Search Results (16)

Host-specific Lactobacillus and Bifidobacterium species constitute the core microbiota of the honey bee digestive tract and are recognized for their probiotic properties. One of the properties of these bacteria is the inhibition of bacterial pathogens such as Paenibacillus larvae and Melissococcus plutonius, the causative agents of American and European foulbrood, respectively. Additionally, Serratia marcescens has emerged as a relevant opportunistic pathogen. Although several previously published studies have examined the inhibition of selected bacterial pathogens of bees by members of the bee physiological microbiota, none have simultaneously investigated the inhibition of multiple clinical isolates of P. larvae, M. plutonius, and S. marcescens using a wide range of bifidobacterial and lactobacilli strains isolated from various locations within a single country. Thus, this study evaluated the antimicrobial potential of Lactobacillus and Bifidobacterium strains against these pathogens, with a focus on strain-dependent inhibition. A total of 111 bacterial strains (62 Lactobacillus and 49 Bifidobacterium) were isolated from the digestive tracts of honey bees collected from eight sites across the Czech Republic. Using 16S rRNA gene sequencing, the isolates were classified and tested in vitro against four P. larvae isolates, one M. plutonius isolate, and the S. marcescens strain sicaria in modified BHI medium. Twenty-eight strains (~26%) exhibited strong inhibition (≥21 mm) against at least two P. larvae isolates, while 12 strains showed moderate inhibition (16–20 mm) against all four isolates. Inhibition of M. plutonius and S. marcescens was observed in three and twenty strains, respectively. The most effective strains belonged to Bifidobacterium asteroides, B. choladohabitans, B. polysaccharolyticum, Lactobacillus apis, L. helsingborgensis, L. kullabergensis, and L. melliventris. These results underscore the strain-dependent nature of antimicrobial activity and highlight the importance of selecting probiotic strains with broad-spectrum pathogen inhibition to support honey bee health. Full article

Bee colonies are constantly threatened by a bacterial larvae disease called American foulbrood, caused by the Gram-positive bacterium Paenibacillus larvae. This is a highly specialized pathogen with only one established host, the honey bee larvae. The current state of legislation throughout the European Union prevents the inclusion of pharmacotherapy treatment, and the only control is based on the physical elimination of infected colonies upon veterinary orders. The purpose of this study was to investigate the antimicrobial activity of selected bacteria with proven probiotic potential with typical characteristics meeting the definition of a probiotic that could reduce the American foulbrood pressure by promoting the development of the larvae microbiome that competes with and blocks the excessive proliferation and production of P. larvae endospores. The antimicrobial activity of inoculants of the following selected strains was studied: Bacillus pumilus, Bacillus licheniformis, Streptomyces narbonensis, Lysinibacillus fusiformis, Levilactobacillus brevis, Bacillus megaterium against Paenibacillus larvae ATCC 9545 (formerly Paenibacillus larvae sub sp. larvae), and Paenibacillus larvae CCUG 48973. Analyses were performed by the well diffusion method according to EUCAST standards (clinical breakpoints and dosing of antibiotics) with modifications due to the specificity of the bacteria used. The largest zone of growth inhibition of P. larvae was confirmed with S. narbonensis, B. licheniformis, and B. megaterium, and medium activity was observed with L. brevis and B. pumilus. Negligible activity was shown by L. fusiformis. Differences were noticed in the resistance of indicator strains of P. larvae and between the media and carriers used. Full article

Background/Objectives: In a collaborative effort, FAO, the International Federation of Beekeepers’ Association “Apimondia”, the Appalachian State University, and the Istituto Zooprofilattico Sperimentale del Lazio e Toscana (IZSLT), the FAO Reference Centre for Animal Health and Food Security Discipline Apiculture, health, and biosecurity, designed an online international survey (“Knowledge, Awareness and Practice”-KAP) as a risk assessment tool to validate biosecurity measures able to prevent and control the main honeybee (Apis mellifera subsp.) infectious diseases. Methods: The KAP survey was disseminated through various channels for 14 months (January 2019–March 2020). Beekeepers’ knowledge on nosemosis, American foulbrood (AFB), and European foulbrood (EFB) management was assessed. Beekeepers’ attitudes were investigated by asking them to provide a score called “Acceptance by beekeepers”. Results: Of the 410 respondents, the majority of them (68.3%, n = 252) were from Europe. European beekeepers (n = 252) considered “Highly acceptable” the following practices: removing combs that show signs of dysentery and feeding colonies for nosemosis; the quick identification and management of affected hives for American foulbrood and European foulbrood. Instead, the following practices were considered as not acceptable by beekeepers: for nosemosis, the use of antibiotics and sampling of hive debris for early detection; for American foulbrood and European foulbrood, the shook swarm, the destruction of the whole apiary, as well as their treatment with antibiotics. Conclusion: This study demonstrated the validity of the present “Knowledge, Awareness and Practice” (KAP) survey to validate the best practices for the main infectious honeybee diseases, considering the pragmatic point of view of beekeepers. Sustainable practices for disease control are preferred by the European beekeepers. While having an adequate knowledge base for the early detection of the investigated honeybee diseases, European beekeepers tend to be aware of the health status of their hives, embracing advanced, practice-oriented training. Authors highlight that the selection of practices and their validation should be revised on a regular basis, to be adapted in a timely manner to the current infectious honeybee disease situation, in order to build up a resilient and effective stock of practices. Full article

