Glyphosate perturbs the gut microbiota of honey bees

Uncovering hidden dangers: The combined toxicity of abamectin and lambda-cyhalothrin on honey bees

Studying the toxic effects of pesticides on bees has consistently been a prominent area of interest for researchers. Nonetheless, existing research has predominantly concentrated on individual toxicity assessments, leaving a gap in our understanding of mixed toxicity. This study delves into the individual and combined toxic effects of abamectin (ABA) and lambda-cyhalothrin (LCY) on honey bees (Apis mellifera) in laboratory settings. We discovered that ABA (96 h-LC50 value of 0.079 mg/L) exhibited greater acute toxicity to honey bees compared to LCY (96 h-LC50 value of 9.177 mg/L). Moreover, the mixture of ABA and LCY presented an acute antagonistic effect on honey bees. Additionally, our results indicated that exposure to LCY, at medium concentration, led to a reduction in the abundance of gut core bacterium Snodgrassella. However, an increase in the abundance of Bifidobacterium was noted when exposed to a medium concentration of LCY and its mixture with ABA. Transcriptomic analysis revealed significant regulation of certain genes in the medium concentration of all three treatments compared to the control group, primarily enriching in metabolism and immune-related pathways. Following chronic exposure to field-relevant concentrations of ABA, LCY, and their mixture, there were significant alterations in the activities of immunity-related enzyme polyphenol oxidase (PPO) and detoxification enzymes glutathione S-transferase (GST) and carboxylesterase (CarE). Additionally, the expression of four genes (abaecin, cyp9e2, cyp302a1, and GstD1) associated with immune and detoxification metabolism was significantly altered. These findings suggest a potential health risk posed by the insecticides ABA and LCY to honey bees. Despite exhibiting acute antagonistic effect, mixed exposure still induced damage to bees at all levels. This study advances our knowledge of the potential adverse effects of individual or combined exposure to these two pesticides on non-target pollinators and offers crucial guidance for the use of insecticides in agricultural production.

With a little help from my friends: the roles of microbial symbionts in insect populations and communities

To understand insect abundance, distribution and dynamics, we need to understand the relevant drivers of their populations and communities. While microbial symbionts are known to strongly affect many aspects of insect biology, we lack data on their effects on populations or community processes, or on insects' evolutionary responses at different timescales. How these effects change as the anthropogenic effects on ecosystems intensify is an area of intense research. Recent developments in sequencing and bioinformatics permit cost-effective microbial diversity surveys, tracking symbiont transmission, and identification of functions across insect populations and multi-species communities. In this review, we explore how different functional categories of symbionts can influence insect life-history traits, how these effects could affect insect populations and their interactions with other species, and how they may affect processes and patterns at the level of entire communities. We argue that insect-associated microbes should be considered important drivers of insect response and adaptation to environmental challenges and opportunities. We also outline the emerging approaches for surveying and characterizing insect-associated microbiota at population and community scales. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'.

Impact of chronic exposure to field level glyphosate on the food consumption, survival, gene expression, gut microbiota, and metabolomic profiles of honeybees

Glyphosate (GLY) is among the most widely used pesticides in the world. However, there are a lot of unknowns about chronic exposure to GLY's effects on Honeybee (HB) behavior and physiology. To address this, we carried out five experiments to study the impact of chronic exposure to 5 mg/kg GLY on sugar consumption, survival, gene expression, gut microbiota, and metabolites of HB workers. Our results find a significant decrease in sugar consumption and survival probability of HB after chronic exposure to GLY. Further, genes associated with immune response, energy metabolism, and longevity were conspicuously altered. In addition, a total of seven metabolites were found to be differentially expressed in the metabolomic profiles, mainly related the sucrose metabolism. There was no significant difference in the gut microbiota. Results suggest that chronic exposure to field-level GLY altered the health of HB and the intricate toxic mechanisms. Our data provided insights into the chronic effects of GLY on HB behavior in food intake and health, which represents the field conditions where HB are exposed to pesticides over extended periods.

Exploring environmental exposomes and the gut-brain nexus: Unveiling the impact of pesticide exposure

This review delves into the escalating concern of environmental pollutants and their profound impact on human health in the context of the modern surge in global diseases. The utilisation of chemicals in food production, which results in residues in food, has emerged as a major concern nowadays. By exploring the intricate relationship between environmental pollutants and gut microbiota, the study reveals a dynamic bidirectional interplay, as modifying microbiota profile influences metabolic pathways and subsequent brain functions. This review will first provide an overview of potential exposomes and their effect to gut health. This paper is then emphasis the connection of gut brain function by analysing microbiome markers with neurotoxicity responses. We then take pesticide as example of exposome to elucidate their influence to biomarkers biosynthesis pathways and subsequent brain functions. The interconnection between neuroendocrine and neuromodulators elements and the gut-brain axis emerges as a pivotal factor in regulating mental health and brain development. Thus, manipulation of gut microbiota function at the onset of stress may offer a potential avenue for the prevention and treatment for mental disorder and other neurodegenerative illness.

Vairimorpha (Nosema) ceranae can promote Serratia development in honeybee gut: an underrated threat for bees?

The genus Serratia harbors opportunistic pathogenic species, among which Serratia marcescens is pathogenic for honeybees although little studied. Recently, virulent strains of S. marcescens colonizing the Varroa destructor mite's mouth were found vectored into the honeybee body, leading to septicemia and death. Serratia also occurs as an opportunistic pathogen in the honeybee's gut with a low absolute abundance. The Serratia population seems controlled by the host immune system, but its presence may represent a hidden threat, ready to arise when honeybees are weakened by biotic and abiotic stressors. To shed light on the Serratia pathogen, this research aims at studying Serratia's development dynamics in the honeybee body and its interactions with the co-occurring fungal pathogen Vairimorpha ceranae. Firstly, the degree of pathogenicity and the ability to permeate the gut epithelial barrier of three Serratia strains, isolated from honeybees and belonging to different species (S. marcescens, Serratia liquefaciens, and Serratia nematodiphila), were assessed by artificial inoculation of newborn honeybees with different Serratia doses (104, 106, and 108 cells/mL). The absolute abundance of Serratia in the gut and in the hemocoel was assessed in qPCR with primers targeting the luxS gene. Moreover, the absolute abundance of Serratia was assessed in the gut of honeybees infected with V. ceranae at different development stages and supplied with beneficial microorganisms and fumagillin. Our results showed that all tested Serratia strains could pass through the gut epithelial barrier and proliferate in the hemocoel, with S. marcescens being the most pathogenic. Moreover, under cage conditions, Serratia better proliferates when a V. ceranae infection is co-occurring, with a positive and significant correlation. Finally, fumagillin and some of the tested beneficial microorganisms could control both Serratia and Vairimorpha development. Our findings suggest a correlation between the two pathogens under laboratory conditions, a co-occurring infection that should be taken into consideration by researches when testing antimicrobial compounds active against V. ceranae, and the related honeybees survival rate. Moreover, our findings suggest a positive control of Serratia by the environmental microorganism Apilactobacillus kunkeei in a in vivo model, confirming the potential of this specie as beneficial bacteria for honeybees.

Exposure of the stingless bee Melipona scutellaris to imidacloprid, pyraclostrobin, and glyphosate, alone and in combination, impair its walking activity and fat body morphology and physiology

The stingless bee Melipona scutellaris performs buzz pollination, effectively pollinating several wild plants and crops with economic relevance. However, most research has focused on honeybees, leaving a significant gap in studies concerning native species, particularly regarding the impacts of pesticide combinations on these pollinators. Thus, this study aimed to evaluate the sublethal effects of imidacloprid (IMD), pyraclostrobin (PYR), and glyphosate (GLY) on the behavior and fat body cell morphology and physiology of M. scutellaris. Foragers were orally exposed to the different pesticides alone and in combination for 48 h. Bees fed with contaminated solution walked less, moved slower, presented morphological changes in the fat body, including vacuolization, altered cell shape and nuclei morphology, and exhibited a higher count of altered oenocytes and trophocytes. In all exposed groups, alone and in combination, the number of cells expressing caspase-3 increased, but the TLR4 number of cells expressing decreased compared to the control groups. The intensity of HSP70 immunolabeling increased compared to the control groups. However, the intensity of the immunolabeling of HSP90 decreased in the IMD, GLY, and I + G (IMD + GLY) groups but increased in I + P-exposed bees (IMD + PYR). Alternatively, exposure to PYR and P + G (PYR + GLY) did not affect the immunolabeling intensity. Our findings demonstrate the hazardous effects and environmental consequences of isolated and combined pesticides on a vital neotropical pollinator. Understanding how pesticides impact the fat body can provide crucial insights into the overall health and survival of native bee populations, which can help develop more environmentally friendly approaches to agricultural practices.

