Effects of Vairimorpha (Nosema) ceranae and Lotmaria passim on antimicrobial peptide expression in the digestive tract of honey bees (Apis mellifera L.).

The global decline of honeybee colonies represents a major ecological concern, primarily attributed to simultaneous exposure to multiple stressors. These include biotic pressures, such as parasitic infections, and abiotic pressures, such as exposure to ionizing radiation, which remains poorly understood. Assessing their combined effects provides novel insights into how biological and radiological stressors interact within the organism. Here, we investigated the individual and combined effects of Vairimorpha ceranae (formerly Nosema ceranae) infection and chronic gamma irradiation (14 µGy/h or 14 × 10³ µGy/h) on honeybee health. Measurements included survival, syrup consumption, spore load, and biomarkers related to energy metabolism, antioxidant defenses, immunity, detoxification, and neural enzyme activity. Two successive experiments, conducted at different collection periods, allowed us to account for biological variability between bee cohorts. Infection by V. ceranae caused high mortality and major impairments in metabolic, antioxidant, and immune functions. Ionizing radiation induced more moderate effects, characterized by redox imbalance and reduced detoxification capacity, which varied with dose rate. Under combined exposure, the two stressors produced mainly antagonistic interactions affecting antioxidant, immune, and detoxification systems. However, a synergistic effect was observed on ATP production, suggesting an energetic compensation mechanism. These findings highlight complex physiological disturbances, revealing the multifactorial vulnerability of honeybees and emphasizing the need to integrate interactions between multiple stressors and natural biological variability into ecotoxicological assessments.

ace-miR-182-x modulates host immunity and microsporidian proliferation through targeting MMP14 and CRQ genes in Apis cerana cerana.

Honey bees play a crucial role in pollination and global food security, yet their populations are declining due to various environmental stressors, including pathogenic infections. Recently, molecular research in honey has been proposed as a powerful, non-invasive tool for detecting and monitoring honey bee pathogens and parasites. This study analysed 679 honey samples from all Italian regions to detect the presence of 8 pathogens (DWV, CBPV, ABPV, BQCV, KBV, Nosema ceranae, Crithidia mellificae, Lotmaria passim) using qPCR assays. Overall, 97.5% of the honey samples tested positive for at least one pathogen, with the most prevalent being DWV (81.7%), N. ceranae (56.1%), and CBPV (56.0%). None of the samples tested positive for KBV or C. mellificae. Statistical analyses revealed significant variations in pathogen prevalence and copy number depending on the honey type, geographic origin and correlations among different pathogens. Additionally, co-presence was common, with over 77% of honey samples containing multiple pathogens. These findings support honey analysis as an effective and valid method for pathogen surveillance in honey bee populations. By providing valuable insights into disease dynamics, this approach could enhance epidemiological monitoring and contribute to improved honey bee health management strategies.

Nosemosis, caused by Vairimorpha (Nosema) ceranae or V. (Nosema) apis, is the main fungal disease affecting the Western honey bee (Apis mellifera). We evaluated the use of histology in the diagnosis of disease, identified the histologic patterns, and compared the efficacy of different staining techniques. We sampled 10 hives, collecting ~80 bees per hive. Spore counts were performed on 60 bees per sample using a hemocytometer in accordance with the standard procedure. Slides of whole bees were produced from the remaining bees, stained with 15 different techniques, and observed under a light microscope at 400×. Infection in the ventriculus was graded using hematoxylin-phloxine-saffron stain; prevalence and severity of the infection were determined; and an intra-class coefficient (ICC) was calculated to correlate the histologic results with the standard counting method. Based on contrast, specificity, and sensitivity, we found hot Gram chromotrope and Ziehl-Neelsen stains offered the best approach for highlighting Vairimorpha spores. These stains were optimized to find the ideal staining times for Vairimorpha by testing different immersion durations in key steps to enhance spore contrast. There was a notable association between histologic observations and spore count, with an ICC of 0.74 (95% CI [0.36, 0.91]) and 0.82 (95% CI [0.54, 0.93]) for the percentage of infected bees and histologic grade, respectively. Lesions included distension of ventricular epithelial cells, intracellular microsporidia, reduced ciliation, and disintegration of the peritrophic membrane. No spores were detected in extra-ventricular organs.

