Robert Brodschneider

Nutrition and health in honey bees.

Adequate nutrition supports the development of healthy honey bee colonies. We give an overview of the nutritional demands of honey bee workers at three levels: (1) colony nutrition with the possibility of supplementation of carbohydrates and proteins; (2) adult nutrition and (3) larval nutrition. Larvae are especially dependant on protein and brood production is strongly affected by shortages of this nutrient. The number of larvae reared may be reduced to maintain the quality of remaining offspring. The quality of developing workers also suffers under conditions of larval starvation, leading to slightly affected workers. Larval starvation, alone or in combination with other stressors, can weaken colonies. The potential of different diets to meet nutritional requirements or to improve survival or brood production is outlined. We discuss nutrition-related risks to honey bee colonies such as starvation, monocultures, genetically modified crops and pesticides in pollen and nectar.ZusammenfassungEine ausgewogene Ernährung mit ausreichend Proteinen, Kohlenhydraten, Fetten, Vitaminen und Mineralstoffen ist notwendig für das Überleben eines Bienenvolkes, die Entwicklung der Arbeiterinnen und die Aufzucht von Brut. Im Superorganismus Honigbiene sind diese drei Ebenen der Ernährung eng miteinander verknüpft (Abb. 1), und Defizite in einer dieser Ebenen wirken sich negativ auf die anderen aus.Für das Überleben des Volkes sind vor allem Kohlenhydrate notwendig. Eine Arbeiterin benötigt pro Tag etwa 4 mg verwertbaren Zucker. Allerdings sind nicht alle Zucker verwertbar, einige sind für Bienen giftig. Ebenfalls giftig ist Hydroxymethylfurfural (HMF) das sich bei thermischer Zersetzung und langer Lagerung aus Zuckern bildet. Der HMF Gehalt erhältlicher Maissirupe liegt zwischen 3,1 und 28,7 ppm, kann aber durch Lagerung bei zu hohen Temperaturen drastisch ansteigen und die Mortalität von Bienen erhöhen.Pollen ist die natürliche Proteinquelle von Bienen. Daraus bilden Ammenbienen ein proteinreiches Futter für die Brut. Ist nicht genügend Pollen vorhanden, reduziert das Bienenvolk die Zahl der produzierten Larven durch Kannibalismus. Ein Mangel von Protein in der Larval-oder Adultnahrung führt zur reduzierten Entwicklung der Brutfutterdrüsen und Ovarien sowie einer kürzeren Lebensdauer. Proteinmangel während der Larvalernährung führt darüber hinaus zu beeinträchtigter Thoraxentwicklung, Flugleistung und Verhaltensänderungen. Bei Pollenmangel können dem Bienenvolk andere Proteinquellen angeboten werden, Tabelle I zeigt die pro Tag konsumierten Mengen unterschiedlicher Diäten, deren Bestandteile, Proteingehalt und die Größe der untersuchten Einheit. Ein Proteingehalt zwischen 23 und 30 % hat sich als zur Brutaufzucht geeignet erwiesen. Unseren Berechnungen zufolge erhält ein Volk mit jedem konsumierten Gramm etwa die Menge Protein die 4 Larven bis zur Verdeckelung benötigen.Pollen liefert ebenfalls Fette, die vor allem in der Larvalentwicklung benötigt werden. Honigbienen können Sterole nicht selbst herstellen, und verfüttern überwiegend 24-Methylen-Cholesterin an die Brut. Das tun sie, unter Verwendung von Körperreserven auch dann, wenn kein Cholesterin in der Nahrung vorhanden ist.Arbeiterinnen (oder symbiontische Mikroorganismen) sind in der Lage Vitamin C zu synthetisieren. Pyridoxin, ein Vitamin aus dem B-Komplex, ist hingegen notwendig für erfolgreiche Brutaufzucht. Obwohl fettlösliche Vitamine nicht essentiell für die Honigbiene sind, steigert ihre Anwesenheit in der Diät die Menge an produzierter Brut.Neben dem Verhungern oder der erwähnten Mangelernährung stellen einseitige Ernährung durch Monokulturen, genetisch modifizierte Pflanzen oder vom Menschen oder der Pflanze produzierte Giftstoffe die mit der Nahrung eingetragen werden Gefahren für die Honigbiene dar.

