Nosema ceranae in South American Native Stingless Bees and Social Wasp

Environmental Sources of Possible Associated Pathogens and Contaminants of Stingless Bees in the Neotropics

Stingless bees are crucial for pollination and support diverse ecological relationships, offering economic benefits and contributing to enhanced crop yields. Their tropical pollinator status makes them highly sensitive to environmental changes and disruptions, which could affect their survival, as well as to pathogens that threaten their health. The lack of comprehensive research and the scattering of reports make it difficult to identify pathogens and contaminants. This review aims to provide an overview of diseases in stingless bees, examine chemical contaminants in their products, and explore threatened sources. Using the PRISMA flowchart, a total of 30 articles from 2009 to 2024 concerning pathogens and contaminants in stingless bees were retrieved. A total of 15 pathogens and 26 pollutants affect life expectancy and survival rate of stingless bees (mainly the genera Melipona and Tetragonisca) were identified in five major areas of the Neotropics, including Brazil, Mexico, Costa Rica, Australia, and Asia. Studies indicated that the bacterial genera Pseudomonas, Melissococcus, and Lysinibacillus are affecting the survival of stingless bees, particularly their brood, and contributing to annual colony deaths. Heavy metals, polycyclic aromatic hydrocarbons (PAHs), and microplastics have been detected in by-products of stingless bees, especially honey. Epidemiological research is crucial, including studies on pathogens associated with diseases, the effects of contaminants on bees, and the development of quality guidelines for stingless-bee products.

Development of Tools to Understand the Relationship between Good Management Practices and Nest Losses in Meliponiculture: A Pilot Study in Latin American Countries

Insect pollination services amount to USD 235-577 billion. Seventy five percent of agricultural production for human consumption depends on pollination, mainly by bees. A decline in pollinators, including Meliponini tribe bees, will impact the economy, food security, human health, and ecosystem stability, especially in tropical forests where stingless bees are the main pollinators. The objective of this survey was to understand the relationship between good management practices and nest losses in meliponiculture, encompassing biosecurity and conservation criteria. A 36-question survey was organized and spread. We received 92 responses, representing 4548 managed nests. The primary motivation for engaging in meliponiculture was biodiversity conservation (92%). More than 50% of the questions on biosecurity were answered as "applied". Hand washing before any activity with bees was the main rule, followed by material sterilization and personal protective equipment use. The annual mortality rate of stingless bee nests was estimated at 15%. Nest invaders (72%) and nearby sources of pollution (60%) were identified as the main potential causes of nest losses. From a general perspective, meliponiculture practices continue to expand remarkably. The implementation of effective nest management strategies is associated with a reduction in nest losses. It is important to consider One Health's perspective to ensure optimal management practices.

Ecological and social factors influence interspecific pathogens occurrence among bees

The interspecific transmission of pathogens can occur frequently in the environment. Among wild bees, the main spillover cases are caused by pathogens associated with Apis mellifera, whose colonies can act as reservoirs. Due to the limited availability of data in Italy, it is challenging to accurately assess the impact and implications of this phenomenon on the wild bee populations. In this study, a total of 3372 bees were sampled from 11 Italian regions within the BeeNet project, evaluating the prevalence and the abundance of the major honey bee pathogens (DWV, BQCV, ABPV, CBPV, KBV, Nosema ceranae, Ascosphaera apis, Crithidia mellificae, Lotmaria passim, Crithidia bombi). The 68.4% of samples were positive for at least one pathogen. DWV, BQCV, N. ceranae and CBPV showed the highest prevalence and abundance values, confirming them as the most prevalent pathogens spread in the environment. For these pathogens, Andrena, Bombus, Eucera and Seladonia showed the highest mean prevalence and abundance values. Generally, time trends showed a prevalence and abundance decrease from April to July. In order to predict the risk of infection among wild bees, statistical models were developed. A low influence of apiary density on pathogen occurrence was observed, while meteorological conditions and agricultural management showed a greater impact on pathogen persistence in the environment. Social and biological traits of wild bees also contributed to defining a higher risk of infection for bivoltine, communal, mining and oligolectic bees. Out of all the samples tested, 40.5% were co-infected with two or more pathogens. In some cases, individuals were simultaneously infected with up to five different pathogens. It is essential to increase knowledge about the transmission of pathogens among wild bees to understand dynamics, impact and effects on pollinator populations. Implementing concrete plans for the conservation of wild bee species is important to ensure the health of wild and human-managed bees within a One-Health perspective.

