Isolation of bacterial microbiota associated to honey bees and evaluation of potential biocontrol agents of Varroa destructor

2020 ◽  
pp. 1-14
Author(s):  
M.L. Saccà ◽  
M. Lodesani
Keyword(s):  
Honey Bee ◽  
Honey Bees ◽  
Varroa Destructor ◽  
Bacterial Species ◽  
Common Species ◽  
Protective Role ◽  
Biocontrol Agents ◽  
Bioactive Molecules ◽  
Bacterial Strains ◽  
Bacterial Cultures

The honey bee parasitic mite Varroa destructor is one of the main causes of depopulation of bee colonies. Bacterial symbionts associated to honey bees are known to produce a variety of bioactive molecules that have been suggested to play a protective role against honey bee pathogens. We hypothesised that among these bacteria, those colonising the external body of honey bees, and therefore able to survive and reproduce in the hive environment outside the insect gut, may be good candidate biocontrol agents to be tested against V. destructor. The aim of this study was to isolate bacterial species from healthy honey bees and dead varroa mites and to evaluate the potential miticidal effect of their spent medium containing both bacterial metabolites and viable cells, with the final objective of finding a long-lasting solution for mite control. 61 bacterial strains belonging to the Firmicutes, Proteobacteria and Actinobacteria phyla were isolated from the surface of foragers, nurse bees and larvae collected in 10 different apiaries. The most common species was Lactobacillus kunkeei (62%). Growth capability of a selection of isolates was observed at 30 and 34 °C with 1% and 20% glucose and fructose. Laboratory bioassays were conducted by spraying mites with six-day-grown bacterial cultures containing 107 cfu/ml of four strains of L. kunkeei, Bacillus thuringiensis, Bifidobacterium asteroides and an Acetobacteraceae bacterium. The effect of each strain on varroa survival was tested independently. The first three caused 95-100% mortality of mites in 3 days, indicating a potential role as natural antagonists towards varroa. The mediation of pH of the bacterial cultures did not appear to be determinant in mite inhibition, suggesting the involvement of other modes of action against varroa. The exploitation of honey bee microbiota for controlling one of the major threats for honey bee health may be a promising approach deserving further investigation.

scholarly journals Exploring Two Honey Bee Traits for Improving Resistance Against Varroa destructor: Development and Genetic Evaluation

Insects ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 216
Author(s):  
Matthieu Guichard ◽  
Benoît Droz ◽  
Evert W. Brascamp ◽  
Adrien von Virag ◽  
Markus Neuditschko ◽  
...  
Keyword(s):  
Apis Mellifera ◽  
Honey Bee ◽  
Honey Bees ◽  
Varroa Destructor ◽  
Field Trial ◽  
Genetic Evaluation ◽  
Phenotypic Correlation ◽  
Apis Mellifera Mellifera ◽  
Novel Traits ◽  
Resistance Traits

For the development of novel selection traits in honey bees, applicability under field conditions is crucial. We thus evaluated two novel traits intended to provide resistance against the ectoparasitic mite Varroa destructor and to allow for their straightforward implementation in honey bee selection. These traits are new field estimates of already-described colony traits: brood recapping rate (‘Recapping’) and solidness (‘Solidness’). ‘Recapping’ refers to a specific worker characteristic wherein they reseal a capped and partly opened cell containing a pupa, whilst ‘Solidness’ assesses the percentage of capped brood in a predefined area. According to the literature and beekeepers’ experiences, a higher recapping rate and higher solidness could be related to resistance to V. destructor. During a four-year field trial in Switzerland, the two resistance traits were assessed in a total of 121 colonies of Apis mellifera mellifera. We estimated the repeatability and the heritability of the two traits and determined their phenotypic correlations with commonly applied selection traits, including other putative resistance traits. Both traits showed low repeatability between different measurements within each year. ‘Recapping’ had a low heritability (h2 = 0.04 to 0.05, depending on the selected model) and a negative phenotypic correlation to non-removal of pin-killed brood (r = −0.23). The heritability of ‘Solidness’ was moderate (h2 = 0.24 to 0.25) and did not significantly correlate with resistance traits. The two traits did not show an association with V. destructor infestation levels. Further research is needed to confirm the results, as only a small number of colonies was evaluated.

scholarly journals Winter Survival of Individual Honey Bees and Honey Bee Colonies Depends on Level of Varroa destructor Infestation