Synergistic resistance of honeybee (Apis mellifera) and their gut microorganisms to fluvalinate stress

Fluvalinate is widely used in the control of Varroa destructor, but its residues in colonies threaten honeybees. The effect of fluvalinate-induced dysbiosis on honeybee-related gene expression and the gut microenvironment of honeybees has not yet been fully elucidated. In this study, two-day-old larvae to seven-day-old adult worker bees were continuously fed different amounts of fluvalinate-sucrose solutions (0, 0.5, 5, and 50 mg/kg), after which the expression levels of two immune-related genes (Hymenoptaecin and Defensin1) and three detoxication-related genes (GSTS3, CAT, and CYP450) in worker bees (1, 7, and 20 days old) were measured. The effect of fluvalinate on the gut microbes of worker bees at seven days old also was explored using 16S rRNA Illumina deep sequencing. The results showed that exposure of honeybees to the insecticide fluvalinate affected their gene expression and gut microbial composition. As the age of honeybees increased, the effect of fluvalinate on the expression of Hymenoptaecin, CYP450, and CAT decreased, and the abundance of honeybee gut bacteria was affected by increasing the fluvalinate concentration. These findings provide insights into the synergistic defense of honeybee hosts against exogenous stresses in conjunction with honeybee gut microbes.

Biotic and abiotic stresses on honeybee health

Honeybees are the most critical pollinators providing key ecosystem services that underpin crop production and sustainable agriculture. Amidst a backdrop of rapid global change, this eusocial insect encounters a succession of stressors during nesting, foraging, and pollination. Ectoparasitic mites, together with vectored viruses, have been recognized as central biotic threats to honeybee health, while the spread of invasive giant hornets and small hive beetles also increasingly threatens colonies worldwide. Cocktails of agrochemicals, including acaricides used for mite treatment, and other pollutants of the environment have been widely documented to affect bee health in various ways. Additionally, expanding urbanization, climate change, and agricultural intensification often result in the destruction or fragmentation of flower-rich bee habitats. The anthropogenic pressures exerted by beekeeping management practices affect the natural selection and evolution of honeybees, and colony translocations facilitate alien species invasion and disease transmission. In this review, the multiple biotic and abiotic threats and their interactions that potentially undermine bee colony health are discussed, while taking into consideration the sensitivity, large foraging area, dense network among related nestmates, and social behaviors of honeybees.

A review on recent taxonomic updates of gut bacteria associated with social bees, with a curated genomic reference database

Honeybees and bumblebees play a crucial role as essential pollinators. The special gut microbiome of social bees is a key factor in determining the overall fitness and health of the host. Although bees harbor relatively simple microbial communities at the genus level, recent studies have unveiled significant genetic divergence and variations in gene content within each bacterial genus. However, a comprehensive and refined genomics-based taxonomic database specific to social bee gut microbiomes remains lacking. Here, we first provided an overview of the current knowledge on the distribution and function of social bee gut bacteria, as well as the factors that influence the gut population dynamics. We then consolidated all available genomes of the gut bacteria of social bees and refined the species-level taxonomy, by constructing a maximum-likelihood core genome phylogeny and calculating genome-wide pairwise average nucleotide identity. On the basis of the refined species taxonomy, we constructed a curated genomic reference database, named the bee gut microbe genome sequence database (BGM-GDb). To evaluate the species-profiling performance of the curated BGM-GDb, we retrieved a series of bee gut metagenomic data and inferred the species-level composition using metagenomic intra-species diversity analysis system (MIDAS), and then compared the results with those obtained from a prebuilt MIDAS database. We found that compared with the default database, the BGM-GDb excelled in aligned read counts and bacterial richness. Overall, this high-resolution and precise genomic reference database will facilitate research in understanding the gut community structure of social bees.

Prospects of probiotics in beekeeping: a review for sustainable approach to boost honeybee health

Honeybees are vital for global crop pollination, making indispensable contributions to agricultural productivity. However, these vital insects are currently facing escalating colony losses on a global scale, primarily attributed to parasitic and pathogenic attacks. The prevalent response to combat these infections may involve the use of antibiotics. Nevertheless, the application of antibiotics raises concerns regarding potential adverse effects such as antibiotic resistance and imbalances in the gut microbiota of bees. In response to these challenges, this study reviews the utilization of a probiotic-supplemented pollen substitute diet to promote honeybee gut health, enhance immunity, and overall well-being. We systematically explore various probiotic strains and their impacts on critical parameters, including survival rate, colony strength, honey and royal jelly production, and the immune response of bees. By doing so, we emphasize the significance of maintaining a balanced gut microbial community in honeybees. The review also scrutinizes the factors influencing the gut microbial communities of bees, elucidates the consequences of dysbiosis, and evaluates the potential of probiotics to mitigate these challenges. Additionally, it delineates different delivery mechanisms for probiotic supplementation and elucidates their positive effects on diverse health parameters of honeybees. Given the alarming decline in honeybee populations and the consequential threat to global food security, this study provides valuable insights into sustainable practices aimed at supporting honeybee populations and enhancing agricultural productivity.

Microbiome-conferred herbicides resistance

This article is a Commentary on Hu et al. (2023), 242: 333–343.

Colony performance of three native bumblebee species from South China and association with their gut microbiome

Bumblebees play an important ecological economic role as pollinators in nature and agriculture. For reasons of biosecurity, many countries promote the cultivation of native bumblebee species for crop pollination instead of importing "alien" species. In South China, a few bumblebee species are considered useful in this way, particularly, Bombus atripes, Bombus bicoloratus and Bombus breviceps. However, whether they are suitable for artificial rearing and forming healthy colonies for pollination, remains unknown. In this project, queens from the 3 native species of Guizhou Province were collected and colonies were started under standardized conditions. The colonies were scored based on 19 parameters, including the stage of colony development, number and weight of offspring, and diet consumed. The data revealed that B. breviceps had the best performance, produced more workers and consumed the smallest diet. Next, we performed 16S rDNA sequencing of the bacterial communities found in the guts of offspring workers, and then a correlation analysis between colony performance and gut bacteria was conducted. Here, B. breviceps showed the highest diversity in gut bacterial composition, dominated by the bacteria Gilliamella, Snodgrassella, Enterobacter, and Lactobacillus Firm5. The higher the abundance of Snodgrassella, the better the performance of the colony in the foundation stage, and later Lactobacillus Firm5, Apibacter and Bifidobacterium were beneficial during the stages of rapid growth and colony decline. Although we do not understand all of the interactions yet, these correlations explain why B. breviceps demonstrated better colony performance. Our data provide valuable information for breeding local Bombus species and will contribute to developing strong colonies for crop pollination.

Targeting imidazole-glycerol phosphate dehydratase in plants: novel approach for structural and functional studies, and inhibitor blueprinting

The histidine biosynthetic pathway (HBP) is targeted for herbicide design with preliminary success only regarding imidazole-glycerol phosphate dehydratase (IGPD, EC 4.2.1.19), or HISN5, as referred to in plants. HISN5 catalyzes the sixth step of the HBP, in which imidazole-glycerol phosphate (IGP) is dehydrated to imidazole-acetol phosphate. In this work, we present high-resolution cryoEM and crystal structures of Medicago truncatula HISN5 (MtHISN5) in complexes with an inactive IGP diastereoisomer and with various other ligands. MtHISN5 can serve as a new model for plant HISN5 structural studies, as it enables resolving protein-ligand interactions at high (2.2 Å) resolution using cryoEM. We identified ligand-binding hotspots and characterized the features of plant HISN5 enzymes in the context of the HISN5-targeted inhibitor design. Virtual screening performed against millions of small molecules not only revealed candidate molecules but also identified linkers for fragments that were experimentally confirmed to bind. Based on experimental and computational approaches, this study provides guidelines for designing symmetric HISN5 inhibitors that can reach two neighboring active sites. Finally, we conducted analyses of sequence similarity networks revealing that plant HISN5 enzymes derive from cyanobacteria. We also adopted a new approach to measure MtHISN5 enzymatic activity using isothermal titration calorimetry and enzymatically synthesized IGP.

