Current Results
WP1 - WP2 - WP3 - WP4 - WP5 - WP6 - WP7 - WP8
Current Results: Workpackage 1
Forsgren E, Fries I (2010):
Comparative virulence of Nosema ceranae and Nosema apis in individual European honey bees.
VETERINARY PARASITOLOGY 170: 212-217
ABSTRACT:
Nosema apis and Nosema ceranae are intracellular microsporidian parasites infecting the midgut epithelial cells of adult honey bees. N. ceranae was considered
to be restricted to the Asian honey bee, Apis cerana, but is nowadays a parasite found also in the European honey bee (Apis mellifera) across most of the world.
Recent surveys and experimental work suggest that N. ceranae is a serious threat to the global beekeeping industry. It has been suggested that N. ceranae induces
significantly higher mortality in honey bees than N. apis, but little is known about their comparative virulence. In this study, we used in vivo infection
experiments to study the two parasites' different virulence (i.e. multiplication rate and infectivity). A qPCR was developed to elucidate within host competition
between the two parasites using mixed infections. The outcome of the experiments indicates minor differences in infectious dose and multiplication rate between
the two species. Moreover, the mortality caused by N. ceranae was not significantly higher than for N. apis and N. ceranae appeared to have no competitive
advantage within host.
Current Results: Workpackage 2
Gauthier L, Ravallec M, Tournaire M, Cousserans F, Bergoin M, Dainat B, de Miranda JR (2011):
Viruses Associated with Ovarian Degeneration in Apis mellifera L. Queens.
PLOS ONE 6: e16217
ABSTRACT:
Queen fecundity is a critical issue for the health of honeybee (Apis mellifera L.) colonies, as she is the only reproductive female in the colony
and responsible for the constant renewal of the worker bee population. Any factor affecting the queen's fecundity will stagnate colony development,
increasing its susceptibility to opportunistic pathogens. We discovered a pathology affecting the ovaries, characterized by a yellow discoloration
concentrated in the apex of the ovaries resulting from degenerative lesions in the follicles. In extreme cases, marked by intense discoloration, the
majority of the ovarioles were affected and these cases were universally associated with egg-laying deficiencies in the queens. Microscopic examination
of the degenerated follicles showed extensive paracrystal lattices of 30 nm icosahedral viral particles. A cDNA library from degenerated ovaries contained
a high frequency of deformed wing virus (DWV) and Varroa destructor virus 1 (VDV-1) sequences, two common and closely related honeybee Iflaviruses.
These could also be identified by in situ hybridization in various parts of the ovary. A large-scale survey for 10 distinct honeybee viruses showed
that DWV and VDV-1 were by far the most prevalent honeybee viruses in queen populations, with distinctly higher prevalence in mated queens
(100% and 67%, respectively for DWV and VDV-1) than in virgin queens (37% and 0%, respectively). Since very high viral titres could be recorded in
the ovaries and abdomens of both functional and deficient queens, no significant correlation could be made between viral titre and ovarian degeneration
or egg-laying deficiency among the wider population of queens. Although our data suggest that DWV and VDV-1 have a role in extreme cases of ovarian
degeneration, infection of the ovaries by these viruses does not necessarily result in ovarian degeneration, even at high titres, and additional factors
are likely to be involved in this pathology.
Current Results: Workpackage 3
Alaux C, Folschweiller M, McDonnell C, Beslay D, Cousin M, Dussaubat C, Brunet JL, Le Conte Y (2011):
Pathological effects of the microsporidium Nosema ceranae on honey bee queen physiology (Apis mellifera).
JOURNAL OF INVERTEBRATE PATHOLOGY 106: 380-385
ABSTRACT:
Nosema ceranae, a microsporidian parasite originally described in the Asian honey bee Apis cerana, has recently been found to be cross-infective and to also parasitize
the European honey bee Apis mellifera. Since this discovery, many studies have attempted to characterize the impact of this parasite in A. mellifera honey bees.
Nosema species can infect all colony members, workers, drones and queens, but the pathological effects of this microsporidium has been mainly investigated in workers,
despite the prime importance of the queen, who monopolizes the reproduction and regulates the cohesion of the society via pheromones. We therefore analyzed the impact
of N. ceranae on queen physiology. We found that infection by N. ceranae did not affect the fat body content (an indicator of energy stores) but did alter the vitellogenin
titer (an indicator of fertility and longevity), the total antioxidant capacity and the queen mandibular pheromones, which surprisingly were all significantly increased
in Nosema-infected queens. Thus, such physiological changes may impact queen health, leading to changes in pheromone production, that could explain Nosema-induced
supersedure (queen replacement).
Current Results: Workpackage 4
Behrens D, Huang Q, Gessner C, Rosenkranz P, Frey E, Locke B, Moritz RFA, Kraus FB (2011):
Three QTL in the honey bee Apis mellifera L. suppress reproduction of the parasitic mite Varroa destructor.
ECOLOGY AND EVOLUTION 1: 451-458
ABSTRACT:
Varroa destructor is a highly virulent ectoparasitic mite of the honey bee Apis mellifera and a major cause of colony losses for global apiculture.
Typically, chemical treatment is essential to control the parasite population in the honey bee colony. Nevertheless a few honey bee populations
survive mite infestation without any treatment. We used one such Varroa mite tolerant honey bee lineage from the island of Gotland, Sweden, to
identify quantitative trait loci (QTL) controlling reduced mite reproduction. We crossed a queen from this tolerant population with drones from
susceptible colonies to rear hybrid queens. Two hybrid queens were used to produce a mapping population of haploid drones. We discriminated drone
pupae with and without mite reproduction, and screened the genome for potential QTL using a total of 216 heterozygous microsatellite markers in a
bulk segregant analysis. Subsequently, we fine mapped three candidate target regions on chromosomes 4, 7, and 9. Although the individual effect of
these three QTL was found to be relatively small, the set of all three had significant impact on suppression of V. destructor reproduction by epistasis.
Although it is in principle possible to use these loci for marker-assisted selection, the strong epistatic effects between the three loci complicate
selective breeding programs with the Gotland Varroa tolerant honey bee stock.
Current Results: Workpackage 5
Coming soon
Current Results: Workpackage 6
Locke B, Fries I (2011):
Characteristics of honey bee colonies (Apis mellifera) in Sweden surviving Varroa destructor infestation.
APIDOLOGIE 42: 533-542
ABSTRACT:
A population of European honey bees (Apis mellifera) surviving Varroa destructor mite infestation in Sweden for over 10 years without treatment, demonstrate
that a balanced host-parasite relationship may evolve over time. Colony-level adaptive traits linked to Varroa tolerance were investigated in this population
to identify possible characteristics that may be responsible for colony survival in spite of mite infestations. Brood removal rate, adult grooming rate, and the
mite distribution between brood and adults were not significantly different in the untreated population compared with treated control colonies. However, colony size
and the reproductive success of the mite were significantly reduced in surviving colonies compared with control colonies. Our data suggest that colony-level adaptive
traits may limit mite population growth by reducing mite reproduction opportunities and also by suppressing the mite reproductive success.
Current Results: Workpackage 7
Truchado P, Ponce A, Tomás-Barberán FA, Allende A (2011):
Selected Phytochemical Bioactive Compounds as Quorum Sensing Inhibitors.
Acta Horticulturae (in press)
ABSTRACT:
Coming soon.
Current Results: Workpackage 8
Aebi A, Neumann P (2011):
Endosymbionts and honey bee colony losses?
TRENDS IN ECOLOGY & EVOLUTION 26: 494-494
