Das serotonerge System besitzt sowohl bei Invertebraten als auch bei Vertebraten eine große Bedeutung für die Kontrolle und Modulation vieler physiologischer Prozesse und Verhaltensleistungen. Bei der Honigbiene Apis mellifera spielt Serotonin (5-Hydroxytryptamin, 5-HT) eine wichtige Rolle bei der Arbeitsteilung und dem Lernen. Die 5-HT-Rezeptoren, die überwiegend zur Familie der G-Protein gekoppelten Rezeptoren (GPCRs) gehören, besitzen eine Schlüsselstellung für das Verständnis der molekularen Mechanismen der serotonergen Signalweiterleitung. Ziel dieser Arbeit war es, 5-HT-Rezeptoren der Honigbiene zu charakterisieren. Dazu zählt die Identifizierung der molekularen Struktur, die Ermittlung der intrazellulären Signalwege, die Erstellung von pharmakologischen Profilen, die Ermittlung der Expressionsmuster und die Ermittlung der physiologischen Funktionen der Rezeptoren. Mit Hilfe der Informationen aus dem Honey Bee Genome Project, konnten drei RezeptorcDNAs kloniert werden. Vergleiche der abgeleiteten Aminosäuresequenzen mit den Aminosäuresequenzen bereits charakterisierter Rezeptoren legten nahe, dass es sich dabei um einen 5-HT1- (Am5-HT1) und zwei 5-HT2-Rezeptoren (Am5-HT2α und Am5-HT2β) handelt. Die strukturelle Analyse der abgeleiteten Aminosäuresequenz dieser Rezeptoren postuliert das Vorhandensein der charakteristischen heptahelikalen Architektur von GPCRs und zeigt starkkonservierte Motive, die bedeutend für die Ligandenbindung, die Rezeptoraktivierung und die Kopplung an G-Proteine sind. Für die beiden 5 HT2-Rezeptoren konnte zudem alternatives Spleißen nachgewiesen werden. Mit den cDNAs des Am5-HT1- und des Am5-HT2α-Rezeptors wurden HEK293-Zellen stabil transfiziert und anschließend die Rezeptoren funktionell und pharmakologisch analysiert. Am5-HT1 hemmt bei Aktivierung abhängig von der 5-HT-Konzentration die cAMPProduktion.Die Substanzen 5-Methoxytryptamin (5-MT) und 5-Carboxamidotryptamin konnten als Agonisten identifiziert werden. Methiothepin dagegen blockiert die 5-HTWirkung vollständig. Prazosin und WAY100635 stellen partielle Antagonisten des Am5-HT1-Rezeptors dar. Der Am5-HT2_-Rezeptor stimuliert bei Aktivierung die Synthese des sekundären Botenstoffs Inositoltrisphosphat, was wiederum zu einer messbaren Erhöhung der intrazellulären Ca2+-Konzentration führt. 5-MT und 8-OH-DPAT zeigen eine deutliche agonistische Wirkung auf Am5-HT2α. Dagegen besitzen Clozapin, Methiothepin, Mianserin und Cyproheptadin die Fähigkeit, die 5-HT-Wirkung um 51-64 % zu vermindern. Die bereits erwähnte alternative Spleißvariante von Am5-HT2α wurde ebenfalls in HEK293-Zellen exprimiert und analysiert, scheint jedoch eigenständig nicht funktionell zu sein. Gegen die dritte cytoplasmatische Schleife (CPL3) wurde ein polyklonales Antiserum generiert. Dieses erkennt in Western-Blot-Analysen ein Protein mit einer Masse von ca. 50 kDa. Durch immunhistochemische Analysen am Bienengehirn wurde die Verteilung des Rezeptors genauer untersucht. Dabei zeigten die optischen Neuropile, besonders die Lamina und die Ocellarnerven, stets eine starke Markierung. Außerdem wird der Rezeptor in den α- und β-Loben sowie der Lippe, dem Basalring und dem Pedunculus der Pilzkörper exprimiert. Doppelmarkierungen zeigen stets eine enge Nachbarschaft von serotonergen Fasern und dem Am5-HT1-Rezeptor. Weiterhin konnte gezeigt werden, dass der Am5-HT1-Rezeptor sehr wahrscheinlich an der Regulation des phototaktischen Verhalten der Honigbiene beteiligt ist. Verfütterung von 5-HT hat eine deutlich negative Wirkung auf das phototaktischen Verhalten. Diese kann durch den Am5-HT1-Rezeptor-Agonisten 5-CT imitiert werden. Schließlich konnte gezeigt werden, dass der Am5-HT1-Antagonist Prazosin die 5-HT-Wirkung deutlich vermindern kann. / The serotonergic system plays an important role in the control and modulation of many physiological and behavioral processes in both vertebrates and invertebrates. In the honeybee Apis mellifera, serotonin (5-hydroxytryptamine, 5-HT) has been implicated in the control and regulation of division of labor as well as learning and memory. A key role in understanding the serotonergic system plays the molecular and functional characterization of 5-HT receptor subtypes. In most cases, serotonin receptors represent G protein-coupled receptors (GPCRs). This work describes the characterization of honeybee serotonin receptors. This comprises the identification of their molecular structure, intracellular second messenger pathways, pharmacological properties, expression profiles and functions. By screening the honeybee genome, we found three candidate genes encoding for putative serotonin receptors. The cDNAs of these genes were cloned and the deduced amino acid sequences were analysed. The sequence information was used to isolate the cDNAs encoding for these three receptors. Comparison of the deduced amino acid sequences with sequences of other known receptors suggests that one receptor belongs to the 5-HT1 (Am5-HT1) and the other two receptors to the 5-HT2 receptor class (Am5-HT2α and Am5-HT2β). Major characteristics common to all GPCRs (e.g. the heptahelical architecture) were confirmed by structural analyses of the deduced amino acid sequences. Furthermore, truncated receptor transcripts representing alternative splice variants of both 5-HT2 receptors could be detected. HEK293 cells were stably transfected with the cDNAs of Am5-HT1 or Am5-HT2_ and functionally and pharmacologically analysed. The activation of Am5-HT1 by 5-HT results in the dose dependent attenuation of adenylyl cyclase activity. 5-methoxytryptamine (5-MT) and 5-carboxamidotryptamine are able to imitate the 5-HT effect. In contrast, methiothepin is able to block the entire 5-HT effect, whereas prazosine and WAY100635 block the 5-HT effect only partially. The Am5-HT2α receptor stimulates the synthesis of the second messenger inositol trisphosphate which in turn mediates an increase in the intracellular Ca2+. The substances 5-MT and 8-OH-DPAT were identified as agonists of the Am5-HT2α receptor. In contrast, clozapine, methiothepine, mianserine, and cyproheptadine show strong antagonistic actions. A truncated alternative splice variant of the Am5-HT2α-receptor was also analysed but didn’t show any functional coupling by itself. An antiserum was raised against the third cytoplasmic loop (CPL3) of the Am5-HT1 receptor. This antiserum detects a protein with a molecular mass of 50 kDa in western blot analyses. The expression of the Am5-HT1 receptor was studied in detail using immunohistochemistry. Strong Am5-HT1-like immunofluorescence was observed in the ocellar nerve, in the three optic ganglia and in the α- and β-lobes, the pedunculi, the lip and the basal ring of the mushroom bodies. Furthermore, co-labeling with an antibody against 5-HT showed that this receptor is expressed in close vicinity to serotonergic neurons. Finally, behavioral experiments suggest a possible role of the Am5-HT1 receptor in phototactic behavior. Feeding of 5-HT to worker honeybees results in a decrease of phototactic behavior. This 5-HT action could be mimiced by feeding of the Am5-HT1 agonist 5-CT. In contrast, the Am5-HT1 antagonist prazosine prevents the 5-HT-induced decrease in phototaxis.

