Andreas Thrasyvoulou - Academia.edu (original) (raw)

Papers by Andreas Thrasyvoulou

Journal of Apicultural Research, May 19, 2022

Journal of the Hellenic Veterinary Medical Society, 2021

Bee venom was collected by electrical stimulation from Apis mellifera macedonica every six and tw... more Bee venom was collected by electrical stimulation from Apis mellifera macedonica every six and twenty-four days respectively for two years.Collections were accomplished from April to October the first year, and from May to October the second year. The bee venom yield and the bees' behavior like the aggressiveness, the number of dead bees on the collecting device and the hoarding behavior were studied. A great variation was found among the colonies regarding the collected amount of bee venom. The production was high in spring, decreased in summer and increased again in autumn in both years. Two different tests were used to study the defensive response of honeybees. The rhythmic reflux of a leather ball in front of the hive and the test of rating assay. Both tests showed that bees' aggression did not significantly increase after collection. Furthermore, the aggressiveness of bees did not change during the period of collection. The average number of dead bees found on the wires of collecting device,was below 20 in each collection. Hoarding test indicates that no significant differences existed between before and after the stimulation of worker honey bee by electrical impulses.Τhe collection of BV did not affect brood and adult population of bees.

Journal of Apicultural Research

Journal of AOAC INTERNATIONAL, 2000

A simple, rapid, and accurate method is described for the determination of residual fluvalinate i... more A simple, rapid, and accurate method is described for the determination of residual fluvalinate in beeswax. The procedure consists of partitioning on a disposable column of diatomaceous earth (Extrelut®), followed by chromatographic cleanup on a Florisil cartridge. The final extract is analyzed by capillary gas chromatography with electron-capture detection (GC–ECD). Briefly, wax samples were dissolved in n-hexane, and the solutions were sonicated and transferred to Extrelut columns. The fluvalinate was extracted with acetonitrile, and a portion of the extract was cleaned up on a Florisil cartridge. The fluvalinate was eluted with diethyl ether–n-hexane (1 + 1) and directly determined by GC–ECD. Recoveries from wax samples spiked at 5 fortification levels (100–1500 μg/kg) ranged from 77.4 to 87.3%, with coefficients of variation of 5.12–8.31%. The overall recovery of the method was 81.4 ± 3.2%, and the limit of determination was 100 μg/kg.

Pest Management Science, 2001

The persistence of the acaricide tau‐fluvalinate with time and the factors that can affect its de... more The persistence of the acaricide tau‐fluvalinate with time and the factors that can affect its degradation in honey were investigated. Two honey types of extreme pH values (3.85 and 5.40) were spiked with tau‐fluvalinate at two levels (50 and 200 µg kg−1) and incubated at 35 °C. Samples were analyzed in duplicate at various time intervals for up to 248 days. A simple, rapid and accurate method for the determination of tau‐fluvalinate residues in honey is proposed. Tau‐fluvalinate extraction and sample cleanup was carried out using C8 SPE cartridges with dichloromethane as the elution solvent. Analysis of samples was accomplished using gas chromatography with electron‐capture detection (GC–ECD). The overall recovery of the method was 90.25(±0.85)% and the limit of determination 1 µg kg−1. The results showed that tau‐fluvalinate stays stable in honey for more than 8 months, even at 35 °C. The effect of higher temperatures, similar to those used for honey packing, on tau‐fluvalinate pe...

Apimondia 41st Congress, 2009

Journal of Apicultural Research, 1986

Fresh samples of Greek honey were collected, grouped into categories according to their botanical... more Fresh samples of Greek honey were collected, grouped into categories according to their botanical origin and analysed for hydroxymethylfurfural (HMF) and diastase activity. The effect of storage and heating on these two constituents was also examined. Using HMF and diastase as criteria to assess the quality of the product, some Greek honey could be regarded as industrial honey although it was fresh, unheated and naturally pure. This was particularly true of Thymus honey, which is very low in diastase. On the other hand, Po/ygmzum honey, which is not liked as table honey by the Greek market, fell well within that category on the basis of its HMF and diastase contents. Storage or heating caused different rates of loss of diastase and production of HMF, even in honeys of the same origin. This complicates further the use of HMF and diastase as criteria for detecting overheated honeys.