Bacterial Strains Isolated from Stingless Bee Workers Inhibit the Growth of Apis mellifera Pathogens

Apis mellifera bees are an important resource for the local economy of various regions in Argentina and the maintenance of natural ecosystems. In recent years, different alternatives have been investigated to avoid the reduction or loss of colonies caused by pathogens and parasites such as Ascosphaera apis, Aspergillus flavus, and Paenibacillus larvae. We focused on bacterial strains isolated from the intestine of native stingless bees, to elucidate their antagonistic effect on diseases of A. mellifera colonies. For this purpose, worker bees of the species Tetragonisca fiebrigi, Plebeia spp., and Scaptotrigona jujuyensis were captured from the entrance to tree hives and transported to the laboratory, where their intestines were extracted. Twenty bacterial colonies were isolated from the intestines, and those capable of inhibiting enterobacteria in vitro and producing organic acids, proteases, and chitinases were selected. Four genera, Levilactobacillus, Acetobacter, Lactiplantibacillus, and Pantoea, were selected and identified by the molecular marker that codes for the 16S rRNA gene. For inhibition assays, cell suspensions and cell-free suspensions were performed. All treatments showed significant antibacterial effects, in comparison with the controls, against P. larvae and antifungal effects against A. apis and A. flavus. However, the mechanisms by which these bacteria inhibit the growth of these pathogens were not studied.

Honeybee visitation to shared flowers increases Vairimorpha ceranae prevalence in bumblebees

Vairimorpha (=Nosema) ceranae is a widespread pollinator parasite that commonly infects honeybees and wild pollinators, including bumblebees. Honeybees are highly competent V. ceranae hosts and previous work in experimental flight cages suggests V. ceranae can be transmitted during visitation to shared flowers. However, the relationship between floral visitation in the natural environment and the prevalence of V. ceranae among multiple bee species has not been explored. Here, we analyzed the number and duration of pollinator visits to particular components of squash flowers-including the petals, stamen, and nectary-at six farms in southeastern Michigan, USA. We also determined the prevalence of V. ceranae in honeybees and bumblebees at each site. Our results showed that more honeybee flower contacts and longer duration of contacts with pollen and nectar were linked with greater V. ceranae prevalence in bumblebees. Honeybee visitation patterns appear to have a disproportionately large impact on V. ceranae prevalence in bumblebees even though honeybees are not the most frequent flower visitors. Floral visitation by squash bees or other pollinators was not linked with V. ceranae prevalence in bumblebees. Further, V. ceranae prevalence in honeybees was unaffected by floral visitation behaviors by any pollinator species. These results suggest that honeybee visitation behaviors on shared floral resources may be an important contributor to increased V. ceranae spillover to bumblebees in the field. Understanding how V. ceranae prevalence is influenced by pollinator behavior in the shared floral landscape is critical for reducing parasite spillover into declining wild bee populations.

Fungal microbiota isolated from native stingless bee species inhibited pathogens of Apis mellifera

Social bees can establish interactions with microorganisms to keep their colonies free of pathogens and parasites by developing different protection strategies. We explored the fungal microbiota isolated from three species of stingless bees, Tetragonisca fiebrigi, Plebeias sp., and Scaptotrigona jujuyensis, and its potential ability to suppress pathogenic microorganisms of A. mellifera, namely Paenibacillus larvae, Ascosphaera apis and Aspergillus flavus, which were tested and evaluated. Six filamentous fungal strains, Trametes hirsuta, Alternaria alternata, Curvularia spicifera, Skeletocutis sp., Alternaria tenuissima, Monascus spp., as well as the yeast Wickerhamomyces anomalus, were selected for trials and isolated from the heads of foraging bees. The fungal strains were identified by macroscopic and microscopic taxonomic characteristics and by sequencing of the ITS1-5.8S-ITS2 region of ribosomal DNA. All fungal strains inhibited these pathogens of A. mellifera. We also evaluated the effect of the secondary metabolites extracted with and without ethanol. Both metabolites showed antimicrobial properties, and our results suggest that fungi isolated from stingless bees produce bioactive compounds with antibacterial and antifungal effects that could be used to treat Apis mellifera colony diseases and maintain colony health.

