Occurrence of black queen cell virus in wild bumble bee communities in China.

Wild bumble bees (Hymenoptera: Apidae) play a vital role in agro-ecosystems as important pollinators. However, they are threatened by virus pathogens that are widespread in honey bees. Previous studies have reported that viruses were able to be transmitted across bee genera and caused potential danger to wild bumble bees. China is a global biodiversity hotspot for bumble bees. However, the impact of viruses on the wild bumble bee communities remains elusive. Black queen cell virus (BQCV) is one of the most common honey bee viruses. Here, a total of 72 wild bumble bee samples from 17 geographic regions of China were tested for BQCV. Thirteen positive samples were identified and sequence comparison of partial capsid genes demonstrated a genetic identity of 99.69% to 100%. A phylogenetic tree analysis also showed a close relationship between 13 BQCV isolates and others from a variety of recorded hosts in China. Meanwhile, a distinct evolutionary branch of China isolates was formed when clustering isolates from worldwide bumble bee species. A correlation between BQCV and their geographic locations were observed (P < 0.05). This study not only provides the first evidence of widespread BQCV in wild bumble bee communities in China but also detects a distinct set of genetically identical or closely related BQCV variants that circulate and evolutionarily differ from other countries.

Functional dissection of phytochrome A in plants.

Plants lack behavioral responses to avoid dramatic environmental changes associated with the annual seasons. For survival, they have evolved complex sensory systems to sense fluctuations in light and optimize their architecture in response to changes in these cues. Phytochrome A (phyA) was initially identified as a photoreceptor that senses far-red light signals. It was then identified as playing a central role in promoting hypocotyl growth, fiber development, and flowering time in a variety of plants including Arabidopsis, rice, soybean and cotton. Under dark conditions, phyA is present in the cytoplasm in the physiologically inactive (Pr) form. Far-red light signals induce the transformation of Pr into the physiologically active (Pfr) form, after which Pfr-phyA is recognized by FAR-RED ELONGATED HYPOCOTYL 1 (FHY1) and FHY1-LIKE (FHL) and translocated to the nucleus, initiating a series of signaling cascades. The current review comprehensively summarizes recent advances in understanding the function of phyA in plants, including phyA-mediated shade avoidance and flowering time. Remaining issues and possible directions for future research on phyA are also discussed.

Comparative transcriptome analysis reveals the adaptive mechanisms of halophyte Suaeda dendroides encountering high saline environment.

Suaeda dendroides, a succulent euhalophyte of the Chenopodiaceae family, intermittently spread around northern Xinjiang, China, has the ability to grow and develop in saline and alkali environments. The objective of this study was therefore to investigate the underlying molecular mechanisms of S. dendroides response to high salt conditions. 27 sequencing libraries prepared from low salt (200 mM NaCl) and high salt (800 mM NaCl) treated plants at 5 different stages were sequenced using Illumina Hiseq 2000. A total of 133,107 unigenes were obtained, of which 4,758 were DEGs. The number of DEGs in the high salt group (3,189) was more than the low salt treatment group (733) compared with the control. GO and KEGG analysis of the DEGs at different time points of the high salt treatment group showed that the genes related to cell wall biosynthesis and modification, plant hormone signal transduction, ion homeostasis, organic osmolyte accumulation, and reactive oxygen species (ROS) detoxification were significantly expressed, which indicated that these could be the main mechanisms of S. dendroides acclimate to high salt stress. The study provides a new perspective for understanding the molecular mechanisms of halophytes adapting to high salinity. It also provides a basis for future investigations of key salt-responsive genes in S. dendroides.

Untargeted Lipidomics Analysis Unravels the Different Metabolites in the Fat Body of Mated Bumblebee (Bombus terrestris) Queens.

The fat body has important functions in energy, fertility, and immunity. In female insects, mating stimulates physiological, behavioral, and gene expression changes. However, it remains unclear whether the metabolites in the fat body are affected after the bumblebee (Bombus terrestris) queen mates. Here, the ultrastructure and lipid metabolites in fat body of mated queens were compared with those of virgins. The fat body weight of mated bumblebee queens was significantly increased, and the adipocytes were filled with lipid droplets. Using LC-MS/MS-based untargeted lipidomics, 949 and 748 differential metabolites were identified in the fat body of virgin and mated bumblebee queens, respectively, in positive and negative ion modes. Most lipid metabolites were decreased, especially some biomembrane components. In order to explore the relationship between the structures of lipid droplets and metabolite accumulation, transmission electron microscopy and fluorescence microscopy were used to observe the fat body ultrastructure. The size/area of lipid droplets was larger, and the fusion of lipid droplets was increased in the mated queen's fat body. These enlarged lipid droplets may store more energy and nutrients. The observed differences in lipid metabolites in the fat body of queens contribute to understanding the regulatory network of bumblebees post mating.