2004 ir 2006 m. birželio – rugpjūčio mėn. buvo tiriama medunešių bičių (Apis mellifera L.) tranų skraidymo pradžia, tranų skraidymo dinamika dienos metu ir kokią įtaką jai daro aplinkos temperatūra. Įvertintas išskrendančių ir atskrendančių į tą pačią bičių šeimą tranų skaičius bei tranų skridimas į svetimas bi��ių šeimas. Ištirta 6 stipresnės ir 5 silpnesnės bičių šeimos. Buvo skaičiuojami per 2 min. iš avilio išskridę, po to per 2 min. į avilį atskridę tranai. Kiekvienos bičių šeimos tranai buvo pažymėti skirtinga spalva. Žymėti tranai turėjo savo individualius numerius. Tyrimų rezultatai parodė, tranai pradeda skraidyti 5 parų amžiaus. Tranų skraidymas dieną prasideda nuo 12 val., o baigiasi 18 val. Jų išskridimas iš bičių šeimų pasiekia maksimumą apie 15 val., o sugrįžimas po skraidymo – apie 17 val. Esant daugiau nei 25ºC šilumos tranų skridimas iš šeimų pasiekia maksimumą apie 15 – 16 val., o sugrįžimas į jas – apie 17val. Kiekvienoje bičių šeimoje yra pusiausvyra tarp išskrendančių ir atskrendančių į ją tranų skaičiaus. Po skraidymo sugrįžtantys į bičių šeimą tranai yra dviejų rūšių: pasirenkantys tik savo šeimą ir pasirenkantys ne tik savo, bet ir kitas bičių šeimas (daugiau nei vieną šeimą). / During 2004 and 2006 June – August research was made to ascertain honeybees (Apis mellifera L.) drones starting to fly, their flying dynamic during the day and how it depends on surroundings temperature. Were counted numbers of drones flying in and out the same honeybees colonies and number of drones flying to the other honeybees colonies. For research were taken 6 stronger and 5 weaker honeybees colonies. Were counted number of drones flying out of the hive in 2 minutes period, after - were counted number flying in drones for the same period. Each colony drones were marked in different color and every marked drone had individual number. Researches showed that drones start to fly at the age of 5 days. During the day they begin to fly from 12 p.m. and stop flying at around 6 p.m. Highest number of drones flying out of hive is around 3 p.m., flying in - around 5 p.m. Each honeybees colony keeps balance between flying in and out of hive drones. Here are two kinds of drones, returning back to honeybees colony after flying: the ones, who choose only their own colony, and the others, that choose not only own colony, but others too (more than one colony).

