The pollen analysis is currently the only reliable test to determine honey variety, but the results are sometimes burdened with error. The main reason for this is additional pollen that got into honey in a way other than with nectar collected by bees but through the centrifugation of combs containing bee bread cells.
Studies were conducted in 2012 - 2013 on how different numbers of bee bread cells placed in the honey super influence lime honey pollen analysis. Bee bread pollen getting into honey during extraction in centrifugal-force honey extractors was proven to significantly influence the results of pollen analysis. In some extreme cases, it might skew the results so much that correct determination of honey variety by pollen analysis is no longer possible.
The aim of the study conducted in 2009 - 2011 was to estimate the differences in the nectar and pollen oilseed rape flow exploitation by bee colonies kept in the stationary apiary (permanently located on the rape field) and in the migratory apiary. The migratory apiary was transferred to the rape field at the appropriate time and situated on the same area as the stationary apiary. Every study year, 8 bee colonies per apiary, in two apiaries of different types (stationary and migratory apiary), were prepared. The colonies from the migratory apiary were placed on the rape field when about 10% of rape flowers were blooming. During that time, bottom pollen traps were inserted into the hives of both apiaries. The pollen loads were collected every day, separately from each colony. After the end of the flow season, honey was extracted separately from each colony. The honey was weighed and samples were taken for the palynological analysis. The weather conditions were monitored during the whole study period.
The average harvest of pollen loads from one bee colony during one day, was similar in both apiaries. The content of Brassica napus pollen was significantly higher in the pollen loads harvested from the migratory apiary. Despite the fact that the amounts of honey extracted from both apiaries were similar, the microscopic pollen analysis showed significantly higher percentage content of rape pollen in the honey from the migratory apiary. The results confirmed that placing the migratory apiary in the winter rape field at the time when about 10% of flowers were blooming resulted in a better exploitation of the rape flow by the bee colonies from this apiary in comparison to the colonies from the stationary apiary.
A method was elaborated to determine phenolic compounds (vanillin, caffeic, p-coumaric and salicylic acids, and flavonoids: rutin, hesperetin, quercetin, pinocembrin, apigenin, kaempferol, isorhamnetin, chrysin, and acacetin) in bee pollen loads using highperformance liquid chromatography with a diode array detector (HPLC-DAD). Phenolic compounds from bee pollen were isolated on Cleanert C18-SPE columns (500 mg/6 mL, Agela Technologies). Polyphenols were identified by comparing the retention times and spectra of compounds found in pollen load samples with the ones of the standard mixture. Quantitative analysis was conducted using the external standard method. In addition, basic validation parameters for the method were determined. For the identified compounds (except for the salicylic acid), satisfactory (≥0.997) linear correlations were obtained. The elaborated method showed high repeatability and inter-laboratory reproducibility. Variability coeffcients of the majority of phenolic compounds did not exceed 10% in conditions of repeatability and inter-laboratory reproducibility, and for the total polyphenolic content they were 1.7 and 5.1%, respectively. The pollen load samples (n = 15) differed in qualitative and quantitative composition of the phenolic compounds. In all the samples, we identified the p-coumaric and salicylic acids and flavonoids rutin, hesperetin, and apigenin nevertheless, these compounds’ contents significantly differed among individual samples. The total phenolic content in the tested samples of pollen loads ranged from 0.653 to 5.966 mg/100 g (on average 2.737 mg/100 g).
Maize can be a valuable source of pollen when plants attractive for bees are not available. Honeybees can forage from conventional maize as well as from genetically modified (GM ) maize. The Court of Justice of the European Union (EU ) ruled that pollen in honey must be treated as a food ingredient and therefore falls within the scope of Regulation 1829/2003/EC on GM food and feed and requires authorization. GM pollen unauthorized in the EU cannot be present in honey at any level, and honey must be labelled if it contains more than 0.9% of pollen from authorized GM plants in relation to total pollen content. However, currently available analytical methods allow only for estimation of GM pollen quantity in honey. Therefore, Directive 2001/110/EC related to honey needs to be amended so that pollen can be regarded as a natural constituent of honey. Because the EU is a big honey importer, validated and harmonized detection methods are necessary for the control of GM pollen in honey.