Nosema ceranae, a widespread fungal pathogen affecting honey bees (Apis spp.), may pose health risks to commercial bumble bees through shared foraging behaviors, particularly via pollen from Apis mellifera. This study investigated the impact of N. ceranae infection on commercial Bombus eximius colonies in Taiwan. Bumble bees were inoculated with low, medium, and high spore concentrations (5 × 104, 105, and 106 spores/10 μl), and infection rates, spore distribution, retention time, and immune responses were assessed. Increasing spore concentration had little effect on adult infection (10.0%) or survival rates (90.0%). N. ceranae was detectable in the digestive tract, with distinct patterns in the midgut and hindgut, as well as in fecal samples from 3 to 72 h post-inoculation. Immune gene analysis revealed significant upregulation of cellular immunity-related genes, such as hemomucin (1.67-fold) and vitellogenin (3.11-fold). Infected colonies consumed more pollen and sugar water, likely due to immune-driven food intake and stress responses. The low infection rates in commercial colonies suggest potential resistance mechanisms, requiring further investigation.

Nosemosis is a disease caused by microsporidia, which are strictly intracellular pathogens, currently considered to be most closely related to fungi. These microscopic parasites infect a variety of hosts, significantly affecting honeybees (Apis mellifera). Nosemosis is one of the most serious diseases of bees and is caused primarily by two species: Nosema apis and Nosema ceranae. This infection adversely affects the digestive tract of the bees, causes a reduction in their vitality, and can lead to the death of entire colonies. The diagnosis of nosemosis has undergone extensive development. Traditionally, the identification of microsporidia was performed by examination of bee digestive tract (macerated) by light microscopy. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) are expensive methods that require skilled personnel and were used only when high resolution was necessary. Modern methods, such as polymerase chain reaction (PCR), allow detection of infection at species and genotype levels, thereby increasing the accuracy of diagnosis. Despite advances in molecular techniques, research into nosemosis still faces challenges. This review focuses on a comparison of different diagnostic techniques and their pitfalls that can be integrated into strategies to combat nosemosis and protect the health of honeybee colonies.

Nosema ceranae is a microsporidian parasite that infects the midgut epithelial cells of honey bees (Apis mellifera), causing digestive dysfunction, reduced lifespan, impaired foraging activity and flight performance, and ultimately leading to declines in colony population and productivity. The emergence of resistance to conventional treatments such as fumagillin highlights the need for sustainable and effective alternative control strategies. This study aimed to evaluate the effects of beta-glucan supplementation on food consumption, survival rate, spore load, and antioxidant status in N. ceranae-infected honey bees. A total of 1000 newly emerged, disease-free worker bees (0–3 days old) were randomly allocated into five experimental groups, each comprising four replicates with 50 bees. All bees were provided with a 50% (w/v) sucrose solution ad libitum. The experimental groups were designated as follows: Control (uninfected), N (Nosema-infected,105 spores/bee), BG0.5 (0.5% beta-glucan, uninfected), N + BG0.5 (Nosema-infected + 0.5% beta-glucan), and N + BG1 (Nosema-infected + 1% beta-glucan). Beta-glucan supplementation resulted in a marked reduction in spore load, with a statistically significant decrease observed on day 15 compared to the Nosema-infected group without supplementation (p < 0.001). A non-significant reduction in food consumption was also recorded in the N + BG groups. Malondialdehyde (MDA) levels decreased in a dose-dependent manner with increasing beta-glucan supplementation (p < 0.05). Furthermore, both beta-glucan concentrations (0.5 and 1%) significantly elevated glutathione (GSH) activity, glutathione peroxidase (GSH-Px), and catalase (CAT) levels (p < 0.05), with the 1% beta-glucan dose producing the greatest improvement in these antioxidant markers. In conclusion, beta-glucan supplementation effectively reduced N. ceranae spore load, improved survival and food consumption, alleviated oxidative stress as indicated by lower MDA levels, and enhanced antioxidant enzyme activities in infected honey bees. These results indicate that beta-glucan represents a promising dietary intervention to mitigate the adverse effects of Nosema infection.

