scholarly journals Can supplementary pollen feeding reduce varroa mite and virus levels and improve honey bee colony survival?

2020 ◽  
Vol 82 (4) ◽  
pp. 455-473
Author(s):  
Gloria DeGrandi-Hoffman ◽  
Vanessa Corby-Harris ◽  
Yanping Chen ◽  
Henry Graham ◽  
Mona Chambers ◽  
...  
Keyword(s):  
Honey Bees ◽  
Varroa Destructor ◽  
Colony Growth ◽  
Positive Influence ◽  
Varroa Mite ◽  
Deformed Wing Virus ◽  
Positive Effects ◽  
Bee Colony ◽  
Pollen Feeding ◽  
Colony Survival

AbstractVarroa destructor is an ectoparasitic mite of immature and adult honey bees that can transmit several single-stranded RNA viruses to its host. Varroa reproduce in brood cells, and mite populations increase as colonies produce brood in spring and summer. Mite numbers also can sharply rise, particularly in the fall, by the migration of varroa into hives on foragers. Colonies with high levels of varroa and viruses often die over the winter. Feeding colonies pollen might keep virus levels low and improve survival because of the positive effects of pollen on immunity and colony growth. We compared varroa and virus levels and overwinter survival in colonies with (fed) and without (unfed) supplemental pollen. We also measured the frequency of capturing foragers with mites (FWM) at colony entrances to determine its relationship to varroa and virus levels. Colonies fed supplemental pollen were larger than unfed colonies and survived longer. Varroa populations and levels of Deformed wing virus (DWV) rose throughout the season, and were similar between fed and unfed colonies. The growth of varroa populations was correlated with FWM in fed and unfed colonies, and significantly affected DWV levels. Increasing frequencies of FWM and the effects on varroa populations might reduce the positive influence of supplemental pollen on immune function. However, pollen feeding can stimulate colony growth and this can improve colony survival.

scholarly journals Neonicotinoid Clothianidin reduces honey bee immune response and contributes to Varroa mite proliferation

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Desiderato Annoscia ◽  
Gennaro Di Prisco ◽  
Andrea Becchimanzi ◽  
Emilio Caprio ◽  
Davide Frizzera ◽  
...  
Keyword(s):  
Immune Responses ◽  
Honey Bee ◽  
Honey Bees ◽  
Varroa Destructor ◽  
Negative Impact ◽  
Asymptomatic Infection ◽  
Varroa Mite ◽  
Deformed Wing Virus ◽  
Synergistic Interactions ◽  
Parasitic Mite

AbstractThe neonicotinoid Clothianidin has a negative impact on NF-κB signaling and on immune responses controlled by this transcription factor, which can boost the proliferation of honey bee parasites and pathogens. This effect has been well documented for the replication of deformed wing virus (DWV) induced by Clothianidin in honey bees bearing an asymptomatic infection. Here, we conduct infestation experiments of treated bees to show that the immune-suppression exerted by Clothianidin is associated with an enhanced fertility of the parasitic mite Varroa destructor, as a possible consequence of a higher feeding efficiency. A conceptual model is proposed to describe the synergistic interactions among different stress agents acting on honey bees.

scholarly journals Geographical Distribution and Selection of European Honey Bees Resistant to Varroa destructor

Insects ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 873
Author(s):  
Yves Le Conte ◽  
Marina D. Meixner ◽  
Annely Brandt ◽  
Norman L. Carreck ◽  
Cecilia Costa ◽  
...  
Keyword(s):  
Honey Bees ◽  
Mite Population ◽  
Varroa Mite ◽  
Local Conditions ◽  
Colony Management ◽  
Selection Strategies ◽  
Mite Reproduction ◽  
Natural Infestation ◽  
Practical Experiences ◽  
Colony Survival

