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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.
Varroa destructor is an external parasitic mite that attacks honey bees Apis cerana and Apis mellifera. Varroa mites can be controlled through commercially available miticides, as well as non-chemical means. Our research work has been conducted on plants extracts reducing the mite population. We have obtained promising results for extracts of yew and walnut.
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.
In the raport results of one-year research on determination of the pollution level by insecticides in pollen and the examination of their decay dynamics in pollen are presented. The experiments were conducted on winter raps with the usage of such preparations as: Thiodan, Metox, Sadofos, Zolone, Cymbusz and Decis. It was pointed out that applisd preparations in appreciable degree penetrated into pollen, their amounts depended on dose of the insecticide. The dissapperance rates were differentiated and relatively fast. In laboratory conditions the insecticides residues in pollen dissappeared much slower.
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