Miscellaneous standard methods for Apis mellifera research

Summary A variety of methods are used in honey bee research and differ depending on the level at which the research is conducted. On an individual level, the handling of individual honey bees, including the queen, larvae and pupae are required. There are different methods for the immobilising, killing and storing as well as determining individual weight of bees. The precise timing of developmental stages is also an important aspect of sampling individuals for experiments. In order to investigate and manipulate functional processes in honey bees, e.g. memory formation and retrieval and gene expression, microinjection is often used. A method that is used by both researchers and beekeepers is the marking of queens that serves not only to help to locate her during her life, but also enables the dating of queens. Creating multiple queen colonies allows the beekeeper to maintain spare queens, increase brood production or ask questions related to reproduction. On colony level, very useful techniques are the measurement of intra hive mortality using dead bee traps, weighing of full hives, collecting pollen and nectar, and digital monitoring of brood development via location recognition. At the population level, estimation of population density is essential to evaluate the health status and using beelines help to locate wild colonies. These methods, described in this paper, are especially valuable when investigating the effects of pesticide applications, environmental pollution and diseases on colony survival.

Managed honey bee colony losses in Canada, China, Europe, Israel and Turkey, for the winters of 2008–9 and 2009–10

Summary In 2008 the COLOSS network was formed by honey bee experts from Europe and the USA. The primary objectives set by this scientific network were to explain and to prevent large scale losses of honey bee (Apis mellifera) colonies. In June 2008 COLOSS obtained four years support from the European Union from COST and was designated as COST Action FA0803—COLOSS (Prevention of honey bee Colony Losses). To enable the comparison of loss data between participating countries, a standardized COLOSS questionnaire was developed. Using this questionnaire information on honey bee losses has been collected over two years. Survey data presented in this study were gathered in 2009 from 12 countries and in 2010 from 24 countries. Mean honey bee losses in Europe varied widely, between 7–22% over the 2008–9 winter and between 7–30% over the 2009–10 winter. An important finding is that for all countries which participated in 2008–9, winter losses in 2009–10 were found to be substantially higher. In 2009–10, winter losses in South East Europe were at such a low level that the factors causing the losses in other parts of Europe were absent, or at a level which did not affect colony survival. The five provinces of China, which were included in 2009–10, showed very low mean (4%) A. mellifera winter losses. In six Canadian provinces, mean winter losses in 2010 varied between 16–25%, losses in Nova Scotia (40%) being exceptionally high. In most countries and in both monitoring years, hobbyist beekeepers (1–50 colonies) experienced higher losses than practitioners with intermediate beekeeping operations (51–500 colonies). This relationship between scale of beekeeping and extent of losses effect was also observed in 2009–10, but was less pronounced. In Belgium, Italy, the Netherlands and Poland, 2008–9 mean winter losses for beekeepers who reported ‘disappeared’ colonies were significantly higher compared to mean winter losses of beekeepers who did not report ‘disappeared’ colonies. Mean 2008–9 winter losses for those beekeepers in the Netherlands who reported symptoms similar to “Colony Collapse Disorder” (CCD), namely: 1. no dead bees in or surrounding the hive while; 2. capped brood was present, were significantly higher than mean winter losses for those beekeepers who reported ‘disappeared’ colonies without the presence of capped brood in the empty hives. In the winter of 2009–10 in the majority of participating countries, beekeepers who reported ‘disappeared’ colonies experienced higher winter losses compared with beekeepers, who experienced winter losses but did not report ‘disappeared’ colonies.