Emerging Risk of Cross-Species Transmission of Honey Bee Viruses in the Presence of Invasive Vespid Species

The increase in invasive alien species is a concern for the environment. The establishment of some of these species may be changing the balance between pathogenicity and host factors, which could alter the defense strategies of native host species. Vespid species are among the most successful invasive animals, such as the genera Vespa, Vespula and Polistes. Bee viruses have been extensively studied as an important cause of honey bee population losses. However, knowledge about the transmission of honey bee viruses in Vespids is a relevant and under-researched aspect. The role of some mites such as Varroa in the transmission of honey bee viruses is clearer than in the case of Vespidae. This type of transmission by vectors has not yet been clarified in Vespidae, with interspecific relationships being the main hypotheses accepted for the transmission of bee viruses. A majority of studies describe the presence of viruses or their replicability, but aspects such as the symptomatology in Vespids or the ability to infect other hosts from Vespids are scarcely discussed. Highlighting the case of Vespa velutina as an invader, which is causing huge losses in European beekeeping, is of special interest. The pressure caused by V. velutina leads to weakened hives that become susceptible to pathogens. Gathering this information is necessary to promote further research on the spread of bee viruses in ecosystems invaded by invasive species of Vespids, as well as to prevent the decline of bee populations due to bee viruses.

The gut parasite Nosema ceranae impairs olfactory learning in bumblebees

Pollinators are exposed to numerous parasites and pathogens when foraging on flowers. These biological stressors may affect critical cognitive abilities required for foraging. Here, we tested whether exposure to Nosema ceranae, one of the most widespread parasites of honey bees also found in wild pollinators, impacts cognition in bumblebees. We investigated different forms of olfactory learning and memory using conditioning of the proboscis extension reflex. Seven days after being exposed to parasite spores, bumblebees showed lower performance in absolute, differential and reversal learning than controls. The consistent observations across different types of olfactory learning indicate a general negative effect of N. ceranae exposure that did not specifically target particular brain areas or neural processes. We discuss the potential mechanisms by which N. ceranae impairs bumblebee cognition and the broader consequences for populations of pollinators.

Polymorphism of 16s rRNA Gene: Any Effect on the Biomolecular Quantitation of the Honey Bee (Apis mellifera L., 1758) Pathogen Nosema ceranae?

The microsporidian Nosema ceranae is a severe threat to the western honey bee Apis mellifera, as it is responsible for nosemosis type C, which leads the colonies to dwindle and collapse. Infection quantification is essential to clinical and research aims. Assessment is made often with molecular assays based on rRNA genes, which are present in the N. ceranae genome as multiple and polymorphic copies. This study aims to compare two different methods of Real-Time PCR (qPCR), respectively relying on the 16S rRNA and Hsp70 genes, the first of which is described as a multiple and polymorphic gene. Young worker bees, hatched in the laboratory and artificially inoculated with N. ceranae spores, were incubated at 33 °C and subject to different treatment regimens. Samples were taken post-infection and analyzed with both qPCR methods. Compared to Hsp70, the 16S rRNA method systematically detected higher abundance. Straightforward conversion between the two methods is made impossible by erratic 16s rRNA/Hsp70 ratios. The 16s rRNA polymorphism showed an increase around the inoculated dose, where a higher prevalence of ungerminated spores was expected due to the treatment effects. The possible genetic background of that irregular distribution is discussed in detail. The polymorphic nature of 16S rRNA showed to be a limit in the infection quantification. More reliably, the N. ceranae abundance can be assessed in honey bee samples with methods based on the single-copy gene Hsp70.