Propolis is a natural material that honeybees produce from resinous secretions of the plants and ... more Propolis is a natural material that honeybees produce from resinous secretions of the plants and wax. It is used from bees to protect their hive from adverse external conditions and pathogens. Because of the bioactive compounds included in propolis, it is used as therapeutic agent. The medical applications of this bee hive product led to an increased interest in its production and chemical composition. In this research, propolis samples collected during the whole active beekeeping period for three years and the variations caused to season and type of collection investigated. Parameters such as the yield per hive, the wax content, the dry matter, the total phenols and antioxidant activity of the extracts were evaluated. The results showed a strong seasonal variation, with the maximum production have been recorded between May and July. Bees collect/produce more propolis during the warm periods of the year because of the viscosity of the resins. When they need more product, bees cover...

Open Journal of Applied Sciences, 2018

One of the main practices followed by beekeepers during the production of royal jelly (RJ) is the... more One of the main practices followed by beekeepers during the production of royal jelly (RJ) is the artificial sugar feeding. In this study, the effect of carbohydrate supplementary feeding on the composition of the three main sugars (fructose, glucose, sucrose) and on the final quantity of the product was explored using one-way ANOVA and non-parametric tests. Also, the correlations among the parameters were examined. The average yield per colony for non-supplemented colonies (Group A) was 12.8 g, while the average content of fructose, glucose and sucrose was 4.32%, 3.78%, and 0.04%, respectively. For the colonies fed at the grafting day one time (Group B), these values were 12.76 g, 3.11%, 3.19% and 3.71%, and for the colonies fed from the insertion until the collection day (Group C), 12.81 g, 3.05%, 3.12% and 3.54% respectively. It should also be noted that the sucrose content in all samples from supplemented colonies was found greater than 1.97%. The statistical tests highlighted the impact of artificial feeding on fructose and glucose contents, while the produced quantity remained uninfluenced. Finally, the Spearman (rho) coefficient test showed statistically significantly negative correlation between the monosaccharides (fructose, glucose) and sucrose.

Journal of Apicultural Research, 2021

Bee pollen" is pollen collected from flowers by honey bees. It is used by the bees to nourish the... more Bee pollen" is pollen collected from flowers by honey bees. It is used by the bees to nourish themselves, mainly by providing royal jelly and brood food, but it is also used for human nutrition. For the latter purpose, it is collected at the hive entrance as pellets that the bees bring to the hive. Bee pollen has diverse bioactivities, and thus has been used as a health food, and even as medication in some countries. In this paper, we provide standard methods for carrying out research on bee pollen. First, we introduce a method for the production and storage of bee pollen which assures quality of the product. Routine methods are then provided for the identification of the pollen's floral sources, and determination of the more important quality criteria such as water content and content of proteins, carbohydrates, fatty acids, vitamins, alkaloids, phenolic and polyphenolic compounds. Finally, methods are described for the determination of some important bioactivities of bee pollen such as its antioxidant, anti-inflammatory, antimicrobial and antimutagenic properties. M etodos est andar Para la investigaci on del polen El "polen de abeja" es el polen recogido de las flores por las abejas mel ıferas. El polen de abeja es utilizado para nutrir a las propias abejas, principalmente para proporcionar jalea real y alimento para las cr ıas, pero tambi en se utiliza para la nutrici on humana. Para este ultimo fin, se recoge en la entrada de la colmena en forma de gr anulos que las abejas llevan a la colmena. El polen de abeja tiene diversas bioactividades, por lo que se hautilizado como alimento para la salud, e incluso como medicamento en algunos pa ıses. En este art ıculo, proporcionamos m etodos est andar para llevar a cabo investigaciones sobre el polen de abeja. En primer lugar, presentamos un m etodo de producci on y almacenamiento de polen de abeja que garantiza la calidad del producto. A continuaci on, se ofrecen m etodos de rutina para la identificaci on de las fuentes florales del polen y la determinaci on de los criterios de calidad m as importantes, como el contenido de

