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Krystyna Pohorecka, Teresa Szczęsna, Monika Witek, Artur Miszczak and Piotr Sikorski

Abstract

The present studies are the second part of the research project dedicated to finding the causes for increased winter mortality of honey bee colonies. The aim of this task was to investigate incidents of overwintered colonies′ death with regard to the potential interrelation to the exposure to pesticides. The samples of winter stores of bee bread and sugar food (honey or syrup processed by bees), beeswax and bees collected from apiaries with low and high rates of winter colony mortality were searched for acaricides used to control V. destructor and plant protection pesticides. The presence of acaricides used in apiculture has been detected in the 51% beeswax samples. The most abundant acaricide was tau-fluvalinate. The stores of bee bread and sugar food had a similar frequency of plant protection pesticide occurrence, ranging between 50-60%, but the number of active substances and their concentrations were substantially lower in sugar food samples. The most prevalent pesticides in pollen were fungicides (carbendazim and boscalid) and insecticides (acetamiprid and thiacloprid). Only a few pesticides were found in the several dead honey bees. The level of pesticide contamination (frequency, concentration, toxicity) of hive products and bees originating from apiaries with both a high and low winter colony survival rates, was similar, which created a similar extent of risk. Although the multiple varroacides and pesticides were present in the hive environment we not found unequivocal links between their residues and high winter colony mortality.

Open access

Ewa Waś, Teresa Szczęsna, Helena Rybak-Chmielewska, Dariusz Teper and Katarzyna Jaśkiewicz

Abstract

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).

Open access

Ewa Waś, Teresa Szczęsna and Helena Rybak-Chmielewska

Abstract

Here we describe a method of hydrocarbon (alkanes, alkenes, dienes) identification and quantitative determination of linear saturated hydrocarbons (n-alkanes) in beeswax using gas chromatography with a mass detector technique (GC -MS ). Beeswax hydrocarbons were isolated using a solid-phase extraction (SPE ) technique with neutral aluminum oxide (Alumina - N, 1000 mg, 6 mL), then were separated on a non-polar gas chromatography column ZB-5HT INFERNO (20 m×0.18 mm×0.18 μm). Qquantitative analysis of n-alkanes was conducted by the method of internal standard with squalane used as the internal standard. The basic parameters of validation (linearity and working range, limit of determination, repeatability and reproducibility, recovery) were determined. For all of the identified compounds, satisfactory (≥0.997) coefficients of correlation in the working ranges of the method (from 0.005 to 5.0 g/100 g) were obtained. The elaborated method was characterized by satisfactory repeatability and within-laboratory reproducibility. The average coefficients of variation for the total n-alkanes did not exceed 2% under conditions of repeatability or 4% under conditions of reproducibility. The recovery for individual n-alkanes was above 94%; for their total content, it was 100.5%. In beeswax originating from Apis mellifera, n-alkanes containing from 20 to 35 carbon atoms in their molecules were determined. The total content of these alkanes was between 9.08 g and 10.86 g/100 g (on average, 9.81 g/100 g). Additionally, apart from the saturated hydrocarbons, unsaturated hydrocarbons and dienes were identified.

Open access

Ewa Waś, Teresa Szczęsna and Helena Rybak-Chmielewska

Abstract

The hydrocarbon composition of beeswax secreted by Apis mellifera was characterised. In the studies, analyses were made of virgin beeswax (obtained from light combs, socalled „wild-built combs“) that was collected at different dates, and beeswax obtained from dark combs („brood combs“). A qualitative analysis did not show any differences in the hydrocarbon composition of beeswax originating from light and dark coloured combs. The same hydrocarbons (n-alkanes, alkenes, and dienes) were identified in virgin beeswax and beeswax collected from brood combs. However, the studies showed differences in the content of n-alkanes in the beeswax obtained from light and dark coloured combs. In comparison to the virgin beeswax, the beeswax obtained from dark combs had higher content of the total n-alkanes, higher total contents of even-numbered alkanes and odd-numbered alkanes, and higher contents of certain alkanes. Furthermore, it has been found that the hydrocarbon composition of beeswax did not depend on the collection period.

Open access

Helena Rybak-Chmielewska, Teresa Szczęsna, Ewa Waś, Katarzyna Jaśkiewicz and Dariusz Teper

Summary

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.

Open access

Ewa Waś, Teresa Szczęsna and Helena Rybak-Chmielewska

Abstract

To detect beeswax adulteration with hydrocarbons of alien origin (e.g. paraffin), gas chromatography with mass detector (GC-MS) technique was used. The method has been verified here on beeswax samples with different addition (3, 5, 10, 30, and 50%) of paraffin and validated under the conditions of repeatability and within - laboratory reproducibility. The addition of paraffin to beeswax can already be detected on the basis of an analysis of the chromatograms. The intensity of individual alkane peaks increased with the increase of the amount of paraffin added to the beeswax. This increase was the mostly visible for the alkanes with even numbers of carbon atoms in the molecule: C24H50, C26H54, C28H58, C30H62, C32H66, and C34H70. These observations have also been proven by quantitative analysis performed using the internal standard method. Adding paraffin to beeswax resulted in an increase in the total contents of n-alkanes as well as individual alkanes, and in particular, of the even-numbered alkanes. The addition of paraffin to beeswax also resulted in the appearance of alkanes containing over 35 carbon atoms in the molecule, which were not detected in beeswax. The method for determination of beeswax hydrocarbons with the GC-MS technique is characterised by satisfactory repeatability and within-laboratory reproducibility. This method can be used for the detection of beeswax adulteration with hydrocarbons of alien origin (e.g. paraffin).

Open access

Ewa Waś, Teresa Szczęsna and Helena Rybak-Chmielewska

Abstract

The efficiency of the gas chromatography - mass detector (GC-MS) technique for the detection of beeswax adulterated with paraffin, was evaluated. For this purpose, beeswax samples with paraffin additions (3, 5, 10, 30, 50%) were analysed. Since not enough is known about paraffin compositions, and since it is difficult to detect paraffin in beeswax, the aim of our research was also to compare the hydrocarbon composition of different types of paraffin. The analysis showed that the types of paraffin available on the market, differ qualitatively and quantitatively as far as their hydrocarbon compositions are concerned. In all kinds of paraffin, we found homologous series of n-alkanes that were much longer than those in beeswax. In beeswax, the amount of added paraffin that is possible to detect, differs and depends on the kind of paraffin used for adulteration. In this study, the minimum estimated percent that was detected using the GC-MS technique, was 3%. The adulteration is indicated by the presence of hydrocarbons containing over 35 carbon atoms in the molecule, and by the higher contents of n-alkanes (C20H42 - C35H72), in comparison to the concentration of these compounds determined in pure beeswax. We also presented the results of the quality control of commercial beeswax. Based on our results, it can be stated that beeswax adulteration is currently a problem.