Enhancing knowledge of chemical exposures and fate in honey bee hives: Insights from colony structure and interactions

Honey bees are unintentionally exposed to a wide range of chemicals through various routes in their natural environment, yet research on the cumulative effects of multi-chemical and sublethal exposures on important caste members, including the queen bee and brood, is still in its infancy. The hive's social structure and food-sharing (trophallaxis) practices are important aspects to consider when identifying primary and secondary exposure pathways for residential hive members and possible chemical reservoirs within the colony. Secondary exposures may also occur through chemical transfer (maternal offloading) to the brood and by contact through possible chemical diffusion from wax cells to all hive members. The lack of research on peer-to-peer exposures to contaminants and their metabolites may be in part due to the limitations in sensitive analytical techniques for monitoring chemical fate and dispersion. Combined application of automated honey bee monitoring and modern chemical trace analysis techniques could offer rapid progress in quantifying chemical transfer and accumulation within the hive environment and developing effective mitigation strategies for toxic chemical co-exposures. To enhance the understanding of chemical fate and toxicity within the entire colony, it is crucial to consider both the intricate interactions among hive members and the potential synergistic effects arising from combinations of chemical and their metabolites.

The hidden threat: Environmental toxins and their effects on gut microbiota

The human gut microbiota (GM), which consists of a complex and diverse ecosystem of bacteria, plays a vital role in overall wellness. However, the delicate balance of this intricate system is being compromised by the widespread presence of environmental toxins. The intricate connection between contaminants in the environment and human well-being has garnered significant attention in recent times. Although many environmental pollutants and their toxicity have been identified and studied in laboratory settings and animal models, there is insufficient data concerning their relevance to human physiology. Consequently, research on the toxicity of environmental toxins in GM has gained prominence in recent years. Various factors, such as air pollution, chemicals, heavy metals, and pesticides, have a detrimental impact on the composition and functioning of the GM. This comprehensive review aims to comprehend the toxic effects of numerous environmental pollutants, including antibiotics, endocrine-disrupting chemicals, heavy metals, and pesticides, on GM by examining recent research findings. The current analysis concludes that different types of environmental toxins can lead to GM dysbiosis and have various potential adverse effects on the well-being of animals. We investigate the alterations to the GM composition induced by contaminants and their impact on overall well-being, providing a fresh perspective on research related to pollutant exposure.

The honeybee microbiota and its impact on health and disease

Honeybees (Apis mellifera) are key pollinators that support global agriculture and are long-established models for developmental and behavioural research. Recently, they have emerged as models for studying gut microbial communities. Earlier research established that hindguts of adult worker bees harbour a conserved set of host-restricted bacterial species, each showing extensive strain variation. These bacteria can be cultured axenically and introduced to gnotobiotic hosts, and some have basic genetic tools available. In this Review, we explore the most recent research showing how the microbiota establishes itself in the gut and impacts bee biology and health. Microbiota members occupy specific niches within the gut where they interact with each other and the host. They engage in cross-feeding and antagonistic interactions, which likely contribute to the stability of the community and prevent pathogen invasion. An intact gut microbiota provides protection against diverse pathogens and parasites and contributes to the processing of refractory components of the pollen coat and dietary toxins. Absence or disruption of the microbiota results in altered expression of genes that underlie immunity, metabolism, behaviour and development. In the field, such disruption by agrochemicals may negatively impact bees. These findings demonstrate a key developmental and protective role of the microbiota, with broad implications for bee health.

Glyphosate exposure affected longevity-related pathways and reduced survival in asian honey bees (Apis cerana)

Glyphosate (N-(phosphonomethyl)glycine, GLY) ranks among the most extensively used and effective herbicides globally. However, excessive GLY utilization poses a substantial threat to the survival of honey bees (Apis cerana). Here we monitored the survival status of A. cerana treated with GLY, and conducted transcriptome sequencing of the bee gut and head to further explore potential GLY influences at the molecular level. We observed that the mortality rate of bees increased as GLY concentration escalated. Pivotal pathways emerged in response to the GLY treatment, with a substantial number of differentially expressed genes enriched in the longevity regulating pathway - multiple species. This strongly suggested that GLY may influence the physiological behavior of bees by impacting this particular pathway. Moreover, our analysis revealed a notable reduction in the enzymatic activities of CYP450 and AChE in both the bee head and intestines of when exposed to GLY. Conversely, the enzymatic activity of superoxide dismutase (SOD) in the head remained unaffected, whereas in the intestines, it exhibited a significant increase. Additionally, prophenol oxidase (PPO) and glutathione-S-transferases (GSTs) displayed contrasting trends in enzymatic activity in both organs. This study offers valuable insights into how GLY impacted the survival of A. cerana.

Exposure to a fungicide for a field-realistic duration does not alter bumble bee fecal microbiota structure

Social bees are frequently exposed to pesticides when foraging on nectar and pollen. Recent research has shown that pesticide exposure not only impacts social bee host health but can also alter the community structure of social bee gut microbiotas. However, most research on pesticide-bee gut microbiota interactions has been conducted in honey bees; bumble bees, native North American pollinators, have received less attention and, due to differences in their ecology, may be exposed to certain pesticides for shorter durations than honey bees. Here, we examine how exposure to the fungicide chlorothalonil for a short, field-realistic duration alters bumble bee fecal microbiotas (used as a proxy for gut microbiotas) and host performance. We expose small groups of Bombus impatiens workers (microcolonies) to field-realistic chlorothalonil concentrations for 5 days, track changes in fecal microbiotas during the exposure period and a recovery period, and compare microcolony offspring production between treatments at the end of the experiment. We also assess the use of fecal microbiotas as a gut microbiota proxy by comparing community structures of fecal and gut microbiotas. We find that chlorothalonil exposure for a short duration does not alter bumble bee fecal microbiota structure or affect microcolony production at any concentration but that fecal and gut microbiotas differ significantly in community structure. Our results show that, at least when exposure durations are brief and unaccompanied by other stressors, bumble bee microbiotas are resilient to fungicide exposure. Additionally, our work highlights the importance of sampling gut microbiotas directly, when possible.IMPORTANCEWith global pesticide use expected to increase in the coming decades, studies on how pesticides affect the health and performance of animals, including and perhaps especially pollinators, will be crucial to minimize negative environmental impacts of pesticides in agriculture. Here, we find no effect of exposure to chlorothalonil for a short, field-realistic period on bumble bee fecal microbiota community structure or microcolony production regardless of pesticide concentration. Our results can help inform pesticide use practices to minimize negative environmental impacts on the health and fitness of bumble bees, which are key native, commercial pollinators in North America. We also find that concurrently sampled bumble bee fecal and gut microbiotas contain similar microbes but differ from one another in community structure and consequently suggest that using fecal microbiotas as a proxy for gut microbiotas be done cautiously; this result contributes to our understanding of proxy use in gut microbiota research.

Metagenomic analysis of the honey bee queen microbiome reveals low bacterial diversity and Caudoviricetes phages

In eusocial insects, the health of the queens-the colony founders and sole reproductive females-is a primary determinant for colony success. Queen failure in the honey bee Apis mellifera, for example, is a major concern of beekeepers who annually suffer colony losses, necessitating a greater knowledge of queen health. Several studies on the microbiome of honey bees have characterized its diversity and shown its importance for the health of worker bees, the female non-reproductive caste. However, the microbiome of workers differs from that of queens, which, in comparison, is still poorly studied. Thus, direct investigations of the queen microbiome are required to understand colony-level microbiome assembly, functional roles, and evolution. Here, we used metagenomics to comprehensively characterize the honey bee queen microbiome. Comparing samples from different geographic locations and breeder sources, we show that the microbiome of queens is mostly shaped by the environment experienced since early life and is predicted to play roles in the breakdown of the diet and protection from pathogens and xenobiotics. We also reveal that the microbiome of queens comprises only four candidate core bacterial species, Apilactobacillus kunkeei, Lactobacillus apis, Bombella apis, and Commensalibacter sp. Interestingly, in addition to bacteria, we show that bacteriophages infect the queen microbiome, for which Lactobacillaceae are predicted to be the main reservoirs. Together, our results provide the basis to understand the honey bee colony microbiome assemblage, can guide improvements in queen-rearing processes, and highlight the importance of considering bacteriophages for queen microbiome health and microbiome homeostasis in eusocial insects.IMPORTANCEThe queen caste plays a central role in colony success in eusocial insects, as queens lay eggs and regulate colony behavior and development. Queen failure can cause colonies to collapse, which is one of the major concerns of beekeepers. Thus, understanding the biology behind the queen's health is a pressing issue. Previous studies have shown that the bee microbiome plays an important role in worker bee health, but little is known about the queen microbiome and its function in vivo. Here, we characterized the queen microbiome, identifying for the first time the present species and their putative functions. We show that the queen microbiome has predicted nutritional and protective roles in queen association and comprises only four consistently present bacterial species. Additionally, we bring to attention the spread of phages in the queen microbiome, which increased in abundance in failing queens and may impact the fate of the colony.

