Dorothea Brückner, Germany
Norberto Milani, Italy
Robert Paxton, Great Britain
Dalibor Titěra, Czech Republic
Bernard Vaissiere, France
Ingemar Fries, Sweden
Coordinator of Bee shop 6FP project PL 02568
Robin FA Moritz, Halle, Germany
Team of Bee Research Institute Dol, CZ
Team of Congress Prague, CZ
Proceedings of the Second European Conference of Apidology EurBee
Prague (Czech Republic) 10-16 September 2006
Edited by Vladimir Vesely, Marcela Vořechovská and Dalibor Titěra
Published by Bee Research Institute Dol, CZ
On-line version, last update 20 January 2007
Proceedings of the Second European Conference of Apidology EurBee bring texts of abstracts of oral and poster presentations. The texts of the participants are printed in the paper book form that it may be handy during the stay in Prague. Simultaneously you find the whole publication also on www.eurbee.org. From the security reasons the character @ is replaced by ©. The paper edition of Proceedings was compiled on the basis of e-mailed texts. For this reason we are aware of possible errors. We are convinced that you apologize involuntary shortcomings.
We ask you to read your texts and to send us kindly your corrections. We can correct the internet version of this Proceedings at any time.
We also would like to publish fulltext of your presentations in time. Fulltexts are to be published on www.eurbee.org. Would you be so kind to send us your texts and keep the deadline for the shipment of fulltexts December 31, 2006.
The Second European Conference Eurbee has attracted more than 300 particapants who present about 95 oral presentations and 170 posters. Under all scientific papers are signed 539 authors.
Prague becomes a meeting point of scientists and researchers not only from Europe but from the whole world. We believe that the most important benefit is just the personal meeting of many participants. We hope that this is the way how to fulfil the EurBee ambitions as stated by Norberto Milani in the introduction of the Proceedings book of the First European conference of Apidology EurBee in Udine in the year 2004: "bring together all the European researchers in different fields of Apidology and Apiculture, offering an opportunity to present recent advances achieved in Europe and promoting a multidisciplinary approach to open problems".
Local Organizing Committee
Summary Program of the EurBee Conference
Registration, Welcome cocktail
Plenary session I - Biology
Plenary session II - Genetics
Honey bee genetics
Bee vision and learning
Physiology and behaviour
Plenary session III - Pollination
Diversity and conservation
BEESHOP - 6FP project conference
Plenary session IV - Pathology
Pathogens & Diseases
Honey bee viruses
Round table discussions
Gala Evening & Traditional Dinner
Satellite meetings (IHC, BEESHOP Beekeepers forum)
Table of contents
Plenary sessions................................................................ 1
Bee vision and learning .................................................. 7
Physiology and Behaviour .............................................. 11
Honey bee viruses............................................................ 18
Pathogens and Diseases................................................... 27
Macroparasites ................................................................. 42
Honey bee genetics ........................................................... 51
Diversity and conservation.................................................. 59
Non-Apis Bees ................................................................ 61
Environmental Hazards to Honey Bees .......................... 79
Pollination ....................................................................... 91
Bee products ................................................................... 105
Management ................................................................... 132
Beeshop .......................................................................... 142
Authors Index.................................................................. 149
Reproductive biology of honeybees (Genus Apis) a uniform pattern varied by diverse adaptations
Nikolaus Koeniger and Gudrun Koeniger
Institut fuer Bienenkunden (Polytechnische Gesellschaft)
Fachbereich Biowissenschaften, Johann-Wolfgang-Goethe Universität Frankfurt a.M.
Karl-von-Frisch-Weg 2 , 61440 Oberursel, Germany
The basic social structure of the honeybee colony seems to be congruent throughout the genus indicating that eusociality arose early in the common ancestors of the recent species. During the last decades, however, the exploration of African and mainly Asian honeybees resulted in a surprisingly high variability within and among the species. This detailed diversity of honeybees was primarily demonstrated by morphometric data (see Ruttner 1989) and more recently by thorough molecular and genetic analysis (see Oldroyd + Wongsiri 2005). A comparative synopsis of the reproductive biology is still missing and will be presented here. We focus on the following topics: production of queens and drones; sexual maturation; sex ratio; mating on the wings; sperm transfer; and sperm storage.
