The influence of pulverised sugar dusting on the degree of infestation of honey bee colonies with Varroa destructor

Abstract

The aim of this work was the investigation on the efficacy of pulverised sugar dusting on knocking-down Varroa destructor mites and the influence of the dynamics of the treatment on the degree of infestation in honey bee colonies. Two methods were deployed to measure the degree of infestation of bee colonies with V. destructor mites: the sugar shake method and the technique which involves mesh bottom boards equipped with sticky inserts. The research was carried out on 30 strong honey bee colonies in three successive years. The results proved that dusting with pulverised sugar (particle diameter below 40 μm) influenced the fall of V. destructor in comparison with both their fall off prior to the treatment and the negative control. The most discernible effects on the mite fall and the decline in their population in the hives was obtained with dustings repeated at threeday intervals. To conclude, the dynamics of the treatment affected the degree of infestation in bee colonies. However, the efficacy of sugar dusting was significantly lower in comparison with the one of flumethrin (positive control). Thus, in spite of considerable favourable effects on the decline in the degree of infestation with mites, by no means may dusting with pulverised sugar be advised to beekeepers as the one and only means of bee protection against V. destructor. The use of the technique which involves mesh bottom boards equipped with sticky inserts proved more efficacious and sensitive in the judgment of the degree of infestation of bee colonies in comparison with the sugar shake method, which includes dusting 300 bees with 40 g of pulverised sugar (particle diameter below 40 μm).

Cilj rada bio je da se ispita efikasnost primene šećernog praha u obaranju krpelja Varroa destructor i uticaja dinamike tretmana na stepen infestiranosti pčelinjih zajednica. Za procenu stepena infestacije pčelinjih društava krpeljima V. destructor korišćene su dve metode: metoda rolovanja sa šećerom i metoda žičane podnjače sa lepljivim ulošcima. Istraživanje je obavljeno na 30 jakih pčelinjih zajednica tokom tri godine. Rezultati su ukazali da je zaprašivanje prah šećerom čestica dijametra ispod 40 μm imalo efekat u obaranju krpelja V. destructor, u odnosu na stanje pre tretmana i u odnosu na negativnu kontrolu. Najbolji efekat u obaranju krpelja i smanjenju populacije krpelja u košnici imala je primena prah šećera svakog trećeg dana. To znači da je dinamika tretmana uticala na stepen infestiranosti pčelinjih zajednica. Međutim, efikasnost metode zaprašivanja šećerom u prahu bila je značajno manja u odnosu na efikasnost flumetrina (pozitivnu kontrolu). Stoga se tretman prah šećerom nikako ne može preporučiti pčelarima kao jedina mera zaštite pčelinjih zajednica od ektoparazita V. destructor i pored uočenih pozitivnih efekata na smanjenje stepena infestiranosti tim krpeljom. Korišćenje žičane podnjače sa lepljivim ulošcima predstavlja mnogo efikasniji i osetljiviji metod za procenu stepena infestiranosti pčelinjih zajednica Varroa krpeljom u odnosu na metod rolovanja u tegli sa 300 pčela posutih sa 16 grama šećera u prahu sa česticama čiji je dijametar manji od 40 μm.