Thesis (Ph.D.) -- University of Western Sydney, Hawkesbury, 1999. / Thesis submitted for the degree of Doctor of Philosophy. Includes bibliographical references (leaves 210-230).

Thesis (Ph.D. (Biochemistry, Microbiology & Biotechnology)) - Rhodes University, 2005.

The Western Honeybee (Apis mellifera) is an important species, not only ecologically and economically, but as a source of recreation to many. The pollination services the species provides benefit a number of crops worldwide, and, as the honeybee is domesticated and kept in hives, can be directed commercially. Recently, although overall global stocks are growing, there have been reports of high colony losses worldwide. Due to the value of this species, this is a worrying trend. There are many stressors facing the honeybee, both natural and anthropogenic in origin. Two of the most prevalent, both in the popular media and in monitoring studies of colonies are insecticidal pesticides and the parasitic mite Varroa destructor. Due to the difficulties and expense of carrying out large-scale field studies required to properly investigate the multiple stressors and their interaction, the use of modelling to explore the problem and direct field work is a vital resource. In this thesis, I present research using the BEEHAVE model and a novel model to explore the exposure and potential impacts of pesticides and the varroa mite. The results show that the timing of a pesticide exposure in the year greatly changes the resultant impact on the colony. Pesticides can have many impacts on different stages of the honeybee, and I show that increased mortalities of different life stages of the honeybee (larvae, in-hive adults, foragers) and decreasing egg-laying rate, affect the development of the colony to different extents at different times of the year, with the colony being highly sensitive to losses of in-hive bees during the summer, and the over-wintering bees at the beginning and end of the year. A novel model is presented exploring the in-hive distribution of pesticide-containing nectar and the effect it has on the exposure of in-hive receiving bees and larvae. The results from this model show that, in-hive distribution is not important to consider for the adults, but may be for the larvae. The landscape, specifically the distance to pesticide-treated forage in relation to untreated forage also has an impact on the result of a pesticide exposure, and this is a potential avenue for the mitigation of pesticide impacts. I also present work towards the validation of BEEHAVE with regards to varroa mite infestation, finding that the model results are close to empirical data, both for datasets from the UK and USA, but the impact of varroa is underestimated. The results are discussed in the context of pesticide risk assessment, the mitigation of potential stressors and the modelling of the varroa mite. The BEEHAVE model is a vital tool for many applications, one being the risk assessment of pesticides. A review of the model by the European Food Security Agency (EFSA) highlighted extensions to the model required before it can be incorporated. This research begins to answer some questions asked in that review.

