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EurBee board Dorothea Brückner, Germany Norberto Milani, Italy Robert Paxton, Great Britain Dalibor Titěra, Czech Republic Bernard Vaissiere, France Program consultant


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Honey bee genetics


Symposium organized by Michael Lattorf

A third generation linkage map of the honey bee, Apis mellifera

Michel Solignac1, Florence Mougel1*, Dominique Vautrin1, Monique Monnerot1, Jean-Marie Cornuet2

1 Laboratoire Populations, Génétique et Evolution, CNRS, 91198 Gif-sur-Yvette cedex, France

2 Centre de Biologie et de Gestion des Populations, INRA, CS 30016 Montferrier-sur-Lez, F34988 Saint-Gély-du-Fesc, France.

The construction of the genetic map of the honey bee genome was initiated ten years ago and was constructed using the genotypes of worker progeny of one or two queens (respectively 92 and 95 workers per queen). It involved three steps:

The first version was mainly built with microsatellites prepared at the laboratory (screening of genomic libraries and sequencing of positive clones, Solignac et al., 2003) and was recently published (Solignac et al., 2004). This map comprised 541 markers on 24 linkage groups and hence was not saturated, the complement comprising 16 chromosomes.

The second version of the map was considerably denser thanks to two sources of sequences that became available in Genbank. The first source was a library of about 15,000 sequences of cDNA prepared from brain (Whitfield et al., 2002). A priori such sequences are not highly favourable for microsatellite extraction but we were able to map 493 markers prepared from these expressed sequences. In addition, a first read of short sequences of the genome also became available and 108 markers were prepared from them. A total of 601 markers was thus added which allowed saturating the map. This second generation was not published but was used for the first assembly of the genome sequences.

From this time, the successive assemblies became an inexhaustible source of new markers. Mapping took advantage of the sequence to considerably increase the density of the map. On the other hand, the map was useful for the sequence to assign the scaffolds to their respective linkage groups, to order them within these groups and to add numerous previously unplaced scaffolds to their respective chromosomes. Moreover, interaction between the two approaches also allowed eliminating most of mapping and assembly errors.

The genetic map of the honey bee is now based on 2,008 microsatellite markers with a total genome length of 4,114.5 cM (Kosambi function of distance). The genetic length of linkage groups varies from 575.9 to 138.0 cM The density of markers is 2.05 cM (corresponding to a physical length of only 93 kb and 5 to 6 genes) and all genetic distances are lower than 10 cM.

Analysis of the queen meiosis reveals that (i) recombiantion rate is a linear function of the physical distance and is homogeneous for all chromosomes and (ii) chiasmas are subjected to positive interference suggesting a highly regulated process.

Selection of honey bee strains for pollination of specific crops

Arnon Dag1, Ohad Afik2, Raphael A. Stern3 and Sharoni Shafir2

1 Institute of Horticulture, Agricultural Research Organization, Gilat Research Station, 85280, Israel

2 B. Triwaks Bee Research Center, Department of Entomology, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot 76100, Israel.

3 Migal, Galilee Technology Center, P.O.B. 831, Kiryat Shmona 11016, Israel

The value of increased agricultural production attributable to honey bee pollination is much higher than the direct value of hive products. Still, most of the selection and breeding effort is aimed for increased honey production and better resistance to bee diseases and pests and not for better pollination performance. One of the main problems in using honey bees for pollination is that bees placed in the target crop often neglect it in favor of competing flora. We studied the genetic background of bee preference for two important bee-pollinated crops that suffer from competition. In apple, pollen collectors are the main pollinators. We found significant differences between various genetic strains in the proportion of apple pollen that they collected. Furthermore, colonies that were progenies of colonies with high preference for apple pollen one year ('High strain') tended to collect a higher proportion of apple pollen than 'Low strain' colonies the following year.

In avocado, nectar collectors are the main pollinators. Based on the amount of the unique avocado sugar perseitol in their honey, we estimated that bees of the New World Carniolan strain collected 1.4 to 18.1 times more avocado nectar than Italian bees in the northern part of Israel. This trend repeated for several years, but was confounded by a gene-environment interaction. A genetic basis for the propensity to visit avocado flowers was further supported by the consistently high honey perseitol content of selected colonies over two years. A genetic component for preference to target crops attests the possibility of breeding honey bee strains that will be effective pollinators where competition with alternative flora may be a problem.


