of Varroa destructor management with medications used in Poland Summary Despite a wide choice of methods for V. destructor control, beekeepers are still uncertain as to which one is the most effective. Does one anti-Varroa procedure a year sufice or is it better to strike the population of mites several times during the season? Or perhaps is it better to treat bee colonies relying on essential oils and organic acids? The aim of the assay was to show which method for V. destructor management is most effective. The results of the investigations show that the applied treatment pattern signiicantly affects the eficiency of Varroa destructor management and the degree of bees’ infestation in spring. The best way to control Varroa destructor was determined to be integrated anti-Varroa treatment. Keywords: Varroa control, integrated parasite management, amitraz, lumethrin, thymol formic acid, oxalic acid * ) The study supported by the Polish Ministry of Science and Higher Education, research project No. 520/N-COST/2009/0.