Pathogens Spillover from Honey Bees to Other Arthropods

Honey bees, and pollinators in general, play a major role in the health of ecosystems. There is a consensus about the steady decrease in pollinator populations, which raises global ecological concern. Several drivers are implicated in this threat. Among them, honey bee pathogens are transmitted to other arthropods populations, including wild and managed pollinators. The western honey bee, Apis mellifera, is quasi-globally spread. This successful species acted as and, in some cases, became a maintenance host for pathogens. This systematic review collects and summarizes spillover cases having in common Apis mellifera as the mainteinance host and some of its pathogens. The reports are grouped by final host species and condition, year, and geographic area of detection and the co-occurrence in the same host. A total of eighty-one articles in the time frame 1960-2021 were included. The reported spillover cases cover a wide range of hymenopteran host species, generally living in close contact with or sharing the same environmental resources as the honey bees. They also involve non-hymenopteran arthropods, like spiders and roaches, which are either likely or unlikely to live in close proximity to honey bees. Specific studies should consider host-dependent pathogen modifications and effects on involved host species. Both the plasticity of bee pathogens and the ecological consequences of spillover suggest a holistic approach to bee health and the implementation of a One Health approach.

Immunity and physiological changes in adult honey bees (Apis mellifera) infected with Nosema ceranae: The natural colony environment

Nosema ceranae is a microsporidium that infects Apis mellifera, causing diverse physiological and behavioral alterations. Given the existence of individual and social mechanisms to reduce infection and fungal spread in the colony, bees may respond differently to infection depending on their rearing conditions. In this study, we investigated the effect of N. ceranae in honey bee foragers naturally infected with different fungal loads in a tropical region. In addition, we explored the effects of N. ceranae artificially infected young bees placed in a healthy colony under field conditions. Honey bees naturally infected with higher loads of N. ceranae showed downregulation of genes from Toll and IMD immune pathways and antimicrobial peptide (AMP) genes, but hemolymph total protein amount and Vitellogenin (Vg) titers were not affected. Artificially infected bees spread N. ceranae to the controls in the colony, but fungal loads were generally lower than those observed in cages, probably because of social immunity. Although no significant changes in mRNA levels of AMP-encoding were observed, N. ceranae artificially infected bees showed downregulation of miR-989 (an immune-related microRNA), lower vitellogenin gene expression, and decreased hemolymph Vg titers. Our results demonstrate for the first time that natural infection by N. ceranae suppresses the immune system of honey bee foragers in the field. This parasite is detrimental to the immune system of young and old bees, and disease spread, mitigation and containment will depend on the colony environment.

Parasites and RNA viruses in wild and laboratory reared bumble bees Bombus pauloensis (Hymenoptera: Apidae) from Uruguay

Bumble bees (Bombus spp.) are important pollinators insects involved in the maintenance of natural ecosystems and food production. Bombus pauloensis is a widely distributed species in South America, that recently began to be managed and commercialized in this region. The movement of colonies within or between countries may favor the dissemination of parasites and pathogens, putting into risk while populations of B. pauloensis and other native species. In this study, wild B. pauloensis queens and workers, and laboratory reared workers were screened for the presence of phoretic mites, internal parasites (microsporidia, protists, nematodes and parasitoids) and RNA viruses (Black queen cell virus (BQCV), Deformed wing virus (DWV), Acute paralysis virus (ABCV) and Sacbrood virus (SBV)). Bumble bee queens showed the highest number of mite species, and it was the only group where Conopidae and S. bombi were detected. In the case of microsporidia, a higher prevalence of N. ceranae was detected in field workers. Finally, the bumble bees presented the four RNA viruses studied for A. mellifera, in proportions similar to those previously reported in this species. Those results highlight the risks of spillover among the different species of pollinators.