Dispersal distances and drifting of drones

Gabriele Soland

University of Bern, E-mail: gabriele.soland©honigbiene.ch

Mating of honeybee drones and queens (Apis mellifera) takes place in midair at drone-congregation-areas (DCAs). It is unknown, how far drones are actually able to fly and whether they return to their mother apiary or return to another apiary after a mating flight. Both aspects may influence the management of populations but also the control of parasites and diseases. To examine the mating flight distances of drones, we combined a capture-mark-recapture experiment with genetic parentage analyses. Drones were captured and marked at a DCA in a study area (radius: 2.5 km) where all occurring queens were genetically known. Of all marked drones 47% were recaptured in the hives within the study area. The genotype of each queen was compared with the ones of the recaptured drones using 12 microsatellite loci. We found that a majority of drones drifted within their apiary of origin but no drifting among the apiaries within the study area could be detected. Nevertheless 3% of all recaptured drones did not descend from any known queen within the study area and were therefore identified as dispersers. Neither the homecoming drones nor the drifting drones were equally distributed among the hives

within an apiary. Our results suggest that drones at a DCA are not a random sample of the population and that the number of drones contributed by apiaries or hives may not follow a simple distance-dependent relationship. The results on long-distance dispersal of male honeybees are discussed in regard to the conservation of endangered subspecies and their potential role as a vector for the spread of diseases.




Genetic structure of Turkish honeybee populations based on RAPD and mtDNA RFLP markers

Fulya Özdil, Mehmet Ali Yıldız, Hasan Meydan, H. Vasfi Gençer

Ankara University, Agricultural Faculty, Biometry and Genetics, 06110, Dışkapı-Ankara / TURKEY; E-mail of the corresponding Author: ozdil©agri.ankara.edu.tr, maliyildiz©hotmail.com

The aim of this research is to determine the genetic structure of Turkish honeybee populations based on RAPD and mtDNA RFLP markers. 175 honeybee colonies were sampled from 16 different locations. A total of 149 amplified bands were scored from 20 RAPD primers and 92.6% (138 bands) polymorphic bands were found. Based on RAPD markers the average heterozygosity () was 0.331. High genetic differentiation was found among subpopulations with genetic distances (=0.0716-0.2283) and the average coefficient of population differentiation (=0.2889). The average coefficient of population differentiation revealed that 71.11% of total genetic diversity (=0.3299) was within subpopulations (=0.2346). On the other hand gene flow (=1.2301) was very low. The mtDNA of honeybees were characterized by DraI restriction profile of the COI–COII intergenic region, HincII and HinfI restriction profile of cytochrome oxidase I (COI) gene, BglII restriction profile of cytochrome oxidase b (cytob) gene, EcoRI restriction profile of large subunit of ribosomal RNA (lsrRNA) and XbaI restriction profile of inter COI–COII region within the COI gene. BglII digestion in Cytob gene, EcoRI digestion in lsrRNA and XbaI digestion in inter COI–COII region within the COI gene was present in Turkish honeybees. On the other hand HincII and HinfI digestions were absent in Turkish honeybees. In the COI-COII intergenic region, DraI digestion revealed 3 restrictions that gave 420, 64, 49 and 41 bp. fragment size that may be a new haplotype in the C1 pattern of the Mediterranean lineage.
Microsatellite repeats in the honeybee genome

H.M.G. Lattorff, R.F.A. Moritz

Institut für Zoologie, Molekulare Ökologie, Martin-Luther-Universität Halle-Wittenberg, Germany, email: lattorff©zoologie.uni-halle.de

The honeybee, Apis mellifera, is the third species, which genome has been sequenced completely. Besides eusociality honeybees differ from other species with respect to their genetic system, which is characterized by male haploidy, and a complementary sex determination system. The genome has the highest recombination rate amongst multicellular eukaryotes. These special genomic features seem not to affect tandem repeat characteristics like nucleotide content of DNA, motif lengths and frequency distributions of tandem repeats. For 19 eukaryotic genomes the frequency distributions of tandem repeats showed phylogenetic footprints indicating selective processes rather than random evolutionary change. Nevertheless, the distribution of motif types for di-, tri- and tetra nucleotide repeats also show phylogenetic footprints. The only exception is the honeybee, which shows a completely different composition of microsatellite motifs. Moreover, there is a highly significant correlation between recombination rate and number of tandem repeats in 19 eukaryotic genomes. The honeybee significantly deviates from this pattern in that it has more repeats then expected due to its high recombination rate.