Journal of the Science of Food and Agriculture, 2017

BACKGROUND: Pollen analysis of honey is the basic method for the determination of its botanical o... more BACKGROUND: Pollen analysis of honey is the basic method for the determination of its botanical origin. However, the presence of over-represented pollen in honeys may lead the analysis to false results. This can be more severe if this pollen is present in unifloral under-represented honeys of commercial importance, for instance thyme honey. In this study, we investigated the abundance of over-represented pollen grains on several quality characteristics in honey samples. In particular, we mixed honeys characterised as overrepresented, specifically chestnut and eucalyptus, with thyme honeys in different analogies; and we analysed the melissopalynological, organoleptic, physicochemical (water content, electrical conductivity, colour) and volatile characteristics of the blends. RESULTS: The most sensitive parameters were the microscopic characteristics, followed by the organoleptic ones. Blends of thyme honey with originally low percentage of thyme pollen were the most influenced and could not be characterised as unifloral, regarding their melissopalynological characteristics even when they were mixed with small quantities of honeys with overrepresented pollen (i.e. 5 %). CONCLUSION: This study confirms that in case of presence of over-represented pollen in honeys, the pollen analysis alone cannot give trustworthy results for This article is protected by copyright. All rights reserved. This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as

Journal of Apicultural Research, 1982

Growth rates of honeybee larvae (Apis mellzfera) were determined in the period April-July by weig... more Growth rates of honeybee larvae (Apis mellzfera) were determined in the period April-July by weighing individual larvae at definite age intervals. Larval weight was correlated to larval age and the relationship expressed in terms of regression equations. A coefficient of variation of 20% was established as a maximum acceptable variation for pooled samples of 20 larvae.

Journal of Apicultural Research, 2004

The prothoracic and propodeal spiracles of three honey bee strains used commercially in Greece (f... more The prothoracic and propodeal spiracles of three honey bee strains used commercially in Greece (from N Greece, N Italy and Slovenia) were examined with a light microscope in order to detect possible morphological differences between the strains. This is an attempt to explain the apparent resistance against Acarapis woodi shown by the Greek Macedonian (N Greece) strain but not by the others. The propodeal spiracles of honey bees from N Greece and N Italy were examined, in addition, using a scanning electron microscope. Certain dimensions, like the length and the area of aperture in the prothoracic spiracle, were found to be significantly larger in honey bees from N Italy and Slovenia compared with the honey bees from N Greece. The length of aperture was found to be 648 µm in the honey bees from N Greece, while it was 13% larger in the honey bees from N Italy and 10% larger in the honey bees from Slovenia; the area of the aperture was found to be 103000 µm 2 in the honey bees from N Greece, while it was 26% larger in the honey bees from N Italy and 27% larger in the honey bees from Slovenia. The dimensions of the propodeal spiracle were found to be similar between the strains examined. The fact that the prothoracic spiracle of honey bees from N Greece was significantly smaller compared to other honey bee groups (from N Italy and Slovenia), is discussed as a possible mechanism for resistance developed by this strain against Acarapis woodi.

Journal of Apicultural Research, 2015

The existing literature classifies bee pollen as “excellent” or “poor” according to protein conte... more The existing literature classifies bee pollen as “excellent” or “poor” according to protein content. In this research, we ranked bee pollen according to its contribution to bee nutrition, taking into consideration the seasonal variation. We found that the richness in protein content of each single taxon alone is not enough to classify it, as a “good” pollen source, and seasonal variation in vegetation and colony needs should be taken into account. In many cases, bees collected more pollen from plants poorer in protein, which were in total more beneficial to the colony compared to pollen rich in protein, but collected in smaller amounts. We concluded that the amount of the collected pollen was the most important factor and this is relative to the population of the plants at the surrounding area, the flowering period, and the season. The attractiveness of pollen, as indicated by the amount of pollen collected by the bees, was not correlated to the protein content of different taxa. Bees collected pollen from a large number of taxa, but only few of those contributed significantly to their nutritional requirements. We found that only 14 out of 46 pollen taxa included the 88.8% of the total proteins that were available for bees. The crude protein of these “selected” pollen sources ranged from 13.9 to 25.5%. Pollen from plants blooming in spring had higher protein content (20–24.7%) than those from summer (15.1–19.9%) and autumn (19.3–23.1%). The great amount of pollen that honey bees collected in spring and its richness in proteins could explain the strong growth of brood and population during this period.