Standard methods for maintaining adult Apis mellifera in cages under in vitro laboratory conditions

Summary Adult honey bees are maintained in vitro in laboratory cages for a variety of purposes. For example, researchers may wish to perform experiments on honey bees caged individually or in groups to study aspects of parasitology, toxicology, or physiology under highly controlled conditions, or they may cage whole frames to obtain newly emerged workers of known age cohorts. Regardless of purpose, researchers must manage a number of variables, ranging from selection of study subjects (e.g. honey bee subspecies) to experimental environment (e.g. temperature and relative humidity). Although decisions made by researchers may not necessarily jeopardize the scientific rigour of an experiment, they may profoundly affect results, and may make comparisons with similar, but independent, studies difficult. Focusing primarily on workers, we provide recommendations for maintaining adults under in vitro laboratory conditions, whilst acknowledging gaps in our understanding that require further attention. We specifically describe how to properly obtain honey bees, and how to choose appropriate cages, incubator conditions, and food to obtain biologically relevant and comparable experimental results. Additionally, we provide broad recommendations for experimental design and statistical analyses of data that arises from experiments using caged honey bees. The ultimate goal of this, and of all COLOSS BEEBOOK papers, is not to stifle science with restrictions, but rather to provide researchers with the appropriate tools to generate comparable data that will build upon our current understanding of honey bees.

Honeybee Colony Thermoregulation – Regulatory Mechanisms and Contribution of Individuals in Dependence on Age, Location and Thermal Stress

Honeybee larvae and pupae are extremely stenothermic, i.e. they strongly depend on accurate regulation of brood nest temperature for proper development (33–36°C). Here we study the mechanisms of social thermoregulation of honeybee colonies under changing environmental temperatures concerning the contribution of individuals to colony temperature homeostasis. Beside migration activity within the nest, the main active process is “endothermy on demand” of adults. An increase of cold stress (cooling of the colony) increases the intensity of heat production with thoracic flight muscles and the number of endothermic individuals, especially in the brood nest. As endothermy means hard work for bees, this eases much burden of nestmates which can stay ectothermic. Concerning the active reaction to cold stress by endothermy, age polyethism is reduced to only two physiologically predetermined task divisions, 0 to ∼2 days and older. Endothermic heat production is the job of bees older than about two days. They are all similarly engaged in active heat production both in intensity and frequency. Their active heat production has an important reinforcement effect on passive heat production of the many ectothermic bees and of the brood. Ectothermy is most frequent in young bees (<∼2 days) both outside and inside of brood nest cells. We suggest young bees visit warm brood nest cells not only to clean them but also to speed up flight muscle development for proper endothermy and foraging later in their life. Young bees inside brood nest cells mostly receive heat from the surrounding cell wall during cold stress, whereas older bees predominantly transfer heat from the thorax to the cell wall. Endothermic bees regulate brood comb temperature more accurately than local air temperature. They apply the heat as close to the brood as possible: workers heating cells from within have a higher probability of endothermy than those on the comb surface. The findings show that thermal homeostasis of honeybee colonies is achieved by a combination of active and passive processes. The differential individual endothermic and behavioral reactions sum up to an integrated action of the honeybee colony as a superorganism.

Standard methods for artificial rearing of Apis mellifera larvae

Summary Originally, a method to rear worker honey bee larvae in vitro was introduced into the field of bee biology to analyse honey bee physiology and caste development. Recently, it has become an increasingly important method in bee pathology and toxicology. The in vitro method of rearing larvae is complex and can be developed as an art by itself, especially if the aim is to obtain queens or worker bees which, for example, can be re-introduced into the colony as able members. However, a more pragmatic approach to in vitro rearing of larvae is also possible and justified if the aim is to focus on certain pathogens or compounds to be tested. It is up to the researcher(s) to decide on the appropriate experimental establishment and design. This paper will help with this decision and provide guidelines on how to adjust the method of in vitro rearing according to the specific needs of the scientific project.