Developing resistance to the varroa mite in honey bees is a major goal for apicultural science and practice, the development of selection strategies and the availability of resistant stock. Here we present an extended literature review and survey of resistant populations and selection programs in the EU and elsewhere, including expert interviews. We illustrate the practical experiences of scientists, beekeepers, and breeders in search of resistant bees. We describe numerous resistant populations surviving without acaricide treatments, most of which developed under natural infestation pressure. Their common characteristics: reduced brood development; limited mite population growth; and low mite reproduction, may cause conflict with the interests of commercial beekeeping. Since environmental factors affect varroa mite resistance, particular honey bee strains must be evaluated under different local conditions and colony management. The resistance traits of grooming, hygienic behavior and mite reproduction, together with simple testing of mite population development and colony survival, are significant in recent selection programs. Advanced breeding techniques and genetic and physiological selection tools will be essential in the future. Despite huge demand, there is no well-established market for resistant stock in Europe. Moreover, reliable experience or experimental evidence regarding the resistance of stocks under different environmental and management conditions is still lacking.

scholarly journals Biology and Management of Varroa destructor (Mesostigmata: Varroidae) in Apis mellifera (Hymenoptera: Apidae) Colonies

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Morgan A Roth ◽  
James M Wilson ◽  
Keith R Tignor ◽  
Aaron D Gross
Keyword(s):  
Apis Mellifera ◽  
Honey Bee ◽  
Varroa Destructor ◽  
Sampling Methods ◽  
Apis Cerana ◽  
Varroa Mite ◽  
Resistance Development ◽  
Deformed Wing Virus ◽  
The Past ◽  
Asian Honey Bee

Abstract Varroa mite (Varroa destructor Anderson and Trueman) infestation of European honey bee (Apis mellifera L.) colonies has been a growing cause of international concern among beekeepers throughout the last 50 yr. Varroa destructor spread from the Asian honey bee (Apis cerana Fabricius [Hymenoptera: Apidae]) to A. mellifera populations in Europe in the 1970s, and subsequently traveled to the Americas. In addition to causing damage through feeding upon lipids of larval and adult bees, V. destructor also facilitates the spread of several viruses, with deformed wing virus being most prevalent. Several sampling methods have been developed for estimating infestation levels of A. mellifera colonies, and acaricide treatments have been implemented. However, overuse of synthetic acaricides in the past has led to widespread acaricide resistant V. destructor populations. The application of Integrated Pest Management (IPM) techniques is a more recent development in V. destructor control and is suggested to be more effective than only using pesticides, thereby posing fewer threats to A. mellifera colonies. When using IPM methods, informed management decisions are made based upon sampling, and cultural and mechanical controls are implemented prior to use of acaricide treatments. If acaricides are deemed necessary, they are rotated based on their mode of action, thus avoiding V. destructor resistance development.

scholarly journals New Viruses from the Ectoparasite Mite Varroa destructor Infesting Apis mellifera and Apis cerana

Viruses ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 94 ◽  
Author(s):  
Sofia Levin ◽  
Noa Sela ◽  
Tal Erez ◽  
David Nestel ◽  
Jeffery Pettis ◽  
...  
Keyword(s):  
Apis Mellifera ◽  
Varroa Destructor ◽  
Rna Virus ◽  
Apis Cerana ◽  
Virus Genome ◽  
Deformed Wing Virus ◽  
Viral Loads ◽  
Short Period ◽  
Honeybee Subspecies ◽  
Colony Survival

Varroa destructor is an ectoparasitic mite of Asian or Eastern honeybees Apis cerana (A. cerana) which has become a serious threat to European subspecies of Western honeybees Apis mellifera (A. mellifera) within the last century. V. destructor and its vectored honeybee viruses became serious threats for colony survival. This is a short period for pathogen- and host-populations to adapt. To look for possible variation in the composition of viral populations we performed RNA metagenomic analysis of the Western honeybee subspecies A. m. ligustica, A. m. syriaca, A. m. intermissa, and A. cerana and their respective V. destructor mites. The analysis revealed two novel viruses: Varroa orthomyxovirus-1 (VOV-1) in A. mellifera and V. destructor and a Hubei like-virga virus-14 homolog in V. destructor. VOV-1 was more prevalent in V. destructor than in A. mellifera and we found evidence for viral replication in both hosts. Interestingly, we found differences in viral loads of A. cerana and their V. destructor, A. m. intermissa, and its V. destructor showed partial similarity, while A. m. ligustica and A. m. syriaca and their varroa where very similar. Deformed wing virus exhibited 82.20%, 99.20%, 97.90%, and 0.76% of total viral reads in A. m. ligustica, A. m. syriaca, A. m. intermissa, and A. cerana, respectively. This is the first report of a complete segmented-single-stranded negative-sense RNA virus genome in honeybees and V. destructor mites.