Seasonal variation of phosphoglucomutase (Pgm) enzyme polymorphism in honeybees (Apis mellifera L.) of Turkey

M.Kence, Z. Gulduren, A. Kence

Middle East Technical University, Department of Biology, 06531 Ankara Turkey, E-mail of the corresponding Author:mkence©metu.edu.tr

The allozyme variability on many loci of several species is associated with a variety of morphological, physiological, and fitness-related traits. Climatic conditions also can affect the physiological performance of organisms through their influences on enzyme function.

Phosphoglucomutase (Pgm; 2.7.5.1) is an enzyme that contributes to the regulation of energy metabolism by catalyzing the conversion of glucose-1-phosphate to glucose-6-phosphate at glycolitic pathway.

In a previous study on honey bees Pgm was found as the most polymorphic locus with three alleles (F=fast, M=medium, S=slow) and it exhibited polymorphism in all of the provinces in Turkey. Applying horizontal starch-gel electrophoresis we had determined the Pgm genotypes of worker bees that were collected from the same hives belonging to three apiaries, in each month from October to April, 2006 for the time being, that will continue to cover a whole year. Based on seven month collection of 140 worker bees, the level of heterozygosity we detected is quite remarkable; heterozygote (MF) frequency had declined from 1.00 to 0.80 and the frequency of homozygote, (MM) increased from October to April. The frequencies of F, M, and S alleles were 0.486, 0.511, and 0.004 respectively.

Characterization of thermostability variants and measurements of enzyme activity parameters for different Pgm genotypes will allow us to relate biochemical characteristics to changes in enzyme genotype frequencies. Investigation of mechanisms by which honeybees respond to temperature changes will contribute to the understanding of biochemical and physiological consequences of the Pgm polymorphism and seasonal variation of its genotypes.


Breeders selection work in Serbian apiculture

Mića Mladenović, Nebojša Nedić, Ljubiša Stanisavljević, Slađan Rašić

Faculty of Agriculture, Nemanjina 6, 11081 Belgrade Zemun, Serbia&Montenegro

Faculty of Biology, Studentski trg 3, 11000 Belgrade
E-mail: pcela©agrifaculty.bg.ac.yu

There are around 20.000 apiculturists in Serbia nowadays who own around 320.000 bee hives. The possibilities of Serbia for bee breeding are much greater than the present number of bee colonies and it is estimated that it can be as much as 800.000 bee hives. Based on several years of research and surveys of apiculturals it is estimated that the annual need for selected queen bees in Serbia ranges between 50.000 and 60.000. With regard to the great need for quality biological material five centers for the selection with breeded material have been established, and a network of reproductive stations is under elaboration.

Breeders selection work is based on selecting and protecting ecotypes Apis mellifera carnica in which 39 morphological parameters and several important productive features are investigated .

Based on morphometric researches three lines of bees, on the sample of three lines with 30 bees each, the length of tongue varied from 6,2264 to 6,4397 mm and it was statistically significant, while the measures of cubital index ranged from 2,55 to 2,89 and were statistically very significant. The number of hooks on the rear wing was not significantly different in the tested lines and ranged approximately from 21.49 to 21.85. The length of the front wing ranged from 8,8771 to 8,9168 mm with very low variation coefficient (0,86 % and 1,74%), while a statistically significant difference was determined by measuring the length of the rear wing (variations from 6,2378 to 6,3585 mm).

By researching honey productivity of some selection lines it was established that the lines of the central region (21, 78 and 27,13 kg) had the greatest yield of honey per bee hive in 2004 and 2005. Studying the behaviour of bees with pin test we determined the difference of 14.25% after 24 h, i.e. 15.05% after 48 h between certain lines.

After the first study phase which included the investigation of morphometric and productive economic characteristics, genetical DNA analysis of is planned which is expected to be in accordance with the established differences in the previous research phase.