We tested an integrated pest management (IPM) strategy to control European foulbrood (EFB) in honey bees. Colonies affected by EFB were assigned to two homogenous groups: an oxytetracycline-treated group (1.5 g OTC/hive) that underwent partial shook swarm (PSS) in combination with queen caging (QC) and an untreated group where only two beekeeping techniques, PSS and QC, were applied. The consumption of sucrose solution, the strength of the colonies, side effects of the mentioned techniques, clinical as well as subclinical relapses of EFB, and the amount of OTC residues in the honey were assessed over a 7-month-long monitoring period. Regarding the consumption of the sucrose solution, there was no significant difference between the OTC-treated and untreated groups. The strength of the untreated colonies was consistently but not significantly higher than those treated with OTC. PSS combined with QC resulted in various side effects in both groups: queen loss (52%), absconding (8%), and drone-laying queen (4%). Untreated colonies (16.7%) showed clinical EFB relapses 4 months after the application of PSS along with QC, while 15.4% of the OTC-treated colonies were confirmed EFB-positive by PCR. OTC residues were detected in the honey yielded in the cases of both groups. Two months after the PSS, the amount of OTC residues in the untreated group was 0.6 ± 0.2 µg/kg, while that in the OTC-treated group amounted to 5.8 ± 11.6 µg/kg; both results are below the maximum residue limit (MRL) of 100 ppb considered in the EU for cascade use. Full article

Honey bees coexist with fungi that colonize hive surfaces and pollen. Some of these fungi are opportunistic pathogens, but many are beneficial species that produce antimicrobial compounds for pollen conservation and the regulation of pathogen populations. In this study, we tested the in vitro antimicrobial activity of Talaromyces purpureogenus strains isolated from bee bread against Paenibacillus alvei (associated with European foulbrood disease) and three Aspergillus species that cause stonebrood disease. We found that methanol extracts of T. purpureogenus strains B18 and B195 inhibited the growth of P. alvei at a concentration of 0.39 mg/mL. Bioactivity-guided dereplication revealed that the activity of the crude extracts correlated with the presence of diketopiperazines, a siderophore, and three unknown compounds. We propose that non-pathogenic fungi such as Talaromyces spp. and their metabolites in bee bread could be an important requirement to prevent disease. Agricultural practices involving the use of fungicides can disrupt the fungal community and thus negatively affect the health of bee colonies. Full article

The declining honeybee populations are a significant risk to the productivity and security of agriculture worldwide. Although there are many causes of these declines, parasites are a significant one. Disease glitches in honeybees have been identified in recent years and increasing attention has been paid to addressing the issue. Between 30% and 40% of all managed honeybee colonies in the USA have perished annually over the past few years. American foulbrood (AFB) and European foulbrood (EFB) have been reported as bacterial diseases, Nosema as a protozoan disease, and Chalkbrood and Stonebrood as fungal diseases. The study aims to compare the bacterial community related to the Nosema ceranae and Ascosphaera apis infection on the gut of the honeybee and compare it with the weakly active honeybees. The Nosema-infected honeybees contain the phyla Proteobacteria as the significantly dominant bacterial phyla, similar to the weakly active honeybees. In contrast, the Ascosphaera (Chalkbrood) infected honeybee contains large amounts of Firmicutes rather than Proteobacteria. Full article

American foulbrood (AFB) and European foulbrood (EFB) are the two most important bacterial diseases that affect honey bee brood. The aim of this study was to evaluate the effects of an integrated treatment of AFB and EFB in naturally infected colonies in spring, using the beekeeping technique partial shook swarm combined with oxytetracycline treatment. The following parameters were assessed: strength of the colonies, consumption of antibiotic solution, queen losses, honey production and relapses. An increase in strength was observed in both (AFB and EFB) groups. Mean syrup consumption in the AFB colonies was 444.2 mL, while in the EFB colonies it was 497.3 mL. Linear correlation between the strength of the colonies and consumption (p-values < 0.0001; R² = 0.448) was observed. Three queens out of thirty (10%) were lost during the shook swarm procedure: one in the AFB group (5.3%) and two in the EFB group (18.2%). The results highlighted four clinical relapses (22.2%) of AFB, and no relapse (0%) of EFB after two years of observation. Six colonies (four in the AFB group and two in the EFB group) produced honey in the same beekeeping season that the shook swarm and antibiotic treatment were performed. Partial shook swarm is a good alternative to colony destruction, especially for EFB, and provides productive colonies during the foraging season. Full article