Nosemosis, caused by microsporidians of the genus Vairimorpha, is one of the most significant diseases affecting the honey bee Apis mellifera L. (Apidae: Hymenoptera), with negative impacts on its health and productivity. This study aimed to assess the presence of Vairimorpha ceranae in apiaries from the state of Campeche, Mexico. Honey bee samples were collected from 79 colonies across 29 apiaries, and DNA was extracted for analysis. Detection of the microsporidian parasite was achieved through amplification of the 16S small subunit ribosomal RNA gene by PCR and PAGE, revealing a high prevalence of Vairimorpha ceranae. The results represent the first confirmed record of Vairimorpha ceranae in this region, with widespread infection detected among sampled colonies. This finding is crucial for identifying the frequency and geographic distribution of this parasite in Mexico and will support the development of targeted management and control strategies adapted to local conditions, ultimately contributing to the conservation and health of honey bee populations in Campeche.

BackgroundMicrosporidia are a group of single-celled fungi which infect various chordates including humans, where they mainly pose a risk to immunocompromised individuals. This study aimed to investigate the occurrence of microsporidia in groups of very low birth weight (VLBW) and extremely low birth weight (ELBW) infants, comparing the findings with a publicly available dataset of term infant samples.MethodsMetagenomic sequencing was conducted on stool samples from two cohorts of preterm infants: cohort 1, which included 10 samples collected at 2, 4, and 8 weeks, and cohort 2, which consisted of 12 samples taken at 6 weeks and 2 years. These results were compared with data from a previously published cohort of term infants (cohort 3), which had 19 samples (in duplicates) collected between 1 and 14 weeks. Microsporidia identified from the data were separated and principal component analysis (PCA) was utilized to compare the microbiome of term and preterm infants. Microsporidia species that were significantly different between the two groups were identified using ALDEx2.ResultsEarly-stage microsporidia distribution did not show significant differences between the cohorts. However, significant differences emerged as the preterm infants grew, particularly at the age of 2 years (cohort 2). The levels of Mitosporidium daphniae (p = 0.03) and Nematocida homosporus (p = 0.04) were significantly higher in preterm infants compared to those born at term. Additionally, Encephalitozoon romaleae and Nosema ceranae, revealed an increase in cohort 2 from 6 weeks to 2 years.ConclusionsThis manuscript reports, to the best of our knowledge, the first occurrence of microsporidia in the early stages of human life. Some microsporidia not only persist into childhood but also become more prevalent during this time. However, we wish to emphasize that the findings from this study should be interpreted with caution, considering the low sample size and comparing cohorts examined at different time points of infants' age. Future studies with larger sample sizes and more mechanistic approaches could help clarify their role in childhood development and long-term health.

The use of gut bacteria isolated from Thai honey bees (Apis spp.) to control Nosema ceranae infection in the giant honey bee, Apis dorsata.

Pathogen-pesticide-host interaction: Apoptosis modulation by Nosema ceranae increases honeybee susceptibility to the insecticide cyantraniliprole.

Nosema or Vairimorpha: Genomic/proteomic support to a complex socio-economic issue rooted in taxonomic change.