Unexpected worker mating and colony-founding in a superorganism.

The emergence of caste-differentiated colonies, which have been defined as 'superorganisms', in ants, bees, and wasps represents a major transition in evolution. Lifetime mating commitment by queens, pre-imaginal caste determination and lifetime unmatedness of workers are key features of these animal societies. Workers in superorganismal species like honey bees and many ants have consequently lost, or retain only vestigial spermathecal structures. However, bumble bee workers retain complete spermathecae despite 25-40 million years since their origin of superorganismality, which remains an evolutionary mystery. Here, we show (i) that bumble bee workers retain queen-like reproductive traits, being able to mate and produce colonies, underlain by queen-like gene expression, (ii) the social conditions required for worker mating, and (iii) that these abilities may be selected for by early queen-loss in these annual species. These results challenge the idea of lifetime worker unmatedness in superorganisms, and provide an exciting new tool for the conservation of endangered bumble bee species.

Potential role of the gut microbiota of bumblebee Bombus pyrosoma in adaptation to high-altitude habitats.

The gut microbiota affects the health and overall fitness of bumblebees. It can enhance the host's ecological range by leveraging their metabolic capacities. However, the diversity of the gut microbiota and adaptive functional evolution in high-altitude regions remain unclear. To explore how the gut microbiota helps the host adapt to high-altitude environments, we analyzed the differences in diversity and function of the gut microbiota between high- and low-altitude regions through full-length 16S rRNA sequencing. Our results show that high-altitude regions have a lower abundance of Fructobacillus and Saccharibacter compared to low-altitude regions. Additionally, some individuals in low-altitude regions were invaded by opportunistic pathogens. The gut microbiota in high-altitude regions has a greater number of pathways involved in "Protein digestion and absorption" and "Biosynthesis of amino acids," while fewer carbohydrate pathways are involved in "digestion and absorption" and "Salmonella infection." Our finding suggests that plateau hosts typically reduce energy metabolism and enhance immunity in response to adverse environments. Correspondingly, the gut microbiota also makes changes, such as reducing carbohydrate degradation and increasing protein utilization in response to the host. Additionally, the gut microbiota regulates their abundance and function to help the host adapt to adverse high-altitude environments.

Divergence and convergence of gut microbiomes of wild insect pollinators.

Pollination services provided by wild insect pollinators are critical to natural ecosystems and crops around the world. There is an increasing appreciation that the gut microbiota of these insects influences their health and consequently their services. However, pollinator gut microbiota studies have focused on well-described social bees, but rarely include other, more phylogenetically divergent insect pollinators. To expand our understanding, we explored the insect pollinator microbiomes across three insect orders through two DNA sequencing approaches. First, in an exploratory 16S amplicon sequencing analysis of taxonomic community assemblages, we found lineage-specific divergences of dominant microbial genera and microbiota community composition across divergent insect pollinator genera. However, we found no evidence for a strong broad-scale phylogenetic signal, which we see for community relatedness at finer scales. Subsequently, we utilized metagenomic shotgun sequencing to obtain metagenome-assembled genomes and assess the functionality of the microbiota from pollinating flies and social wasps. We uncover a novel gut microbe from pollinating flies in the family Orbaceae that is closely related to Gilliamella spp. from social bees but with divergent functions. We propose this novel species be named Candidatus Gilliamella eristali. Further metagenomes of dominant fly and wasp microbiome members suggest that they are largely not host-insect adapted and instead may be environmentally derived. Overall, this study suggests selective processes involving ecology or physiology, or neutral processes determining microbe colonization may predominate in the turnover of lineages in insect pollinators broadly, while evolution with hosts may occur only under certain circumstances and on smaller phylogenetic scales. IMPORTANCE Wild insect pollinators provide many key ecosystem services, and the microbes associated with these insect pollinators may influence their health. Therefore, understanding the diversity in microbiota structure and function, along with the potential mechanisms shaping the microbiota across diverse insect pollinators, is critical. Our study expands beyond existing knowledge of well-studied social bees, like honey bees, including members from other bee, wasp, butterfly, and fly pollinators. We infer ecological and evolutionary factors that may influence microbiome structure across diverse insect pollinator hosts and the functions that microbiota members may play. We highlight significant differentiation of microbiomes among diverse pollinators. Closer analysis suggests that dominant members may show varying levels of host association and functions, even in a comparison of closely related microbes found in bees and flies. This work suggests varied importance of ecological, physiological, and non-evolutionary filters in determining structure and function across largely divergent wild insect pollinator microbiomes.

