Most cited article - PubMed ID 27129319
Comparison of Varroa destructor and Worker Honeybee Microbiota Within Hives Indicates Shared Bacteria
Varroa destructor mite is a major threat to honeybee (Apis mellifera) populations, contributing to colony losses through parasitism and pathogen transmission. While extensive research has focused on Varroa biology and its role as a virus vector, its microbiome remains poorly understood, particularly regarding geographic variation. Here, we investigated the microbial diversity, composition, and functional potential of Varroa mite microbiota collected from two neighboring countries, Czechia and Slovakia. Using high-throughput sequencing and network analysis, we assessed alpha and beta diversity metrics, microbial co-occurrence patterns, and predicted metabolic functions. Our results revealed significant differences in microbial diversity between the two regions, with some bacterial taxa appearing more prevalent in specific populations. Network analysis suggested potential variation in the structural stability of microbial communities in Varroa mites, raising the possibility that geographic factors may influence microbial interactions. Functional profiling indicated region-associated differences in predicted metabolic pathways, possibly linked to certain bacterial taxa. While these findings provide new insights into the Varroa microbiome and its potential ecological role, the interpretation of geographic influence remains a subject of ongoing investigation to better understand its scope and underlying mechanisms. A deeper understanding of these microbial dynamics may contribute to the development of novel strategies for Varroa mite management and the conservation of honeybee health.
- Keywords
- Varroa destructor, Geographical variation, Microbial co-occurrence networks, Microbiome, Predicted functional pathways,
- Publication type
- Journal Article MeSH
The honeybee (Apis mellifera) is a key pollinator critical to global agriculture, facing threats from various stressors, including the ectoparasitic Varroa mite (Varroa destructor). Previous studies have identified shared bacteria between Varroa mites and honeybees, yet it remains unclear if these bacteria assemble similarly in both species. This study builds on existing knowledge by investigating co-occurrence patterns in the microbiomes of both Varroa mites and honeybees, shedding light on potential interactions. Leveraging 16S rRNA datasets, we conducted co-occurrence network analyses, explored Core Association Networks (CAN) and assess network robustness. Comparative network analyses revealed structural differences between honeybee and mite microbiomes, along with shared core features and microbial motifs. The mite network exhibited lower robustness, suggesting less resistance to taxa extension compared to honeybees. Furthermore, analyses of predicted functional profiling and taxa contribution revealed that common central pathways in the metabolic networks have different taxa contributing to Varroa mites and honeybee microbiomes. The results show that while both microbial systems exhibit functional redundancy, in which different taxa contribute to the functional stability and resilience of the ecosystem, there is evidence for niche specialization resulting in unique contributions to specific pathways in each part of this host-parasite system. The specificity of taxa contribution to key pathways offers targeted approaches to Varroa microbiome management and preserving honeybee microbiome. Our findings provide valuable insights into microbial interactions, aiding farmers and beekeepers in maintaining healthy and resilient bee colonies amid increasing Varroa mite infestations.