The male genital system of Apis mellifera: A morphological approach

L.Moors, G. Koeniger, J. Billen

Catholic University of Leuven, E-mail: lien.moors©bio.kuleuven.be

In spite of their rather short lives, males perform an extremely important function, as it is only after insemination with their sperm that queens are able to produce female offspring. Copulation occurs high in the air on the wing. Sperm transfer is a complicated process during which the male everts and injects his endophallus into the queen. The endophallus can be divided into three parts, the vestibulum with the paired cornua, the cervix, and the bulbus accompanied by the lobe. The most conspicuous part of the endophallus, the bulbus, is very complex. Almost nothing is known concerning its functioning. We therefore investigated its detailed structure. In order to get more insight, we started an ontogenetic study, focusing on the pupal stage of the drone. It starts as an elongated tube which progressively invaginates and curves. For adult drones, we describe the different epithelial regions of the bulbus “gland”, including its externally located epithelia and its more internally located epithelia. The dorsal epithelium above the chitine plates appears to be secretory active and is highly cylindrical prior to the sexually mature stage. Its cuticle encloses greenish droplets within an extremely irregular cuticular matrix. This is in contrast with the ventral epithelial lining which is highly squamous. The ventral and dorsal epithelia differ from the anterior and the posterior epithelia. Besides the bulbus, we also examined the mucus glands. These glands have three parts, the muscle layer, the glandular epithelium and the lumen which change with respect to age in the distal and proximal region.


The weight changes and reproductive traits of honey bee queens (A. m. caucasica)

Yasin Kahya and H. Vasfi Gençer

Ankara University, Faculty of Agriculture, Dept. of Animal Science, Ankara, Turkey, E-mail: gencer©agri.ankara.edu.tr

Weight changes of honeybee queens reared from a breeder caucasian colony (A. m. caucasica) were monitored during reproductive development after emergence. The mature queen cups kept in an incubator were inspected at 5-min intervals and emerging queens were boxed immediately after weighing. The queens in mating boxes were inspected regularly to identify the days when they mated and started egg laying. The queens were weighed at different periods and when they became 1-month old, they were dissected.

Five of 50 queens (10%) were lost during pre-mating period and 2 of 45 queens (4.4%) did not return from mating flight. Twenty one of 43 queens (48.9%) mated once, while 22 queens flew out second time. All mating flights were performed in the late afternoon between 16.00-17.30. The average interval from emergence to first mating flight and the average onset of oviposition after emergence were 6.9 days and 10.6 days, respectively. The mean weight of queens at emergence, 3 days after emergence, one day after last mating flight, the day of onset of oviposition, three days after onset of oviposition, and 1-month old were 195.9 mg, 164.8 mg, 159.6 mg, 203.6 mg, 220.9 mg, 214.1 mg, respectively. The weight of queens at emergence decreased continuously till mating. After mating they gained weight. The diameter and the volume of spermatheca, the fresh and dry weights of ovaries, and the number of spermatozoa entering the spermatheca were found to be 1.1 mm, 0.7 mm3, 53.7 mg, 9.4 mg, 4.877.000, respectively. There were significant correlations (P < 0.01) between the weight at emergence and the diameter of spermatheca (r = 0.619) and the volume of spermatheca (r = 0.607).


Study on factors accelerating oviposition of instrumentally inseminated queen bees

Z. Jasiński1, J. Prabucki2, J.Wilde3, J.Woyke1, B.Chuda-Mickiewicz2, M. Siuda3, B.Madras-Majewska1, J.Samborski2, J. Bratkowski3, A. Jojczyk1, B. Bąk3

1 WarsawAgricultural University, Poland

2 Agricultural University in Szczecin, Poland

3 University of Warmia and Mazury in Olsztyn, Poland
E-mail. AGATA.JOJCZYK©INTERIA.PL

Investigations on the improvement of instrumental inseminations of queen bees are conducted in Poland from the beginning of the 60ties in XXth century. The precursor of these investigations is prof. J. Woyke. One of the results is the common use of instrumentally inseminated queens in most apiaries in Poland. This speed up the breeding progress of bees, and results in increase of honey production by the apiaries.

Nowadays, Poland is the largest producer of instrumentally inseminated queen bees in the world. We are producing some thousands of instrumentally inseminated queens each year.

Besides unquestionable advantages, instrumental insemination has some disadvantages. The greatest obstacle is the prolonged period of starting oviposition by instrumentally inseminated queens, which may last from 4 days to a dozen or so. Bee-keepers maybe discouraged to buy instrumentally inseminated queens, which start egg laying after many days, because lack of brood for some period results in decrease of honey production. It should be however, noticed that the breeding value of queens starting oviposition later is the same as of those beginning egg laying earlier.