Identification of elite fiber quality loci in upland cotton based on the genotyping-by-target-sequencing technology.

Genome-wide association studies (GWAS) of fiber quality traits of upland cotton were conducted to identify the single-nucleotide polymorphic (SNP) loci associated with cotton fiber quality, which lays the foundation for the mining of elite] cotton fiber gene resources and its application in molecular breeding. A total of 612 upland cotton accessions were genotyped using the ZJU Cotton Chip No. 1 40K chip array via the liquid-phase probe hybridization-based genotyping-by-target-sequencing (GBTS) technology. In the present study, five fiber quality traits, namely fiber length, fiber strength, micronaire, uniformity and elongation, showed different degrees of variation in different environments. The average coefficient of variation of fiber strength was the greatest, whereas the average coefficient of variation of uniformity was the least. Significant or extremely significant correlations existed among the five fiber quality traits, especially fiber length, strength, uniformity and elongation all being significantly negative correlated with micronaire. Population cluster analysis divided the 612 accessions into four groups: 73 assigned to group I, 226 to group II, 220 to group III and 93 to group IV. Genome-wide association studies of five fiber quality traits in five environments was performed and a total of 42 SNP loci associated with target traits was detected, distributed on 19 chromosomes, with eight loci associated with fiber length, five loci associated with fiber strength, four loci associated with micronaire, twelve loci associated with fiber uniformity and thirteen loci associated with fiber elongation. Of them, seven loci were detected in more than two environments. Nine SNP loci related to fiber length, fiber strength, uniformity and elongation were found on chromosome A07, seven loci related to fiber length, fiber strength, micronaire and elongation were detected on chromosome D01, and five loci associated with fiber length, uniformity and micronaire were detected on chromosome D11. The results from this study could provide more precise molecular markers and genetic resources for cotton breeding for better fiber quality in the future.

Pan-Genome Analysis Reveals Functional Divergences in Gut-Restricted Gilliamella and Snodgrassella.

Gilliamella and Snodgrassella, members of core gut microbiota in corbiculate bees, have high species diversity and adaptability to a wide range of hosts. In this study, we performed species taxonomy and phylogenetic analysis for Gilliamella and Snodgrassella strains that we isolated in our laboratory, in combination with published whole-genome. Functional effects of accessory and unique genes were investigated by KEGG category and pathway annotation in pan-genome analysis. Consequently, in Gilliamella, we inferred the importance of carbohydrate metabolism, amino acid metabolism, membrane transport, energy metabolism, and metabolism of cofactors and vitamins in accessory or unique genes. The pathway mentioned above, plus infectious disease, lipid metabolism, nucleotide metabolism as well as replication and repair exert a pivotal role in accessory or unique genes of Snodgrassella. Further analysis revealed the existence of functional differentiation of accessory and unique genes among Apis-derived genomes and Bombus-derived genomes. We also identified eight and four biosynthetic gene clusters in all Gilliamella and Snodgrassella genomes, respectively. Our study provides a good insight to better understand how host heterogeneity influences the bacterial speciation and affects the versatility of the genome of the gut bacteria.

Adenosine and L-proline can possibly hinder Chinese Sacbrood virus infection in honey bees via immune modulation.

