Bacterial Communities in Central European Bumblebees: Low Diversity and High Specificity

Recent studies on the microbial flora of the honeybee gut have revealed an apparently highly specific community of resident bacteria that might play a role in immune defence and food preservation for their hosts. However, at present, very little is known about the diversity and ecology of bacteria occurring in non-domesticated bees like bumblebees, which are of similar importance as honeybees for the pollination of agricultural and wild flowers. To fill this gap in knowledge, we examined six of the most common bumblebee species in Central Europe from three locations in Germany and Switzerland for their bacterial communities. We used a culture-independent molecular approach based on sequencing the 16S rRNA gene from a selection of individuals and examining a larger number of samples by terminal restriction fragment length polymorphism profiles. The gut flora was dominated by very few and mostly undescribed groups of bacteria belonging to the Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria. This core set of bacteria was present in all of the examined bumblebee species. These bacteria are similar to, but distinct from, bacteria previously described from the honeybee gut. Significant differences were observed between the communities of bacteria in the different bumblebee species; the effect of sampling location was less strong. A novel group of Betaproteobacteria additionally shows evidence for host species-specific genotypes. The gut flora of bumblebees therefore is apparently composed of relatively few highly specialized bacteria, indicating a strong interaction and possibly important functions with their host

Influence of co-evolution with a parasite, Nosema whitei, and population size on recombination rates and fitness in the red flour beetle, Tribolium castaneum

The high prevalence of meiotic recombination—an important element of sexual reproduction—represents one of the greatest puzzles in biology. The influence of either selection by a co-evolving parasite alone or in combination with genetic drift on recombination rates was tested in the host-parasite system Tribolium castaneum and Nosema whitei. After eight generations, populations with smaller genetic drift had a lower recombination rate than those with high drift whereas parasites had no effect. Interestingly, changes in recombination rate at one site of the chromosome negatively correlated with changes at the adjacent site on the same chromosome indicating an occurrence of crossover interference. The occurrence of spontaneous or plastic changes in recombination rates could be excluded with a separate experimen

The genetic architecture of susceptibility to parasites

<p>Abstract</p> <p>Background</p> <p>The antagonistic co-evolution of hosts and their parasites is considered to be a potential driving force in maintaining host genetic variation including sexual reproduction and recombination. The examination of this hypothesis calls for information about the genetic basis of host-parasite interactions – such as how many genes are involved, how big an effect these genes have and whether there is epistasis between loci. We here examine the genetic architecture of quantitative resistance in animal and plant hosts by concatenating published studies that have identified quantitative trait loci (QTL) for host resistance in animals and plants.</p> <p>Results</p> <p>Collectively, these studies show that host resistance is affected by few loci. We particularly show that additional epistatic interactions, especially between loci on different chromosomes, explain a majority of the effects. Furthermore, we find that when experiments are repeated using different host or parasite genotypes under otherwise identical conditions, the underlying genetic architecture of host resistance can vary dramatically – that is, involves different QTLs and epistatic interactions. QTLs and epistatic loci vary much less when host and parasite types remain the same but experiments are repeated in different environments.</p> <p>Conclusion</p> <p>This pattern of variability of the genetic architecture is predicted by strong interactions between genotypes and corroborates the prevalence of varying host-parasite combinations over varying environmental conditions. Moreover, epistasis is a major determinant of phenotypic variance for host resistance. Because epistasis seems to occur predominantly between, rather than within, chromosomes, segregation and chromosome number rather than recombination via cross-over should be the major elements affecting adaptive change in host resistance.</p

Experimentally evolved trypanosome: infection success and virulence in the bumblebee

In this paper, Beer's Viable System Model (VSM) is applied to knowledge management. Based on the VSM, domains of knowledge are identified that an organization should possess to maintain its viability. The logic of the VSM is also used to support the diagnosis, design and implementation of the knowledge processes that should make and keep organizationally viable knowledge available

Parasites delay worker reproduction in bumblebees: consequences for eusociality

Workers in eusocial insects usually tend the brood of the queen and so achieve representation in the next generation through aiding relatives to reproduce. However, workers of some eusocial species, such as bumblebees, are capable of reproductive activity even in the presence of the queen (in queen-right colonies), and worker reproduction is associated with aggressive behaviors and egg cannibalism, both of which reduce colony efficiency. Thus, factors that affect worker ovariandevelopment, a precondition for reproduction, can influence social harmony and colony productivity. Parasites are a ubiquitous and important part of the biotic environment of all organisms. Here we show that parasites play an important role in the reproductive physiology of worker bumblebees in queen-right colonies of Bombus terrestris, affecting the pattern and timing of ovarian development and oviposition. Workers from colonies parasitized with the intestinal trypanosome Crithidia bombi had less developed ovaries than workers of the same age from unparasitized colonies. In addition, parasitized colonies were smaller than unparasitized colonies for about the first half of colony development. This generated further demographic effects such that workers were on average younger in parasitized than in unparasitized colonies around the time of the onset of worker oviposition, and worker oviposition occurred significantly later in parasitized colonies. Workers in parasitized colonies therefore had lower individual reproductive potential and were cooperative for a larger proportion of the colony cycle than those in unparasitized colonies. In this system, where transmission of the parasite between years probably occurs only in infested, young queens, this effect may represent an adaptation on the part of the parasite to ensure its successful passage through the winter. Parasites, by reducing the cost of worker cooperation, may facilitate queen control over her worker force and play an important role in moderating the social organization of eusocial insect colonie