Nosematosis belongs to the intestinal disease of bees, which is widely spread both in the world and in the Czech Republic. It is caused by Nosema apis and Nosema ceranae. The aim of this diploma thesis was to evaluate the occurrence of the Nosema dispute in the territory of ČSV Bystřice, to describe species variability and to assess the effect of the season on the occurrence of Nosema apis and Nosema ceranae. To detect infection of colonies, 5 bees from selected hives were examined under the microscope. In positive specimens on nosematosis, the species of Nosema spore was molecularly examined. In total, 93 samples from 15 breeders were examined. Samples were taken in the spring and summer of 2017. The sampling took place both for malachists and for farmers with more than 150 bee colonies. During the summer sampling more positive bees were found than in spring sampling. Beekeepers were further assessed by the number of hives. Following the analysis of the samples obtained using the PCR method, Nosema ceranae disputes were present in the vast majority of colonies.

The main objective of my work was to evaluate if it is possible to use the honey bee - Apis mellifera as a bioindicator of the environmental contamination by heavy metals. Two areas were being compared. The first one was more affected by emission (The Capital city of Prague) and the second one was less hit by emission (The Highlands). During the course of three years five samples of bee honey were taken from each area. The analysis was made to show how much cadmium, lead and mercury the samples contained. In most samples higher concentration of these chemicals were dealt out in honey taken from the more polluted area. Although not all the concentrations of heavy metals in honey reflect the emission burden of the examined areas. It would be necessary to take samples from a larger number of areas in order to confirm the conclusion that bee honey is a suitable bioindicator of the environmental contamination by heavy metals.

The role of the queen in wax secretion and comb building was studied in the the Cape honeybee, Apis mellifera capensis (Escholtz). The percentage of bees bearing wax and the amount of wax borne by these bees did not differ between the experiments. This meant that the queenless and queenright colonies had the potential to construct equal amounts of comb as the amounts of wax available for comb building was the same. Contrary to this prediction, queenright colonies constructed 8 times more comb than their queenless counterparts. Queenright Apis mellifera scutellata colonies constructed 4 times more comb than their queenless counterparts. The increased amount of 9-oxo-2-decanoic acid (90DA) in the A.m.capensis mandibular gland secretions could not alone account for this difference. In fact, A.m.capensis and A.m.scutellata colonies constructed similar amounts of comb when they were given their own queens or queens from the other race. Worker bees need to have direct contact with their queen for comb building to be enhanced. Even when the queen had her mandibular glands extirpated and tergite glands occluded large amounts of comb were constructed than when access to the queen was limited. Direct access to the head of a mated queen proved to be the stimulus enhancing comb building. No comb was constructed when the workers had access to the abdomen of the queen. Virgin queens did not stimulate comb building. The relatively large amounts of 90DA and 9HDA from the mandibular glands of Cape virgin queens had not influenced comb building. Worker sized cells were generally constructed. These cells were slightly smaller than those constructed by European honeybees, but were indicative of African bees. A few queen less colonies constructed cells that were of an intermediate drone and worker size. Four mandibular gland pneromones were measured by gas chromatography. No correlations between these pheromones and the comb construction measurements were found. It is unlikely that the mandibular gland pheromones are the only pheromones that stimulate comb building. Pheromones from other glands on the head may contribute towards the enhancement of comb building, and they are not present in virgin queens