Sacbrood virus (SBV) infects larvae of honey bees, resulting in infected larvae becoming fluid-filled sacs. Our previous studies showed that the extract of herbal medicine, Radix Isatidis, could inhibit Chinese SBV (CSBV) infection in Asian honey bees (Apis cerana). Here, two compounds, adenosine and L-proline, which were previously reported to be associated with immune modulation, were identified in R. Isatidis extract and then selected for an evaluation of their antiviral effect on CSBV infection in A. cerana. Our results revealed that both adenosine and L-proline could significantly mitigate the impact of CSBV on the growth and development of infected larvae and modulate hosts' immune responses by downregulating the expression of immune genes in infected larvae. The results gained from this study suggest that adenosine and L-proline could possibly interfere CSBV infection via immune modulation to avoid exacerbations and nonspecific damage to infected larvae's own tissues.

Self-Care Efficacy-Mediated Associations Between Healthcare Provider-Patient Communication and Psychological Distress Among Patients With Gastrointestinal Cancers.

BACKGROUND: Both healthcare provider-patient communication and self-care efficacy affect psychological distress, which is prevalent among patients with gastrointestinal (GI) cancers. It is essential to explore the underlying mechanism among them to relieve psychological distress. OBJECTIVE: The aim of this study was to examine whether self-care efficacy mediated the association between healthcare provider-patient communication and psychological distress among patients with GI cancers. METHODS: A cross-sectional study was conducted between March 2018 and May 2019 in China. In total, 219 patients with GI cancers were recruited before discharge from chemotherapy. Healthcare provider-patient communication was assessed by the revised Physician-Patient Communication Scale; patient self-care efficacy was assessed by the Strategies Used by People to Promote Health; and psychological distress was assessed by the Distress Thermometer and the Hospital Anxiety and Depression Scale. Mediation analyses were conducted to examine the mediating effect of self-care efficacy on the association between healthcare provider-patient communication and psychological distress. RESULTS: A total of 54.34% of patients experienced psychological distress. Patients reported a mean score of 89.93 (SD, 13.81) for healthcare provider-patient communication and 93.91 (SD, 23.39) for self-care efficacy. Self-care efficacy completely mediated the association between healthcare provider-patient communication and psychological distress, and communication outcome was the only domain that significantly influenced self-care efficacy. CONCLUSION: Psychological distress is prevalent among patients with GI cancers. Healthcare provider-patient communication, especially communication outcome, promoted patients' self-care efficacy to reduce psychological distress. IMPLICATIONS FOR PRACTICE: Healthcare providers should design interventions to improve communication outcomes and eventually increase self-care efficacy to relieve psychological distress among patients with GI cancers.

Effects of spinetoram and glyphosate on physiological biomarkers and gut microbes in Bombus terrestris.

The sublethal effects of pesticide poisoning will have significant negative impacts on the foraging and learning of bees and bumblebees, so it has received widespread attention. However, little is known about the physiological effects of sublethal spinetoram and glyphosate exposure on bumblebees. We continuously exposed Bombus terrestris to sublethal (2.5 mg/L) spinetoram or glyphosate under controlled conditions for 10 days. The superoxide dismutase, glutathione-S-transferase, carboxylesterase, prophenoloxidase, α-amylase and protease activities, and changes in gut microbes were measured to understand the effects of sublethal pesticide exposure on the physiology and gut microbes of bumblebees. Sublethal pesticide exposure to significantly increased superoxide dismutase activity and significantly decreased gut α-amylase activity in bumblebees but had no significant effect on glutathione-S-transferase, carboxylesterase or gut protease activities. In addition, glyphosate increased the activity of prophenoloxidase. Interestingly, we observed that neither of the two pesticides had a significant effect on dominant gut bacteria, but glyphosate significantly altered the structure of the dominant gut fungal community, and reduced the relative abundance of Zygosaccharomyces associated with fat accumulation. These results suggest that sublethal spinetoram and glyphosate do not significantly affect the detoxification system of bumblebees, but may affect bumblebee health by inhibiting energy acquisition. Our results provide information on the sublethal effects of exposure to low concentrations of glyphosate and spinetoram on bumblebees in terms of physiology and gut microbes.

Mating Stimulates the Immune Response and Sperm Storage-Related Genes Expression in Spermathecae of Bumblebee (Bombus terrestris) Queen.