BACKGROUNDHoney bees face significant threats from pathogens like Nosema ceranae, a microsporidian parasite that contributes to global colony declines. Immune priming, exposure to pathogen antigens to stimulate protective responses, could mitigate infection risks. We tested whether priming honey bee larvae and adults with heat‐killed N. ceranae spores reduces susceptibility to subsequent live infections in laboratory and field conditions.RESULTSPriming consistently lowered infection levels and rates. The strongest effect occurred in laboratory‐reared larvae, with a 97% reduction in mean spore counts relative to unprimed controls. Newly emerged adults primed and maintained in field colonies showed a 56% decrease, larvae primed by nurse bees in colonies had a 52% reduction, and newly emerged adults primed in laboratory cages showed a 34% reduction. Primed adults in field colonies also exhibited increased survival following live pathogen exposure as compared to positive controls. However, immune priming alone sometimes reduced bee lifespan. Priming altered expression of Toll pathway immune genes associated with Nosema resistance, particularly defensin‐1.CONCLUSIONImmune priming significantly protects honey bees from N. ceranae infection, reducing pathogen loads and enhancing survival across diverse conditions. Despite potential longevity trade‐offs, these findings support immune priming as a viable strategy to improve honey bee health and to reduce microsporidian‐induced colony losses. © 2025 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Ground beetles of the genus Poecilus (Carabidae) play key ecological roles in pest control and soil health. However, their gut microbiome remains largely unexplored despite increasing interest in insect-associated microbiota and its environmental implications. This study used next-generation sequencing and qPCR to characterise the gut microbiome of Poecilus beetles collected from organic and conventional tomato fields. Core microbiota were identified through prevalence-abundance filtering, revealing dominant genera including Gilliamella, Weissella, Enterobacter, and Enterococcus, alongside several low-abundance but consistently present taxa. Notably, Carnobacterium was detected for the first time in an insect host, and Nosema ceranae was identified for the first time in Carabidae, expanding the known host range of this microsporidian pathogen. Functional predictions based on 16S rRNA data and comparative genomic analysis showed enrichment in pathways related to amino acid synthesis, protein degradation, and monosaccharide metabolism. Significant inter-individual variation in microbial diversity and predicted functionality was observed, with lowest diversity and metabolic potential in beetles from conventionally managed fields, potentially indicating dysbiosis and environmental stress. The detection of Nosema and Serratia pathogens in some individuals adds new insights into pathogen dynamics within carabid beetles. Our findings reveal that the gut microbiome of Poecilus may be shaped by environmental factors and agricultural practices, influencing host health and ecological performance. These insights support the use of Poecilus as a bioindicator for soil ecosystem health and highlight the potential of microbiome-based metrics in agroecological monitoring.

The European honey bee (Apis mellifera) significantly contributes to Australian agriculture, especially in honey production and the pollination of key crops. However, managed bee populations are declining due to pathogens, agrochemicals, poor forage, climate change, and habitat loss. Major threats include bacteria, fungi, mites, and pests. With the increasing demand for pollination and the movement of bee colonies, monitoring these threats is essential. It has been demonstrated that honey constitutes an easily accessible source of environmental DNA. Environmental DNA in honey comes from all organisms that either directly or indirectly aid in its production and those within the hive environments. In this study, we extracted eDNA from 135 honey samples and tested for the presence of DNA for seven key honey bee pathogens and pests-Paenibacillus larvae, Melissococcus plutonius (bacterial pathogens), Nosema apis, Nosema ceranae (microsporidian fungi), Ascosphaera apis (fungal pathogen), Aethina tumida, and Galleria mellonella (arthropod pests) by using end-point singleplex and multiplex PCR assays. N. ceranae emerged as the most prevalent pathogen, present in 57% of the samples. This was followed by the pests A. tumida (40%) and G. mellonella (37%), and the pathogens P. larvae (21%), N. apis (19%), and M. plutonius (18%). A. apis was detected in a smaller proportion of the samples, with a prevalence of 5%. Additionally, 19% of the samples tested negative for all pathogens and pests analysed. The data outlines essential information about the prevalence of significant arthropod, fungal, and bacterial pathogens and pests affecting honey bees in Australia, which is crucial for protecting the nation's beekeeping industry.