The Herbal Supplements NOZEMAT HERB® and NOZEMAT HERB PLUS®: An Alternative Therapy for N. ceranae Infection and Its Effects on Honey Bee Strength and Production Traits

Honey bees (Apis mellifera L.) are the most effective pollinators for different crops and wild flowering plants, thus maintaining numerous ecosystems in the world. However, honey bee colonies often suffer from stress or even death due to various pests and diseases. Among the latter, nosemosis is considered to be one of the most common diseases, causing serious damage to beekeeping every year. Here, we present, for the first time, the effects from the application of the herbal supplements NOZEMAT HERB^® (NH) and NOZEMAT HERB PLUS^® (NHP) for treating N. ceranae infection and positively influencing the general development of honey bee colonies. To achieve this, in autumn 2019, 45 colonies were selected based on the presence of N. ceranae infections. The treatment was carried out for 11 months (August 2019–June 2020). All colonies were sampled pre- and post-treatment for the presence of N. ceranae by means of light microscopy and PCR analysis. The honey bee colonies’ performance and health were evaluated pre- and post-treatment. The obtained results have shown that both supplements have exhibited statistically significant biological activity against N. ceranae in infected apiaries. Considerable enhancement in the strength of honey bee colonies and the amount of sealed workers was observed just one month after the application of NH and NHP. Although the mechanisms of action of NH and NHP against N. ceranae infection are yet to be completely elucidated, our results suggest a new holistic approach as an alternative therapy to control nosemosis and to improve honey bee colonies’ performance and health.

Artificial Diets Modulate Infection Rates by Nosema ceranae in Bumblebees

Parasites alter the physiology and behaviour of their hosts. In domestic honey bees, the microsporidia Nosema ceranae induces energetic stress that impairs the behaviour of foragers, potentially leading to colony collapse. Whether this parasite similarly affects wild pollinators is little understood because of the low success rates of experimental infection protocols. Here, we present a new approach for infecting bumblebees (Bombus terrestris) with controlled amounts of N. ceranae by briefly exposing individual bumblebees to parasite spores before feeding them with artificial diets. We validated our protocol by testing the effect of two spore dosages and two diets varying in their protein to carbohydrate ratio on the prevalence of the parasite (proportion of PCR-positive bumblebees), the intensity of parasites (spore count in the gut and the faeces), and the survival of bumblebees. Overall, insects fed a low-protein, high-carbohydrate diet showed the highest parasite prevalence (up to 70%) but lived the longest, suggesting that immunity and survival are maximised at different protein to carbohydrate ratios. Spore dosage did not affect parasite infection rate and host survival. The identification of experimental conditions for successfully infecting bumblebees with N. ceranae in the lab will facilitate future investigations of the sub-lethal effects of this parasite on the behaviour and cognition of wild pollinators.

Use of Essential Oils in Veterinary Medicine to Combat Bacterial and Fungal Infections

Essential oils (EOs) are secondary metabolites of plants employed in folk medicine for a long time thanks to their multiple properties. In the last years, their use has been introduced in veterinary medicine, too. The study of the antibacterial properties of EOs is of increasing interest, because therapies with alternative drugs are welcome to combat infections caused by antibiotic-resistant strains. Other issues could be resolved by EOs employment, such as the presence of antibiotic residues in food of animal origin and in environment. Although the in vitro antimicrobial activity of EOs has been frequently demonstrated in studies carried out on bacterial and fungal strains of different origins, there is a lack of information about their effectiveness in treating infections in animals. The scientific literature reports some studies about in vitro EOs' activity against animal clinical bacterial and fungal isolates, but in vivo studies are very scanty. The use of EOs in therapy of companion and farm animals should follow careful studies on the toxicity of these natural products in relation to animal species and route of administration. Moreover, considering the different behavior of EOs in relation to both species and strain pathogen, before starting a therapy, an aromatogram should be executed to choose the oil with the best antimicrobial activity.