Enhanced capacity of a leaf beetle to combat dual stress from entomopathogens and herbicides mediated by associated microbiota

Herbicides have demonstrated their impact on insect fitness by affecting their associated microbiota or altering the virulence of entomopathogenic fungi toward insects. However, limited research has explored the implications of herbicide stress on the intricate tripartite interaction among insects, associated bacterial communities, and entomopathogens. In this study, we initially demonstrated that associated bacteria confer a leaf beetle, Plagiodera versicolora, with the capability to resist the entomopathogenic fungus Aspergillus nomius infection, a capability sustained even under herbicide glyphosate stress. Further analysis of the associated microbiota revealed a significant alteration in abundance and composition due to glyphosate treatment. The dominant bacterium, post A. nomius infection or following a combination of glyphosate treatments, exhibited strong suppressive effects on fungal growth. Additionally, glyphosate markedly inhibited the pathogenic associated bacterium Pseudomonas though it inhibited P. versicolora's immunity, ultimately enhancing the beetle's tolerance to A. nomius. In summary, our findings suggest that the leaf beetle's associated microbiota bestow an augmented resilience against the dual stressors of both the entomopathogen and glyphosate. These results provide insight into the effects of herbicide residues on interactions among insects, associated bacteria, and entomopathogenic fungi, holding significant implications for pest control and ecosystem assessment.

Passive sampling of herbicides above sediments at sites with losses of submerged macrophytes in a mesotrophic lake

Declines of submerged macrophytes (SUM) were monitored in littoral zones of the deep, mesotrophic lake Suhrer See (Northern Germany) since 2017. Drastic losses coincided with intense agriculture in sandy sub-catchments and precipitation. All lines of evidence pointed to a causal connection with subsurface discharge indicating that herbicide application might have caused the effects. Passive sampling was applied in 2022 to elucidate, whether herbicides were really present at sites of losses and if so, in ecotoxicological relevant concentrations. Samplers were exposed on top of lake sediments in 2 m depth and under worst case conditions, i.e., at sites, known for losses of the whole functional group of SUM and at the beginning of the vegetation period. At this time, SUM diaspores were most vulnerable to repression of development and the subsurface discharge was high in the same instance. The potential ecotoxicological relevance of detected herbicide concentrations was assessed with a toxic units (TU) approach, with reference to acute effect concentrations (EC50 of green algae, 72 h, growth). The TU ranged from 0.001 to 0.03. Most concentrations exceeded the threshold of relevance set by an assessment factor of 1000, i.e., TU > 0.001. Locally applied herbicides acted by suppressing developmental stages, and the sum of TU exceeded 0.02 at all sites, mainly due to diflufenican. Not applied locally, terbuthylazine and its relevant metabolites, including terbutryn, acted by inhibiting photosynthesis, and the sum of TU reached 0.005. On this base, diflufenican was assessed to be likely a main stressor, all other detected herbicides to be potentially relevant. Uncertainties and knowledge gaps were specified. The result of the chemical risk assessment was counterchecked for consistence with biological monitoring data within a whole lake perspective. Concepts of empirical and advanced causal attribution methodology were applied to get a grip to the ecological causal field and to protection.

Toxic effects of the heavy metal Cd on Apis cerana cerana (Hymenoptera: Apidae): Oxidative stress, immune disorders and disturbance of gut microbiota

Cadmium (Cd) is a toxic non-essential metal element that can enter the honey bee body through air, water and soil. Currently, there is a lack of sufficient research on the effects of Cd on A. cerana cerana, especially the potential risks of long-term exposure to sublethal concentrations. In order to ascertain the toxicological effects of the heavy metal Cd on bees, we performed laboratory-based toxicity experiments on worker bees and conducted analyses from three distinctive facets: antioxidative, immunological, and gut microbiota. The results showed that exposure of bees to high concentrations of Cd resulted in acute mortality, and the increase in mortality was concentration dependent. In long-term exposure to sublethal concentrations, Cd reduced the number of transcripts of antioxidant genes (AccSOD1, AccTPx3 and AccTPx4) and superoxide dismutase activity, causing an increase in malondialdehyde content. Simultaneously, the transcription of immune-related genes (AccAbaecin and AccApidaecin) and acetylcholinesterase activities was inhibited. Furthermore, Cd changes the structural characteristics of bacterial and fungal communities in the gut, disrupting the balance of microbial communities. In conclusion, the health and survival of honey bees are affected by Cd. This study provides a scientific basis for investigating the toxicological mechanisms and control strategies of the heavy metal Cd on honey bees, while facilitating a better understanding and protection of these valuable honey bees.

Glyphosate: Impact on the microbiota-gut-brain axis and the immune-nervous system, and clinical cases of multiorgan toxicity

Glyphosate (GLP) and GLP-based herbicides (GBHs), such as polyethoxylated tallow amine-based GLP surfactants (GLP-SH), developed in the late 70', have become the most popular and controversial agrochemicals ever produced. Nowadays, GBHs have reached 350 million hectares of crops in over 140 countries, with an annual turnover of 5 billion and 11 billion USD in the U.S.A. and worldwide, respectively. Because of the highly efficient inhibitory activity of GLP targeted to the 5-enolpyruvylshikimate-3-phosphate synthase pathway, present in plants and several bacterial strains, the GLP-resistant crop-based genetic agricultural revolution has decreased famine and improved the costs and quality of living in developing countries. However, this progress has come at the cost of the 50-year GBH overuse, leading to environmental pollution, animal intoxication, bacterial resistance, and sustained occupational exposure of the herbicide farm and companies' workers. According to preclinical and clinical studies covered in the present review, poisoning with GLP, GLP-SH, and GBHs devastatingly affects gut microbiota and the microbiota-gut-brain (MGB) axis, leading to dysbiosis and gastrointestinal (GI) ailments, as well as immunosuppression and inappropriate immunostimulation, cholinergic neurotransmission dysregulation, neuroendocrinal system disarray, and neurodevelopmental and neurobehavioral alterations. Herein, we mainly focus on the contribution of gut microbiota (GM) to neurological impairments, e.g., stroke and neurodegenerative and neuropsychiatric disorders. The current review provides a comprehensive introduction to GLP's microbiological and neurochemical activities, including deviation of the intestinal Firmicutes-to-Bacteroidetes ratio, acetylcholinesterase inhibition, excitotoxicity, and mind-altering processes. Besides, it summarizes and critically discusses recent preclinical studies and clinical case reports concerning the harmful impacts of GBHs on the GI tract, MGB axis, and nervous system. Finally, an insightful comparison of toxic effects caused by GLP, GBH-SH, and GBHs is presented. To this end, we propose a first-to-date survey of clinical case reports on intoxications with these herbicides.

The buzz within: the role of the gut microbiome in honeybee social behavior

Gut symbionts influence the physiology and behavior of their host, but the extent to which these effects scale to social behaviors is an emerging area of research. The use of the western honeybee (Apis mellifera) as a model enables researchers to investigate the gut microbiome and behavior at several levels of social organization. Insight into gut microbial effects at the societal level is critical for our understanding of how involved microbial symbionts are in host biology. In this Commentary, we discuss recent findings in honeybee gut microbiome research and synthesize these with knowledge of the physiology and behavior of other model organisms to hypothesize how host-microbe interactions at the individual level could shape societal dynamics and evolution.

