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Hohen Neuendorf, Germany

McMenamin A.J.,Pennsylvania State University | Genersch E.,Institute for Bee Research
Current Opinion in Insect Science | Year: 2015

Recent large-scale colony losses among managed Western honey bees (Apis mellifera) have alarmed researchers and apiculturists alike. Here, the existing correlative evidence provided by monitoring studies is reviewed which (i) identified members of the deformed wing virus and acute bee paralysis virus clades as lethal pathogens for entire colonies, and (ii) identified novel viruses whose impact on honey bee health remains elusive. Also discussed in this review is related evidence obtained via controlled experimental infection assays and RNAi approaches underscoring the damage inflicted by some of these viruses on individuals and colonies. The relevance of the ectoparasitic mite Varroa destructor acting as mechanical and biological virus vector for the enhanced virulence of certain viruses or mite selected virus strains is carefully considered. © 2015 Elsevier Inc. Source

de Miranda J.R.,Swedish University of Agricultural Sciences | Genersch E.,Institute for Bee Research
Journal of Invertebrate Pathology | Year: 2010

Deformed wing virus (DWV; Iflaviridae) is one of many viruses infecting honeybees and one of the most heavily investigated due to its close association with honeybee colony collapse induced by Varroa destructor. In the absence of V. destructor DWV infection does not result in visible symptoms or any apparent negative impact on host fitness. However, for reasons that are still not fully understood, the transmission of DWV by V. destructor to the developing pupae causes clinical symptoms, including pupal death and adult bees emerging with deformed wings, a bloated, shortened abdomen and discolouration. These bees are not viable and die soon after emergence. In this review we will summarize the historical and recent data on DWV and its relatives, covering the genetics, pathobiology, and transmission of this important viral honeybee pathogen, and discuss these within the wider theoretical concepts relating to the genetic variability and population structure of RNA viruses, the evolution of virulence and the development of disease symptoms. © 2009 Elsevier Inc. All rights reserved. Source

Genersch E.,Institute for Bee Research
Journal of Invertebrate Pathology | Year: 2010

After more than a century of American Foulbrood (AFB) research, this fatal brood infection is still among the most deleterious bee diseases. Its etiological agent is the Gram-positive, spore-forming bacterium Paenibacillus larvae. Huge progress has been made, especially in the last 20 years, in the understanding of the disease and of the underlying host-pathogen interactions. This review will place these recent developments in the study of American Foulbrood and of P. larvae into the general context of AFB research. © 2009 Elsevier Inc. All rights reserved. Source

Lichtenberg-Kraag B.,Institute for Bee Research
Journal of Apicultural Research | Year: 2014

Analysis of the honey enzymes diastase and invertase is one important parameter in honey quality control. Limits for enzyme activity are given by food legislation or directives of national brands, because enzyme activity is one of the measures of adequate conversion of nectar to honey during the ripening process. In addition, certain activity levels of invertase or diastase activity can also act as indicators for heat damage of honey samples. Depending on the botanical origin, enormous differences in enzyme activity can be observed, even though the enzymes are mostly added by the bees. We therefore collected nectar and honey samples during the ripening process of honey and investigated enzyme activity depending on the floral source. Based on the analysis of nectar samples, we could demonstrate that floral source and environmental conditions affect the total sugars and sucrose concentration. We therefore hypothesized that the composition of the nectar, especially the amount of sucrose, may interact with the activity of invertase. We found that correlation between sucrose concentration and invertase activity is highly significant during the ripening process of honey (p < 0.0001) confirming an interaction between these two parameters. This effect was further substantiated by a sugar feeding experiment with defined sucrose concentrations. Possibly a high turn-over at high sucrose concentrations may lead to enzyme exhaustion for invertase. Source

Garcia-Gonzalez E.,Institute for Bee Research | Garcia-Gonzalez E.,Humboldt University of Berlin | Genersch E.,Institute for Bee Research
Environmental Microbiology | Year: 2013

Summary: Paenibacillus larvae, the aetiological agent of American foulbrood (AFB) of honey bees, causes a fatal intestinal infection in larvae and invades the haemocoel by breaching the midgut. The peritrophic matrix lining the midgut epithelium in insects constitutes an effective barrier against abrasive food particles, xenobiotics, toxins and pathogens. Pathogens like P.larvae entering the host through the gut first need to overcome this barrier. To better understand AFB pathogenesis, we analysed the fate of the peritrophic matrix in honey bee larvae during P.larvae infection. Using histochemical techniques, we first established that chitin is a major component of the honey bee larval peritrophic matrix. Rearing larvae on a diet containing a fluorochrome blocking formation of the peritrophic matrix or a bacterial endochitinase revealed that a fully formed peritrophic matrix is essential for larval survival. Larvae infected by P.larvae showed total degradation of the peritrophic matrix enabling the bacteria to directly attack the epithelial cells. Carbon source utilization tests confirmed that P.larvae is able to metabolize colloidal chitin. We propose that P.larvae degrades the peritrophic matrix to allow direct access of the bacteria or of bacterial toxins to the epithelium to prepare the breakthrough of the epithelial layer. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd. Source

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