Results of international standardised beekeeper surveys of colony losses for winter 2012-2013: analysis of winter loss rates and mixed effects modelling of risk factors for winter loss

Summary This article presents results of an analysis of winter losses of honey bee colonies from 19 mainly European countries, most of which implemented the standardised 2013 COLOSS questionnaire. Generalised linear mixed effects models (GLMMs) were used to investigate the effects of several factors on the risk of colony loss, including different treatments for Varroa destructor, allowing for random effects of beekeeper and region. Both winter and summer treatments were considered, and the most common combinations of treatment and timing were used to define treatment factor levels. Overall and within country colony loss rates are presented. Significant factors in the model were found to be: percentage of young queens in the colonies before winter, extent of queen problems in summer, treatment of the varroa mite, and access by foraging honey bees to oilseed rape and maize. Spatial variation at the beekeeper level is shown across geographical regions using random effects from the fitted models, both before and after allowing for the effect of the significant terms in the model. This spatial variation is considerable.

Surveys as a tool to record winter losses of honey bee colonies: a two year case study in Austria and South Tyrol

Summary Alarmed by reports of high losses of honey bee colonies in other countries, and with no field data available for Austria, a mixed media survey on winter mortality of honey bee colonies was carried out in Austria for the overwintering periods of 2007–8 and 2008–9. In addition, the survey was extended to South Tyrol (Italy) in 2007–8. Data presented for 2007–8 were gathered at eight beekeeping conventions in Austria (374 beekeepers; 16,217 colonies, representing 1.7% of beekeepers and 5.8% of colonies, respectively) and one convention in South Tyrol (115 beekeepers; 3,999 colonies, representing 3.7% of beekeepers and 10.6% of colonies, respectively). During the overwintering period of 2007–8 we calculated a total loss of 13.3% of colonies in Austria, ranging from 9.2 to 17.1% in different regions. Overwintering mortality in South Tyrol was 12.3%. In 2009, data were collected at nine beekeeping conventions in Austria and from some respondents who returned the questionnaire which was also published in the Austrian beekeeping journal and on our website (575 beekeepers; 18,141 colonies, representing 2.6% of beekeepers and 6.5% of colonies, respectively). Total colony losses were calculated as 9.3%, ranging from 6.0% to 17.8% in different provinces of Austria. Respondents attributed Varroa destructor as a key factor in the occurrence of high colony losses during overwintering in our area of investigation, followed by queen loss and starvation. We analyzed the impact of hive management (operation size, date of carbohydrate feeding, type of carbohydrates fed before winter, V. destructor treatment and migratory beekeeping) on colony loss. We also reported observed biases due to different survey methods in the second year.

Standard methods for behavioural studies of Apis mellifera

Summary In this BEEBOOK paper we present a set of established methods for quantifying honey bee behaviour. We start with general methods for preparing bees for behavioural assays. Then we introduce assays for quantifying sensory responsiveness to gustatory, visual and olfactory stimuli. Presentation of more complex behaviours like appetitive and aversive learning under controlled laboratory conditions and learning paradigms under free-flying conditions will allow the reader to investigate a large range of cognitive skills in honey bees. Honey bees are very sensitive to changing temperatures. We therefore present experiments which aim at analysing honey bee locomotion in temperature gradients. The complex flight behaviour of honey bees can be investigated under controlled conditions in the laboratory or with sophisticated technologies like harmonic radar or RFID in the field. These methods will be explained in detail in different sections. Honey bees are model organisms in behavioural biology for their complex yet plastic division of labour. To observe the daily behaviour of individual bees in a colony, classical observation hives are very useful. The setting up and use of typical observation hives will be the focus of another section. The honey bee dance language has important characteristics of a real language and has been the focus of numerous studies. We here discuss the background of the honey bee dance language and describe how it can be studied. Finally, the mating of a honey bee queen with drones is essential to survival of the entire colony. We here give detailed and structured information how the mating behaviour of drones and queens can be observed and experimentally manipulated. The ultimate goal of this chapter is to provide the reader with a comprehensive set of experimental protocols for detailed studies on all aspects of honey bee behaviour including investigation of pesticide and insecticide effects.