Architecture and potential roles of a delta-class glutathione S-transferase in protecting honey bee from agrochemicals

The European honey bee, Apis mellifera, serves as the principle managed pollinator species globally. In recent decades, honey bee populations have been facing serious health threats from combined biotic and abiotic stressors, including diseases, limited nutrition, and agrochemical exposure. Understanding the molecular mechanisms underlying xenobiotic adaptation of A. mellifera is critical, considering its extensive exposure to phytochemicals and agrochemicals present in the environment. In this study, we conducted a comprehensive structural and functional characterization of AmGSTD1, a delta class glutathione S-transferase (GST), to unravel its roles in agrochemical detoxification and antioxidative stress responses. We determined the 3-dimensional (3D) structure of a honey bee GST using protein crystallography for the first time, providing new insights into its molecular structure. Our investigations revealed that AmGSTD1 metabolizes model substrates, including 1-chloro-2,4-dinitrobenzene (CDNB), p-nitrophenyl acetate (PNA), phenylethyl isothiocyanate (PEITC), propyl isothiocyanate (PITC), and the oxidation byproduct 4-hydroxynonenal (HNE). Moreover, we discovered that AmGSTD1 exhibits binding affinity with the fluorophore 8-Anilinonaphthalene-1-sulfonic acid (ANS), which can be inhibited with various herbicides, fungicides, insecticides, and their metabolites. These findings highlight the potential contribution of AmGSTD1 in safeguarding honey bee health against various agrochemicals, while also mitigating oxidative stress resulting from exposure to these substances.

Urbanization reduces gut bacterial microbiome diversity in a specialist ground beetle, Carabus convexus

Urbanization is rapidly shaping and transforming natural environments, creating networks of modified land types. These urbanization-driven modifications lead to local extinctions of several species, but the surviving ones also face numerous novel selection pressures, including exposure to pollutants, habitat alteration, and shifts in food availability and diversity. Based on the assumption that the environmental pool of microorganisms is reduced in urban habitats due to habitat alteration, biodiversity loss, and pollution, we hypothesized that the diversity of bacterial microbiome in digestive tracts of arthropods would be lower in urban than rural habitats. Investigating the gut bacterial communities of a specialist ground beetle, Carabus convexus, in forested rural versus urban habitats by next generation high-throughput sequencing of the bacterial 16S rRNA gene, we identified 3839 bacterial amplicon sequence variants. The composition of gut bacterial samples did not significantly differ by habitat (rural vs. urban), sex (female vs. male), sampling date (early vs. late spring), or their interaction. The microbiome diversity (evaluated by the Rényi diversity function), however, was higher in rural than urban adults. Our findings demonstrate that urbanization significantly reduced the diversity of the gut bacterial microbiome in C. convexus.

Investigating adverse effects of chronic dietary exposure to herbicide glyphosate on zootechnical characteristics and clinical, biochemical and immunological blood parameters in broiler chickens

Although the herbicide glyphosate is widely used globally and considered safe, more evidence of its adverse effects on animals and humans is accumulating. The present investigation was aimed at evaluating the impact of different glyphosate concentrations on zootechnical characteristics and clinical, biochemical and immunological blood parameters in Ross 308 broiler chickens. Four groups were employed, including untreated control and three experimental groups fed diets enriched with glyphosate at doses of 10, 20 and 100 ppm that conformed to 0.5, 1 and 5 maximum residue limits, respectively. The results showed that glyphosate is a stress factor triggering a multifaceted effect on important blood parameters (e.g., white blood cell and phagocytic counts), which was shown for the first time in the experiments involving productive meat-type poultry. It was first revealed that glyphosate-induced changes in blood parameters may be related to a negative impact on the zootechnical characteristics including the digestive tract organ development and body weight gain. The study findings suggested that exposure to glyphosate in the feedstuffs can adversely affect the physiological condition and productivity of broilers.

From dysbiosis to neuropathologies: Toxic effects of glyphosate in zebrafish

Glyphosate, a globally prevalent herbicide known for its selective inhibition of the shikimate pathway in plants, is now implicated in physiological effects on humans and animals, probably due to its impacts in their gut microbiomes which possess the shikimate pathway. In this study, we investigate the effects of environmentally relevant concentrations of glyphosate on the gut microbiota, neurotransmitter levels, and anxiety in zebrafish. Our findings demonstrate that glyphosate exposure leads to dysbiosis in the zebrafish gut, alterations in central and peripheral serotonin levels, increased dopamine levels in the brain, and notable changes in anxiety and social behavior. While the dysbiosis can be attributed to glyphosate's antimicrobial properties, the observed effects on neurotransmitter levels leading to the reported induction of oxidative stress in the brain indicate a novel and significant mode of action for glyphosate, namely the impairment of the microbiome-gut-axis. While further investigations are necessary to determine the relevance of this mechanism in humans, our findings shed light on the potential explanation for the contradictory reports on the safety of glyphosate for consumers.

Effect of glyphosate, its metabolite AMPA, and the glyphosate formulation Roundup® on brown trout (Salmo trutta f. fario) gut microbiome diversity

Glyphosate is used worldwide as a compound of pesticides and is detectable in many environmental compartments. It enters water bodies primarily through drift from agricultural areas so that aquatic organisms are exposed to this chemical, especially after rain events. Glyphosate is advertised and sold as a highly specific herbicide, which interacts with the EPSP synthase, an enzyme of the shikimate metabolism, resulting in inhibition of the synthesis of vital aromatic amino acids. However, not only plants but also bacteria can possess this enzyme so that influences of glyphosate on the microbiomes of exposed organisms cannot be excluded. Those influences may result in subtle and long-term effects, e.g., disturbance of the symbiotic interactions of bionts with microorganisms of their microbiomes. Mechanisms how the transformation product aminomethylphosphonic acid (AMPA) of glyphosate might interfere in this context have not understood so far. In the present study, molecular biological fingerprinting methods showed concentration-dependent effects of glyphosate and AMPA on fish microbiomes. In addition, age-dependent differences in the composition of the microbiomes regarding abundance and diversity were detected. Furthermore, the effect of exposure to glyphosate and AMPA was investigated for several fish pathogens of gut microbiomes in terms of their gene expression of virulence factors associated with pathogenicity. In vitro transcriptome analysis with the fish pathogen Yersinia ruckeri revealed that it is questionable whether the observed effect on the microbiome is caused by the intended mode of action of glyphosate, such as the inhibition of EPSP synthase activity.

Exposure to sublethal concentrations of imidacloprid, pyraclostrobin, and glyphosate harm the behavior and fat body cells of the stingless bee Scaptotrigona postica

Pesticide use in agriculture threatens non-target insects such as bees. Considering the ecological and economic relevance of native bees, such as Scaptotrigona postica, and the insufficient studies on the effects of pesticides on their behavior and physiology, improving the current knowledge on this issue is essential. Therefore, this study investigated the sublethal effects of imidacloprid, pyraclostrobin, and glyphosate on the behavior and fat body cells of S. postica. Pesticide ingestion decreased the walking distance and mean velocity of bees compared to the control and solvent control groups. The oenocytes of the control groups were spherical, with central nuclei containing decondensed chromatin, and the trophocytes presented irregular morphology, with cells varying in shape and the cytoplasm filled with vacuoles and granules. However, bees exposed to pesticides showed extensive cytoarchitectural disruption in the fat body, such as vacuolization and shape changes in oenocytes and altered nuclei morphology in trophocytes. Moreover, pesticide exposure increased the number of atypical oenocytes and altered trophocytes, except for the PYR group, which showed a lower number of atypical oenocytes. Caspase-positive labeling significantly increased in all exposed bee groups. Alternatively, TLR4 labeling was significantly decreased in the exposed groups compared to the control groups. There was a significant increase in HSP90 immunolabeling in all exposed groups compared to the control. These findings reinforce the importance of research on the sublethal effects of low pesticide concentrations on key neotropical pollinators and prove that these toxic substances can impair their detoxification and immune defense.

Phytochemicals, Probiotics, Recombinant Proteins: Enzymatic Remedies to Pesticide Poisonings in Bees

The ongoing global decline of bees threatens biodiversity and food safety as both wild plants and crops rely on bee pollination to produce viable progeny or high-quality products in high yields. Pesticide exposure is a major driving force for the decline, yet pesticide use remains unreconciled with bee conservation since studies demonstrate that bees continue to be heavily exposed to and threatened by pesticides in crops and natural habitats. Pharmaceutical methods, including the administration of phytochemicals, probiotics (beneficial bacteria), and recombinant proteins (enzymes) with detoxification functions, show promise as potential solutions to mitigate pesticide poisonings. We discuss how these new methods can be appropriately developed and applied in agriculture from bee biology and ecotoxicology perspectives. As countless phytochemicals, probiotics, and recombinant proteins exist, this Perspective will provide suggestive guidance to accelerate the development of new techniques by directing research and resources toward promising candidates. Furthermore, we discuss practical limitations of the new methods mentioned above in realistic field applications and propose recommendations to overcome these limitations. This Perspective builds a framework to allow researchers to use new detoxification techniques more efficiently in order to mitigate the harmful impacts of pesticides on bees.

