Robin F. A. Moritz

High degree of polyandry in Apis dorsata queens detected by DNA microsatellite variability

Workers of six colonies of the giant honeybee Apis dorsata from Sabah, Malaysia (five colonies) and Java (one colony) were genotyped using single locus DNA fingerprinting. The colonies from Sabah nested in colony aggregations of 5 and 28 nests respectively on two trees. Three DNA microsatellite loci (A14, A76, A88) with a total of 27 alleles provided sufficient genetic variability to classify the workers into distinct sub-families revealing the degree of polyandry of the queens. Queens mated on average with 30.17 ± 5.98 drones with a range from 19 to 53. The average effective number of matings per queen was 25.56 ± 11.63. In the total sample of 192 workers, 22 individuals were found that were not offspring of the colonys queen. Three of these were potentially drifted offspring workers from genotyped queens of colonies nesting on the same tree.

Nestmate recognition and the genetic relatedness of nests in the ant Formica pratensis

Genetic relatedness of the mound-building ant Formica pratensis was determined by means of microsatellite DNA polymorphism, and its impact on nestmate recognition was tested in a population in Southern Sweden (Oeland). Recognition between nests was measured by testing aggression levels between single pairs of workers. The genetic distances of nests (Neis genetic distance) and the spatial distance of nests were correlated and both showed a strong relation to the aggression behavior. Multiple regression analysis revealed a stronger impact of genetic relatedness rather than spatial distances on aggression behavior. Neighbouring nests were more closely related than distant nests, which may reflect budding as a possible spreading mechanism. The genetic distance data showed that nestmate recognition was strongly genetically influenced in F. pratensis.

Nestmate recognition and the genetic gestalt in the mound-building ant Formica polyctena

Summary: The genetic gestalts of nests of the mound-building ant Formica polyctena were determined and its impact on nestmate recognition was tested in two populations in Eastern Germany (Berlin/Schwedt). Nestmate recognition was measured by testing aggression levels between single workers of different nests in arena tests. Multilocus fingerprinting was used to determine the genetic gestalts of nests using pooled worker samples. Therefore we proposed a new metric for quantifying resemblance using DNA fingerprint data. The levels of aggression differed substantially between the two sampling locations. Nests in site A showed a strong relationship of genetic gestalt distances and aggressive behavior between individual nest members (P<0.0001). Nests in site B showed low levels of aggression, with no detectable differences in the genetic gestalt. Nestmate recognition seems to be strongly genetically influenced in F. polyctena.

Transfer of paternal mitochondrial DNA during fertilization of honeybee (Apis mellifera L.) eggs

Strict maternal inheritance of mitochondrial (mt) DNA is believed to be the rule in most eukaryotic organisms because of exclusion of paternal mitochondria from the egg cytoplasm during fertilization. In honeybees, polyspermic fertilization occurs, and many spermatozoa, including their mitochondria-rich flagellum, can completely penetrate the egg, thus allowing for a possibly high paternal leakage. In order to identify paternal mtDNA in honeybee eggs, restriction fragment length polymorphisms (RFLP) of different subspecies were used. Total DNA extracts of different developmental stages of an Apis mellifera carnica x Apis mellifera capensis hybrid brood were tested with a radioactively-labelled diagnostic mtDNA probe. Densitograms of autoradiographs indicated that the male contribution represents up to 27% of the total mitochondrial DNA in the fertilized eggs 12 h after oviposition. In subsequent developmental stages the portion of paternal mtDNA slowly decreased until hatching of the larvae when only traces were found. Although rapid disintegration of paternal mtDNA does not occur, the initially high paternal mitochondrial contribution is not maintained in the adult animal.

Lack of meiotic recombination in thelytokous parthenogenesis of laying workers of Apis Mellifera Capensis (the cape honeybee)

Offspring of thelytokous laying workers of Apis mellifera capensis were screened using multilocus DNA fingerprinting with the (GATA)4 oligonucleotide. All screened offspring workers revealed an identical DNA fingerprint pattern, lacking evidence of any meiotic recombination. This finding supports earlier cytological studies that postulated a central fusion in the automictic thelytokous parthenogenesis of honeybees. Furthermore, crossing-over did not contribute to detectable genetic variability in this study.

Self-organization of circadian rhythms in groups of honeybees (Apis mellifera L.)

