Christian Walter Werner Pirk

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The honeybee Apis mellifera has major ecological and economic importance. We analyze patterns of genetic variation at 8.3 million SNPs, identified by sequencing 140 honeybee genomes from a worldwide sample of 14 populations at a combined total depth of 634×. These data provide insight into the evolutionary history and genetic basis of local adaptation in(More)
The nutritional needs of bees are supplied by nectar carbohydrates and by protein and other nutrients in pollen but little is known of how bees achieve nutritional balance. Using newly emerged caged worker honeybees (Apis mellifera scutellata), we investigated whether bees maintain their intake target when confined to pairs of imbalanced complementary diets(More)
Honeybees are native to Africa and Europe but have been spread worldwide as the basis for an apicultural industry. To date, large and diverse wild populations only remain in Africa. On this continent the beekeeping industry is relatively undeveloped and relies on trapping swarms from wild populations to constitute the managed stocks. Bee breeding is seldom(More)
Hemocytes and the (prophenol-) phenoloxidase system constitute the immediate innate immune system in insects. These components of insect immunity are present at any post-embryonic life stage without previous infection. Differences between individuals and species in these immune parameters can reflect differences in infection risk, life expectancy, and(More)
Pollen is the natural source of protein for bees and it is commonly assumed that a high protein content in pollen is beneficial. Investigation of the optimal nutrient ratio for honeybees was prompted by our earlier study showing surprisingly high mortality in caged honeybees fed with the protein-rich pollen of Aloe greatheadii var davyana, although field(More)
Ongoing expansion of large-scale agriculture critically threatens natural habitats and the pollination services they offer. Creating patches with high plant diversity within farmland is commonly suggested as a measure to benefit pollinators. However, farmers rarely adopt such practice, instead removing naturally occurring plants (weeds). By combining(More)
Protein-rich diets are known to promote ovarian and egg development in workers of the honeybee, Apis mellifera, even in the presence of a queen. Since the main source of protein for honeybees is pollen, its quality and digestibility might be important dietary factors determining reproductive capacity. We have compared the effect of two types of(More)
In many species of social Hymenoptera, unmated workers can lay eggs that will produce males by parthenogenesis. Nevertheless, in queenright honey bee colonies (Apis mellifera), worker reproduction is low. One possible mechanism for this difference is worker policing, the removal of worker-laid eggs by other workers. This behavior can evolve in species in(More)
Automatic tracking and identification of individuals has the potential to revolutionize the study of insects, especially social insects, by opening up options for questions which could not be asked before. To achieve this we developed a reliable and cost-sensible RFID (Radio-Frequency Identification) based solution that automatically recognises a virtually(More)
The recent invasion by self-replicating socially parasitic Cape honeybee workers, Apis mellifera capensis, of colonies of the neighbouring African subspecies Apis mellifera scutellata represents an opportunity to study evolution of intraspecific parasitism in real time. As honeybee workers compete pheromonally for reproductive dominance, and as A. m.(More)