Bumblebee queens have remarkable spermathecae that store sperm for year-round reproduction. The spermathecal gland is regarded as a secretory organ that could benefit sperm storage. Queen mating provokes substantial physiological, behavioral, and gene expression changes. Here, the transcriptomes of spermathecae were compared between virgins and mated queens of the bumblebee, Bombus terrestris L., at 24 h post mating. Differentially expressed genes were further validated by real time quantitative PCR and immunofluorescence assay. In total, the expression of 11, 069 and 10, 862 genes were identified in virgins and mated queens, respectively. We identified that 176 differentially expressed genes between virgin and mated queen spermathecae: 110 (62.5%) genes were upregulated, and 66 (37.5%) genes were downregulated in mated queens. Most of the differentially expressed genes validated by RT-qPCR were concentrated on immune response [i.e., leucine-rich repeat-containing protein 70 (35.8-fold), phenoloxidase 2 (41.9-fold), and defensin (4.9-fold)] and sperm storage [i.e., chymotrypsin inhibitor (6.2-fold), trehalose transporter Tret1 (1.7-, 1.9-, 2.4-, and 2.4-fold), and heterogeneous nuclear ribonucleoprotein A3 (1.2-, and 2.6-fold)] functions in the spermathecae of mated queens. Procollagen-lysine, 2-oxoglutarate 5-dioxygenase 1 (PLOD1) was hypothesized to promote the mating behavior according to RT-qPCR and immunofluorescence assay. The expression levels of most upregulated immune genes were decreased significantly at 3 days post mating. In conclusion, the external sperm transfer into spermathecae led to the significantly upregulated immune response genes in bumblebees. These gene expression differences in queen spermathecae contribute to understanding the bumblebee post mating regulatory network.

Transcriptome Profiling Reveals a Novel Mechanism of Antiviral Immunity Upon Sacbrood Virus Infection in Honey Bee Larvae (Apis cerana).

The honey bee is one of the most important pollinators in the agricultural system and is responsible for pollinating a third of all food we eat. Sacbrood virus (SBV) is a member of the virus family Iflaviridae and affects honey bee larvae and causes particularly devastating disease in the Asian honey bees, Apis cerana. Chinese Sacbrood virus (CSBV) is a geographic strain of SBV identified in China and has resulted in mass death of honey bees in China in recent years. However, the molecular mechanism underlying SBV infection in the Asian honey bee has remained unelucidated. In this present study, we employed high throughput next-generation sequencing technology to study the host transcriptional responses to CSBV infection in A. cerana larvae, and were able to identify genome-wide differentially expressed genes associated with the viral infection. Our study identified 2,534 differentially expressed genes (DEGs) involved in host innate immunity including Toll and immune deficiency (IMD) pathways, RNA interference (RNAi) pathway, endocytosis, etc. Notably, the expression of genes encoding antimicrobial peptides (abaecin, apidaecin, hymenoptaecin, and defensin) and core components of RNAi such as Dicer-like and Ago2 were found to be significantly upregulated in CSBV infected larvae. Most importantly, the expression of Sirtuin target genes, a family of signaling proteins involved in metabolic regulation, apoptosis, and intracellular signaling was found to be changed, providing the first evidence of the involvement of Sirtuin signaling pathway in insects' immune response to a virus infection. The results obtained from this study provide novel insights into the molecular mechanism and immune responses involved in CSBV infection, which in turn will contribute to the development of diagnostics and treatment for the diseases in honey bees.

Differential Viral Distribution Patterns in Reproductive Tissues of Apis mellifera and Apis cerana Drones.

Honeybee drones are male bees that mate with virgin queens during the mating flight, consequently transferring their genes to offspring. Therefore, the health of drones affects the overall fitness of the offspring and ultimately the survivability of the colony. Honeybee viruses are considered to be a major threat to the health of honeybees. In the present study, we demonstrated the pattern of common honeybee viruses in various tissues of drones in the western honeybee, Apis mellifera, and the eastern honeybee, Apis cerana. Drones were collected during the mating flight and analyzed using quantitative real-time (qRT-PCR) to detect the presence of seven honeybee viruses. The qRT-PCR result revealed that three honeybee viruses, namely Black Queen Cell Virus (BQCV), Deformed Wing Virus (DWV), and Chinese Sacbrood Virus (CSBV), were detected in the reproductive tissues of A. mellifera and A. cerana drones. The results from qRT-PCR showed that the Israeli Acute Paralysis Virus (IAPV) was only detected in A. mellifera drone body tissues. Moreover, the prevalence of DWV and BQCV in the drones collected from A. mellifera colonies was significantly higher than that of A. cerana. In addition, virus multiple infections were higher in A. mellifera drones compared to those in A. cerana. CSBV was found predominantly in the reproductive tissues of A. cerana drones. This study is the first report describing the presence of the CSBV in reproductive tissues of A. mellifera drones. Our results may reflect the preference of honeybee viruses in honeybee species and may provide a piece of interesting evidence for understanding the virus transmission in A. cerana.

