K r y s t y n a P

S u m m a r yAmitraz is a varroacide used the longest (over thirty years) and most commonly by Polish beekeepers. This involves high risk of V. destructor developing amitraz resistance. Therefore it is necessary to monitor the effectiveness of treatments to ensure appropriate protection of the honeybee colonies. The objective of this study was to evaluate the efficacy of amitraz used as the contact varroacide (Biowar 500 formulation) to control V. destructor in honeybee colonies. Field studies were conducted in 2011 and 2012. In both years, the amitraz treatments started in the last weeks of August. Two strips of Biowar 500 (500 mg of amitraz per strip) were inserted into each colony and removed after 8 weeks. The control colonies were left untreated for 8 weeks. After removing the strips the control therapy was conducted in all colonies. The average efficacy of amitraz (E%) calculated for the two years combined, after 6 and 8 weeks of treatment, amounted to 90.6% and 94.6%, respectively. As a result of the natural mortality in the control colonies, the population of parasites lowered only by 16.4% and 23.9% during 6 and 8 weeks. The efficacy of the strips was lower in colonies with larger amount of brood.

A b s t r a c t The effects to honeybee colonies (Apis mellifera L.) during and after exposure to flowering maize (Zea mays L.), grown from seeds coated with clothianidin and imidacloprid was assessed in field-realistic conditions. The experimental maize crops were adjacent to the other flowering agriculture plants. Honey bee colonies were placed in three differently protected maize fields throughout the blooming period, and thereafter they were transferred to a stationary apiary. Samples of pollen loads, bee bread, and adult bees were collected and analyzed for neonicotinoid residues. To ensure high specificity and sensitivity of detection of the analyzed pesticides, a modified QuEChERS extraction method and liquid chromatography coupled with tandem mass spectrometry were used. Clothianidin was detected only in the samples of pollen loads. Their residue levels ranged from 10.0 to 41.0 ng/g (average 27.0 ng/g). Imidacloprid was found in no investigated sample. No negative effects of neonicotinoid seed-treated maize on the development and long-term survival of honey bee colonies were observed. The low proportion of Zea mays pollen in total bee-collected pollen during the maize flowering period was noted. The findings suggest that maize plants are less attractive forage for honey bees than phacelia (Phacelia tanacetifolia Benth.), buckwheat (Fagopyrum Mill.), white clover (Trifolium repens L.), goldenrod (Solidago L.), and vegetation from Brassicaceae family. The results indicate a possibility of reducing the risk of bees being exposed to the toxic effect of insecticidal dusts dispersed during maize sowing by seeding, in the areas surrounding maize crops, plants that bloom later in the year.

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Summary In 2010 - 2011 the influence of beeswax foundation adulterated with different percentages of paraffin, on comb construction, brood rearing and bee colonies development was evaluated. Beeswax foundation adulterated with different rate of paraffin (10%, 30%, 50%) was prepared. Each year of the study into 7 experimental bee colonies set in Dadant type bee-hives, the three-frames queen insulators were inserted. Every frame in the insulators had a half of the foundation made from pure beeswax (the control - 0% paraffin) and a second half made from wax adulterated with paraffin (experimental). As a result every colony had an insulator with 3 frames with beeswax foundation with different percentages of paraffin (10 and 0%, 30 and 0%, 50 and 0%). The queens were put in the insulators what stimulated bees to prepare a place for laying eggs, thus, to construct the combs on the foundation. Paraffin used in our experiment had no negative impact on the bee colonies. Bees drew out the foundation properly, and no destruction was observed. The queens laid eggs on the systematically drawn out comb cells. Brood development was normal and its quality was suitable. The worker bees emerged after 21 days. No case of brood or emerging worker bees death was noted. Because of the different chemical compositions and purities of the paraffin available on the domestic market, it is impossible to exclude the fact that such paraffin may cause harmful effects on bee colonies.