scholarly journals Deformed wing virus type A, a major honey bee pathogen, is vectored by the mite Varroa destructor in a non-propagative manner

2019 ◽  
Author(s):  
Francisco Posada-Florez ◽  
Anna K. Childers ◽  
Matthew C. Heerman ◽  
Noble I. Egekwu ◽  
Steven C. Cook ◽  
...  
Keyword(s):  
Honey Bee ◽  
Honey Bees ◽  
Varroa Destructor ◽  
Rna Virus ◽  
Fold Increase ◽  
Type A ◽  
Deformed Wing Virus ◽  
Negative Strand ◽  
Viral Loads ◽  
Insect Pollinator

AbstractHoney bees, the primary managed insect pollinator, suffer considerable losses due to Deformed wing virus (DWV), an RNA virus vectored by the mite Varroa destructor. Mite vectoring has resulted in the emergence of virulent DWV variants. The basis for such changes in DWV is poorly understood. Most importantly, it remains unclear whether replication of DWV occurs in the mite. In this study, we exposed Varroa mites to DWV type A via feeding on artificially infected honey bees. A significant, 357-fold increase in DWV load was observed in these mites after 2 days. However, after 8 additional days of passage on honey bee pupae with low viral loads, the DWV load dropped by 29-fold. This decrease significantly reduced the mites’ ability to transmit DWV to honey bees. Notably, negative-strand DWV RNA, which could indicate viral replication, was detected only in mites collected from pupae with high DWV levels but not in the passaged mites. We also found that Varroa mites contain honey bee mRNAs, consistent with the acquisition of honey bee cells which would additionally contain DWV replication complexes with negative-strand DWV RNA. We propose that transmission of DWV type A by Varroa mites occurs in a non-propagative manner.

scholarly journals Direct Evidence for Infection of Varroa destructor Mites with the Bee-Pathogenic Deformed Wing Virus Variant B - but Not Variant A - via Fluorescence-in situ-Hybridization Analysis.

2020 ◽  
Author(s):  
Sebastian Gisder ◽  
Elke Genersch
Keyword(s):  
Salivary Glands ◽  
Honey Bees ◽  
Varroa Destructor ◽  
Direct Evidence ◽  
Rna Virus ◽  
Colony Losses ◽  
Deformed Wing Virus ◽  
Brain Infection ◽  
Biological Vector

Deformed wing virus (DWV) is a bee pathogenic, single- and positive-stranded RNA virus that has been involved in severe honey bee colony losses worldwide. DWV, when transmitted horizontally or vertically from bee to bee, causes mainly covert infections not associated with any visible symptoms or damage. Overt infections occur after vectorial transmission of DWV to the developing bee pupae through the ectoparasitic mite Varroa destructor. Symptoms of overt infections are pupal death, bees emerging with deformed wings and shortened abdomens, or cognitive impairment due to brain infection. So far, three variants of DWV, DWV-A, DWV-B, and DWV-C, have been described. While it is widely accepted that V. destructor acts as vector of DWV, the question of whether the mite only functions as a mechanical vector or whether DWV can infect the mite thus using it as a biological vector is hotly debated, because in the literature data can be found that support both hypotheses. In order to settle this scientific dispute, we analyzed putatively DWV-infected mites with a newly established protocol for fluorescence-in situ-hybridization of mites and demonstrated DWV-specific signals inside mite cells. We provide compelling and direct evidence that DWV-B infects the intestinal epithelium and the salivary glands of V. destructor. In contrast, no evidence for DWV-A infecting mite cells was found. Our data are key to understanding the pathobiology of DWV, the mite’s role as a biological DWV vector and the quasispecies dynamics of this RNA virus when switching between insect and arachnid host species. IMPORTANCE Deformed wing virus (DWV) is a bee pathogenic, originally rather benign, single- and positive-stranded RNA virus. Only the vectorial transmission of this virus to honey bees by the ectoparasitic mite Varroa destructor leads to fatal or symptomatic infections of individuals, usually followed by collapse of the entire colony. Studies on whether the mite only acts as a mechanical virus vector or whether DWV can infect the mite and thus use it as a biological vector have led to disparate results. In our study using fluorescence-in situ-hybridization we provide compelling and direct evidence that at least the DWV-B variant infects the gut epithelium and the salivary glands of V. destructor. Hence, the host range of DWV includes both, bees (Insecta) and mites (Arachnida). Our data contribute to a better understanding of the triangular relationship between honey bees, V. destructor and DWV and the evolution of virulence in this viral bee pathogen.