Workers in social groups of honeybees (Apis mellifera L.) synchronize their individual free-running circadian rhythms to an overall group rhythm. By monitoring the activity of bees by recording the oxygen consumption and intragroup temperature, it is shown that the rhythm coordination is in part achieved by temperature fluctuations as an intragroup Zeitgeber. Trophallaxis was shown to have only a minor (if any) effect on circadian rhythm synchronization. A model incorporating a feed back loop between temperature and activity can plausibly explain the observed synchronization of individual rhythms in social groups as a self-organization phenomenon.

Lack of kin recognition in swarming honeybees ( Apis mellifera )

Abstract Honeybee colonies reproduce by colony fission and swarming. The primary swarm leaves the nest with the mated mother queen. Further “after-swarms” can leave the nest. These are composed of virgin queens and sister workers. Since all workers in the primary swarm have the same relationship to the mother queen, kin recognition cannot have any effect on the worker distribution in the swarm. Because of polyandry of the mother queen, the after-swarm is composed of super- and halfsister workers of the virgin queen. In this case kin recognition might affect swarm composition if workers increase their inclusive fitness by preferentially investing in a supersister queen. The distribution of workers in the mother colony, the primary and the after-swarm was analyzed using single-locus DNA fingerprinting in two colonies of the honeybee (Apis mellifera). The colonies were composed of 21 and 24 worker subfamilies because of multiple mating of the queen. The subfamily distribution in the mother colonies before swarming was significantly different from the subfamily frequencies in the primary swarm. This indicates different propensities for swarming in the various subfamilies. The subfamily distribution was also significantly different between the mother colony and the after-swarm. There was however no significant difference between the subfamily composition of the primary and the after-swarm. The average effects of kin recognition on the distribution of the subfamilies in the two after-swarms were less than 2%. We conclude that colony-level selection sets the evolutionary framework for swarming behaviour.

Sequence analysis of the D1 and D2 regions of 28S rDNA in the hornet (Vespa crabro) (Hymenoptera, Vespinae)

The two variable domains D1 and D2 near the 5 end of the 28S ribosomal RNA gene (large subunit rRNA) have been sequenced for Vespa crabro. The sequence was aligned to corresponding rDNA regions of the wasp species Nasonia vitripennis, Melittobia digitata and the fruit fly Drosophila melanogaster. We analysed the nucleotide composition and sequence similarity for the different regions of the investigated sequences and present the inferred secondary structure of Vespa crabro.

Selection of resistance againstVarroa jacobsoni across caste and sex in the honeybee (Apis mellifera L., Hymenoptera: Apidae)

Honeybee workers (Apis mellifera) with a short postcapping stage in their development are partially resistant against theVarroa mite. Selection of sexual reproductives, with a short postcapping stage offers a possibility to establish genetic lines withVarroa-resistant worker brood. Particularly the use of selected drones in the procedure allows for rapid genetic progress. They have a large phenotypic variance for the duration of the postcapping stage and the evaluation of the breeding value is more precise than for queens because of the male haploidy.

Molecular Biology of the Honeybee

Publisher Summary This chapter focuses on the molecular biology of the honeybee. The biological rules that govern the honeybee colony have fascinated scientists since Aristotle. The honeybee riddle of chaos on the one hand and yet pattern on the other hand was to occupy generations of scientists after Aristotle. The focus on behavioral ecology was not always so strong, and in fact honeybees also entered the arena of modern research as a genetic model system. The molecular revolution of genetics took place leaving the honeybees aside. The molecular genetics of Drosophila melanogaster boomed, while bee geneticists felt more attracted to applied breeding research. Because honeybees are of significant economical and ecological importance, there is obviously also a compelling need to understand their population and breeding genetics. The molecular genetics of honeybees can both increase the understanding of basic genetic mechanisms and improve the knowledge of honeybee specific genetic problems. The mitochondria1 genome of the honeybee is much better known than its nuclear counterpart. The segmentation of the embryo is one of the best understood steps in insect embryogenesis. In particular, the findings in Drosophila melanogaster have given an important insight into gene regulation in early embryonic development. The pattern of gene activity corresponds to the external metameric subdivision in the larval body. Genetic variability in populations has been analyzed with isozyme polymorphisms. Although this technique has proved very powerful for the study of many insect populations, isozyme analysis in honeybees has often posed a problem. The consequent use of the advantages offered by honeybees over other test systems ensure a rapidly increasing body of most exciting studies, re-establishing its position as a most rewarding study organism in both physiological and genetical research.