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.
Three different starch syrups available on the Polish market for winter feeding of bees were evaluated for two consecutive beekeeping seasons (2012/2013 and 2013/2014). Sugar syrup and inverted sucrose syrup were used as the control. Winter feeding was conducted at two times: earlier and later in the season. After supplementation of winter feeding was stopped, we measured colony strength (number of combs covered by bees) and brood area. After overwintering (spring 2013 and 2014), we estimated the influence of these foods on: bee mortality during overwintering (number of dead bees in winter debris), food consumption, colony strength and brood area in spring (two measurements in three-week intervals), development dynamics and honey yield from spring flow. An analysis of the results for the parameters assessed before overwintering, after its end and during spring development did not show significant differences between bee colonies fed with different types of food. No relevant difficulties concerning food crystallisation were encountered. The analysed syrups turned out to be as suitable for winter feeding of bees as sugar and inverted sucrose syrups.
Amitraz 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.
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.
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.
Field trials were conducted to evaluate the effectiveness of amitraz fumigation against Varroa destructor in honey bee colonies with brood. Within this project the following aspects were taken into consideration: strength of colony, the number of treatments, time intervals between treatments and way of its performance. Honey bee colonies with brood were fumigated four times with one tablet of Apiwarol® per each treatment every four, six, eight and ten days. The tablets with amitraz were burned in the electrical device Wakont or directly in hives. In case of amitraz fumigation with Wakont even four treatments reduced infestations of V. destructor to a limited extent, on average from 40 to 61% of mite populations. A similar effectiveness among the treatments has been ascertained regardless of intervals between them. The efficacy of amitraz combustion in hives was slightly higher and statistically significant only after four treatments. Moreover, beyond brood area, the population of worker bees turned out to determine treatment efficacy with amitraz in this form and modes of administration. In honey bee colonies with brood, even four amitraz fumigations do not decrease the level V. destructor infestation to the extent that it is safe for wintered bees.
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.
Amitraz is a formamide exhibiting both acaricidal and insecticidal activity and is frequently used by beekeepers to protect honeybee colonies against Varroa destructor mites. The aim of this apiary trial was to evaluate the impact of honeybee colony fumigation with amitraz on the level of contamination of honey stored in combs.
Material and Methods
Experimental colonies were fumigated four times every four days with one tablet of Apiwarol per treatment. Honey was sampled from combs of brood chambers and combs of supers one day after each amitraz application and from harvested honey. Amitraz marker residues (as a total of amitraz and metabolites containing parts of molecules with properties specific to the 2,4-DMA group, expressed as amitraz) were evaluated in honey.
All analysed samples were contaminated with amitraz metabolites. 2,4-DMA and DMPF were the most frequently determined compounds. The average concentration of amitraz marker residue in honey from groups where a smouldering tablet was located directly in beehives was significantly higher than that of residue in honey from groups with indirect smoke generation. No significant effect on the honey contamination deriving from the place where it was exposed to smoke (combs of brood chambers and supers) was noted. Amitraz marker residues exceeded the MRL in 10% of honey samples from combs.
Fumigation of beehives with amitraz results in contamination of honey stored in combs.