- Keywords
- Apis mellifera, Varroa destructor, Community assembly, Microbiomes, Networks,
- MeSH
- Bacteria * classification genetics isolation & purification MeSH
- Microbiota * MeSH
- RNA, Ribosomal, 16S genetics MeSH
- Varroidae * microbiology MeSH
- Bees microbiology parasitology MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- RNA, Ribosomal, 16S MeSH
The Western honey bee (Apis mellifera) is a vital agricultural pollinator whose populations are threatened by the parasitic mite Varroa destructor and associated pathogens. While the impact of Paenibacillus species on honey bees, particularly Paenibacillus larvae causing American foulbrood, is documented, their effect on the microbiota of Varroa mites remains unclear. This study aimed to investigate the influence of Paenibacillus sp. on the bacterial communities of Varroa mites and adult honey bees. We hypothesized that Paenibacillus sp. would significantly alter the microbiota of Varroa mites but have minimal effect on that of adult honey bees. Utilizing 16S rRNA sequencing data from a previous study, we reanalyzed samples categorized into four groups based on Paenibacillus sp. infection load: highly infected and lowly infected honey bees (A. mellifera) and mites (V. destructor). Infection status was determined by Paenibacillus sp. read counts, with more than three reads indicating high infection. Microbial diversity was assessed using alpha and beta diversity metrics. Co-occurrence networks were constructed to visualize bacterial community assemblies, and network robustness was evaluated through node addition and removal tests. Keystone taxa were identified based on eigenvector centrality and relative abundance. Highly infected Varroa mites exhibited a significant reduction in alpha diversity and a markedly different bacterial community composition compared to lowly infected mites (p < 0.05). Their bacterial co-occurrence networks showed decreased connectivity and robustness, indicating a disruptive effect of Paenibacillus sp. In contrast, adult honey bees displayed no significant differences in alpha diversity or network structure between highly and lowly infected groups (p > 0.05), suggesting a resilient microbiota. Keystone taxa analysis revealed fewer central species in highly infected Varroa mites, potentially impacting network stability. High Paenibacillus sp. infection is associated with significant alterations in the microbiota of Varroa mites, disrupting bacterial communities and potentially affecting mite physiology. The microbiota of adult honey bees appears more robust against Paenibacillus sp. influence. These findings enhance our understanding of the complex interactions within the "honey bee-mite-microorganism" system and may inform future strategies for managing Varroa mite infestations and associated pathogens.
- Keywords
- Apis mellifera, Microbial networks, Microbiota analysis, Paenibacillus sp., Varroa destructor,
- Publication type
- Journal Article MeSH
BACKGROUND: Melissococcus plutonius is an entomopathogenic bacterium that causes European foulbrood (EFB), a honeybee (Apis mellifera L.) disease that necessitates quarantine in some countries. In Czechia, positive evidence of EFB was absent for almost 40 years, until an outbreak in the Krkonose Mountains National Park in 2015. This occurrence of EFB gave us the opportunity to study the epizootiology of EFB by focusing on the microbiome of honeybee workers, which act as vectors of honeybee diseases within and between colonies. METHODS: The study included worker bees collected from brood combs of colonies (i) with no signs of EFB (EFB0), (ii) without clinical symptoms but located at an apiary showing clinical signs of EFB (EFB1), and (iii) with clinical symptoms of EFB (EFB2). In total, 49 samples from 27 honeybee colonies were included in the dataset evaluated in this study. Each biological sample consisted of 10 surface-sterilized worker bees processed for DNA extraction. All subjects were analyzed using conventional PCR and by metabarcoding analysis based on the 16S rRNA gene V1-V3 region, as performed through Illumina MiSeq amplicon sequencing. RESULTS: The bees from EFB2 colonies with clinical symptoms exhibited a 75-fold-higher incidence of M. plutonius than those from EFB1 asymptomatic colonies. Melissococcus plutonius was identified in all EFB1 colonies as well as in some of the control colonies. The proportions of Fructobacillus fructosus, Lactobacillus kunkeei, Gilliamella apicola, Frischella perrara, and Bifidobacterium coryneforme were higher in EFB2 than in EFB1, whereas Lactobacillus mellis was significantly higher in EFB2 than in EFB0. Snodgrassella alvi and L. melliventris, L. helsingborgensis and, L. kullabergensis exhibited higher proportion in EFB1 than in EFB2 and EFB0. The occurrence of Bartonella apis and Commensalibacter intestini were higher in EFB0 than in EFB2 and EFB1. Enterococcus faecalis incidence was highest in EFB2. CONCLUSIONS: High-throughput Illumina sequencing permitted a semi-quantitative analysis of the presence of M. plutonius within the honeybee worker microbiome. The results of this study indicate that worker bees from EFB-diseased colonies are capable of transmitting M. plutonius due to the greatly increased incidence of the pathogen. The presence of M. plutonius sequences in control colonies supports the hypothesis that this pathogen exists in an enzootic state. The bacterial groups synergic to both the colonies with clinical signs of EFB and the EFB-asymptomatic colonies could be candidates for probiotics. This study confirms that E. faecalis is a secondary invader to M. plutonius; however, other putative secondary invaders were not identified in this study.
