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A b s t r a c t Explaining the reasons for the increased mortality of the honey bee (Apis mellifera L.) in recent years, in Europe and North America, has become a global research priority in apicultural science. Our project was aimed at determining the relationship between environmental conditions, beekeeping techniques, the epidemiological situation of pathogens, and the mortality rate of bee colonies. Dead bee samples were collected by beekeepers from 2421 colonies. The samples were examined for the presence of V. destructor, Nosema spp. (Nosema apis and Nosema ceranae), chronic bee paralysis virus (CBPV), acute bee paralysis virus (ABPV), deformed wing virus (DWV), and Israeli acute paralysis virus (IAPV). Among the environmental and colony management factors under analysis, significant differences between apiaries with high (>10%), low (≤10%) or no losses of the colonies were only found in the case of the methods used by beekeepers to combat varroa mites. However, the epidemiological patterns in the case of V. destructor infestation and the DWV and ABPV infections highly differed. The data we obtained indicated that co-infections play a decisive role in the etiology of the significant collapse of colonies in apiaries in Poland. The main reason for this phenomenon can be described as strong infestation with V. destructor, followed by an intensive development of viral infections caused by DWV and (much less frequently) by ABPV. Despite a high prevalence of Nosema spp. microsporidia (with a dominant incidence of N. ceranae), a direct relationship between these parasites and the mortality rate of colonies was not proved.

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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Screening of the prevalence of Paenibacillus larvae spores in honey bee colonies in apiaries from 162 districts, belonging to nine provinces was carried out during 2009-2011. The honey samples were examined by the use of a culture method. Based on the number of CFUs grown on Columbia sheep blood agar medium, the level of infection and probability of American foulbrood outbreak was estimated. Altogether, 6,510 pooled honey samples from 32,550 bee colonies located in 2,294 apiaries were collected. P. larvae was identified in 45% of the surveyed apiaries. The widest distribution of P. larvae was found in the Małopolskie province. Culture-positive honey samples were obtained for 71% of the apiaries and in a half of them, the level of spores was high. In the Warmińsko-Mazurskie province, the presence of the bacterium was detected in 58% of the apiaries. In the remaining provinces, from 26% to 47% of the apiaries were contaminated with P. larvae spores.