PLoS ONE ◽  
2012 ◽  
Vol 7 (4) ◽  
pp. e36285 ◽  
Author(s):  
Coby van Dooremalen ◽  
Lonne Gerritsen ◽  
Bram Cornelissen ◽  
Jozef J. M. van der Steen ◽  
Frank van Langevelde ◽  
...  
Keyword(s):  
Honey Bee ◽  
Honey Bees ◽  
Varroa Destructor ◽  
Winter Survival ◽  
Bee Colonies

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 Advances and perspectives in selecting resistance traits against the parasitic mite Varroa destructor in honey bees

2020 ◽  
Vol 52 (1) ◽  
Author(s):  
Matthieu Guichard ◽  
Vincent Dietemann ◽  
Markus Neuditschko ◽  
Benjamin Dainat
Keyword(s):  
Honey Bee ◽  
Environmental Effects ◽  
Honey Bees ◽  
Varroa Destructor ◽  
Selection Strategy ◽  
Pollination Services ◽  
Colony Losses ◽  
New Host ◽  
Parasitic Mite ◽  
Resistance Traits

Abstract Background In spite of the implementation of control strategies in honey bee (Apis mellifera) keeping, the invasive parasitic mite Varroa destructor remains one of the main causes of colony losses in numerous countries. Therefore, this parasite represents a serious threat to beekeeping and agro-ecosystems that benefit from the pollination services provided by honey bees. To maintain their stocks, beekeepers have to treat their colonies with acaricides every year. Selecting lineages that are resistant to infestations is deemed to be a more sustainable approach. Review Over the last three decades, numerous selection programs have been initiated to improve the host–parasite relationship and to support honey bee survival in the presence of the parasite without the need for acaricide treatments. Although resistance traits have been included in the selection strategy of honey bees, it has not been possible to globally solve the V. destructor problem. In this study, we review the literature on the reasons that have potentially limited the success of such selection programs. We compile the available information to assess the relevance of selected traits and the potential environmental effects that distort trait expression and colony survival. Limitations to the implementation of these traits in the field are also discussed. Conclusions Improving our knowledge of the mechanisms underlying resistance to V. destructor to increase trait relevance, optimizing selection programs to reduce environmental effects, and communicating selection outcomes are all crucial to efforts aiming at establishing a balanced relationship between the invasive parasite and its new host.

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 New Reference Genome Sequences for 17 Bacterial Strains of the Honey Bee Gut Microbiota

2018 ◽  
Vol 7 (3) ◽  
Author(s):  
Kirsten M. Ellegaard ◽  
Philipp Engel
Keyword(s):  
Gut Microbiota ◽  
Honey Bee ◽  
Honey Bees ◽  
Reference Genome ◽  
Reference Database ◽  
Bacterial Strains ◽  
Genome Sequences ◽  
Content Type ◽  
Future Analysis ◽  
Comprehensive Reference

We sequenced the genomes of 17 strains isolated from the gut of honey bees, including strains representing the genera Lactobacillus, Bifidobacterium, Gilliamella, Snodgrassella, Frischella, and Commensalibacter. These genome sequences represent an important step forward in the development of a comprehensive reference database to aid future analysis of this emerging gut microbiota model.

scholarly journals Norwegian honey bees surviving Varroa destructor mite infestations by means of natural selection

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3956 ◽  
Author(s):  
Melissa A.Y. Oddie ◽  
Bjørn Dahle ◽  
Peter Neumann
Keyword(s):  
Natural Selection ◽  
Reproductive Success ◽  
Honey Bee ◽  
Honey Bees ◽  
Varroa Destructor ◽  
Apis Cerana ◽  
Mite Infestation ◽  
Colony Losses ◽  
Key Factor ◽  
Colony Survival