Nosema ceranae is a widespread microsporidian parasite that primarily affects adult honeybees (Apis mellifera) but has also been reported to infect honeybee larvae. It has been considered as a main cause of colony losses. This study evaluated the anti-microsporidian activity of atmospheric non-thermal plasma against N. ceranae, which could provide a new technology for controlling Nosema disease. Argon and helium plasma substantially decreased N. ceranae spores, with the maximal reductions of 96.55% and 96.05%, respectively. Also, plasma activated water (PAW) generated by argon gas affected spores by a 50.51-77.14% of reduction, with H2O2 concentrations ranging from 50 to 200mg/L, depending on the plasma exposure time. Therefore, the effect of H2O2 on the inactivation of N. ceranae spores was evaluated. The results showed that H2O2 concentration up to 100mg/L reduced spore numbers by approximately 42.64-49.75%. H2O2 levels remained stable for up to 6 days, followed by a reduction of 50-80% in argon-generated PAW and 33.33-80% in helium-generated PAW by day 14. Moreover, this study demonstrated that both direct plasma and PAW treatments resulted in a significant reduction in the number of N. ceranae spores infecting adult bees, especially on day 14 after inoculation (71.88-87.42% of reduction). To elucidate the anti-N. ceranae activity of gas plasma and PAW, we performed an integrity of cell membrane and scanning electron microscopy analysis. The results of the cell membrane tests and microscopy reveal much about how these two methods could work, both plasma discharge and PAW. However, the development of plasma devices and PAW, as well as their safety for honeybees should be further investigated for effective control of N. ceranae and other pathogens in honeybees.

This article presents the results of a monitoring study on the spread of nosematosis among honey bees in Ukraine from 2022 to 2024. This parasitic disease, caused by Nosema apis and Nosema ceranae, significantly disrupts bee physiology, reduces immunity and lifespan, weakens colonies, and leads to substantial losses in beekeeping. The article analyzes veterinary reports and laboratory data, allowing researchers to trace the dynamics of infection and identify regional patterns. The highest infection rates were observed in Kherson, Khmelnytskyi, and Volyn regions. It was found that Nosema ceranae is gradually displacing Nosema apis in bee populations, complicating disease control strategies. The study emphasizes the need to improve diagnostic systems, ensure regular laboratory monitoring, develop effective preventive programs, and conduct educational outreach for beekeepers. The authors stress the importance of the «One Health» approach in protecting pollinators as a vital component of agroecosystems. Directions for future research are proposed, including adapting control measures to climate change, local environmental conditions, and the biological characteristics of the pathogens.

Propolis can reduce Nosema ceranae infection and enhance the immune response in honey bees, without disrupting the gut microbiota.

The article deals with methods of diagnostics of nosema disease in honey bees, as well as factors contributing to its spread. Diagnosis of the disease is based on epizootologic data, clinical signs, morphologic changes in the middle intestine and microscopic examination of pathmaterial. The lifetime diagnosis is carried out by coprological examination method, which allows to determine the degree of lesion according to a four-point system. The main factors of nosema spreading in apiaries are the use of infected equipment, wandering bees, improper expansion of families, unfavorable climatic conditions, as well as keeping southern breeds of bees less adapted to low temperatures. The disease is manifested by mass death of bees in winter and spring periods, reduction of their flight activity and productivity, as well as frequent change of mothers. Analysis of statistical data for 2019-2023 in West Kazakhstan region showed an increase in the defeat of bee families, especially by the pathogen Nosema ceranae, which has become dominant. In 2023, 36.7% of apiaries were unfavorable for nosemosis, and the greatest spread of the disease was noted in Zelenov and Syrym regions. The data obtained indicate the need for strict control and preventive measures to prevent further spread of nosema among bees.