Honeybee (Apis mellifera L.) workers act as passive vectors of Paenibacillus larvae spores, which cause the quarantine disease American foulbrood (AFB). We assessed the relative proportions of P. larvae within the honeybee microbiome using metabarcoding analysis of the 16 S rRNA gene. The microbiome was analyzed in workers outside of the AFB zone (control - AFB0), in workers from asymptomatic colonies in an AFB apiary (AFB1), and in workers from colonies exhibiting clinical AFB symptoms (AFB2). The microbiome was processed for the entire community and for a cut-off microbiome comprising pathogenic/environmental bacteria following the removal of core bacterial sequences; varroosis levels were considered in the statistical analysis. No correlation was observed between AFB status and varroosis level, but AFB influenced the worker bee bacterial community, primarily the pathogenic/environmental bacteria. There was no significant difference in the relative abundance of P. larvae between the AFB1 and AFB0 colonies, but we did observe a 9-fold increase in P. larvae abundance in AFB2 relative to the abundance in AFB1. The relative sequence numbers of Citrobacter freundii and Hafnia alvei were higher in AFB2 and AFB1 than in AFB0, whereas Enterococcus faecalis, Klebsiella oxytoca, Spiroplasma melliferum and Morganella morganii were more abundant in AFB0 and AFB1 than in AFB2.
The honey bee, Apis mellifera, is a globally important species that suffers from a variety of pathogens and parasites. These parasites and pathogens may have sublethal effects on their bee hosts via an array of mechanisms, including through a change in symbiotic bacterial taxa. Our aim was to assess the influence of four globally widespread parasites and pathogens on the honey bee bacteriome. We examined the effects of the ectoparasitic mite Varroa destructor, the fungal pathogens Nosema apis and Nosema ceranae, and the trypanosome Lotmaria passim. Varroa was detected by acaricidal treatment, Nosema and L. passim by PCR, and the bacteriome using MiSeq 16S rRNA gene sequencing. Overall, the 1,858,850 obtained sequences formed 86 operational taxonomic units (OTUs) at 3 % dissimilarity. Location, time of year, and degree of infestation by Varroa had significant effects on the composition of the bacteriome of honey bee workers. Based on statistical correlations, we found varroosis more important factor than N. ceranae, N. apis, and L. passim infestation influencing the honey bee bacteriome and contributing to the changes in the composition of the bacterial community in adult bees. At the population level, Varroa appeared to modify 20 OTUs. In the colonies with high Varroa infestation levels (varroosis), the relative abundance of the bacteria Bartonella apis and Lactobacillus apis decreased. In contrast, an increase in relative abundance was observed for several taxa including Lactobacillus helsingborgensis, Lactobacillus mellis, Commensalibacter intestini, and Snodgrassella alvi. The results showed that the "normal" bacterial community is altered by eukaryotic parasites as well as displaying temporal changes and changes associated with the geographical origin of the beehive.
- Keywords
- Bacteria, Lotmaria passim, Nosema apis, Nosema ceranae, Sequencing, Varroa destructor,
- MeSH
- Bartonella classification genetics isolation & purification MeSH
- Mite Infestations pathology MeSH
- Kinetoplastida pathogenicity MeSH
- Lactobacillus classification genetics isolation & purification MeSH
- Microbiota genetics MeSH
- Nosema pathogenicity MeSH
- RNA, Ribosomal, 16S genetics MeSH
- Symbiosis MeSH
- Varroidae pathogenicity MeSH
- Bees microbiology parasitology MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- RNA, Ribosomal, 16S MeSH