Beekeeping has yet to reach its full potential in terms of productivity in Turkey where it has a relatively large role in the economy. Poor colony health is suspected to be the reason for this, but comprehensive disease monitoring programs are lacking to support this notion. We sampled a total of 115 colonies across five different apiaries throughout the Marmara region of Turkey and screened for all of the major bee pathogens using PCR and RNA-seq methods. We found that Varroa mites are more prevalent in comparison to Nosema infections. The pathogens ABPV, DWV, KV, and VDV1 are near 100% prevalent and are the most abundant across all locations, which are known to be vectored by the Varroa mite. We therefore suspect that controlling Varroa mites will be key for improving bee health in Turkey moving forward. We also documented significant interactions between DWV, KV, and VDV1, which may explain how the more virulent strain of the virus becomes abundant. ABPV had a positive interaction with VDV1, thereby possibly facilitating this more virulent viral strain, but a negative interaction with Nosema ceranae. Therefore, these complex pathogen interactions should be taken into consideration in the future to improve bee health. Full article

The balance of the gut microbiome is important for the honey bee’s growth and development, immune function and defense against pathogens. The use of a beneficial bacteria-based strategy for the prevention and biocontrol of American foulbrood (AFB) and European foulbrood (EFB) diseases in honey bees offers interesting prospects. Lactic acid bacteria (LAB) are common inhabitants of the gastrointestinal tract of the honey bee. Among LABs associated with bee gut microbiota, Lactiplantibacillus plantarum (previously Lactobacillus plantarum) and Apilactobacillus kunkeei (formerly classified as Lactobacillus kunkeei) are two of the most abundant species. In this study, four Lactiplantibacillus plantarum strains and four Apilactobacillus kunkeei strains, isolated from the gastrointestinal tract of honey bee (Apis mellifera L.) were selected for their in vitro inhibition ability of Paenibacillus larvae ATCC 9545 and Melissococccus plutonius ATCC 35311. In addition, these LABs have been characterized through some biochemical and functional characteristics: cell surface properties (hydrophobicity and auto-aggregation), carbohydrates assimilation and enzymatic activities. The antimicrobial, biochemical and cell surface properties of these LABs have been functional to their candidature as potential probiotics in beekeeping and for the biocontrol of AFB and EFB diseases. Full article

Honey bees (Apis mellifera) are agriculturally important pollinators. Over the past decades, significant losses of wild and domestic bees have been reported in many parts of the world. Several biotic and abiotic factors, such as change in land use over time, intensive land management, use of pesticides, climate change, beekeeper’s management practices, lack of forage (nectar and pollen), and infection by parasites and pathogens, negatively affect the honey bee’s well-being and survival. The gut microbiota is important for honey bee growth and development, immune function, protection against pathogen invasion; moreover, a well-balanced microbiota is fundamental to support honey bee health and vigor. In fact, the structure of the bee’s intestinal bacterial community can become an indicator of the honey bee’s health status. Lactic acid bacteria are normal inhabitants of the gastrointestinal tract of many insects, and their presence in the honey bee intestinal tract has been consistently reported in the literature. In the first section of this review, recent scientific advances in the use of LABs as probiotic supplements in the diet of honey bees are summarized and discussed. The second section discusses some of the mechanisms by which LABs carry out their antimicrobial activity against pathogens. Afterward, individual paragraphs are dedicated to Chalkbrood, American foulbrood, European foulbrood, Nosemosis, and Varroosis as well as to the potentiality of LABs for their biological control. Full article

American and European Foulbrood (AFB and EFB) are considered the most contagious infectious diseases affecting honeybees worldwide. New sustainable strategies need to be implemented for their prevention and control, and probiotics may represent one solution to investigate. In our study, we evaluated the efficacy of one strain of Lactobacillus plantarum (L. plantarum) isolated from northern Italy, orally administered to the bees for AFB and EFB prevention. From March to September 2014, a total of 979 honeybee colonies (9.6% of Viterbo province—Central Italy) were taken under observation from 22 apiaries. Overall prevalence of AFB was 5.3% in treated colonies and 5.1% in the untreated ones. On the contrary, EFB prevalence was lower in the treated colonies (2.5%) compared to the untreated ones (4.5%). L. plantarum showed a significant effect in reducing insurgence of cases of EFB up to 35 days after the end of the treatment (p-value: 0.034). Thanks to this study we could investigate the preventive efficacy of L. plantarum in controlling AFB and EFB, and obtain official data on their clinical prevalence in Central Italy. Full article

