Viruses Associated with Ovarian Degeneration in Apis mellifera L. Queens

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.

Dead or Alive: Deformed Wing Virus and Varroa destructor Reduce the Life Span of Winter Honeybees

“…Despite that, however, a negative correlation between vitellogenin gene expression and DWV loads was not observed in the study. This absence of a relationship between DWV and vitellogenin expression was recently described for honeybee queens as well (26). Conversely, ABPV seems to have an impact on the expression of this gene, since strong positive correlations from November through March were identified.…”

Seasonal prevalence of pathogens and parasites in the savannah honeybee (Apis mellifera scutellata)

“…obs.). VDV-1 was only found in four apiaries during summer 2010-2011, once again illustrating a low prevalence in South Africa, whereas it appears to be quite prevalent in parts of Europe (Ongus, 2006) and was also found to be widespread in queens collected in France (Gauthier et al, 2011).…”

“…ABPV, CBPV, DWV, VdMLV and SBV were not detected in the honeybee or Varroa mite samples. With the exception of VdMLV, a recently discovered virus (Gauthier et al, 2011), all these viruses have previously been detected in South Africa (Allen and Ball, 1996;Davison et al, 1999). The non-detection of five of the eight viruses may indicate, that these viruses are either present at very low levels in the form of covert infections (Sumpter and Martin, 2004), or that they are simply not present in these apiaries.…”

Characteristics of Honey Bee (Apis Mellifera Carnica, Pollman 1879) Queens Reared in Slovenian Commercial Breeding Stations

“…The objective of breeding activities and queen marketing, is also to reduce the potential transmission of the causative agents of disease. It was found that mating can transmit viral disease; mated queens are older than virgin queens, which results in a higher probability of infection from workers or as a result of vertical virus transmission (Gauthier et al, 2011). In our previous research, we noted that DWV was found in normally-developed, laying queens despite Varroa control (Gregorc and Bakony, 2012).…”