Nosema ceranae (Microspora: Nosematidae): A Sweet Surprise? Investigating the Viability and Infectivity of N. ceranae Spores Maintained in Honey and on Beeswax

Nosema disease is a prominent malady among adult honey bees [Apis mellifera L. (Hymenoptera: Apidae)], caused by the microsporidian parasites, Nosema apis Zander (Microspora: Nosematidae) and N. ceranae Fries et al. 1996. The biology of N. apis is well understood, as this parasite was first described over a century ago. As N. ceranae is an emerging parasite of the honey bee, we do not yet understand how long spores of this parasite survive in honey bee colonies, or all the potential modes of transmission among bees. We investigated the viability and infectivity of N. ceranae spores in honey and on beeswax over time after exposure to 33, 20, -12, and -20°C. Spores in honey maintained viability at freezing temperatures for up to 1 yr and remained viable considerably longer than those on beeswax. Based on this evidence, honey may act as an important reservoir for infective spores to initiate or perpetuate N. ceranae infections in honey bee colonies. This work provides information that may help enhance current management recommendations for apiculturalists.

Nosema ceranae causes cellular immunosuppression and interacts with thiamethoxam to increase mortality in the stingless bee Melipona colimana

The microsporidian parasite Nosema ceranae and neonicotinoid insecticides affect the health of honey bees (Apis mellifera). However, there is limited information about the effect of these stressors on other pollinators such as stingless bees (Hymenoptera: Meliponini). We examined the separate and combined effects of N. ceranae and the neonicotinoid thiamethoxam at field-exposure levels on the survivorship and cellular immunity (hemocyte concentration) of the stingless bee Melipona colimana. Newly-emerged bees were subjected to four treatments provided in sucrose syrup: N. ceranae spores, thiamethoxam, thiamethoxam and N. ceranae, and control (bees receiving only syrup). N. ceranae developed infections of > 467,000 spores/bee in the group treated with spores only. However, in the bees subjected to both stressors, infections were < 143,000 spores/bee, likely due to an inhibitory effect of thiamethoxam on the microsporidium. N. ceranae infections did not affect bee survivorship, but thiamethoxam plus N. ceranae significantly increased mortality. Hemocyte counts were significantly lower in N. ceranae infected-bees than in the other treatments. These results suggest that N. ceranae may infect, proliferate and cause cellular immunosuppression in stingless bees, that exposure to sublethal thiamethoxam concentrations is toxic to M. colimana when infected with N. ceranae, and that thiamethoxam restrains N. ceranae proliferation. These findings have implications on pollinators' conservation.

Effect of Api-Bioxal® and ApiHerb® Treatments against Nosema ceranae Infection in Apis mellifera Investigated by Two qPCR Methods

Nosema ceranae is a worldwide distributed midgut parasite of western honey bees, leading to dwindling colonies and their collapse. As a treatment, only fumagillin is available, causing issues like resistance and hampered bee physiology. This study aimed to evaluate ApiHerb^® and Api-Bioxal^® as treatments against N. ceranae. The efficacy was tested using two qPCR methods based on the 16S rRNA and Hsp70 genes. In addition, these methods were compared for their aptitude for the quantification of the infection. For this, 19 colonies were selected based on the presence of N. ceranae infections. The colonies were divided into three groups: treated with ApiHerb, Api-Bioxal with previous queen caging and an untreated control. All colonies were sampled pre- and post-treatment. The bees were analyzed individually and in duplicate with both qPCR methods. All bees in the pre-treatment tested positive for N. ceranae. Both treatments reduced the abundance of N. ceranae, but ApiHerb also decreased the prevalence of infected bees. Analysis with the 16S rRNA method resulted in several orders of magnitude more copies than analysis with the Hsp70 method. We conclude that both products are suitable candidates for N. ceranae treatment. From our analysis, the qPCR method based on the Hsp70 gene results as more apt for the exact quantification of N. ceranae as is needed for the development of veterinary medicinal products.