Therefore three Bee Divisions of Agricultural Academies in Olsztyn, Szczecin and Warsaw, Poland, undertook investigations on accelerating the start of oviposition of instrumentally inseminated queens.

Experiments were carried out from 2003 to 2005, three times in each season. Carniolan bees (Apis mellifera carnica) were used in this investigation. The queens were introduced into trapezoid mating nuclei. The nuclei with accepted queens were randomly divided into 6 groups, of 15 nuclei each.

All queens were inseminated with 8 cu mm of semen at the age 8 day. They were treated with CO2 for 3 minutes, once at the age of 6 days and the second time during insemination.

Plugging with mucous and flying were chosen as possible equivalent of natural factors, like mating sign and mating flight of queen bees.




Influence of various concentrations of CO2 on results of instrumental insemination of honeybee queens

M.Bieńkowska, D.Gerula, B.Panasiuk

Research Institue of Pomology and Floriculture, Division of Apiculture, Kazimierska 2Str., 24-100 Pulawy, POLAND, E-mail: malgorzata.bienkowska©man.pulawy.pl

Carbon dioxide is the most often used anaesthetic during insemination. Negative effects are the more harmful the longer exposure to anaesthetic and the older individual is narcotized. Ebadi and Gary (1980) used to bee queens’ narcosis a various CO2 concentrations by mixing pure CO2 with air. Bee queens narcotized with diluted CO2 started oviposition earlier that those treated with pure CO2. The objects of the study were to determine the optimal dose and CO2 concentration and its effects on honeybee queens.

The study was run in the laboratory of Bee Breeding of the Institute of Pomology and Floriculture, Apiculture Division in Pulawy in 2004,2005 and 2006. The sister Carniolan queens after emerging were placed in mating hives. Queens were instrumentally inseminated when 8 days old with 8 μl of semen of Caucasian drones using 50%, 75%, 805, 90% and 100% carbon dioxide. The time to immobilize the queen, the time to wake up the queen and latency period were estimated. A control group was naturally mated queens.

Queens treated with 100%, 90%, and 80% CO2 concentrations were immobilized faster, respectively in 13.8, 20.3, and 23.2 s. Queens treated with 75% CO2 were immobilized in 33.8 s and with 50% CO2 in average 99.1 s. The shortest walking up time was noted in group of queens treated with 50% CO2 and it was 19.9 s. from the moment of insemination. Out of all examined queens, 87% started oviposition average in 16.6 days after insemination. The shortest latency period was observed in group of queens treated with pure CO2 (10.4 days) and significant longer in other compared groups (21 to 27 days). There were significant differences between means for years of research.


Injuries formation in production of artificially inseminated queens and its influence on their useful value

D. Gerula ,M. Bieńkowska

Research Institute of Pomology and Floriculture. Apicultural Division Puławy. Poland, E-mail: dariusz.gerula©man.pulawy.pl

Observation of injuries of artificially inseminated bee queens during all period of their production was done. The effect of bee queens injuries on their useful value and workers behaviour was examined. Queens before insemination were kept with attendant bees in cages in room temperature, and after the insemination they stayed in incubators. Before introducing queens into commercial colonies they were introduced to nucleuses to time of oviposition. The period of production of instrumental inseminated queens has been divided into 4 steps related with queen age and production technology: I-from emerging to insemination, II-from insemination to 2nd CO2 treatment, III-from 2nd CO2 treatment to acceptation in nucleuses, IV-from introducing to acceptation in commercial colonies. The criteria of elimination of those stages was also a contact with new workers which could cause queen injuries. Queens with similar injuries were divided into following groups: A-uninjured-as a control group, B-injured arolium and claws, C-missing legs or its part, D- paralyzed legs, E-injured antennae, F-injured wings. The greatest number of queens (83 %) had one leg injured with no preferences to the pair of legs. The older queens the greater number of injured individuals. In the stage I- 2 %. II- 4 %, III- 13 % and IV- 32 %. Also losses of queens were greater in following stages and differences were significant. Queens body weight has no influence on its injuries and losses. Workers in commercial colonies accepted queens with injuries and uninjured ones. Brood rearing in bee colonies with queens from B and C groups was similar like in colonies with uninjured queens. Substantially lower number of brood was in colonies with queens from groups D and E. Injured queens were more frequently supersedured by bees than uninjured ones.

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