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In consequence of occuring and expansion of Varroa Jacobsoni mite new problem has been arised to ensure of effective honey bee protection. In this paper, research-developmental works, realised in 1984-1991, to solve that problem have been presented. Through RD works production of I generation varroacidal formulations (Warosekt and Apiwarol AS) have been started and up-to-date formulations are being prepared.
A complete loss or decrease of varroacid efficacy of Apistan (tau-fluvalinate) has been stated in some Mediterranean and Austrian regions. The results of studies on this problem presented at the 34-th International Congress of Apimondia in Lausanne - 1995 poited to the development of Varroa jacobsoni mites resistant to Tau-fluvalinate and other acaracid pyrethroids. Since tau-fluvalinate has been used in Poland for a number of years, the development of V. jacobsoni resistance to this preparate cannot be neglected. The efficacy of Fluvarol (tau-fluvalinate) in relation to the multiplicity of its application has been examined. The examinations were done in the honey bee colonies (the Bielsko-Biała region) treated with tau-fluvalinate four times in 1991-94 or twice in 1993-94. Un treated colonies served as a control. The efficacy (66.4%) after four applications tau-fluvalinate points to the development of V. jacobsoni strains resistans to this chemical.
The residues of fluvalinate accumulated in the wax promote the selection and development of Varroa jacobsoni resistance to fluvalinate activity. Probably Varroa jacobsoni will be resistant to other acaricidal synthetic pyrethroids (due to cross-resistance). The possibilities of using for honey-bee protection the inserted to hives strips, containing known pesticides, such as amitraz, malathion and bromfenvinphos, which have different, than synthetic pyretroids, mode of biological action, and which are suitable to overcome fluvalinate resistant mites were tested in Poland. The high varroacidal effectiveness of the strips with above mentioned pesticides during 6 weeks exposition was found. However, amitraz, at the concentration of 5% in PVC strip, was decomposed after 5 months of storage. Malathion at the same concentration is not quite safe for bees. The promising results with bromfenvinphos incorporated in PVC strip (5%), as well as in the form of microlayer (50-60 mg a.i.) on PE strip were obtained (the average varroacidal effectiveness achieved 99%). The dorsal bromfenvinphos apitoxicity LD50 was 7310 ng/bee.
The technological method of obtaining 0,0-dimethyl-0-/2,4,5-trichlorphenyl/thiophosphate has been worked out in chemical Institute of Organic Industry. The toxicity of purified product was established. LD₅₀ per os for female rats was 3430 mg/kg and for males - 2628 mg/kg. The technical product containing 92% of the active substance was more toxic. LD₅₀ per os for rats was 2150 mg/kg. The investigations on the control of Hypoderma sp. showed a good efficacy of automn and spring application of 6-10% water emulsion rubbed in the animal back. Good results have been also obtained using 100 mg/kg per os.
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