Brood cells for rearing queens are cone shaped and, in contrast to the “other” horizontal comb cells, are uniform with the longitude axis vertically orientated in all honeybee species. Queens are reared from fertilized eggs by feeding royal jelly to young larvae. The mechanism seems to be similar across species. Queenless colonies of Apis koschevnikovi accepted young female Apis cerana larvae and reared successfully Apis cerana queens.
Honeybee queens are regularly bigger than worker bees. These size differences, however, differ significantly among the species: in Apis dorsata queens are only slightly larger than worker bees and in Apis florea the queen’s weight is nearly two times more than the weight of a worker bee.
After emergence from the cell, surplus young queens fight and eliminate each other until monogyny is reached (1 queen per colony) and the origin of queen recognition signals seems to be located at the abdominal tergite glands. Experiments demonstrated that fights among queens occur across species borders. Not only queens of the closely related species Apis koschevnikovi and Apis cerana fight but also queens of Apis mellifera attacked young queens of Apis florea. The mechanism of recognition among young queens and the releaser of queen’s fighting behaviour seems to be similar within the genus Apis.
Brood cells for rearing drones are bigger than worker cells in all species. Mostly this is achieved by a bigger diameter and a domed sealing, although in Apis dorsata and Apis laboriosa the sealing is only slightly elevated. Further, drones are reared from unfertilised eggs. Queens can actively regulate the fertilisation of an egg; thus, she can regulate the number of drones per season.
Honeybee drones are regularly bigger than worker bees. These size differences, however, differ significantly among the species: drones in giant honey bees weigh only slightly more than worker bees, whereas in the dwarf species and in A. mellifera the drone’s weight is more than double the weight of workers.
Drones need about 12 days for sexual maturation. Only then are all sperm mobile and fit for transfer into the queen. The number of spermatozoa is dependent on the individual size of the drone. Environmental conditions like temperature during pupal development and care of newly emerged drones by workers may also effect sperm number.
The sex ratio in honeybees is male biased, the number of drones produced in a colony exceeds the number of queens by far. A. mellifera colonies produce 2 to 10 queens and 5 000 to 10 000 drones the relation is about 1 to 1 000. In A.florea 9.6 ± 1.3 queen cups and 568 ± 106 drone cells are built per season. If the drone cells are used only once per season, the relation is only about 1 to 60. In contrast to queens which take only 1 to 4 mating flights and almost always mate successfully, drones fly repeatedly until the age of up to 30 days and only few have a chance to mate. Thus the relation of queens to drones at the drone congregation area (DCA) is even more drone biased.
Mating on the wings
Mating never occurs within the colony. Drones and queens of all species perform mating flights and mating takes place outside the colony. Wind velocity, cloudiness and temperature are more critical for mating than for foraging, and mating flights occur only during favourable weather conditions. Mating flights take place at species-specific daily periods. Under allopatric conditions (only one Apis species), daily periods of mating occur around noon and are extended to the afternoon. Under sympatric conditions the mating periods are short and well separated among the different Apis species. Regularly under sympatric conditions, the sequence of mating periods correlates with the size of the drones, i.e. smaller species fly earlier than the larger ones.
The mating flight period seems to be independent of the colony rhythm. Drones of Apis mellifera which were kept in flight rooms under a shifted LD cycle were transferred to a colony outside and flew at first according to their shifted internal clock. Cross fostering experiments in Borneo confirmed the dominance of the individual rhythm. Drones and queens of Apis koschevnikovi and Apis cerana followed their species’ specific mating flight period regardless whether they were in alien or conspecific host colonies. Apparently, in all species queen’s mating flight period is relatively shorter and centred within drone’s flight period.
Congregation of flying drones above distinct locations that are used consistently over many years seems to a common pattern of most (if not all?) honeybee species. In Apis mellifera, drones assemble in the open air and their distribution seems to depend of physiographic factors. Although the DCAs of Apis cerana were found bordering the branches and canopies of trees, the Apis cerana drones flew under the open sky. Apis koschevnikovi drones, however, avoided congregating in the open and stayed under dense layer of branches. Also drones of Apis dorsata assembled under the canopy of trees. They chose large ,outstanding trees as a landmark and were flying at a height of 15 to 25m above the ground. The DCA of the dwarf bees (Apis florea and Apis florea) is still unknown and remains to be detected.