Flight performance of artificially reared honeybees (Apis mellifera)

Artificially reared larvae are an ideal model for experiments involving brood diseases or testing pesticides. Because conditions during larval development can influence the general performance of adult honeybees, we created an evaluation method for the viability of artificially reared honeybees. We compared the flight performance of honeybees artificially reared in the laboratory with that of their sisters naturally reared in the colony. Fresh and dry weight, wing surface area, flight speed, flight duration, and distance covered by honeybee workers after feeding defined amounts of different sugar solutions were measured during tethered flight in a roundabout. Our results demonstrate that after artificial rearing, adult honeybees at the natural age of flight exhibit similar flight performances to their naturally reared sisters. The naturally reared honeybees, however, attained higher maximum flight speeds when fed energy-rich 2molar glucose solution.ZusammenfassungHonigbienen können im Labor künstlich aufgezogen werden. Dazu werden Larven aus Brutwaben in Plastikschälchen übersiedelt und die umfassende Brutpflege der Ammenbienen im Stock durch wenige definierte Fütterungen ersetzt sowie die Temperatur und die Luftfeuchtigkeit genau reguliert. Diese Methode ermöglicht es nun standardisierte Untersuchungen über die Auswirkungen von Chemikalien wie Pflanzenschutzmitteln oder Infektionen mit Krankheitserregern durchzuführen, ohne gesamte Völker in Kontakt mit den Schadstoffen oder Erregern zu bringen. Wir haben erstmals die Qualität von Arbeiterinnen die mit Hilfe dieser Technik aufgezogen wurden anhand ihrer Flugleistung in einem Karussell analysiert und mit der Leistung ihrer natürlich aufgezogener Schwestern verglichen (Abb. 1). Die durchschnittliche Fluggeschwindigkeit im Karussell betrug etwa 1 m/s und die maximale Fluggeschwindigkeit 1,4 m/s (Tab. I). Diese unterschieden sich bei künstlich und natürlich aufgezogenen Bienen nicht, wenn 10 μL einer 1-Molaren Glukoselösung gefüttert werden. Bei Fütterung von hochenergetischer 2-Molarer Glukoselösung flogen die Kontrollbienen, nicht aber die künstlich aufgezogenen, schneller als mit 1-Molarer Glukoselösung nämlich mit 1,2 m/sec Durchschnittsgeschwindigkeit. Die Maximalgeschwindigkeit (1,6 m/s) der Kontrollbienen war bei dieser Fütterung auch höher als die der künstlich aufgezogenen (1,4 m/s, Tab. I).Ein guter Indikator für die Qualität der Larvalernährung ist das Gewicht der Arbeiterinnen, und wir fanden, dass das Trockengewicht bei den von uns künstlich aufgezogenen Bienen niedriger als bei den Kontrollbienen war. Wir konnten auch zeigen, dass dieser Unterschied vor allem in einem leichteren Thorax, in dem sich die Flugmuskulatur befindet, der künstlich aufgezogenen Bienen begründet ist (Abb. 2). Außerdem fanden wir schwache Unterschiede in den Flächen der Vorder- und Hinterflügel: wiederum waren die der künstlich aufgezogenen etwas kleiner als die der Kontrollbienen.Unsere Ergebnisse zeigen, dass künstlich aufgezogene Bienen das Alter von Sammlerinnen (über 20 Tage) erreichen können. Trotz eines etwas leichteren Thoraxgewichtes, in dem sich die Flugmuskulatur befindet, und etwas kleinerer Flügel zeigten sie annähernd ähnliche Flugleistungen wie natürlich aufgezogene Honigbienen.