Chronic bee paralysis virus exploits host antimicrobial peptides and alters gut microbiota composition to facilitate viral infection

The significance of gut microbiota in regulating animal immune response to viral infection is increasingly recognized. However, how chronic bee paralysis virus (CBPV) exploits host immune to disturb microbiota for its proliferation remains elusive. Through histopathological examination, we discovered that the hindgut harbored the highest level of CBPV, and displayed visible signs of damages. The metagenomic analysis showed that a notable reduction in the levels of Snodgrassella alvi and Lactobacillus apis, and a significant increase in the abundance of the opportunistic pathogens such as Enterobacter hormaechei and Enterobacter cloacae following CBPV infection. Subsequent co-inoculation experiments showed that these opportunistic pathogens facilitated the CBPV proliferation, leading to accelerated mortality in bees and exacerbation of bloated abdomen symptoms after CBPV infection. The expression level of antimicrobial peptide (AMP) was found to be significantly up-regulated by over 1000 times in response to CBPV infection, as demonstrated by subsequent transcriptome and quantitative real-time PCR investigations. In particular, through correlation analysis and a bacteriostatic test revealed that the AMPs did not exhibit any inhibitory effect against the two opportunistic pathogens. However, they did demonstrate inhibitory activity against S. alvi and L. apis. Our findings provide different evidence that the virus infection may stimulate and utilize the host's AMPs to eradicate probiotic species and facilitate the proliferation of opportunistic bacteria. This process weakens the intestinal barrier and ultimately resulting in the typical bloated abdomen.

Recent technologies for glyphosate removal from aqueous environment: A critical review

The growing demand for food has led to an increase in the use of herbicides and pesticides over the years. One of the most widely used herbicides is glyphosate (GLY). It has been used extensively since 1974 for weed control and is currently classified by the World Health Organization (WHO) as a Group 2A substance, probably carcinogenic to humans. The industry and academia have some disagreements regarding GLY toxicity in humans and its effects on the environment. Even though this herbicide is not mentioned in the WHO water guidelines, some countries have decided to set maximum acceptable concentrations in tap water, while others have decided to ban its use in crop production completely. Researchers around the world have employed different technologies to remove or degrade GLY, mostly at the laboratory scale. Water treatment plants combine different technologies to remove it alongside other water pollutants, in some cases achieving acceptable removal efficiencies. Certainly, there are many challenges in upscaling purification technologies due to the costs and lack of factual information about their adverse effects. This review presents different technologies that have been used to remove GLY from water since 2012 to date, its detection and removal methods, challenges, and future perspectives.

Evaluation of neurological behavior alterations and metabolic changes in mice under chronic glyphosate exposure

Glyphosate is a widely used active ingredient in agricultural herbicides, inhibiting the biosynthesis of aromatic amino acids in plants by targeting their shikimate pathway. Our gut microbiota also facilitates the shikimate pathway, making it a vulnerable target when encountering glyphosate. Dysbiosis in the gut microbiota may impair the gut-brain axis, bringing neurological outcomes. To evaluate the neurotoxicity and biochemical changes attributed to glyphosate, we exposed mice with the reference dose (RfD) set by the U.S. EPA (1.75 mg/Kg-BW/day) and its hundred-time-equivalence (175 mg/Kg-BW/day) chronically via drinking water, then compared a series of neurobehaviors and their fecal/serum metabolomic profile against the non-exposed vehicles (n = 10/dosing group). There was little alteration in the neurobehavior, including motor activities, social approach, and conditioned fear, under glyphosate exposure. Metabolomic differences attributed to glyphosate were observed in the feces, corresponding to 68 and 29 identified metabolites with dysregulation in the higher and lower dose groups, respectively, compared to the vehicle-control. There were less alterations observed in the serum metabolome. Under 175 mg/Kg-BW/day of glyphosate exposure, the aromatic amino acids (phenylalanine, tryptophan, and tyrosine) were reduced in the feces but not in the serum of mice. We further focused on how tryptophan metabolism was dysregulated based on the pathway analysis, and identified the indole-derivatives were more altered compared to the serotonin and kynurenine derivatives. Together, we obtained a three-dimensional data set that records neurobehavioral, fecal metabolic, and serum biomolecular dynamics caused by glyphosate exposure at two different doses. Our data showed that even under the high dose of glyphosate irrelevant to human exposure, there were little evidence that supported the impairment of the gut-brain axis.

Roadside habitat: Boon or bane for pollinating insects?

Pollinators, which provide vital services to wild ecosystems and agricultural crops, are facing global declines and habitat loss. As undeveloped land becomes increasingly scarce, much focus has been directed recently to roadsides as potential target zones for providing floral resources to pollinators. Roadsides, however, are risky places for pollinators, with threats from vehicle collisions, toxic pollutants, mowing, herbicides, and more. Although these threats have been investigated, most studies have yet to quantify the costs and benefits of roadsides to pollinators and, therefore, do not address whether the costs outweigh the benefits for pollinator populations using roadside habitats. In this article, we address how, when, and under what conditions roadside habitats may benefit or harm pollinators, reviewing existing knowledge and recommending practical questions that managers and policymakers should consider when planning pollinator-focused roadside management.

Chronic exposure to pesticides disrupts the bacterial and fungal co-existence and the cross-kingdom network characteristics of honey bee gut microbiome

Gut microbiome communities have a significant impact on bee health and disease and have been shown to be shaped by a variety of factors, including exposure to pesticides and inhive chemicals. However, it is unknown whether pesticide exposure affects the coexistence and cross-kingdom network parameters of bee gut microbiome communities because microbes may compete in the gut environment under different stressors. Therefore, we conducted additional analysis of the microbiome data from our previous study in which we discovered that exposure to two novel insecticides flupyradifurone (FPF) and sulfoxaflor (Sulf) or/and a fungicide, azoxystrobin (Azoxy) caused dysbiosis of bee gut microbiota that was associated with an increase in the relative abundance of opportunistic pathogens such as Serratia marcescens. We investigated for the first time the potential cross-kingdom fungal-bacterial interactions using co-occurrence pattern correlation and network analysis. We discovered that exposure to FPF or Sulf alone or in combination with Azoxy fungicide influenced the co-existence patterns of fungal and bacterial communities. Significant differences in degree centrality, closeness centrality, and eigenvector centrality distribution indices were also found in single and double-treatment groups compared to controls. The effects of FPF and Sulf alone on cross-kingdom parameters (bacterial to fungal node ratio, degree of centrality, closeness centrality, and eigenvector centrality) were distinct, but this was reversed when they were combined with Azoxy fungicide. The fungal and bacterial hub taxa identified differed, with only a few shared hubs across treatments, suggesting microbial cross-kingdom networks may be disrupted differently under different stressors. Our findings add to our understanding of pesticide effects on the bee gut microbiome and bee health in general, while also emphasizing the importance of cross-kingdom network analysis in future microbiome research.

Molecular ecology of microbiomes in the wild: Common pitfalls, methodological advances and future directions

The study of microbiomes across organisms and environments has become a prominent focus in molecular ecology. This perspective article explores common challenges, methodological advancements, and future directions in the field. Key research areas include understanding the drivers of microbiome community assembly, linking microbiome composition to host genetics, exploring microbial functions, transience and spatial partitioning, and disentangling non-bacterial components of the microbiome. Methodological advancements, such as quantifying absolute abundances, sequencing complete genomes, and utilizing novel statistical approaches, are also useful tools for understanding complex microbial diversity patterns. Our aims are to encourage robust practices in microbiome studies and inspire researchers to explore the next frontier of this rapidly changing field.

Combined effect of a neonicotinoid insecticide and a fungicide on honeybee gut epithelium and microbiota, adult survival, colony strength and foraging preferences

Fungicides, insecticides and herbicides are widely used in agriculture to counteract pathogens and pests. Several of these molecules are toxic to non-target organisms such as pollinators and their lethal dose can be lowered if applied as a mixture. They can cause large and unpredictable problems, spanning from behavioural changes to alterations in the gut. The present work aimed at understanding the synergistic effects on honeybees of a combined in-hive exposure to sub-lethal doses of the insecticide thiacloprid and the fungicide penconazole. A multidisciplinary approach was used: honeybee mortality upon exposure was initially tested in cage, and the colonies development monitored. Morphological and ultrastructural analyses via light and transmission electron microscopy were carried out on the gut of larvae and forager honeybees. Moreover, the main pollen foraging sources and the fungal gut microbiota were studied using Next Generation Sequencing; the gut core bacterial taxa were quantified via qPCR. The mortality test showed a negative effect on honeybee survival when exposed to agrochemicals and their mixture in cage but not confirmed at colony level. Microscopy analyses on the gut epithelium indicated no appreciable morphological changes in larvae, newly emerged and forager honeybees exposed in field to the agrochemicals. Nevertheless, the gut microbial profile showed a reduction of Bombilactobacillus and an increase of Lactobacillus and total fungi upon mixture application. Finally, we highlighted for the first time a significant honeybee diet change after pesticide exposure: penconazole, alone or in mixture, significantly altered the pollen foraging preference, with honeybees preferring Hedera pollen. Overall, our in-hive results showed no severe effects upon administration of sublethal doses of thiacloprid and penconazole but indicate a change in honeybees foraging preference. A possible explanation can be that the different nutritional profile of the pollen may offer better recovery chances to honeybees.