Also the sex attractants of the queen seem to be similar across species. A small black wooden dummy (pencil) contaminated by 1 microgram 9 - oxi decenoic acid attracted large numbers of drones when brought into the centre of a DCA for several different species. Further, when we offered a small hole in a seize comparable to the queen’s sting chamber at the end of this, dummy drones copulated and got stuck by their everted endophalli. This was demonstrated in Apis mellifera, Apis cerana Apis koschevnikovi and Apis dorsata.
The monogamy of the male is typical for all species (drones die after copulation), whereas queens are highly polygamous. They mate, depending on species, with 12 or 50 or more drones on up to 4 mating flights. Drones get paralysed during copulation before transferring sperm and thus need mechanical support for keeping a strong connection between the flying queen and the paralysed drone until sperm transfer into the oviducts is completed. In most species this is accomplished mainly by the large endophallus, filled with mucus of the male accessory glands. In the dwarf species the hind legs have a special “thumb” to keep the connection of the copulating pair.
Sperm is transferred into the oviducts (cavity dwelling species) or into the ductus spermaticus (dwarf honey bees). When separating from the queen, drones of the cavitynesting species, and probably also of the giant honey bee species, leave a mating sign (secretions of 3 male accessory glands) which remains in the sting chamber. The next drone removes the mating sign of his predecessor and leaves his own.
In the cavity dwelling species, spermatozoa of many drones are present in the oviducts at the same time. Only small portions of them (3 to 8% ) reach the spermatheca. In the dwarf honey bee species, this value is 40-06% after deposition of sperm into the ductus spermaticus In spite of the high differences in sperm numbers and sperm transfer there is a uniform pattern in the paternity skew of the most frequent patrilines.
Only 1-2 days after mating the queen starts egg laying. She uses 6 to 12 spermatozoa from the sperm storage in the spermatheca. We still do not know much about the biochemical mechanism of sperm storage. The spermatheca is surrounded by a dense tracheal net and a huge gland is connected to its lumen. The fluid of both contain sugars and many proteins. The protein concentration varies from 8.5 and 15.3 mg/mL in the spermathecal fluid, and from 5 to 8.5 mg/mL in the gland secretion. Until the age of 3 days the pattern of the gland secretion and spermathecal fluid was identical. In sexually mature queens (10 days or older) the gland secretion and spermathecal fluid each had one additional band at 79 kDa and at 29 kDa respectively. From the 29 kDa protein several peptide fragments were sequenced after digestion with LysC protease. Some of the sequences showed a distinct homology to the glycolytic enzyme triosephosphate isomerase (TPI), but the enzymatic activity was only 1/100 compared to TPI of hemolymph. The possible function of the protein is still under debate.
Generally, a loss or removal of a queen honeybee from a colony releases the construction of emergency queen cells and rearing of new queens. Further, queen loss has an effect on the development of the worker’s ovaries and sooner or later – if no new queen inhibits this effect - Apis workers start egg laying. The period between queen loss and worker egg laying varies between 6 and 30 days among tropical and temperate subspecies of Apis mellifera. Apis florea (8 days) and Apis cerana (16 days) are positioned well in the range of Apis mellifera.
The reproductive biology of the genus Apis is shaped by the highly eusocial status of each species, and the uniform and strong influence of colony selection seems to be obvious. An individual selection, however, among queens and among drones surely proceeds as well. Looking at the fight between young virgin queens (see above) we can assume that individual selection would favour queens which hide from their sisters. The tergite glands, however, produce essential queen signals for workers and therefore queens cannot hide. Similary, an individual “arms race” among drones would surely lead to a drone’s mating sign which effectively seals the queen’s bursa copulatrix and excludes competitors. The successful hiding queen and the sperm of the single drone, however, do not succeed in colony competition, which apparently favours queens with strong worker signals and populous colonies with a high genetic variance among its workers. We suggest that the uniform pattern of the reproductive biology of honeybees varied by diverse adaptations is a result of a limited individual selection and a final influence of colony level selection.
The evolution of division of labor and foraging specialization
Robert E. Page, Jr.,
School of Life Sciences, Arizona State University, Tempe, AZ
How does complex social behavior evolve? What are the developmental building blocks of division and labor and specialization, the hallmarks of insect societies? Recent behavioral, genetic, and genomic studies have revealed the developmental origins in the evolution of division of labor and specialization in foraging worker honey bees, the hallmarks of complex insect societies. Selective breeding for a single social trait, the amount of surplus pollen stored in the nest (pollen hoarding) revealed a phenotypic architecture of correlated traits at multiple levels of biological organization in facultatively-sterile female worker honey bees. Genetic mapping has demonstrated that the phenotypic architecture is a consequence of a genetic architecture rich in pleiotropy and epistasis possibly affecting a reproductive signaling pathway. Gene knockdown of a single hormone involved in reproductive signaling affects the entire phenotypic architecture and provides strong support for our hypothesis that division of labor and foraging specialization are derived from the reproductive cycle of solitary insects.