Comparative analysis of the gut microbiota of Apis cerana in Yunnan using high-throughput sequencing.

Gut microbes play an important role in host disease and health. The Asian honey bee Apis cerana is an important pollinator of agricultural crops in China. However, there are still few studies on the structure and composition of the microbiota in the intestine of A. cerana, especially A. cerana in Yunnan. To understand the species and composition of the microbiota in the intestine of A. cerana in Yunnan, we used high-throughput sequencing technology to carry out 16S rRNA sequencing on 50 samples from Kunming, Xishuangbanna and Mengzi. The results show that both from the phylum level and the genus level, the structure and abundance of the microbiota in the gut of A. cerana from the three regions tended to be the same. At the phylum level, the abundance of Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, Acidobacteria and other species was high in A. cerana from different areas. At the genus level, the abundance of Lactobacillus, Gilliamella, Snodgrassella, Apibacter, Candidatus Schmidhempelia and other species was high in A. cerana from different areas. Due to its unique geographical environment and climatic conditions, at the genus level, the diversity of bacterial communities in Xishuangbanna was significantly lower than that in the other two regions, which was about 100 genera less. In conclusion, our results reveal the composition and structure of the intestinal microbiota of bees in Yunnan and deepen our understanding of the intestinal microbiota of bees.

Using the combined gene approach and multiple analytical methods to improve the phylogeny and classification of Bombus (Hymenoptera, Apidae) in China.

Bumble bees are vital to our agro-ecological system, with approximately 250 species reported around the world in the single genus Bombus. However, the health of bumble bees is threatened by multiple factors: habitat loss, climate change, pesticide use, and disease caused by pathogens and parasites. It is therefore vitally important to have a fully developed phylogeny for bumble bee species as part of our conservation efforts. The purpose of this study was to explore the phylogenetic relationships of the dominant bumble bees on the Tibetan plateau and in northern China as well as their placement and classification within the genus Bombus. The study used combined gene analysis consisting of sequence fragments from six genes, 16S rRNA, COI, EF-1α, Argk, Opsin and PEPCK, and the phylogenetic relationships of 209 Bombus species were explored. Twenty-six species, including 152 gene sequences, were collected from different regions throughout China, and 1037 gene sequences representing 183 species were obtained from GenBank or BOLD. The results suggest that the 209 analyzed species belong to fifteen subgenera and that most of the subgenera in Bombus are monophyletic, which is in accordance with conventional morphology-based classifications. The phylogenetic trees also show that nearly all subgenera easily fall into two distinct clades: short-faced and long-faced. The study is the first to investigate the phylogenetic placement of Bombus turneri (Richards), Bombus opulentus Smith, Bombus pyrosoma Morawitz, Bombus longipennis Friese, Bombus minshanensis Bischoff, and Bombus lantschouensis Vogt, all of which are widely distributed throughout different regions of China. The knowledge and understanding gained from the findings can provide a molecular basis to accurately classify Bombus in China and to define strategies to conserve biodiversity and promote pollinator populations.

Colonization of the gut microbiota of honey bee (Apis mellifera) workers at different developmental stages.

The role of the gut microbiome in animal health has become increasingly evident. Although the structure of the gut microbiome of A. mellifera is well known, little is known about the dynamic change across different developmental stages. In this study, we explored the dynamic changes of the gut microbiota of A. mellifera at different developmental stages covering the whole life cycle using high-throughput 16S rRNA gene sequencing. The results indicated that the core (shared) gut microbiota changes significantly among different developmental stages. The diversity of the bacterial community in workers among different ages was significantly different. In addition, by comparing the core gut microbiota among different-aged workers, we found that newly emerged workers had fewer core microbiota. Three genera, Gilliamella, Frischella, and Snodgrassella, were significantly colonized at 1 day poste mergence (dpe); Lactobacillus, Bifidobacterium, Commensalibacter were significantly colonized at 3 dpe and significantly reduced with Gilliamella. Lactobacillus kunkeei and Bartonella were significantly colonized at 12 dpe and were significantly decreased with Lactobacillus helsingborgensis. Commensalibacter and Bifidobacterium were significantly decreased at 25 dpe, and Bacteroides, Escherichia-Shigella, and Porphyromonadaceae were significantly decreased between 19 and 25 dpe. Our results reveal the succession of the gut microbiota of workers from birth to senescence, which provides a theoretical basis for further exploring the roles of gut microbiota during different developmental stages.