In a honeybee colony, the loss of a queen is considered to be a serious occurrence and, if a new queen is not produced, ultimately doomed. However, in colonies of Apis mellifera capensis (Cape honeybees), numerous pathways are available for a colony which unexpectedly losses a queen. At the onset of this experiment, four colonies of A. m. capensis were dequeened. Following this photographs of all brood frames in each colony were taken and the contents of the cells analysed. Cells were chosen at random but once selected were repeatedly analysed for the duration of the experiment. The contents of a total of 44 888 individual cells were analysed. Any queen cells constructed during the sampling period were removed, maintaining a queenless state. In each colony, as predicted, the removal of the queen evoked a variety of responses in an attempt to rectify the sudden loss. However, ultimately three of the four colonies absconded, leaving little by way of stores. Three of the four colonies initially attempted to rear a new queen while one colony was immediately invaded by a presumed foreign queen and hence any attempt at queen cell construction ceased. An increased number of queen cells in the swarm position were recorded in all colonies. The invasion of a colony by a foreign queen was considered to be a new pathway available for queenless colonies of A.m capensis. Worker policing and suspected brood cannibalism was prevalent in all sampled colonies yet in addition, the transfer of eggs and larvae from cell to cell was also observed which may have increased the suspected cases of policing and cannibalism. It was unclear whether an egg or larva had been consumed or simply moved to another cell on the brood frame. All colonies contained eggs from laying workers to varying degrees, based on the length of each individual sampling period which varied between colonies due to differences in absconding dates. A steady breakdown in the effectiveness of the division of labour amongst the worker bees was observed in each of the colonies highlighting the vital role of a queen. This breakdown was clearly seen in the reduction in general housekeeping within a colony. An increase in stores indicated a possible increase in the number of forager bees, thereby reducing the number of worker bees available for other duties. Pathways available to broodright colonies and strategies used following sudden queen loss are discussed.

Pollination is an essential ecosystem service, increasing reproductive success of many crops, which can be provided by managed pollinators, wild bees (including honeybees) and other insect pollinators. However, the pollination services and the economic value of wild pollinators are often underestimated. Better understanding of the factors that influence honeybee foraging behaviour and pollination efficiency can contribute to the improvement of management practices that aim to enhance crop pollination and ecosystem services. The objectives of this study were to investigate the importance of managed honeybees and wild honeybees to sunflower pollination as well as to evaluate the response of honeybees to different levels of floral rewards and to behavioural interactions with wild flower visitors. The study was conducted in 16 commercial sunflower farms and one experimental farm of South Africa during the 2009 sunflower flowering season. The results showed that insects, particularly honeybees, were efficient pollinators, improving sunflower production in all self-fertile sunflower cultivars used in this study. Furthermore, wild honeybee colonies were found to be as efficient as managed honeybee colonies in sunflower pollination near to natural habitat. Both sunflower yield and the abundance of pollinators decreased with distance from natural habitat, suggesting that sunflower yield is directly correlated with the abundance of pollinators. The amount of nectar present in the florets of sunflower significantly affected pollinator behaviour, influencing honeybee visitation length and foraging rate which prefer to exploit floral rewards from the same source if they find the higher amount per foraging trip, possibly having a negative impact on cross-pollination. Moreover, the concentration of nectar collected from honeybees was significantly lower than the nectar concentration from florets, suggesting that honeybees diluted highly concentrated sunflower nectar with their saliva to their optimum concentration level. Interspecific exploitative competition between honeybees and wild pollinators (wild bees, butterflies and moths) significantly increased the movement of honeybees among sunflower heads, which enhances cross-pollination. Furthermore, behavioural interactions influenced the length of foraging time spent by individual honeybees per sunflower head. Butterflies were the most influential in enhancing honeybee foraging movement, followed by wild bees and then moths. The importance of a given flower visitor species to honeybee movement is likely related to the size of the visitor, as the bigger size of butterflies and movement of their wings increases the chance of disturbing a neighbouring honeybee. Conservation of natural habitat is important to maintain the diversity of flower visitors which indirectly contribute to crop production by enhancing honeybee foraging activity and consequent direct pollination service. Furthermore, the pollination effectiveness of wild pollinators, density of wild honeybees surrounding sunflower fields and effects of human activities on pollination disruption are suggested as topics for future research. / Dissertation (MScAgric)--University of Pretoria, 2010. / Zoology and Entomology / unrestricted