scholarly journals How Crucial is the Functional Pit Organ for the Varroa Mite?

Insects ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 395
Author(s):  
Beatrice T. Nganso ◽  
Kannan Mani ◽  
Yam Altman ◽  
Ada Rafaeli ◽  
Victoria Soroker
Keyword(s):  
Honey Bees ◽  
Varroa Destructor ◽  
Varroa Mite ◽  
Altered Expression ◽  
Pit Organ ◽  
Vitellogenin Receptor ◽  
Animal Survival ◽  
Nail Polish ◽  
Parasitic Mite ◽  
Lower Ability

Olfaction as well as gustation, are essential for animal survival, allowing behavioral modulation according to environmental input. We focused our study on an obligate ecto-parasitic mite of honey bees, the Varroa destructor Anderson and Trueman (Parasitiformes, Mesostigmata, Varroidae). By mechanically blocking the main olfactory organ on Varroa forelegs by varnishing with nail polish, we were able to show that other sensory organs cannot significantly compensate chemosensory abilities required for mite’s host selection, identification as well as reproduction. In fact, we found that mites with blocked forelegs had a significantly lower ability to reach a host bee than those with varnished idiosoma and unvarnished control. Furthermore, fewer foreleg blocked mites were feeding on the nurse bees and their reproduction in the brood cells was significantly impaired. The inhibition of reproduction was also reflected in altered expression levels of vitellogenin and vitellogenin receptor genes in foreleg-blocked mites.

scholarly journals Evaluation of Traits for the Selection of Apis Mellifera for Resistance against Varroa Destructor

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 618 ◽  
Author(s):  
Ralph Büchler ◽  
Marin Kovačić ◽  
Martin Buchegger ◽  
Zlatko Puškadija ◽  
Andreas Hoppe ◽  
...  
Keyword(s):  
Apis Mellifera ◽  
Varroa Destructor ◽  
Infestation Rate ◽  
Mite Infestation ◽  
Behavioral Traits ◽  
Bee Colony ◽  
Mite Reproduction ◽  
Varroa Resistance ◽  
Colony Survival ◽  
Selection Of

Infestation with Varroa destructor is a serious cause of bee colony (Apis mellifera) losses on a global level. However, the presence of untreated survivor populations in many different regions supports the idea that selection for resistance can be successful. As colony survival is difficult or impossible to measure, differences in mite infestation levels and tests for specific behavioral traits are used for selective breeding for Varroa resistance. In this paper we looked into different definitions of mite infestation and linked these with brood hygiene (pin test), brood recapping and suppressed mite reproduction. We based our analyses on datasets of Apis mellifera carnica from three countries: Austria (147 records), Croatia (135) and Germany (207). We concluded that bee infestation in summer, adjusted for the level of natural mite fall in spring, is a suitable trait in the breeding objective, and also suggested including brood infestation rate and the increase rate of bee infestation in summer. Repeatability for bee infestation rate was about 0.55, for cells opened in pin test about 0.33, for recapping 0.35 and for suppressed mite reproduction (SMR) virtually zero. Although in most cases we observed correlations with the expected sign between infestation parameters and behavioral traits, the values were generally low (<0.2) and often not significantly different from zero.

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