Characterization of a Vitellogenin Receptor in the Bumblebee, Bombus lantschouensis (Hymenoptera, Apidae).

The vitellogenin receptor (VgR) belongs to the low-density lipoprotein receptor (LDLR) family, responsible for mediating the endocytosis of vitellogenin (Vg) into the ovaries to promote ovarian growth and oviposition. Here, we cloned and measured VgR gene expression characteristics in the bumblebee Bombus lantschouensis. RNA interference was used to validate VgR function. The results showed that the full length of the BLVgR cDNA was 5519 bp, which included a 5280 bp open reading frame encoding 1759 amino acids (AAs). Sequence alignment revealed that the protein contained 12 LDLa, 5 EGF, 2 EGF-CA and 10 LY domains. Phylogenetic analysis showed that BLVgR and the VgR of Bombus terrestris clustered together and the tree of bumblebees (Bombus) appeared as one clade next to honeybees (Apis). Transcript expression analysis showed that BLVgR was expressed in all tested tissues and showed the highest abundance in the ovaries. BLVgR expression was present in all developmental stages. However, the expression level in larvae was extremely low. In addition, the expression of BLVgR was significantly upregulated after egg laying in both workers and queens. In new emerging workers injected with 5 µg of VgR dsRNA, the expression level of BLVgR was 4-fold lower than that in the GFP dsRNA-injected group after 72 h. Furthermore, BLVgR silencing significantly reduced the number of eggs laid (3.67 ± 1.96 eggs) and delayed the first egg-laying time (16.31 ± 2.07 days) in worker microcolonies when compared to dsGFP (37.31 ± 4.09 eggs, 8.15 ± 0.22 days) and DEPC-treated water injected controls (16.42 ± 2.24 eggs, 10.00 ± 0.37 days). In conclusion, the BLVgR gene and its reproductive function were explored in the bumblebee B. lantschouensis. This gene plays an important role in egg laying time and egg number.

Dynamic Changes of Gut Microbial Communities of Bumble Bee Queens through Important Life Stages.

Bumble bees are important pollinators in natural and agricultural ecosystems. Their social colonies are founded by individual queens, which, as the predominant reproductive females of colonies, contribute to colony function through worker production and fitness through male and new queen production. Therefore, queen health is paramount, but even though there has been an increasing emphasis on the role of gut microbiota for animal health, there is limited information on the gut microbial dynamics of bumble bee queens. Employing 16S rRNA amplicon sequencing and quantitative PCR, we investigate how the adult life stage and physiological state influence a queen's gut bacterial community diversity and composition in unmated, mated, and ovipositing queens of Bombus lantschouensis We found significant shifts in total gut microbe abundance and microbiota composition across queen states. There are specific compositional signatures associated with different stages, with unmated and ovipositing queens showing the greatest similarity in composition and mated queens being distinct. The bacterial genera Gilliamella, Snodgrassella, and Lactobacillus were relatively dominant in unmated and ovipositing queens, with Bifidobacterium dominant in ovipositing queens only. Bacillus, Lactococcus, and Pseudomonas increased following queen mating. Intriguingly, however, further analysis of unmated queens matching the mated queens in age showed that changes are independent of the act of mating. Our study is the first to explore the gut microbiome of bumble bee queens across key life stages from adult eclosion to egg laying and provides useful information for future studies of the function of gut bacteria in queen development and colony performance.IMPORTANCE Bumble bee queens undergo a number of biological changes as they transition through adult emergence, mating, overwintering, foraging, and colony initiation including egg laying. Therefore, they represent an important system to understand the link between physiological, behavioral, and environmental changes and host-associated microbiota. It is plausible that the bumble bee queen gut bacteria play a role in shaping the ability of the queen to survive environmental extremes and reproduce, due to long-established coevolutionary relationships between the host and microbiome members.