A peritrophin mediates the peritrophic matrix permeability in the workers of the bees Melipona quadrifasciata and Apis mellifera

The permeability of the peritrophic matrix, essential for its function, depends on its chemical composition. The objective was to determine if the permeability of the peritrophic matrix varies along the midgut and in the presence of anti-peritrophin-55 antibody in Melipona quadrifasciata and Apis mellifera bees. The thickness of the peritrophic matrix in both species varies between the anterior and posterior midgut regions in workers. In A. mellifera dextran molecules with 40 kDa cross the peritrophic matrix, whereas those ≥70 kDa are retained in the endoperitrophic space. In M. quadrifasciata the peritrophic matrix permeability was for molecules <40 kDa. Bees fed on anti-peritrophin-55 antibody showed an increase in peritrophic matrix permeability, but survival was not affected. In the bees studied, the peritrophic matrices have morphological differences between midgut regions, but there is no difference in their permeability along the midgut, which is affected by peritrophin 55.

Pathogen spillover from Apis mellifera to a stingless bee

Pathogen spillover from managed bees is increasingly considered as a possible cause of pollinator decline. Though spillover has been frequently documented, evidence of the pathogen's virulence in the new host or mechanism of transmission is rare. Stingless bees (Apocrita: Meliponini) are crucial pollinators pan-tropically and overlap with managed honeybees (Apis mellifera) in much of their range. Nosema ceranae is the most prevalent disease of adult A. mellifera. We used laboratory experiments and field surveys to investigate the susceptibility of stingless bees (Tetragonula hockingsi) to N. ceranae, infection prevalence and transmissibility via flowers. We found that 67% of T. hockingsi fed sucrose with N. ceranae had detectable spores in their ventriculus, and they died at 2.96 times the rate of sucrose-only fed bees. Five of six field hives harboured bees with N. ceranae present at least once during our five-month survey, with prevalence up to 20%. In our floral transmission experiment, 67% of inflorescences exposed to infected A. mellifera yielded N. ceranae spores, and all resulted in T. hockingsi with N. ceranae spores in their guts. We conclude that N. ceranae is virulent in T. hockingsi under laboratory conditions, is common in the local T. hockingsi population and is transmissible via flowers.

Quantitative real-time PCR with high-throughput automatable DNA preparation for molecular screening of Nosema spp. in Antheraea pernyi

Accurate diagnosis of pathogenic Nosema spp. in Antheraea pernyi samples is considered especially useful for reducing economic losses in sericulture and improving food safety by maintaining pathogen-free pupae. However, microscopy and immunologic methods have poor diagnostic sensitivity, while the more sensitive PCR methods remain costly and time-consuming for template preparation. To address this issue, we introduce a sensitive ALMS-qPCR method that combines fast, simple DNA extraction using Alkali Lysis followed by Magnetic bead Separation (ALMS) and quantitative real-time PCR (qPCR). This approach is especially fit for large-scale pathogen molecular screening, because the DNA preparation procedure is fast (<0.94 min per sample) and is high-throughput (performs on a 96-well plate). It is cost-effective, since the most expensive materials can be made in the lab and can be recycled, while the automated procedure can help to minimize labor cost. Though the DNA preparation procedure was substantially simplified, common PCR inhibitory factors were not observed. The sensitivity of ALMS-qPCR is high and the limit of detection is 0.045 parasites/μL. Large-scale screening of Nosema spp. in 3000 Antheraea pernyi samples confirmed the efficacy of the ALMS-qPCR method. Sensitivity is much higher than clinical microscopy, especially for host groups with low infection prevalence and levels. High-throughput ALMS-qPCR, combining automated DNA preparation and sensitive qPCR, provides an enhanced approach for pébrine screening and epidemiological studies. The application of ALMS-qPCR in the sericulture industry will help to strengthen pébrine control and breed pathogen-free species, which means much safer food provision and better genetic resource conservation.

A novel TaqMan® assay for Nosema ceranae quantification in honey bee, based on the protein coding gene Hsp70

Nosema ceranae is now a widespread honey bee pathogen with high incidence in apiculture. Rapid and reliable detection and quantification methods are a matter of concern for research community, nowadays mainly relying on the use of biomolecular techniques such as PCR, RT-PCR or HRMA. The aim of this technical paper is to provide a new qPCR assay, based on the highly-conserved protein coding gene Hsp70, to detect and quantify the microsporidian Nosema ceranae affecting the western honey bee Apis mellifera. The validation steps to assess efficiency, sensitivity, specificity and robustness of the assay are described also.