Background Managed, feral and wild populations of European honey bee subspecies, Apis mellifera, are currently facing severe colony losses globally. There is consensus that the ectoparasitic mite Varroa destructor, that switched hosts from the Eastern honey bee Apis cerana to the Western honey bee A. mellifera, is a key factor driving these losses. For >20 years, breeding efforts have not produced European honey bee colonies that can survive infestations without the need for mite control. However, at least three populations of European honey bees have developed this ability by means of natural selection and have been surviving for >10 years without mite treatments. Reduced mite reproductive success has been suggested as a key factor explaining this natural survival. Here, we report a managed A. mellifera population in Norway, that has been naturally surviving consistent V. destructor infestations for >17 years. Methods Surviving colonies and local susceptible controls were evaluated for mite infestation levels, mite reproductive success and two potential mechanisms explaining colony survival: grooming of adult worker bees and Varroa Sensitive Hygiene (VSH): adult workers specifically detecting and removing mite-infested brood. Results Mite infestation levels were significantly lower in surviving colonies and mite reproductive success was reduced by 30% when compared to the controls. No significant differences were found between surviving and control colonies for either grooming or VSH. Discussion Our data confirm that reduced mite reproductive success seems to be a key factor for natural survival of infested A. mellifera colonies. However, neither grooming nor VSH seem to explain colony survival. Instead, other behaviors of the adult bees seem to be sufficient to hinder mite reproductive success, because brood for this experiment was taken from susceptible donor colonies only. To mitigate the global impact of V. destructor, we suggest learning more from nature, i.e., identifying the obviously efficient mechanisms favored by natural selection.

scholarly journals Evaluation of potential miticide toxicity to Varroa destructor and honey bees, Apis mellifera, under laboratory conditions

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Rassol Bahreini ◽  
Medhat Nasr ◽  
Cassandra Docherty ◽  
Olivia de Herdt ◽  
Samantha Muirhead ◽  
...  
Keyword(s):  
Apis Mellifera ◽  
Honey Bee ◽  
Honey Bees ◽  
Varroa Destructor ◽  
High Dose ◽  
Agricultural Crops ◽  
High Toxicity ◽  
High Efficacy ◽  
Dose Rates ◽  
Colony Level

AbstractThe honey bee, Apis mellifera L., is the world’s most important managed pollinator of agricultural crops, however, Varroa mite, Varroa destructor Anderson and Trueman, infestation has threatened honey bee survivorship. Low efficacy and development of Varroa mite resistance to currently used Varroacides has increased the demand for innovative, effective treatment tool options that exhibit high efficacy, while minimizing adverse effects on honey bee fitness. In this investigation, the toxicity of 16 active ingredients and 9 formulated products of registered miticides for use on crops from 12 chemical families were evaluated in comparison to amitraz on Varroa mites and honey bees using contact surface and topical exposures. It was found that fenpyroximate (93% mortality), spirotetramat (84% mortality) and spirodiclofen (70% mortality) had greater toxicity to Varroa mites, but high dose rates caused high bee mortality (> 60%). With this in mind, further research is needed to investigate other options to minimize the adverse effect of these compounds on bees. The results also found high toxicity of fenazaquin and etoxazole against Varroa mites causing 92% and 69% mortality, respectively; and were found to be safe on honey bees. Collectively, it is recommended that fenazaquin and etoxazole are candidates for a potential Varroacide and recommended for further testing against Varroa mites at the colony level.

scholarly journals Ten Years of Deformed Wing Virus (DWV) in Hawaiian Honey Bees (Apis mellifera), the Dominant DWV-A Variant Is Potentially Being Replaced by Variants with a DWV-B Coding Sequence

Viruses ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 969
Author(s):  
Isobel Grindrod ◽  
Jessica L. Kevill ◽  
Ethel M. Villalobos ◽  
Declan C. Schroeder ◽  
Stephen John Martin
Keyword(s):  
Apis Mellifera ◽  
Honey Bee ◽  
Honey Bees ◽  
Varroa Destructor ◽  
Original Study ◽  
Viral Diversity ◽  
Deformed Wing Virus ◽  
Complete Dominance ◽  
Coding Sequence ◽  
Bee Colonies

The combination of Deformed wing virus (DWV) and Varroa destructor is arguably one of the greatest threats currently facing western honey bees, Apis mellifera. Varroa’s association with DWV has decreased viral diversity and increased loads of DWV within honey bee populations. Nowhere has this been better studied than in Hawaii, where the arrival of Varroa progressively led to the dominance of the single master variant (DWV-A) on both mite-infested Hawaiian Islands of Oahu and Big Island. Now, exactly 10 years following the original study, we find that the DWV population has changed once again, with variants containing the RdRp coding sequence pertaining to the master variant B beginning to co-dominate alongside variants with the DWV-A RdRp sequence on the mite-infested islands of Oahu and Big Island. In speculation, based on other studies, it appears this could represent a stage in the journey towards the complete dominance of DWV-B, a variant that appears better adapted to be transmitted within honey bee colonies.

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