Bee movement and pollen flow across the landscape
Juliet L Osborne
Plant & Invertebrate Ecology Division, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK
Bees are continually making choices about where and when to forage, and on which plant species. Individual bees make these foraging decisions based on their own experience, or that of others in the colony. The resulting spatial and temporal distribution of bees across the landscape is associated with the spatial and temporal arrangement of nectar and pollen sources. The movement patterns of individual bees, and consequent distribution of foragers affect and define the movement of pollen between entomophilous plants, and thus can drive gene flow between plant patches.
The growing sophistication of GIS techniques, the development of harmonic radar to track individual flying insects, and the ability to analyse genetic relatedness in both bees and plants, have together opened up the possibility of predicting plant pollen flow across the landscape from newly gathered knowledge of bee movement and distribution patterns. These predictions can then be tested with empirical evidence of pollen-mediated gene flow between plants.
I will describe recent studies investigating how bees explore the landscape to find forage, how they distribute themselves amongst patches or fields of plants, and I will discuss different approaches for translating this information into estimates of spatial patterns of plant gene flow, using examples from both crops and wild flowers.
Parallel declines in pollinators and insect-pollinated plants in Northwest Europe
University of Leeds, UK
Despite widespread concern about declines in pollination services, little is known about patterns of change in most pollinator assemblages. We have studied bee and hoverfly assemblages in Britain and the Netherlands, and find evidence of declines (pre vs. post 1980) in local bee diversity in both countries, whereas hoverflies show divergent trends. Depending on the group and country, declines are most frequent in habitat and flower specialists, in univoltine species and/or in non-migrants. In parallel with this, outcrossing plant species reliant on the declining pollinators have themselves declined relative to other plant species. Taken together, these findings strongly suggest a causal connection between local extinctions of functionally linked plant and pollinator species.
American foulbrood – new developments
Institute for Bee Research, Friedrich-Engels-Str. 32, D – 16540 Hohen Neuendorf, Germany
American foulbrood (AFB) is the most devastating bacterial brood disease not only able to kill individual larvae but also resulting in colony collapse. The causative agent of AFB is a spore-forming, gram-positive bacterium, recently reclassified as Paenibacillus larvae (P. larvae). We could show that the species P. larvae consists of at least four ERIC-genotypes which differ morphologically, biochemically and, most importantly, in respect to virulence. Exposure bioassays revealed genotypic differences in the time it took the pathogen to kill the infected individuals. Based on these results we hypothesized that the observed differences in individual virulence will have an impact on the hygienic removal of diseased larvae and, therefore, disease progression in the colony. Experimental infection of mini colonies confirmed this hypothesis. The impact of these findings for disease progression both, within and between colonies and for the evaluation of the disease status of a colony will be discussed.
Bee vision and learning
Symposium organized by Martin Giurfa and Lars Chittka
Searching for flowers - when do honeybees get confused?
Johannes Spaethe1 and Lars Chittka2
1 Department of Evolutionary Biology, University of Vienna, Austria
2 School of Biological Sciences, Queen Mary, University of London, GB
While flying over a meadow and searching for a specific flower species a bee may detect several different flower types per second and thus the task of choosing the right flower and ignoring the others is not trivial. To investigate how the simultaneous occurrence of several flower types together with the sought-after flower species within the visual field of a bee may limit search accuracy we applied the concept of visual search from human psychology to the honeybee. Bees were trained to choose a colored disc (target) among a varying number of differently colored discs (distractors). We measured accuracy and decision time as a function of distractor number and color. We found that for all color combinations, decision time increased and accuracy decreased with increasing distractor number, whereas performance increased when more targets were present. These findings are characteristic for a serial search in humans, when stimuli are examined sequentially. Additionally, decision time and number of errors were found to be significantly higher when bees had to choose a blue target among yellow distractors compared to the inverse color combination, a phenomenon know as search asymmetry in humans.