The Istituto Zooprofilattico Sperimentale del Lazio e della Toscana (IZSLT) and the International Federation of Beekeepers’ Associations (Apimondia) set up a worldwide survey in 2015–2017 to gather information on beekeepers’ perceptions concerning good beekeeping practices, the main honey bee diseases, and the technical assistance they receive. The on-line dissemination of the survey was facilitated by the “Technologies and Practices for Small Agricultural Producers” platform (TECA) of the Food and Agriculture Organization of the United Nations (FAO). In total, 248 questionnaires were received from the European region and the results are reported here. Varroosis remains the biggest concern and is the most important reason for beekeepers’ use of veterinary medicines. However, a sustainable approach to managing Varroa was detected. American foulbrood (AFB) and European foulbrood (EFB) infections are mainly managed through the shook swarm technique or burning the hives. Concerning technical assistance for disease management, beekeepers were mainly supported by their associations or expert beekeepers. Relevant data were collected and analyzed but information from many low-income countries in Africa or Asia is still missing, and more efforts are needed to fill the knowledge gaps. Full article

European foulbrood (EFB) is an infectious disease of honey bees caused by the bacterium Melissococcus plutonius. A method for DNA isolation and conventional PCR diagnosis was developed using hive debris, which was non-invasively collected on paper sheets placed on the bottom boards of hives. Field trials utilized 23 honey bee colonies with clinically positive symptoms and 21 colonies without symptoms. Bayes statistics were applied to calculate the comparable parameters for EFB diagnostics when using honey, hive debris, or samples of adult bees. The reliability of the conventional PCR was 100% at 6.7 × 10³ Colony Forming Unit of M. plutonius in 1 g of debris. The sensitivity of the method for the sampled honey, hive debris, and adult bees was 0.867, 0.714, and 1.000, respectively. The specificity for the tested matrices was 0.842, 0.800, and 0.833. The predictive values for the positive tests from selected populations with 52% prevalence were 0.813, 0.833, and 0.842, and the real accuracies were 0.853, 0.750, and 0.912, for the honey, hive debris, and adult bees, respectively. It was concluded that hive debris can effectively be utilized to non-invasively monitor EFB in honey bee colonies. Full article

European honey bees (Apis mellifera Linnaeus) are beneficial insects that provide essential pollination services for agriculture and ecosystems worldwide. Modern commercial beekeeping is plagued by a variety of pathogenic and environmental stressors often confounding attempts to understand colony loss. European foulbrood (EFB) is considered a larval-specific disease whose causative agent, Melissococcus plutonius, has received limited attention due to methodological challenges in the field and laboratory. Here, we improve the experimental and informational context of larval disease with the end goal of developing an EFB management strategy. We sequenced the bacterial microbiota associated with larval disease transmission, isolated a variety of M.plutonius strains, determined their virulence against larvae in vitro, and explored the potential for probiotic treatment of EFB disease. The larval microbiota was a low diversity environment similar to honey, while worker mouthparts and stored pollen contained significantly greater bacterial diversity. Virulence of M. plutonius against larvae varied markedly by strain and inoculant concentration. Our chosen probiotic, Parasaccharibacter apium strain C6, did not improve larval survival when introduced alone, or in combination with a virulent EFB strain. We discuss the importance of positive and negative controls for in vitro studies of the larval microbiome and disease. Full article

Neonicotinoid and fungicide exposure has been linked to immunosuppression and increased susceptibility to disease in honeybees (Apis mellifera). European foulbrood, caused by the bacterium Melissococcus plutonius, is a disease of honeybee larvae which causes economic hardship for commercial beekeepers, in particular those whose colonies pollinate blueberries. We report for the first time in Canada, an atypical variant of M. plutonius isolated from a blueberry-pollinating colony. With this isolate, we used an in vitro larval infection system to study the effects of pesticide exposure on the development of European foulbrood disease. Pesticide doses tested were excessive (thiamethoxam and pyrimethanil) or maximal field-relevant (propiconazole and boscalid). We found that chronic exposure to the combination of thiamethoxam and propiconazole significantly decreased the survival of larvae infected with M. plutonius, while larvae chronically exposed to thiamethoxam and/or boscalid or pyrimethanil did not experience significant increases in mortality from M. plutonius infection in vitro. Based on these results, individual, calculated field-realistic residues of thiamethoxam and/or boscalid or pyrimethanil are unlikely to increase mortality from European foulbrood disease in honeybee worker brood, while the effects of field-relevant exposure to thiamethoxam and propiconazole on larval mortality from European foulbrood warrant further study. Full article