Coniferous honeydew honey, mainly Abies alba was characterised. Samples chosen for the study had organoleptic traits characteristic for the variety: greenish, opalescence tone of brown colour, mild, sweet flavour with pleasant, slightly resinous aftertaste and aroma as well as electrical conductivity over 0.95 mS/cm. To define composition and physicochemical parameters of the variety, contents of water and total sugars were determined. In addition various carbohydrates were identified and their contents were assessed as well. These were: fructose, glucose, sucrose, maltose, turanose, trehalose, isomaltose, malezitose. Other examined parameters related to honey quality were: free acidity, pH, the content of 5-hydroxymetylofurfural (HMF), the main amino acid - proline, and the activity of α-amylase enzyme (Diastase Number). The following properties were proven to be characteristic for this variety: high electrical conductivity with the average value of 1.14 mS/cm, ranging from 0.96 to 1.32 mS/cm; content of monosaccharides lower by few percent in relation to other honey varieties (from 58.2 to 67.4 g/100 g; on average 62.0 g/100 g) and a higher content of disaccharides and trisaccharide - melezitose. The presence of this sugar confirms that a considerable part of the honey was produced from honeydew. The average value of melezitose was 3.2 g/100 g, ranging from 0.9 to 5.9 g/100 g. Also, the results of the pH measurements were slightly higher than in other honey varieties (from 4.23 to 4.99; on average 4.63). The colour value in mm Pfund ranged from 74 to 105, with the average of 93.
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.
The risk exposure of bee colonies to the toxicity of systemic neonicotinoid insecticides was assessed. Various methods of chemical prevention of commercial winter and spring oilseed rape crops in field-realistic conditions were taken into account in the assessment. Pesticides were applied in accordance with the actual agricultural practice. Commercial crop protection products with thiamethoxam, clothianidin or imidacloprid were used as seed treatment. Formulations containing acetamiprid or thiacloprid were used for spraying. Fifteen healthy bee colonies were placed in close proximity to each of the oilseed rape fields throughout the blooming period. During florescence, the samples of nectar (directly from flowers and nectar flow from combs) and pollen loads were collected repeatedly. Samples of honey, bee bread and adult bees were taken one week after the end of plants flowering. To ensure high specificity and sensitivity of analysed pestcicides modified QuEChERS extraction method and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was used. The five of neonicotinoid insecticides (imidacloprid, clothianidin, thiametoxam, acetamiprid and thiacloprid) were analyzed in multi-residue method with 0.1 - 10 ng/g limits of detection. Palynological analysis was done to determine the botanical origin of the nectar, honey and pollen. Development of bee colonies (brood area, worker biomass, colony health) was assessed every 3 weeks until the end of the beekeeping season. The amount of pollen collected by bees per hive, bee bread area and rape honey yield was also measured. The long-term effects of insecticides on bees were estimated using the same methods in April of the following year.
All the neonicotinoid insecticides applied to control oilseed rape pests were present in the samples of nectar and pollen. Their residue levels were lower than the acute oral and contact LD50 values. Among five examined neonicotinoids, the most frequently detected were: thiamethoxam, thiacloprid and acetamiprid. These substances were present in 65, 64, and 51% of the nectar samples and in 37, 62, and 45% of the pollen samples, respectively. The highest level of residues were noted after the thiamethoxam seed treatment; on average, 4.2 and 3.8 ng/g in the nectar and pollen samples. In the nectar and pollen samples from winter rape fields, lower levels of neonicotinoid residues were found in comparison to spring rape samples. The contaminations of neonicotinoids applied as seed dressing in nectar samples were significantly higher in comparison to the pollen samples. No negative effects of neonicotinoids on the bee mortality, brood development, strength, and honey yield of healthy bee colonies were found throughout the study period. However, the risk exposure of bee colonies on adverse impact of pesticide residues is high in areas of intensively cultivated oilseed rape.