Imidacloprid increases the prevalence of the intestinal parasite Lotmaria passim in honey bee workers

A challenge in bee protection is to assess the risks of pesticide-pathogen interactions. Lotmaria passim, a ubiquitous unicellular parasite in honey bees, is considered harmful under specific conditions. Imidacloprid causes unpredictable side effects. Research indicates that both L. passim and imidacloprid may affect the physiology, behavior, immunity, microbiome and lifespan of honey bees. We designed cage experiments to test whether the infection of L. passim is affected by a sublethal dose of imidacloprid. Workers collected at the time of emergence were exposed to L. passim and 2.5 μg/L imidacloprid in the coexposure treatment group. First, samples of bees were taken from cages since they were 5 days old and 3 days postinfection, i.e., after finishing an artificial 24 h L. passim infection. Additional bees were collected every two additional days. In addition, bees frozen at the time of emergence and collected from the unexposed group were analyzed. Abdomens were analyzed using qPCR to determine parasite load, while corresponding selected heads were subjected to a label-free proteomic analysis. Our results show that bees are free of L. passim at the time of emergence. Furthermore, imidacloprid considerably increased the prevalence as well as parasite loads in individual bees. This means that imidacloprid facilitates infection, enabling faster parasite spread in a colony and potentially to surrounding colonies. The proteomic analysis of bee heads showed that imidacloprid neutralized the increased transferrin 1 expression by L. passim. Importantly, this promising marker has been previously observed to be upregulated by infections, including gut parasites. This study contributes to understanding the side effects of imidacloprid and demonstrates that a single xenobiotic/pesticide compound can interact with the gut parasite. Our methodology can be used to assess the effects of different compounds on L. passim.

Testing the Effectiveness of a Commercially Sold Probiotic on Restoring the Gut Microbiota of Honey Bees: a Field Study

Antibiotic use in apiculture is often necessary to ensure the survival of honey bee colonies. However, beekeepers are faced with the dilemma of needing to combat bacterial brood infections while also knowing that antibiotics kill beneficial bacteria important for bee health. In recent years, bee probiotics have become increasingly purchased by beekeepers because of product claims like being able to "replenish the microbes lost due to agricultural modifications of honey bees' environment" or "promote optimal gut health." Unfortunately, these products have little scientific evidence to support their efficacy, and previous lab experiments have refuted some of their claims. Here, we performed hive-level field experiments to test the effectiveness of SuperDFM-HoneyBee™ - the most commonly purchased honey bee probiotic in the United States - on restoring the honey bee gut microbiota after antibiotic treatment. We found slight but significant changes in the microbiota composition of bees following oxytetracycline (TerraPro) treatment and no difference between the microbiota of antibiotic treated bees with or without subsequent probiotic supplementation. Moreover, the microorganisms in the probiotic supplement were never found in the guts of the worker bee samples. These results highlight that more research is needed to test the efficacy and outcomes of currently available commercial honey bee probiotic supplements.

Sub-lethal but potentially devastating - The novel insecticide flupyradifurone impairs collective brood care in bumblebees

The worldwide decline in pollinating insects is alarming. One of the main anthropogenic drivers is the massive use of pesticides in agriculture. Risk assessment procedures test pesticides for mortality rates of well-fed, parasite free individuals of a few non-target species. Sublethal and synergistic effects of co-occurring stressors are usually not addressed. Here, we present a simple, wildly applicable bio-essay to assess such effects. Using brood thermoregulation in bumblebee microcolonies as readout, we investigate how this collective ability is affected by long-term feeding exposure to the herbicide glyphosate (5 mg/l), the insecticide flupyradifurone (0.4 mg/l) and the combination of both, when co-occurring with the natural stressor of resource limitation. Documenting brood temperature and development in 53 microcolonies we find no significant effect of glyphosate, while flupyradifurone significantly impaired the collective ability to maintain the necessary brood temperatures, resulting in prolonged developmental times and a decrease in colony growth by over 50 %. This reduction in colony growth has the potential to significantly curtail the reproductive chances of colonies in the field. Our findings highlight the potentially devastating consequences of flupyradifurone use in agriculture even at sub-lethal doses and underline the urgent need for improved risk assessment procedures.

Herbicide exposure alters the effect of the enthomopathogen Beauveria bassiana on immune gene expression in mealworm beetles

Concerns have grown worldwide about the potentially far-reaching effects of herbicides on functional biodiversity in agroecosystems. Repeated applications over time can lead to accumulation of residues in soil, water, and food and may have negative impacts on non-target organisms. However, the effects of herbicide residues on interspecific relationships, such as host-pathogen interactions, are poorly studied. In this study, we evaluated the effects of two different concentrations of a commercial pendimethalin-based formulation (PND), the residual contamination (S, 13 ppm) in treated soils and the maximum residue level allowed by the European Commission in cereals (EU, 0.05 ppm). We tested the effect of PND on the biological interaction between the mealworm beetle Tenebrio molitor Linnaeus, 1758 and the entomopathogenic fungus Beauveria bassiana Vuillemin, 1912 (Bb, strain KVL 03-144) at two concentrations (LC50 5 × 105 conidia mL-1 and LC100 1 × 107 conidia mL-1). We checked the survival of beetles exposed to PND or/and inoculated with B. bassiana, the expression of four antimicrobial peptides (AMPs), and finally how PND affects in vitro germination of fungus. The exposure to PND had no significant effects on the survival of either control or Bb-exposed beetles. In the mealworm beetle, upregulation of gene expression of the inducible AMPs Tenecin 1, 2, and 4 was observed in PND-treated beetles after inoculation with Bb, while the levels of the non-inducible AMP Tenecin 3 were similar between treatments. In conclusion, our findings demonstrate that admitted residual doses of currently used herbicides modify an important component of the inducible immune response of an insect. This did not translate into an effect on the survival to B. bassiana in our system. However, residual doses of the herbicide at 13 ppm may temporarily affect fungal germination. These results raise questions about the compatibility of bioinsecticides with synthetic pesticides and the effects of herbicide residues on host-pathogen interactions.

Glyphosate decreases survival, increases fecundity, and alters the microbiome of the natural predator Harmonia axyridis (ladybird beetle)

Glyphosate is a widely-used herbicide that shows toxicity to non-target organisms. The predatory natural enemy Harmonia axyridis may ingest glyphosate present in pollen and aphid prey. The present study characterized the responses of adult H. axyridis to environmentally relevant concentrations of glyphosate (5, 10, and 20 mg/L) for one or five days. There were no obvious effects on adult H. axyridis survival rates or fecundity in response to 5 or 10 mg/L glyphosate. However, exposure to 20 mg/L glyphosate significantly reduced the survival rate and increased fecundity. Analysis of the adult H. axyridis microbiota with 16S rRNA sequencing demonstrated changes in the relative and/or total abundance of specific taxa, including Serratia, Enterobacter, Staphylococcus, and Hafnia-Obesumbacterium. These changes in symbiotic bacterial abundance may have led to changes in survival rates or fecundity of this beetle. This is the first report of herbicide-induced stimulation of fecundity in a non-target predatory natural enemy, reflecting potentially unexpected risks of glyphosate exposure in adult H. axyridis. Although glyphosate resistant crops have been widely planted, the results of this study indicate a need to strengthen glyphosate management to prevent over-use, which could cause glyphosate toxicity and threaten environmental and human health.

Rapeseed bee pollen alleviates chronic non-bacterial prostatitis via regulating gut microbiota

BACKGROUND

Rapeseed bee pollen has been recognized as a critical treatment for chronic non-bacterial prostatitis (CNP) and it also can modulate gut microbiota and improve gut health. This study aimed to explore the anti-prostatitis effects of rapeseed bee pollen with or without wall-disruption, and to investigate the connection between this treatment and gut microbiota.

RESULTS

The results reveal that rapeseed bee pollen can effectively alleviate chronic non-bacteria prostatitis by selectively regulating gut microbiota, with higher doses and wall-disrupted pollen showing greater efficacy. Treatment with a high dose of wall-disrupted rapeseed bee pollen (WDH, 1.26 g kg-1 body weight) reduced prostate wet weight and prostate index by approximately 32% and 36%, respectively, nearly the levels observed in the control group. Wall-disrupted rapeseed bee pollen treatment also reduced significantly (p < 0.05) the expression of proinflammatory cytokines (IL-6, IL-8, IL-1β, and TNF-α), as confirmed by immunofluorescence with laser scanning confocal microscope. Our results show that rapeseed bee pollen can inhibit pathogenic bacteria and enhance probiotics, particularly in the Firmicutes-to-Bacteroidetes (F/B) ratio and the abundance of Prevotella (genus).

CONCLUSION

This is the first study to investigate the alleviation of CNP with rapeseed bee pollen through gut microbiota. These results seem to provide better understanding for the development of rapeseed bee pollen as a complementary medicine. © 2023 Society of Chemical Industry.

Dual roles of nanocrystalline cellulose extracted from jute (Corchorus olitorius L.) leaves in resisting antibiotics and protecting probiotics

Antibiotics can cure diseases caused by bacterial infections, but their widespread use can have some side effects, such as probiotic reduction. There is an urgent need for such agents that can not only alleviate the damage caused by antibiotics, but also maintain the balance of the gut microbiota. In this study, we first characterized the nanocrystalline cellulose (NCC) extracted from plant jute (Corchorus olitorius L.) leaves. Next, we evaluated the protective effect of jute NCC and cellulose on human model gut bacteria (Lacticaseibacillus rhamnosus and Escherichia coli) under antibiotic stress by measuring bacterial growth and colony forming units. We found that NCC is more effective than cellulose in adsorbing antibiotics and defending the gut bacteria E. coli. Interestingly, the low-dose jute NCC clearly maintained the balance of key gut bacteria like Snodgrassella alvi and Lactobacillus Firm-4 in bees treated with tetracycline and reduced the toxicity caused by antibiotics. It also showed a more significant protective effect on human gut bacteria, especially L. rhamnosus, than cellulose. This study first demonstrated that low-dose NCC performed satisfactorily as a specific probiotic to mitigate the adverse effects of antibiotics on gut bacteria.

Jute (Corchorus olitorius L.) Nanocrystalline Cellulose Inhibits Insect Virus via Gut Microbiota and Metabolism

Natural plant nanocrystalline cellulose (NCC), exhibiting a number of exceptional performance characteristics, is widely used in food fields. However, little is known about the relationship between NCC and the antiviral effect in animals. Here, we tested the function of NCC in antiviral methods utilizing honey bees as the model organism employing Israeli acute paralysis virus (IAPV), a typical RNA virus of honey bees. In both the lab and the field, we fed the IAPV-infected bees various doses of jute NCC (JNCC) under carefully controlled conditions. We found that JNCC can reduce IAPV proliferation and improve gut health. The metagenome profiling suggested that IAPV infection significantly decreased the abundance of gut core bacteria, while JNCC therapy considerably increased the abundance of the gut core bacteria Snodgrassella alvi and Lactobacillus Firm-4. Subsequent metabolome analysis further revealed that JNCC promoted the biosynthesis of fatty acids and unsaturated fatty acids, accelerated the purine metabolism, and then increased the expression of antimicrobial peptides (AMPs) and the genes involved in the Wnt and apoptosis signaling pathways against IAPV infection. Our results highlighted that JNCC could be considered as a prospective candidate agent against a viral infection.

Glyphosate impairs aversive learning in bumblebees

Agrochemicals represent prominent anthropogenic stressors contributing to the ongoing global insect decline. While their impact is generally assessed in terms of mortality rates, non-lethal effects on fitness are equally important to insect conservation. Glyphosate, a commonly used herbicide, is toxic to many animal species, and thought to impact a range of physiological functions. In this study, we investigate the impact of long-term exposure to glyphosate on locomotion, phototaxis and learning abilities in bumblebees, using a fully automated high-throughput assay. We find that glyphosate exposure had a very slight and transient impact on locomotion, while leaving the phototactic drive unaffected. Glyphosate exposure also reduced attraction towards UV light when blue was given as an alternative and, most strikingly, impaired learning of aversive stimuli. Thus, glyphosate had specific actions on sensory and cognitive processes. These non-lethal perceptual and cognitive impairments likely represent a significant obstacle to foraging and predator avoidance for wild bumblebees exposed to glyphosate. Similar effects in other species could contribute to a widespread reduction in foraging efficiency across ecosystems, driven by the large-scale application of this herbicide. The high-throughput paradigm presented in this study can be adapted to investigate sublethal effects of other agrochemicals on bumblebees or other important pollinator species, opening up a critical new avenue for the study of anthropogenic stressors.

Investigating the effects of mesotrione/atrazine-based herbicide on honey bee foragers

A mixture of the herbicides mesotrione and atrazine (Calaris®) is a widely used herbicide in agriculture in several countries. However, the possible toxicological effects of this formulation on non-target organisms require investigation. In this study, the effects of acute oral exposure to Calaris® were evaluated in Apis mellifera foragers. The effect of seven different concentrations of Calaris® on survival and sucrose consumption was studied, while the recommended concentration for field use (FC) and its 10× dilution (0.1 FC) were used to assess overall locomotor activity, respiratory rate, flight, midgut morphology, oxidative and nitrosative stresses, and hemocyte counting. The exposure to FC or 0.1 FC decreased locomotor activity and induced damage to the midgut epithelium. Additionally, the two tested concentrations reduced superoxide dismutase activity, nitric oxide levels, and total hemocyte count. FC also increased malondialdehyde content and 0.1 FC increased respiratory rate and decreased the proportion of prohemocytes. Overall, our findings evidenced significant harmful effects on A. mellifera foragers resulting from the ingestion of the Calaris® herbicide.

Microbial-enrichment method enables high-throughput metagenomic characterization from host-rich samples

Host-microbe interactions have been linked to health and disease states through the use of microbial taxonomic profiling, mostly via 16S ribosomal RNA gene sequencing. However, many mechanistic insights remain elusive, in part because studying the genomes of microbes associated with mammalian tissue is difficult due to the high ratio of host to microbial DNA in such samples. Here we describe a microbial-enrichment method (MEM), which we demonstrate on a wide range of sample types, including saliva, stool, intestinal scrapings, and intestinal mucosal biopsies. MEM enabled high-throughput characterization of microbial metagenomes from human intestinal biopsies by reducing host DNA more than 1,000-fold with minimal microbial community changes (roughly 90% of taxa had no significant differences between MEM-treated and untreated control groups). Shotgun sequencing of MEM-treated human intestinal biopsies enabled characterization of both high- and low-abundance microbial taxa, pathways and genes longitudinally along the gastrointestinal tract. We report the construction of metagenome-assembled genomes directly from human intestinal biopsies for bacteria and archaea at relative abundances as low as 1%. Analysis of metagenome-assembled genomes reveals distinct subpopulation structures between the small and large intestine for some taxa. MEM opens a path for the microbiome field to acquire deeper insights into host-microbe interactions by enabling in-depth characterization of host-tissue-associated microbial communities.

The honeybee gut resistome and its role in antibiotic resistance dissemination

There is now general concern about widespread antibiotic resistance, and growing evidence indicates that gut microbiota is critical in providing antibiotic resistance. Honeybee is an important pollinator; the incidence of antibiotic resistance genes in honeybee gut causes potential risks to not only its own health but also to public and animal health, for its potential disseminator role, thus receiving more attention from the public. Recent analysis results reveal that the gut of honeybee serves as a reservoir of antibiotic resistance genes, probably due to antibiotics application history in beekeeping and horizontal gene transfer from the highly polluted environment. These antibiotic resistance genes accumulate in the honeybee gut and could be transferred to the pathogen, even having the potential to spread during pollination, tending, social interactions, etc. Newly acquired resistance traits may cause fitness reduction in bacteria whereas facilitating adaptive evolution as well. This review outlines the current knowledge about the resistome in honeybee gut and emphasizes its role in antibiotic resistance dissemination.